[v3,1/2] MIPS: convert syscall to generic entry

Commit Message

Feiyang Chen Oct. 14, 2021, 8:32 a.m. UTC

Convert MIPS syscall to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on MIPS:

- There is one type of syscall on MIPS32 (scall32-o32) and three types
of syscalls on MIPS64 (scall64-o32, scall64-n32 and scall64-n64). Now
convert to C code to handle different types of syscalls.

- For some special syscalls (e.g. fork, clone, clone3 and sysmips),
save_static_function() wrapper is used to save static registers. Now
SAVE_STATIC is used in handle_sys before calling do_syscall(), so the
save_static_function() wrapper can be removed.

- For sigreturn/rt_sigreturn and sysmips, inline assembly is used to
jump to syscall_exit directly for skipping setting the error flag and
restoring all registers. Now use regs->regs[27] to mark whether to
handle the error flag and restore all registers in handle_sys, so these
functions can return normally as other architecture.

Signed-off-by: Feiyang Chen <[e-mail]>
Signed-off-by: Yanteng Si <[e-mail]>
Reviewed-by: Huacai Chen <[e-mail]>
---
 arch/mips/Kconfig                         |   1 +
 arch/mips/include/asm/entry-common.h      |  13 ++
 arch/mips/include/asm/ptrace.h            |   8 +-
 arch/mips/include/asm/sim.h               |  70 -------
 arch/mips/include/asm/syscall.h           |   5 +
 arch/mips/include/asm/thread_info.h       |  17 +-
 arch/mips/include/uapi/asm/ptrace.h       |   7 +-
 arch/mips/kernel/Makefile                 |  14 +-
 arch/mips/kernel/entry.S                  |  75 ++------
 arch/mips/kernel/linux32.c                |   1 -
 arch/mips/kernel/ptrace.c                 |  78 --------
 arch/mips/kernel/scall.S                  | 137 +++++++++++++
 arch/mips/kernel/scall32-o32.S            | 223 ----------------------
 arch/mips/kernel/scall64-n32.S            | 107 -----------
 arch/mips/kernel/scall64-n64.S            | 116 -----------
 arch/mips/kernel/scall64-o32.S            | 221 ---------------------
 arch/mips/kernel/signal.c                 |  37 ++--
 arch/mips/kernel/signal_n32.c             |  16 +-
 arch/mips/kernel/signal_o32.c             |  31 +--
 arch/mips/kernel/syscall.c                | 148 +++++++++++---
 arch/mips/kernel/syscalls/syscall_n32.tbl |   8 +-
 arch/mips/kernel/syscalls/syscall_n64.tbl |   8 +-
 arch/mips/kernel/syscalls/syscall_o32.tbl |   8 +-
 23 files changed, 354 insertions(+), 995 deletions(-)
 create mode 100644 arch/mips/include/asm/entry-common.h
 delete mode 100644 arch/mips/include/asm/sim.h
 create mode 100644 arch/mips/kernel/scall.S
 delete mode 100644 arch/mips/kernel/scall32-o32.S
 delete mode 100644 arch/mips/kernel/scall64-n32.S
 delete mode 100644 arch/mips/kernel/scall64-n64.S
 delete mode 100644 arch/mips/kernel/scall64-o32.S

Comments

WANG Xuerui Oct. 14, 2021, 8:36 a.m. UTC | #1

Hi Feiyang,

On 2021/10/14 16:32, Feiyang Chen wrote:
> Convert MIPS syscall to use the generic entry infrastructure from
> kernel/entry/*.
>
> There are a few special things on MIPS:
>
> - There is one type of syscall on MIPS32 (scall32-o32) and three types
> of syscalls on MIPS64 (scall64-o32, scall64-n32 and scall64-n64). Now
> convert to C code to handle different types of syscalls.
>
> - For some special syscalls (e.g. fork, clone, clone3 and sysmips),
> save_static_function() wrapper is used to save static registers. Now
> SAVE_STATIC is used in handle_sys before calling do_syscall(), so the
> save_static_function() wrapper can be removed.
>
> - For sigreturn/rt_sigreturn and sysmips, inline assembly is used to
> jump to syscall_exit directly for skipping setting the error flag and
> restoring all registers. Now use regs->regs[27] to mark whether to
> handle the error flag and restore all registers in handle_sys, so these
> functions can return normally as other architecture.
>
> Signed-off-by: Feiyang Chen <[e-mail]>
> Signed-off-by: Yanteng Si <[e-mail]>
> Reviewed-by: Huacai Chen <[e-mail]>
> ---
>  arch/mips/Kconfig                         |   1 +
>  arch/mips/include/asm/entry-common.h      |  13 ++
>  arch/mips/include/asm/ptrace.h            |   8 +-
>  arch/mips/include/asm/sim.h               |  70 -------
>  arch/mips/include/asm/syscall.h           |   5 +
>  arch/mips/include/asm/thread_info.h       |  17 +-
>  arch/mips/include/uapi/asm/ptrace.h       |   7 +-
>  arch/mips/kernel/Makefile                 |  14 +-
>  arch/mips/kernel/entry.S                  |  75 ++------
>  arch/mips/kernel/linux32.c                |   1 -
>  arch/mips/kernel/ptrace.c                 |  78 --------
>  arch/mips/kernel/scall.S                  | 137 +++++++++++++
>  arch/mips/kernel/scall32-o32.S            | 223 ----------------------
>  arch/mips/kernel/scall64-n32.S            | 107 -----------
>  arch/mips/kernel/scall64-n64.S            | 116 -----------
>  arch/mips/kernel/scall64-o32.S            | 221 ---------------------
>  arch/mips/kernel/signal.c                 |  37 ++--
>  arch/mips/kernel/signal_n32.c             |  16 +-
>  arch/mips/kernel/signal_o32.c             |  31 +--
>  arch/mips/kernel/syscall.c                | 148 +++++++++++---
>  arch/mips/kernel/syscalls/syscall_n32.tbl |   8 +-
>  arch/mips/kernel/syscalls/syscall_n64.tbl |   8 +-
>  arch/mips/kernel/syscalls/syscall_o32.tbl |   8 +-
>  23 files changed, 354 insertions(+), 995 deletions(-)
>  create mode 100644 arch/mips/include/asm/entry-common.h
>  delete mode 100644 arch/mips/include/asm/sim.h
>  create mode 100644 arch/mips/kernel/scall.S
>  delete mode 100644 arch/mips/kernel/scall32-o32.S
>  delete mode 100644 arch/mips/kernel/scall64-n32.S
>  delete mode 100644 arch/mips/kernel/scall64-n64.S
>  delete mode 100644 arch/mips/kernel/scall64-o32.S
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 1291774a2fa5..debd125100ad 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -32,6 +32,7 @@ config MIPS
>  	select GENERIC_ATOMIC64 if !64BIT
>  	select GENERIC_CMOS_UPDATE
>  	select GENERIC_CPU_AUTOPROBE
> +	select GENERIC_ENTRY
>  	select GENERIC_GETTIMEOFDAY
>  	select GENERIC_IOMAP
>  	select GENERIC_IRQ_PROBE
> diff --git a/arch/mips/include/asm/entry-common.h b/arch/mips/include/asm/entry-common.h
> new file mode 100644
> index 000000000000..0fe2a098ded9
> --- /dev/null
> +++ b/arch/mips/include/asm/entry-common.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef ARCH_LOONGARCH_ENTRY_COMMON_H
> +#define ARCH_LOONGARCH_ENTRY_COMMON_H
Do you intend to say "MIPS"? ;-)
> +
> +#include <linux/sched.h>
> +#include <linux/processor.h>
> +
> +static inline bool on_thread_stack(void)
> +{
> +	return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));
> +}
> +
> +#endif

YunQiang Su Oct. 14, 2021, 8:38 a.m. UTC | #2

Feiyang Chen <[e-mail]> 于2021年10月14日周四 下午4:32写道：
>
> Convert MIPS syscall to use the generic entry infrastructure from
> kernel/entry/*.
>
> There are a few special things on MIPS:
>
> - There is one type of syscall on MIPS32 (scall32-o32) and three types
> of syscalls on MIPS64 (scall64-o32, scall64-n32 and scall64-n64). Now
> convert to C code to handle different types of syscalls.
>
> - For some special syscalls (e.g. fork, clone, clone3 and sysmips),
> save_static_function() wrapper is used to save static registers. Now
> SAVE_STATIC is used in handle_sys before calling do_syscall(), so the
> save_static_function() wrapper can be removed.
>
> - For sigreturn/rt_sigreturn and sysmips, inline assembly is used to
> jump to syscall_exit directly for skipping setting the error flag and
> restoring all registers. Now use regs->regs[27] to mark whether to
> handle the error flag and restore all registers in handle_sys, so these
> functions can return normally as other architecture.
>
> Signed-off-by: Feiyang Chen <[e-mail]>
> Signed-off-by: Yanteng Si <[e-mail]>
> Reviewed-by: Huacai Chen <[e-mail]>
> ---
>  arch/mips/Kconfig                         |   1 +
>  arch/mips/include/asm/entry-common.h      |  13 ++
>  arch/mips/include/asm/ptrace.h            |   8 +-
>  arch/mips/include/asm/sim.h               |  70 -------
>  arch/mips/include/asm/syscall.h           |   5 +
>  arch/mips/include/asm/thread_info.h       |  17 +-
>  arch/mips/include/uapi/asm/ptrace.h       |   7 +-
>  arch/mips/kernel/Makefile                 |  14 +-
>  arch/mips/kernel/entry.S                  |  75 ++------
>  arch/mips/kernel/linux32.c                |   1 -
>  arch/mips/kernel/ptrace.c                 |  78 --------
>  arch/mips/kernel/scall.S                  | 137 +++++++++++++
>  arch/mips/kernel/scall32-o32.S            | 223 ----------------------
>  arch/mips/kernel/scall64-n32.S            | 107 -----------
>  arch/mips/kernel/scall64-n64.S            | 116 -----------
>  arch/mips/kernel/scall64-o32.S            | 221 ---------------------
>  arch/mips/kernel/signal.c                 |  37 ++--
>  arch/mips/kernel/signal_n32.c             |  16 +-
>  arch/mips/kernel/signal_o32.c             |  31 +--
>  arch/mips/kernel/syscall.c                | 148 +++++++++++---
>  arch/mips/kernel/syscalls/syscall_n32.tbl |   8 +-
>  arch/mips/kernel/syscalls/syscall_n64.tbl |   8 +-
>  arch/mips/kernel/syscalls/syscall_o32.tbl |   8 +-
>  23 files changed, 354 insertions(+), 995 deletions(-)
>  create mode 100644 arch/mips/include/asm/entry-common.h
>  delete mode 100644 arch/mips/include/asm/sim.h
>  create mode 100644 arch/mips/kernel/scall.S
>  delete mode 100644 arch/mips/kernel/scall32-o32.S
>  delete mode 100644 arch/mips/kernel/scall64-n32.S
>  delete mode 100644 arch/mips/kernel/scall64-n64.S
>  delete mode 100644 arch/mips/kernel/scall64-o32.S
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 1291774a2fa5..debd125100ad 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -32,6 +32,7 @@ config MIPS
>         select GENERIC_ATOMIC64 if !64BIT
>         select GENERIC_CMOS_UPDATE
>         select GENERIC_CPU_AUTOPROBE
> +       select GENERIC_ENTRY
>         select GENERIC_GETTIMEOFDAY
>         select GENERIC_IOMAP
>         select GENERIC_IRQ_PROBE
> diff --git a/arch/mips/include/asm/entry-common.h b/arch/mips/include/asm/entry-common.h
> new file mode 100644
> index 000000000000..0fe2a098ded9
> --- /dev/null
> +++ b/arch/mips/include/asm/entry-common.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef ARCH_LOONGARCH_ENTRY_COMMON_H

a typo?

> +#define ARCH_LOONGARCH_ENTRY_COMMON_H
> +
> +#include <linux/sched.h>
> +#include <linux/processor.h>
> +
> +static inline bool on_thread_stack(void)
> +{
> +       return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));
> +}
> +
> +#endif
> diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
> index daf3cf244ea9..1b8f9d2ddc44 100644
> --- a/arch/mips/include/asm/ptrace.h
> +++ b/arch/mips/include/asm/ptrace.h
> @@ -51,6 +51,11 @@ struct pt_regs {
>         unsigned long __last[0];
>  } __aligned(8);
>
> +static inline int regs_irqs_disabled(struct pt_regs *regs)
> +{
> +       return arch_irqs_disabled_flags(regs->cp0_status);
> +}
> +
>  static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
>  {
>         return regs->regs[29];
> @@ -156,9 +161,6 @@ static inline long regs_return_value(struct pt_regs *regs)
>  #define instruction_pointer(regs) ((regs)->cp0_epc)
>  #define profile_pc(regs) instruction_pointer(regs)
>
> -extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall);
> -extern asmlinkage void syscall_trace_leave(struct pt_regs *regs);
> -
>  extern void die(const char *, struct pt_regs *) __noreturn;
>
>  static inline void die_if_kernel(const char *str, struct pt_regs *regs)
> diff --git a/arch/mips/include/asm/sim.h b/arch/mips/include/asm/sim.h
> deleted file mode 100644
> index 59f31a95facd..000000000000
> --- a/arch/mips/include/asm/sim.h
> +++ /dev/null
> @@ -1,70 +0,0 @@
> -/*
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - *
> - * Copyright (C) 1999, 2000, 2003 Ralf Baechle
> - * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> - */
> -#ifndef _ASM_SIM_H
> -#define _ASM_SIM_H
> -
> -
> -#include <asm/asm-offsets.h>
> -
> -#define __str2(x) #x
> -#define __str(x) __str2(x)
> -
> -#ifdef CONFIG_32BIT
> -
> -#define save_static_function(symbol)                                   \
> -__asm__(                                                               \
> -       ".text\n\t"                                                     \
> -       ".globl\t__" #symbol "\n\t"                                     \
> -       ".align\t2\n\t"                                                 \
> -       ".type\t__" #symbol ", @function\n\t"                           \
> -       ".ent\t__" #symbol ", 0\n__"                                    \
> -       #symbol":\n\t"                                                  \
> -       ".frame\t$29, 0, $31\n\t"                                       \
> -       "sw\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"  \
> -       "sw\t$17,"__str(PT_R17)"($29)\n\t"                              \
> -       "sw\t$18,"__str(PT_R18)"($29)\n\t"                              \
> -       "sw\t$19,"__str(PT_R19)"($29)\n\t"                              \
> -       "sw\t$20,"__str(PT_R20)"($29)\n\t"                              \
> -       "sw\t$21,"__str(PT_R21)"($29)\n\t"                              \
> -       "sw\t$22,"__str(PT_R22)"($29)\n\t"                              \
> -       "sw\t$23,"__str(PT_R23)"($29)\n\t"                              \
> -       "sw\t$30,"__str(PT_R30)"($29)\n\t"                              \
> -       "j\t" #symbol "\n\t"                                            \
> -       ".end\t__" #symbol "\n\t"                                       \
> -       ".size\t__" #symbol",. - __" #symbol)
> -
> -#endif /* CONFIG_32BIT */
> -
> -#ifdef CONFIG_64BIT
> -
> -#define save_static_function(symbol)                                   \
> -__asm__(                                                               \
> -       ".text\n\t"                                                     \
> -       ".globl\t__" #symbol "\n\t"                                     \
> -       ".align\t2\n\t"                                                 \
> -       ".type\t__" #symbol ", @function\n\t"                           \
> -       ".ent\t__" #symbol ", 0\n__"                                    \
> -       #symbol":\n\t"                                                  \
> -       ".frame\t$29, 0, $31\n\t"                                       \
> -       "sd\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"  \
> -       "sd\t$17,"__str(PT_R17)"($29)\n\t"                              \
> -       "sd\t$18,"__str(PT_R18)"($29)\n\t"                              \
> -       "sd\t$19,"__str(PT_R19)"($29)\n\t"                              \
> -       "sd\t$20,"__str(PT_R20)"($29)\n\t"                              \
> -       "sd\t$21,"__str(PT_R21)"($29)\n\t"                              \
> -       "sd\t$22,"__str(PT_R22)"($29)\n\t"                              \
> -       "sd\t$23,"__str(PT_R23)"($29)\n\t"                              \
> -       "sd\t$30,"__str(PT_R30)"($29)\n\t"                              \
> -       "j\t" #symbol "\n\t"                                            \
> -       ".end\t__" #symbol "\n\t"                                       \
> -       ".size\t__" #symbol",. - __" #symbol)
> -
> -#endif /* CONFIG_64BIT */
> -
> -#endif /* _ASM_SIM_H */
> diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
> index 25fa651c937d..02ca0d659428 100644
> --- a/arch/mips/include/asm/syscall.h
> +++ b/arch/mips/include/asm/syscall.h
> @@ -157,4 +157,9 @@ static inline int syscall_get_arch(struct task_struct *task)
>         return arch;
>  }
>
> +static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
> +{
> +       return false;
> +}
> +
>  #endif /* __ASM_MIPS_SYSCALL_H */
> diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
> index 0b17aaa9e012..5a5237413065 100644
> --- a/arch/mips/include/asm/thread_info.h
> +++ b/arch/mips/include/asm/thread_info.h
> @@ -29,7 +29,8 @@ struct thread_info {
>         __u32                   cpu;            /* current CPU */
>         int                     preempt_count;  /* 0 => preemptable, <0 => BUG */
>         struct pt_regs          *regs;
> -       long                    syscall;        /* syscall number */
> +       unsigned long           syscall;        /* syscall number */
> +       unsigned long           syscall_work;   /* SYSCALL_WORK_ flags */
>  };
>
>  /*
> @@ -69,6 +70,8 @@ static inline struct thread_info *current_thread_info(void)
>         return __current_thread_info;
>  }
>
> +register unsigned long current_stack_pointer __asm__("$29");
> +
>  #endif /* !__ASSEMBLY__ */
>
>  /* thread information allocation */
> @@ -149,22 +152,10 @@ static inline struct thread_info *current_thread_info(void)
>  #define _TIF_MSA_CTX_LIVE      (1<<TIF_MSA_CTX_LIVE)
>  #define _TIF_SYSCALL_TRACEPOINT        (1<<TIF_SYSCALL_TRACEPOINT)
>
> -#define _TIF_WORK_SYSCALL_ENTRY        (_TIF_NOHZ | _TIF_SYSCALL_TRACE |       \
> -                                _TIF_SYSCALL_AUDIT | \
> -                                _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)
> -
> -/* work to do in syscall_trace_leave() */
> -#define _TIF_WORK_SYSCALL_EXIT (_TIF_NOHZ | _TIF_SYSCALL_TRACE |       \
> -                                _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_TRACEPOINT)
> -
>  /* work to do on interrupt/exception return */
>  #define _TIF_WORK_MASK         \
>         (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_NOTIFY_RESUME |     \
>          _TIF_UPROBE | _TIF_NOTIFY_SIGNAL)
> -/* work to do on any return to u-space */
> -#define _TIF_ALLWORK_MASK      (_TIF_NOHZ | _TIF_WORK_MASK |           \
> -                                _TIF_WORK_SYSCALL_EXIT |               \
> -                                _TIF_SYSCALL_TRACEPOINT)
>
>  /*
>   * We stash processor id into a COP0 register to retrieve it fast
> diff --git a/arch/mips/include/uapi/asm/ptrace.h b/arch/mips/include/uapi/asm/ptrace.h
> index f3c025445e45..27e2c85398bc 100644
> --- a/arch/mips/include/uapi/asm/ptrace.h
> +++ b/arch/mips/include/uapi/asm/ptrace.h
> @@ -102,8 +102,9 @@ struct pt_watch_regs {
>         };
>  };
>
> -#define PTRACE_GET_WATCH_REGS  0xd0
> -#define PTRACE_SET_WATCH_REGS  0xd1
> -
> +#define PTRACE_SYSEMU                  0x1f
> +#define PTRACE_SYSEMU_SINGLESTEP       0x20
> +#define PTRACE_GET_WATCH_REGS          0xd0
> +#define PTRACE_SET_WATCH_REGS          0xd1
>
>  #endif /* _UAPI_ASM_PTRACE_H */
> diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> index 814b3da30501..44875660f6ae 100644
> --- a/arch/mips/kernel/Makefile
> +++ b/arch/mips/kernel/Makefile
> @@ -5,10 +5,10 @@
>
>  extra-y                := head.o vmlinux.lds
>
> -obj-y          += branch.o cmpxchg.o elf.o entry.o genex.o idle.o irq.o \
> -                  process.o prom.o ptrace.o reset.o setup.o signal.o \
> -                  syscall.o time.o topology.o traps.o unaligned.o watch.o \
> -                  vdso.o cacheinfo.o
> +obj-y          += branch.o cacheinfo.o cmpxchg.o elf.o entry.o genex.o \
> +                  idle.o irq.o process.o prom.o ptrace.o reset.o scall.o \
> +                  setup.o signal.o syscall.o time.o topology.o traps.o \
> +                  unaligned.o watch.o vdso.o
>
>  ifdef CONFIG_CPU_R3K_TLB
>  obj-y          += cpu-r3k-probe.o
> @@ -76,11 +76,9 @@ obj-$(CONFIG_IRQ_TXX9)               += irq_txx9.o
>  obj-$(CONFIG_IRQ_GT641XX)      += irq-gt641xx.o
>
>  obj-$(CONFIG_KPROBES)          += kprobes.o
> -obj-$(CONFIG_32BIT)            += scall32-o32.o
> -obj-$(CONFIG_64BIT)            += scall64-n64.o
>  obj-$(CONFIG_MIPS32_COMPAT)    += linux32.o ptrace32.o signal32.o
> -obj-$(CONFIG_MIPS32_N32)       += scall64-n32.o signal_n32.o
> -obj-$(CONFIG_MIPS32_O32)       += scall64-o32.o signal_o32.o
> +obj-$(CONFIG_MIPS32_N32)       += signal_n32.o
> +obj-$(CONFIG_MIPS32_O32)       += signal_o32.o
>
>  obj-$(CONFIG_KGDB)             += kgdb.o
>  obj-$(CONFIG_PROC_FS)          += proc.o
> diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
> index 4b896f5023ff..1a2aec9dab1b 100644
> --- a/arch/mips/kernel/entry.S
> +++ b/arch/mips/kernel/entry.S
> @@ -72,49 +72,32 @@ FEXPORT(ret_from_kernel_thread)
>         jal     schedule_tail           # a0 = struct task_struct *prev
>         move    a0, s1
>         jal     s0
> -       j       syscall_exit
> +       move    a0, sp
> +       jal     syscall_exit_to_user_mode
> +
> +       .set    noat
> +       RESTORE_STATIC
> +       RESTORE_SOME
> +       RESTORE_SP_AND_RET
> +       .set    at
>
>  FEXPORT(ret_from_fork)
>         jal     schedule_tail           # a0 = struct task_struct *prev
> -
> -FEXPORT(syscall_exit)
> -#ifdef CONFIG_DEBUG_RSEQ
>         move    a0, sp
> -       jal     rseq_syscall
> -#endif
> -       local_irq_disable               # make sure need_resched and
> -                                       # signals dont change between
> -                                       # sampling and return
> -       LONG_L  a2, TI_FLAGS($28)       # current->work
> -       li      t0, _TIF_ALLWORK_MASK
> -       and     t0, a2, t0
> -       bnez    t0, syscall_exit_work
> +       jal     syscall_exit_to_user_mode
>
> -restore_all:                           # restore full frame
>         .set    noat
> -       RESTORE_TEMP
> -       RESTORE_AT
>         RESTORE_STATIC
> -restore_partial:               # restore partial frame
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -       SAVE_STATIC
> -       SAVE_AT
> -       SAVE_TEMP
> -       LONG_L  v0, PT_STATUS(sp)
> -#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
> -       and     v0, ST0_IEP
> -#else
> -       and     v0, ST0_IE
> -#endif
> -       beqz    v0, 1f
> -       jal     trace_hardirqs_on
> -       b       2f
> -1:     jal     trace_hardirqs_off
> -2:
> +       RESTORE_SOME
> +       RESTORE_SP_AND_RET
> +       .set    at
> +
> +restore_all:                           # restore full frame
> +       .set    noat
>         RESTORE_TEMP
>         RESTORE_AT
>         RESTORE_STATIC
> -#endif
> +restore_partial:                       # restore partial frame
>         RESTORE_SOME
>         RESTORE_SP_AND_RET
>         .set    at
> @@ -143,32 +126,6 @@ work_notifysig:                            # deal with pending signals and
>         jal     do_notify_resume        # a2 already loaded
>         j       resume_userspace_check
>
> -FEXPORT(syscall_exit_partial)
> -#ifdef CONFIG_DEBUG_RSEQ
> -       move    a0, sp
> -       jal     rseq_syscall
> -#endif
> -       local_irq_disable               # make sure need_resched doesn't
> -                                       # change between and return
> -       LONG_L  a2, TI_FLAGS($28)       # current->work
> -       li      t0, _TIF_ALLWORK_MASK
> -       and     t0, a2
> -       beqz    t0, restore_partial
> -       SAVE_STATIC
> -syscall_exit_work:
> -       LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
> -       andi    t0, t0, KU_USER
> -       beqz    t0, resume_kernel
> -       li      t0, _TIF_WORK_SYSCALL_EXIT
> -       and     t0, a2                  # a2 is preloaded with TI_FLAGS
> -       beqz    t0, work_pending        # trace bit set?
> -       local_irq_enable                # could let syscall_trace_leave()
> -                                       # call schedule() instead
> -       TRACE_IRQS_ON
> -       move    a0, sp
> -       jal     syscall_trace_leave
> -       b       resume_userspace
> -
>  #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR5) || \
>      defined(CONFIG_CPU_MIPSR6) || defined(CONFIG_MIPS_MT)
>
> diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
> index 6b61be486303..2b4b1fc1ff1b 100644
> --- a/arch/mips/kernel/linux32.c
> +++ b/arch/mips/kernel/linux32.c
> @@ -38,7 +38,6 @@
>  #include <net/scm.h>
>
>  #include <asm/compat-signal.h>
> -#include <asm/sim.h>
>  #include <linux/uaccess.h>
>  #include <asm/mmu_context.h>
>  #include <asm/mman.h>
> diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
> index db7c5be1d4a3..04c08e41cfd3 100644
> --- a/arch/mips/kernel/ptrace.c
> +++ b/arch/mips/kernel/ptrace.c
> @@ -46,9 +46,6 @@
>  #include <asm/bootinfo.h>
>  #include <asm/reg.h>
>
> -#define CREATE_TRACE_POINTS
> -#include <trace/events/syscalls.h>
> -
>  /*
>   * Called by kernel/ptrace.c when detaching..
>   *
> @@ -1305,78 +1302,3 @@ long arch_ptrace(struct task_struct *child, long request,
>   out:
>         return ret;
>  }
> -
> -/*
> - * Notification of system call entry/exit
> - * - triggered by current->work.syscall_trace
> - */
> -asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
> -{
> -       user_exit();
> -
> -       current_thread_info()->syscall = syscall;
> -
> -       if (test_thread_flag(TIF_SYSCALL_TRACE)) {
> -               if (tracehook_report_syscall_entry(regs))
> -                       return -1;
> -               syscall = current_thread_info()->syscall;
> -       }
> -
> -#ifdef CONFIG_SECCOMP
> -       if (unlikely(test_thread_flag(TIF_SECCOMP))) {
> -               int ret, i;
> -               struct seccomp_data sd;
> -               unsigned long args[6];
> -
> -               sd.nr = syscall;
> -               sd.arch = syscall_get_arch(current);
> -               syscall_get_arguments(current, regs, args);
> -               for (i = 0; i < 6; i++)
> -                       sd.args[i] = args[i];
> -               sd.instruction_pointer = KSTK_EIP(current);
> -
> -               ret = __secure_computing(&sd);
> -               if (ret == -1)
> -                       return ret;
> -               syscall = current_thread_info()->syscall;
> -       }
> -#endif
> -
> -       if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
> -               trace_sys_enter(regs, regs->regs[2]);
> -
> -       audit_syscall_entry(syscall, regs->regs[4], regs->regs[5],
> -                           regs->regs[6], regs->regs[7]);
> -
> -       /*
> -        * Negative syscall numbers are mistaken for rejected syscalls, but
> -        * won't have had the return value set appropriately, so we do so now.
> -        */
> -       if (syscall < 0)
> -               syscall_set_return_value(current, regs, -ENOSYS, 0);
> -       return syscall;
> -}
> -
> -/*
> - * Notification of system call entry/exit
> - * - triggered by current->work.syscall_trace
> - */
> -asmlinkage void syscall_trace_leave(struct pt_regs *regs)
> -{
> -        /*
> -        * We may come here right after calling schedule_user()
> -        * or do_notify_resume(), in which case we can be in RCU
> -        * user mode.
> -        */
> -       user_exit();
> -
> -       audit_syscall_exit(regs);
> -
> -       if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
> -               trace_sys_exit(regs, regs_return_value(regs));
> -
> -       if (test_thread_flag(TIF_SYSCALL_TRACE))
> -               tracehook_report_syscall_exit(regs, 0);
> -
> -       user_enter();
> -}
> diff --git a/arch/mips/kernel/scall.S b/arch/mips/kernel/scall.S
> new file mode 100644
> index 000000000000..fae8d99f0458
> --- /dev/null
> +++ b/arch/mips/kernel/scall.S
> @@ -0,0 +1,137 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01, 02 by Ralf Baechle
> + * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> + * Copyright (C) 2001 MIPS Technologies, Inc.
> + * Copyright (C) 2004 Thiemo Seufer
> + * Copyright (C) 2014 Imagination Technologies Ltd.
> + */
> +#include <linux/errno.h>
> +#include <asm/asm.h>
> +#include <asm/asmmacro.h>
> +#include <asm/irqflags.h>
> +#include <asm/mipsregs.h>
> +#include <asm/regdef.h>
> +#include <asm/stackframe.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/sysmips.h>
> +#include <asm/thread_info.h>
> +#include <asm/unistd.h>
> +#include <asm/war.h>
> +
> +       .align  5
> +NESTED(handle_sys, PT_SIZE, sp)
> +       .set    noat
> +       SAVE_SOME
> +       SAVE_STATIC
> +       CLI
> +       .set    at
> +
> +       move    a0, sp
> +       jal     do_syscall
> +       beqz    v0, 1f                          # restore all registers?
> +       nop
> +
> +       .set    noat
> +       RESTORE_TEMP
> +       RESTORE_STATIC
> +       RESTORE_AT
> +1:     RESTORE_SOME
> +       RESTORE_SP_AND_RET
> +       .set    at
> +       END(handle_sys)
> +
> +#ifdef CONFIG_32BIT
> +LEAF(sys_syscall)
> +       subu    t0, a0, __NR_O32_Linux          # check syscall number
> +       sltiu   v0, t0, __NR_O32_Linux_syscalls
> +       beqz    t0, einval                      # do not recurse
> +       sll     t1, t0, 2
> +       beqz    v0, einval
> +       lw      t2, sys_call_table(t1)          # syscall routine
> +
> +       move    a0, a1                          # shift argument registers
> +       move    a1, a2
> +       move    a2, a3
> +       lw      a3, 16(sp)
> +       lw      t4, 20(sp)
> +       lw      t5, 24(sp)
> +       lw      t6, 28(sp)
> +       sw      t4, 16(sp)
> +       sw      t5, 20(sp)
> +       sw      t6, 24(sp)
> +       jr      t2
> +       /* Unreached */
> +
> +einval: li     v0, -ENOSYS
> +       jr      ra
> +       END(sys_syscall)
> +
> +#ifdef CONFIG_MIPS_MT_FPAFF
> +       /*
> +        * For FPU affinity scheduling on MIPS MT processors, we need to
> +        * intercept sys_sched_xxxaffinity() calls until we get a proper hook
> +        * in kernel/sched/core.c.  Considered only temporary we only support
> +        * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
> +        * atm.
> +        */
> +#define sys_sched_setaffinity  mipsmt_sys_sched_setaffinity
> +#define sys_sched_getaffinity  mipsmt_sys_sched_getaffinity
> +#endif /* CONFIG_MIPS_MT_FPAFF */
> +
> +#define __SYSCALL_WITH_COMPAT(nr, native, compat)      __SYSCALL(nr, native)
> +#define __SYSCALL(nr, entry)   PTR entry
> +       .align  2
> +       .type   sys_call_table, @object
> +EXPORT(sys_call_table)
> +#include <asm/syscall_table_o32.h>
> +#endif /* CONFIG_32BIT */
> +
> +#ifdef CONFIG_64BIT
> +#ifdef CONFIG_MIPS32_O32
> +LEAF(sys32_syscall)
> +       subu    t0, a0, __NR_O32_Linux          # check syscall number
> +       sltiu   v0, t0, __NR_O32_Linux_syscalls
> +       beqz    t0, einval                      # do not recurse
> +       dsll    t1, t0, 3
> +       beqz    v0, einval
> +       ld      t2, sys32_call_table(t1)        # syscall routine
> +
> +       move    a0, a1                          # shift argument registers
> +       move    a1, a2
> +       move    a2, a3
> +       move    a3, a4
> +       move    a4, a5
> +       move    a5, a6
> +       move    a6, a7
> +       jr      t2
> +       /* Unreached */
> +
> +einval: li     v0, -ENOSYS
> +       jr      ra
> +       END(sys32_syscall)
> +
> +#define __SYSCALL_WITH_COMPAT(nr, native, compat)      __SYSCALL(nr, compat)
> +#define __SYSCALL(nr, entry)   PTR entry
> +       .align  3
> +       .type   sys32_call_table,@object
> +EXPORT(sys32_call_table)
> +#include <asm/syscall_table_o32.h>
> +#endif /* CONFIG_MIPS32_O32 */
> +
> +#ifdef CONFIG_MIPS32_N32
> +#undef __SYSCALL
> +#define __SYSCALL(nr, entry)   PTR entry
> +       .align  3
> +       .type   sysn32_call_table, @object
> +EXPORT(sysn32_call_table)
> +#include <asm/syscall_table_n32.h>
> +#endif /* CONFIG_MIPS32_N32 */
> +
> +#undef __SYSCALL
> +#define __SYSCALL(nr, entry)   PTR entry
> +       .align  3
> +       .type   sys_call_table, @object
> +EXPORT(sys_call_table)
> +#include <asm/syscall_table_n64.h>
> +#endif /* CONFIG_64BIT */
> diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
> deleted file mode 100644
> index b1b2e106f711..000000000000
> --- a/arch/mips/kernel/scall32-o32.S
> +++ /dev/null
> @@ -1,223 +0,0 @@
> -/*
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - *
> - * Copyright (C) 1995-99, 2000- 02, 06 Ralf Baechle <[e-mail]>
> - * Copyright (C) 2001 MIPS Technologies, Inc.
> - * Copyright (C) 2004 Thiemo Seufer
> - * Copyright (C) 2014 Imagination Technologies Ltd.
> - */
> -#include <linux/errno.h>
> -#include <asm/asm.h>
> -#include <asm/asmmacro.h>
> -#include <asm/irqflags.h>
> -#include <asm/mipsregs.h>
> -#include <asm/regdef.h>
> -#include <asm/stackframe.h>
> -#include <asm/isadep.h>
> -#include <asm/sysmips.h>
> -#include <asm/thread_info.h>
> -#include <asm/unistd.h>
> -#include <asm/war.h>
> -#include <asm/asm-offsets.h>
> -
> -       .align  5
> -NESTED(handle_sys, PT_SIZE, sp)
> -       .set    noat
> -       SAVE_SOME
> -       TRACE_IRQS_ON_RELOAD
> -       STI
> -       .set    at
> -
> -       lw      t1, PT_EPC(sp)          # skip syscall on return
> -
> -       addiu   t1, 4                   # skip to next instruction
> -       sw      t1, PT_EPC(sp)
> -
> -       sw      a3, PT_R26(sp)          # save a3 for syscall restarting
> -
> -       /*
> -        * More than four arguments.  Try to deal with it by copying the
> -        * stack arguments from the user stack to the kernel stack.
> -        * This Sucks (TM).
> -        */
> -       lw      t0, PT_R29(sp)          # get old user stack pointer
> -
> -       /*
> -        * We intentionally keep the kernel stack a little below the top of
> -        * userspace so we don't have to do a slower byte accurate check here.
> -        */
> -       addu    t4, t0, 32
> -       bltz    t4, bad_stack           # -> sp is bad
> -
> -       /*
> -        * Ok, copy the args from the luser stack to the kernel stack.
> -        */
> -
> -       .set    push
> -       .set    noreorder
> -       .set    nomacro
> -
> -load_a4: user_lw(t5, 16(t0))           # argument #5 from usp
> -load_a5: user_lw(t6, 20(t0))           # argument #6 from usp
> -load_a6: user_lw(t7, 24(t0))           # argument #7 from usp
> -load_a7: user_lw(t8, 28(t0))           # argument #8 from usp
> -loads_done:
> -
> -       sw      t5, 16(sp)              # argument #5 to ksp
> -       sw      t6, 20(sp)              # argument #6 to ksp
> -       sw      t7, 24(sp)              # argument #7 to ksp
> -       sw      t8, 28(sp)              # argument #8 to ksp
> -       .set    pop
> -
> -       .section __ex_table,"a"
> -       PTR     load_a4, bad_stack_a4
> -       PTR     load_a5, bad_stack_a5
> -       PTR     load_a6, bad_stack_a6
> -       PTR     load_a7, bad_stack_a7
> -       .previous
> -
> -       lw      t0, TI_FLAGS($28)       # syscall tracing enabled?
> -       li      t1, _TIF_WORK_SYSCALL_ENTRY
> -       and     t0, t1
> -       bnez    t0, syscall_trace_entry # -> yes
> -syscall_common:
> -       subu    v0, v0, __NR_O32_Linux  # check syscall number
> -       sltiu   t0, v0, __NR_O32_Linux_syscalls
> -       beqz    t0, illegal_syscall
> -
> -       sll     t0, v0, 2
> -       la      t1, sys_call_table
> -       addu    t1, t0
> -       lw      t2, (t1)                # syscall routine
> -
> -       beqz    t2, illegal_syscall
> -
> -       jalr    t2                      # Do The Real Thing (TM)
> -
> -       li      t0, -EMAXERRNO - 1      # error?
> -       sltu    t0, t0, v0
> -       sw      t0, PT_R7(sp)           # set error flag
> -       beqz    t0, 1f
> -
> -       lw      t1, PT_R2(sp)           # syscall number
> -       negu    v0                      # error
> -       sw      t1, PT_R0(sp)           # save it for syscall restarting
> -1:     sw      v0, PT_R2(sp)           # result
> -
> -o32_syscall_exit:
> -       j       syscall_exit_partial
> -
> -/* ------------------------------------------------------------------------ */
> -
> -syscall_trace_entry:
> -       SAVE_STATIC
> -       move    a0, sp
> -
> -       /*
> -        * syscall number is in v0 unless we called syscall(__NR_###)
> -        * where the real syscall number is in a0
> -        */
> -       move    a1, v0
> -       subu    t2, v0,  __NR_O32_Linux
> -       bnez    t2, 1f /* __NR_syscall at offset 0 */
> -       lw      a1, PT_R4(sp)
> -
> -1:     jal     syscall_trace_enter
> -
> -       bltz    v0, 1f                  # seccomp failed? Skip syscall
> -
> -       RESTORE_STATIC
> -       lw      v0, PT_R2(sp)           # Restore syscall (maybe modified)
> -       lw      a0, PT_R4(sp)           # Restore argument registers
> -       lw      a1, PT_R5(sp)
> -       lw      a2, PT_R6(sp)
> -       lw      a3, PT_R7(sp)
> -       j       syscall_common
> -
> -1:     j       syscall_exit
> -
> -/* ------------------------------------------------------------------------ */
> -
> -       /*
> -        * Our open-coded access area sanity test for the stack pointer
> -        * failed. We probably should handle this case a bit more drastic.
> -        */
> -bad_stack:
> -       li      v0, EFAULT
> -       sw      v0, PT_R2(sp)
> -       li      t0, 1                           # set error flag
> -       sw      t0, PT_R7(sp)
> -       j       o32_syscall_exit
> -
> -bad_stack_a4:
> -       li      t5, 0
> -       b       load_a5
> -
> -bad_stack_a5:
> -       li      t6, 0
> -       b       load_a6
> -
> -bad_stack_a6:
> -       li      t7, 0
> -       b       load_a7
> -
> -bad_stack_a7:
> -       li      t8, 0
> -       b       loads_done
> -
> -       /*
> -        * The system call does not exist in this kernel
> -        */
> -illegal_syscall:
> -       li      v0, ENOSYS                      # error
> -       sw      v0, PT_R2(sp)
> -       li      t0, 1                           # set error flag
> -       sw      t0, PT_R7(sp)
> -       j       o32_syscall_exit
> -       END(handle_sys)
> -
> -       LEAF(sys_syscall)
> -       subu    t0, a0, __NR_O32_Linux  # check syscall number
> -       sltiu   v0, t0, __NR_O32_Linux_syscalls
> -       beqz    t0, einval              # do not recurse
> -       sll     t1, t0, 2
> -       beqz    v0, einval
> -       lw      t2, sys_call_table(t1)          # syscall routine
> -
> -       move    a0, a1                          # shift argument registers
> -       move    a1, a2
> -       move    a2, a3
> -       lw      a3, 16(sp)
> -       lw      t4, 20(sp)
> -       lw      t5, 24(sp)
> -       lw      t6, 28(sp)
> -       sw      t4, 16(sp)
> -       sw      t5, 20(sp)
> -       sw      t6, 24(sp)
> -       jr      t2
> -       /* Unreached */
> -
> -einval: li     v0, -ENOSYS
> -       jr      ra
> -       END(sys_syscall)
> -
> -#ifdef CONFIG_MIPS_MT_FPAFF
> -       /*
> -        * For FPU affinity scheduling on MIPS MT processors, we need to
> -        * intercept sys_sched_xxxaffinity() calls until we get a proper hook
> -        * in kernel/sched/core.c.  Considered only temporary we only support
> -        * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
> -        * atm.
> -        */
> -#define sys_sched_setaffinity  mipsmt_sys_sched_setaffinity
> -#define sys_sched_getaffinity  mipsmt_sys_sched_getaffinity
> -#endif /* CONFIG_MIPS_MT_FPAFF */
> -
> -#define __SYSCALL_WITH_COMPAT(nr, native, compat)      __SYSCALL(nr, native)
> -#define __SYSCALL(nr, entry)   PTR entry
> -       .align  2
> -       .type   sys_call_table, @object
> -EXPORT(sys_call_table)
> -#include <asm/syscall_table_o32.h>
> diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
> deleted file mode 100644
> index f650c55a17dc..000000000000
> --- a/arch/mips/kernel/scall64-n32.S
> +++ /dev/null
> @@ -1,107 +0,0 @@
> -/*
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - *
> - * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01 by Ralf Baechle
> - * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> - * Copyright (C) 2001 MIPS Technologies, Inc.
> - */
> -#include <linux/errno.h>
> -#include <asm/asm.h>
> -#include <asm/asmmacro.h>
> -#include <asm/irqflags.h>
> -#include <asm/mipsregs.h>
> -#include <asm/regdef.h>
> -#include <asm/stackframe.h>
> -#include <asm/thread_info.h>
> -#include <asm/unistd.h>
> -
> -#ifndef CONFIG_MIPS32_O32
> -/* No O32, so define handle_sys here */
> -#define handle_sysn32 handle_sys
> -#endif
> -
> -       .align  5
> -NESTED(handle_sysn32, PT_SIZE, sp)
> -#ifndef CONFIG_MIPS32_O32
> -       .set    noat
> -       SAVE_SOME
> -       TRACE_IRQS_ON_RELOAD
> -       STI
> -       .set    at
> -#endif
> -
> -       dsubu   t0, v0, __NR_N32_Linux  # check syscall number
> -       sltiu   t0, t0, __NR_N32_Linux_syscalls
> -
> -#ifndef CONFIG_MIPS32_O32
> -       ld      t1, PT_EPC(sp)          # skip syscall on return
> -       daddiu  t1, 4                   # skip to next instruction
> -       sd      t1, PT_EPC(sp)
> -#endif
> -       beqz    t0, not_n32_scall
> -
> -       sd      a3, PT_R26(sp)          # save a3 for syscall restarting
> -
> -       li      t1, _TIF_WORK_SYSCALL_ENTRY
> -       LONG_L  t0, TI_FLAGS($28)       # syscall tracing enabled?
> -       and     t0, t1, t0
> -       bnez    t0, n32_syscall_trace_entry
> -
> -syscall_common:
> -       dsll    t0, v0, 3               # offset into table
> -       ld      t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0)
> -
> -       jalr    t2                      # Do The Real Thing (TM)
> -
> -       li      t0, -EMAXERRNO - 1      # error?
> -       sltu    t0, t0, v0
> -       sd      t0, PT_R7(sp)           # set error flag
> -       beqz    t0, 1f
> -
> -       ld      t1, PT_R2(sp)           # syscall number
> -       dnegu   v0                      # error
> -       sd      t1, PT_R0(sp)           # save it for syscall restarting
> -1:     sd      v0, PT_R2(sp)           # result
> -
> -       j       syscall_exit_partial
> -
> -/* ------------------------------------------------------------------------ */
> -
> -n32_syscall_trace_entry:
> -       SAVE_STATIC
> -       move    a0, sp
> -       move    a1, v0
> -       jal     syscall_trace_enter
> -
> -       bltz    v0, 1f                  # seccomp failed? Skip syscall
> -
> -       RESTORE_STATIC
> -       ld      v0, PT_R2(sp)           # Restore syscall (maybe modified)
> -       ld      a0, PT_R4(sp)           # Restore argument registers
> -       ld      a1, PT_R5(sp)
> -       ld      a2, PT_R6(sp)
> -       ld      a3, PT_R7(sp)
> -       ld      a4, PT_R8(sp)
> -       ld      a5, PT_R9(sp)
> -
> -       dsubu   t2, v0, __NR_N32_Linux  # check (new) syscall number
> -       sltiu   t0, t2, __NR_N32_Linux_syscalls
> -       beqz    t0, not_n32_scall
> -
> -       j       syscall_common
> -
> -1:     j       syscall_exit
> -
> -not_n32_scall:
> -       /* This is not an n32 compatibility syscall, pass it on to
> -          the n64 syscall handlers.  */
> -       j       handle_sys64
> -
> -       END(handle_sysn32)
> -
> -#define __SYSCALL(nr, entry)   PTR entry
> -       .type   sysn32_call_table, @object
> -EXPORT(sysn32_call_table)
> -#include <asm/syscall_table_n32.h>
> diff --git a/arch/mips/kernel/scall64-n64.S b/arch/mips/kernel/scall64-n64.S
> deleted file mode 100644
> index 5d7bfc65e4d0..000000000000
> --- a/arch/mips/kernel/scall64-n64.S
> +++ /dev/null
> @@ -1,116 +0,0 @@
> -/*
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - *
> - * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01, 02 by Ralf Baechle
> - * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> - * Copyright (C) 2001 MIPS Technologies, Inc.
> - */
> -#include <linux/errno.h>
> -#include <asm/asm.h>
> -#include <asm/asmmacro.h>
> -#include <asm/irqflags.h>
> -#include <asm/mipsregs.h>
> -#include <asm/regdef.h>
> -#include <asm/stackframe.h>
> -#include <asm/asm-offsets.h>
> -#include <asm/sysmips.h>
> -#include <asm/thread_info.h>
> -#include <asm/unistd.h>
> -#include <asm/war.h>
> -
> -#ifndef CONFIG_MIPS32_COMPAT
> -/* Neither O32 nor N32, so define handle_sys here */
> -#define handle_sys64 handle_sys
> -#endif
> -
> -       .align  5
> -NESTED(handle_sys64, PT_SIZE, sp)
> -#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
> -       /*
> -        * When 32-bit compatibility is configured scall_o32.S
> -        * already did this.
> -        */
> -       .set    noat
> -       SAVE_SOME
> -       TRACE_IRQS_ON_RELOAD
> -       STI
> -       .set    at
> -#endif
> -
> -#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
> -       ld      t1, PT_EPC(sp)          # skip syscall on return
> -       daddiu  t1, 4                   # skip to next instruction
> -       sd      t1, PT_EPC(sp)
> -#endif
> -
> -       sd      a3, PT_R26(sp)          # save a3 for syscall restarting
> -
> -       li      t1, _TIF_WORK_SYSCALL_ENTRY
> -       LONG_L  t0, TI_FLAGS($28)       # syscall tracing enabled?
> -       and     t0, t1, t0
> -       bnez    t0, syscall_trace_entry
> -
> -syscall_common:
> -       dsubu   t2, v0, __NR_64_Linux
> -       sltiu   t0, t2, __NR_64_Linux_syscalls
> -       beqz    t0, illegal_syscall
> -
> -       dsll    t0, t2, 3               # offset into table
> -       dla     t2, sys_call_table
> -       daddu   t0, t2, t0
> -       ld      t2, (t0)                # syscall routine
> -       beqz    t2, illegal_syscall
> -
> -       jalr    t2                      # Do The Real Thing (TM)
> -
> -       li      t0, -EMAXERRNO - 1      # error?
> -       sltu    t0, t0, v0
> -       sd      t0, PT_R7(sp)           # set error flag
> -       beqz    t0, 1f
> -
> -       ld      t1, PT_R2(sp)           # syscall number
> -       dnegu   v0                      # error
> -       sd      t1, PT_R0(sp)           # save it for syscall restarting
> -1:     sd      v0, PT_R2(sp)           # result
> -
> -n64_syscall_exit:
> -       j       syscall_exit_partial
> -
> -/* ------------------------------------------------------------------------ */
> -
> -syscall_trace_entry:
> -       SAVE_STATIC
> -       move    a0, sp
> -       move    a1, v0
> -       jal     syscall_trace_enter
> -
> -       bltz    v0, 1f                  # seccomp failed? Skip syscall
> -
> -       RESTORE_STATIC
> -       ld      v0, PT_R2(sp)           # Restore syscall (maybe modified)
> -       ld      a0, PT_R4(sp)           # Restore argument registers
> -       ld      a1, PT_R5(sp)
> -       ld      a2, PT_R6(sp)
> -       ld      a3, PT_R7(sp)
> -       ld      a4, PT_R8(sp)
> -       ld      a5, PT_R9(sp)
> -       j       syscall_common
> -
> -1:     j       syscall_exit
> -
> -illegal_syscall:
> -       /* This also isn't a 64-bit syscall, throw an error.  */
> -       li      v0, ENOSYS                      # error
> -       sd      v0, PT_R2(sp)
> -       li      t0, 1                           # set error flag
> -       sd      t0, PT_R7(sp)
> -       j       n64_syscall_exit
> -       END(handle_sys64)
> -
> -#define __SYSCALL(nr, entry)   PTR entry
> -       .align  3
> -       .type   sys_call_table, @object
> -EXPORT(sys_call_table)
> -#include <asm/syscall_table_n64.h>
> diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
> deleted file mode 100644
> index cedc8bd88804..000000000000
> --- a/arch/mips/kernel/scall64-o32.S
> +++ /dev/null
> @@ -1,221 +0,0 @@
> -/*
> - * This file is subject to the terms and conditions of the GNU General Public
> - * License.  See the file "COPYING" in the main directory of this archive
> - * for more details.
> - *
> - * Copyright (C) 1995 - 2000, 2001 by Ralf Baechle
> - * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
> - * Copyright (C) 2001 MIPS Technologies, Inc.
> - * Copyright (C) 2004 Thiemo Seufer
> - *
> - * Hairy, the userspace application uses a different argument passing
> - * convention than the kernel, so we have to translate things from o32
> - * to ABI64 calling convention.         64-bit syscalls are also processed
> - * here for now.
> - */
> -#include <linux/errno.h>
> -#include <asm/asm.h>
> -#include <asm/asmmacro.h>
> -#include <asm/irqflags.h>
> -#include <asm/mipsregs.h>
> -#include <asm/regdef.h>
> -#include <asm/stackframe.h>
> -#include <asm/thread_info.h>
> -#include <asm/unistd.h>
> -#include <asm/sysmips.h>
> -
> -       .align  5
> -NESTED(handle_sys, PT_SIZE, sp)
> -       .set    noat
> -       SAVE_SOME
> -       TRACE_IRQS_ON_RELOAD
> -       STI
> -       .set    at
> -       ld      t1, PT_EPC(sp)          # skip syscall on return
> -
> -       dsubu   t0, v0, __NR_O32_Linux  # check syscall number
> -       sltiu   t0, t0, __NR_O32_Linux_syscalls
> -       daddiu  t1, 4                   # skip to next instruction
> -       sd      t1, PT_EPC(sp)
> -       beqz    t0, not_o32_scall
> -#if 0
> - SAVE_ALL
> - move a1, v0
> - ASM_PRINT("Scall %ld\n")
> - RESTORE_ALL
> -#endif
> -
> -       /* We don't want to stumble over broken sign extensions from
> -          userland. O32 does never use the upper half. */
> -       sll     a0, a0, 0
> -       sll     a1, a1, 0
> -       sll     a2, a2, 0
> -       sll     a3, a3, 0
> -
> -       sd      a3, PT_R26(sp)          # save a3 for syscall restarting
> -
> -       /*
> -        * More than four arguments.  Try to deal with it by copying the
> -        * stack arguments from the user stack to the kernel stack.
> -        * This Sucks (TM).
> -        *
> -        * We intentionally keep the kernel stack a little below the top of
> -        * userspace so we don't have to do a slower byte accurate check here.
> -        */
> -       ld      t0, PT_R29(sp)          # get old user stack pointer
> -       daddu   t1, t0, 32
> -       bltz    t1, bad_stack
> -
> -load_a4: lw    a4, 16(t0)              # argument #5 from usp
> -load_a5: lw    a5, 20(t0)              # argument #6 from usp
> -load_a6: lw    a6, 24(t0)              # argument #7 from usp
> -load_a7: lw    a7, 28(t0)              # argument #8 from usp
> -loads_done:
> -
> -       .section __ex_table,"a"
> -       PTR     load_a4, bad_stack_a4
> -       PTR     load_a5, bad_stack_a5
> -       PTR     load_a6, bad_stack_a6
> -       PTR     load_a7, bad_stack_a7
> -       .previous
> -
> -       li      t1, _TIF_WORK_SYSCALL_ENTRY
> -       LONG_L  t0, TI_FLAGS($28)       # syscall tracing enabled?
> -       and     t0, t1, t0
> -       bnez    t0, trace_a_syscall
> -
> -syscall_common:
> -       dsll    t0, v0, 3               # offset into table
> -       ld      t2, (sys32_call_table - (__NR_O32_Linux * 8))(t0)
> -
> -       jalr    t2                      # Do The Real Thing (TM)
> -
> -       li      t0, -EMAXERRNO - 1      # error?
> -       sltu    t0, t0, v0
> -       sd      t0, PT_R7(sp)           # set error flag
> -       beqz    t0, 1f
> -
> -       ld      t1, PT_R2(sp)           # syscall number
> -       dnegu   v0                      # error
> -       sd      t1, PT_R0(sp)           # save it for syscall restarting
> -1:     sd      v0, PT_R2(sp)           # result
> -
> -o32_syscall_exit:
> -       j       syscall_exit_partial
> -
> -/* ------------------------------------------------------------------------ */
> -
> -trace_a_syscall:
> -       SAVE_STATIC
> -       sd      a4, PT_R8(sp)           # Save argument registers
> -       sd      a5, PT_R9(sp)
> -       sd      a6, PT_R10(sp)
> -       sd      a7, PT_R11(sp)          # For indirect syscalls
> -
> -       move    a0, sp
> -       /*
> -        * absolute syscall number is in v0 unless we called syscall(__NR_###)
> -        * where the real syscall number is in a0
> -        * note: NR_syscall is the first O32 syscall but the macro is
> -        * only defined when compiling with -mabi=32 (CONFIG_32BIT)
> -        * therefore __NR_O32_Linux is used (4000)
> -        */
> -       .set    push
> -       .set    reorder
> -       subu    t1, v0,  __NR_O32_Linux
> -       move    a1, v0
> -       bnez    t1, 1f /* __NR_syscall at offset 0 */
> -       ld      a1, PT_R4(sp) /* Arg1 for __NR_syscall case */
> -       .set    pop
> -
> -1:     jal     syscall_trace_enter
> -
> -       bltz    v0, 1f                  # seccomp failed? Skip syscall
> -
> -       RESTORE_STATIC
> -       ld      v0, PT_R2(sp)           # Restore syscall (maybe modified)
> -       ld      a0, PT_R4(sp)           # Restore argument registers
> -       ld      a1, PT_R5(sp)
> -       ld      a2, PT_R6(sp)
> -       ld      a3, PT_R7(sp)
> -       ld      a4, PT_R8(sp)
> -       ld      a5, PT_R9(sp)
> -       ld      a6, PT_R10(sp)
> -       ld      a7, PT_R11(sp)          # For indirect syscalls
> -
> -       dsubu   t0, v0, __NR_O32_Linux  # check (new) syscall number
> -       sltiu   t0, t0, __NR_O32_Linux_syscalls
> -       beqz    t0, not_o32_scall
> -
> -       j       syscall_common
> -
> -1:     j       syscall_exit
> -
> -/* ------------------------------------------------------------------------ */
> -
> -       /*
> -        * The stackpointer for a call with more than 4 arguments is bad.
> -        */
> -bad_stack:
> -       li      v0, EFAULT
> -       sd      v0, PT_R2(sp)
> -       li      t0, 1                   # set error flag
> -       sd      t0, PT_R7(sp)
> -       j       o32_syscall_exit
> -
> -bad_stack_a4:
> -       li      a4, 0
> -       b       load_a5
> -
> -bad_stack_a5:
> -       li      a5, 0
> -       b       load_a6
> -
> -bad_stack_a6:
> -       li      a6, 0
> -       b       load_a7
> -
> -bad_stack_a7:
> -       li      a7, 0
> -       b       loads_done
> -
> -not_o32_scall:
> -       /*
> -        * This is not an o32 compatibility syscall, pass it on
> -        * to the 64-bit syscall handlers.
> -        */
> -#ifdef CONFIG_MIPS32_N32
> -       j       handle_sysn32
> -#else
> -       j       handle_sys64
> -#endif
> -       END(handle_sys)
> -
> -LEAF(sys32_syscall)
> -       subu    t0, a0, __NR_O32_Linux  # check syscall number
> -       sltiu   v0, t0, __NR_O32_Linux_syscalls
> -       beqz    t0, einval              # do not recurse
> -       dsll    t1, t0, 3
> -       beqz    v0, einval
> -       ld      t2, sys32_call_table(t1)                # syscall routine
> -
> -       move    a0, a1                  # shift argument registers
> -       move    a1, a2
> -       move    a2, a3
> -       move    a3, a4
> -       move    a4, a5
> -       move    a5, a6
> -       move    a6, a7
> -       jr      t2
> -       /* Unreached */
> -
> -einval: li     v0, -ENOSYS
> -       jr      ra
> -       END(sys32_syscall)
> -
> -#define __SYSCALL_WITH_COMPAT(nr, native, compat)      __SYSCALL(nr, compat)
> -#define __SYSCALL(nr, entry)   PTR entry
> -       .align  3
> -       .type   sys32_call_table,@object
> -EXPORT(sys32_call_table)
> -#include <asm/syscall_table_o32.h>
> diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
> index c9b2a75563e1..314a6ffa0e07 100644
> --- a/arch/mips/kernel/signal.c
> +++ b/arch/mips/kernel/signal.c
> @@ -32,7 +32,6 @@
>  #include <linux/bitops.h>
>  #include <asm/cacheflush.h>
>  #include <asm/fpu.h>
> -#include <asm/sim.h>
>  #include <asm/ucontext.h>
>  #include <asm/cpu-features.h>
>  #include <asm/war.h>
> @@ -627,7 +626,7 @@ SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
>  #endif
>
>  #ifdef CONFIG_TRAD_SIGNALS
> -asmlinkage void sys_sigreturn(void)
> +asmlinkage long sys_sigreturn(void)
>  {
>         struct sigframe __user *frame;
>         struct pt_regs *regs;
> @@ -649,22 +648,17 @@ asmlinkage void sys_sigreturn(void)
>         else if (sig)
>                 force_sig(sig);
>
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -               "move\t$29, %0\n\t"
> -               "j\tsyscall_exit"
> -               : /* no outputs */
> -               : "r" (regs));
> -       /* Unreached */
> +       regs->regs[0] = 0;      /* No syscall restarting */
> +       regs->regs[27] = 1;     /* return directly */
> +       return regs->regs[2];
>
>  badframe:
>         force_sig(SIGSEGV);
> +       return 0;
>  }
>  #endif /* CONFIG_TRAD_SIGNALS */
>
> -asmlinkage void sys_rt_sigreturn(void)
> +asmlinkage long sys_rt_sigreturn(void)
>  {
>         struct rt_sigframe __user *frame;
>         struct pt_regs *regs;
> @@ -686,21 +680,16 @@ asmlinkage void sys_rt_sigreturn(void)
>         else if (sig)
>                 force_sig(sig);
>
> +       regs->regs[0] = 0;      /* No syscall restarting */
>         if (restore_altstack(&frame->rs_uc.uc_stack))
>                 goto badframe;
>
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -               "move\t$29, %0\n\t"
> -               "j\tsyscall_exit"
> -               : /* no outputs */
> -               : "r" (regs));
> -       /* Unreached */
> +       regs->regs[27] = 1;     /* return directly */
> +       return regs->regs[2];
>
>  badframe:
>         force_sig(SIGSEGV);
> +       return 0;
>  }
>
>  #ifdef CONFIG_TRAD_SIGNALS
> @@ -852,11 +841,11 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
>         signal_setup_done(ret, ksig, 0);
>  }
>
> -static void do_signal(struct pt_regs *regs)
> +void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
>  {
>         struct ksignal ksig;
>
> -       if (get_signal(&ksig)) {
> +       if (has_signal && get_signal(&ksig)) {
>                 /* Whee!  Actually deliver the signal.  */
>                 handle_signal(&ksig, regs);
>                 return;
> @@ -904,7 +893,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
>
>         /* deal with pending signal delivery */
>         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
> -               do_signal(regs);
> +               arch_do_signal_or_restart(regs, thread_info_flags & _TIF_SIGPENDING);
>
>         if (thread_info_flags & _TIF_NOTIFY_RESUME)
>                 tracehook_notify_resume(regs);
> diff --git a/arch/mips/kernel/signal_n32.c b/arch/mips/kernel/signal_n32.c
> index 7bd00fad61af..e282f14747d2 100644
> --- a/arch/mips/kernel/signal_n32.c
> +++ b/arch/mips/kernel/signal_n32.c
> @@ -19,7 +19,6 @@
>  #include <asm/asm.h>
>  #include <asm/cacheflush.h>
>  #include <asm/compat-signal.h>
> -#include <asm/sim.h>
>  #include <linux/uaccess.h>
>  #include <asm/ucontext.h>
>  #include <asm/fpu.h>
> @@ -51,7 +50,7 @@ struct rt_sigframe_n32 {
>         struct ucontextn32 rs_uc;
>  };
>
> -asmlinkage void sysn32_rt_sigreturn(void)
> +asmlinkage long sysn32_rt_sigreturn(void)
>  {
>         struct rt_sigframe_n32 __user *frame;
>         struct pt_regs *regs;
> @@ -73,21 +72,16 @@ asmlinkage void sysn32_rt_sigreturn(void)
>         else if (sig)
>                 force_sig(sig);
>
> +       regs->regs[0] = 0;      /* No syscall restarting */
>         if (compat_restore_altstack(&frame->rs_uc.uc_stack))
>                 goto badframe;
>
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -               "move\t$29, %0\n\t"
> -               "j\tsyscall_exit"
> -               : /* no outputs */
> -               : "r" (regs));
> -       /* Unreached */
> +       regs->regs[27] = 1;     /* return directly */
> +       return regs->regs[2];
>
>  badframe:
>         force_sig(SIGSEGV);
> +       return 0;
>  }
>
>  static int setup_rt_frame_n32(void *sig_return, struct ksignal *ksig,
> diff --git a/arch/mips/kernel/signal_o32.c b/arch/mips/kernel/signal_o32.c
> index 299a7a28ca33..ea6d12dd15cc 100644
> --- a/arch/mips/kernel/signal_o32.c
> +++ b/arch/mips/kernel/signal_o32.c
> @@ -17,7 +17,6 @@
>  #include <asm/abi.h>
>  #include <asm/compat-signal.h>
>  #include <asm/dsp.h>
> -#include <asm/sim.h>
>  #include <asm/unistd.h>
>
>  #include "signal-common.h"
> @@ -151,7 +150,7 @@ static int setup_frame_32(void *sig_return, struct ksignal *ksig,
>         return 0;
>  }
>
> -asmlinkage void sys32_rt_sigreturn(void)
> +asmlinkage long sys32_rt_sigreturn(void)
>  {
>         struct rt_sigframe32 __user *frame;
>         struct pt_regs *regs;
> @@ -173,21 +172,16 @@ asmlinkage void sys32_rt_sigreturn(void)
>         else if (sig)
>                 force_sig(sig);
>
> +       regs->regs[0] = 0;      /* No syscall restarting */
>         if (compat_restore_altstack(&frame->rs_uc.uc_stack))
>                 goto badframe;
>
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -               "move\t$29, %0\n\t"
> -               "j\tsyscall_exit"
> -               : /* no outputs */
> -               : "r" (regs));
> -       /* Unreached */
> +       regs->regs[27] = 1;     /* return directly */
> +       return regs->regs[2];
>
>  badframe:
>         force_sig(SIGSEGV);
> +       return 0;
>  }
>
>  static int setup_rt_frame_32(void *sig_return, struct ksignal *ksig,
> @@ -253,7 +247,7 @@ struct mips_abi mips_abi_32 = {
>  };
>
>
> -asmlinkage void sys32_sigreturn(void)
> +asmlinkage long sys32_sigreturn(void)
>  {
>         struct sigframe32 __user *frame;
>         struct pt_regs *regs;
> @@ -275,16 +269,11 @@ asmlinkage void sys32_sigreturn(void)
>         else if (sig)
>                 force_sig(sig);
>
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -               "move\t$29, %0\n\t"
> -               "j\tsyscall_exit"
> -               : /* no outputs */
> -               : "r" (regs));
> -       /* Unreached */
> +       regs->regs[0] = 0;      /* No syscall restarting */
> +       regs->regs[27] = 1;     /* return directly */
> +       return regs->regs[2];
>
>  badframe:
>         force_sig(SIGSEGV);
> +       return 0;
>  }
> diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
> index 2afa3eef486a..2653f82a8c99 100644
> --- a/arch/mips/kernel/syscall.c
> +++ b/arch/mips/kernel/syscall.c
> @@ -8,6 +8,7 @@
>   * Copyright (C) 2001 MIPS Technologies, Inc.
>   */
>  #include <linux/capability.h>
> +#include <linux/entry-common.h>
>  #include <linux/errno.h>
>  #include <linux/linkage.h>
>  #include <linux/fs.h>
> @@ -35,9 +36,9 @@
>  #include <asm/cacheflush.h>
>  #include <asm/asm-offsets.h>
>  #include <asm/signal.h>
> -#include <asm/sim.h>
>  #include <asm/shmparam.h>
>  #include <asm/sync.h>
> +#include <asm/syscall.h>
>  #include <asm/sysmips.h>
>  #include <asm/switch_to.h>
>
> @@ -79,10 +80,6 @@ SYSCALL_DEFINE6(mips_mmap2, unsigned long, addr, unsigned long, len,
>                                pgoff >> (PAGE_SHIFT - 12));
>  }
>
> -save_static_function(sys_fork);
> -save_static_function(sys_clone);
> -save_static_function(sys_clone3);
> -
>  SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
>  {
>         struct thread_info *ti = task_thread_info(current);
> @@ -182,28 +179,11 @@ static inline int mips_atomic_set(unsigned long addr, unsigned long new)
>                 return err;
>
>         regs = current_pt_regs();
> -       regs->regs[2] = old;
> -       regs->regs[7] = 0;      /* No error */
> -
> -       /*
> -        * Don't let your children do this ...
> -        */
> -       __asm__ __volatile__(
> -       "       move    $29, %0                                         \n"
> -       "       j       syscall_exit                                    \n"
> -       : /* no outputs */
> -       : "r" (regs));
> -
> -       /* unreached.  Honestly.  */
> -       unreachable();
> +       regs->regs[7] = 0;      /* no error */
> +       regs->regs[27] = 1;     /* return directly */
> +       return old;
>  }
>
> -/*
> - * mips_atomic_set() normally returns directly via syscall_exit potentially
> - * clobbering static registers, so be sure to preserve them.
> - */
> -save_static_function(sys_sysmips);
> -
>  SYSCALL_DEFINE3(sysmips, long, cmd, long, arg1, long, arg2)
>  {
>         switch (cmd) {
> @@ -249,3 +229,121 @@ asmlinkage void bad_stack(void)
>  {
>         do_exit(SIGSEGV);
>  }
> +
> +#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
> +static inline int get_args(struct pt_regs *regs)
> +{
> +       int *usp = (int *)regs->regs[29];
> +
> +#ifdef CONFIG_MIPS32_O32
> +       /*
> +        * Hairy, the userspace application uses a different argument passing
> +        * convention than the kernel, so we have to translate things from o32
> +        * to ABI64 calling convention.
> +        *
> +        * We don't want to stumble over broken sign extensions from userland.
> +        * O32 does never use the upper half.
> +        */
> +       regs->regs[4] = (int)regs->regs[4];
> +       regs->regs[5] = (int)regs->regs[5];
> +       regs->regs[6] = (int)regs->regs[6];
> +       regs->regs[7] = (int)regs->regs[7];
> +#endif
> +
> +       /*
> +        * More than four arguments.  Try to deal with it by copying the
> +        * stack arguments from the user stack to the kernel stack.
> +        * This Sucks (TM).
> +        *
> +        * We intentionally keep the kernel stack a little below the top of
> +        * userspace so we don't have to do a slower byte accurate check here.
> +        */
> +       if (!access_ok(usp, 32))
> +               return -1;
> +
> +       get_user(regs->regs[8], usp + 4);
> +       get_user(regs->regs[9], usp + 5);
> +       get_user(regs->regs[10], usp + 6);
> +       get_user(regs->regs[11], usp + 7);
> +
> +       return 0;
> +}
> +#endif
> +
> +typedef long (*sys_call_fn)(unsigned long, unsigned long,
> +       unsigned long, unsigned long, unsigned long, unsigned long);
> +
> +long noinstr do_syscall(struct pt_regs *regs)
> +{
> +       unsigned long nr;
> +       unsigned long ret;
> +       sys_call_fn syscall_fn = NULL;
> +
> +       nr = regs->regs[2];
> +       current_thread_info()->syscall = nr;
> +       nr = syscall_enter_from_user_mode(regs, nr);
> +
> +       regs->cp0_epc += 4;             /* skip syscall on return */
> +                                       /* skip to next instruction */
> +       regs->regs[26] = regs->regs[7]; /* save a3 for syscall restarting */
> +       regs->regs[27] = 0;             /* do not return directly */
> +
> +#ifdef CONFIG_32BIT
> +       if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls) {
> +               if (get_args(regs) < 0) {
> +                       ret = EFAULT;
> +                       goto error;
> +               }
> +               syscall_fn = (sys_call_fn)sys_call_table[nr - __NR_O32_Linux];
> +       }
> +#endif
> +
> +#ifdef CONFIG_MIPS32_O32
> +       if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls) {
> +               if (get_args(regs) < 0) {
> +                       ret = EFAULT;
> +                       goto error;
> +               }
> +               syscall_fn = (sys_call_fn)sys32_call_table[nr - __NR_O32_Linux];
> +       }
> +#endif
> +
> +#ifdef CONFIG_MIPS32_N32
> +       if (nr >= __NR_N32_Linux && nr < __NR_N32_Linux + __NR_N32_Linux_syscalls)
> +               syscall_fn = (sys_call_fn)sysn32_call_table[nr - __NR_N32_Linux];
> +#endif
> +
> +#ifdef CONFIG_64BIT
> +       if (nr >= __NR_64_Linux && nr < __NR_64_Linux + __NR_64_Linux_syscalls)
> +               syscall_fn = (sys_call_fn)sys_call_table[nr - __NR_64_Linux];
> +#endif
> +
> +       if (unlikely(!syscall_fn)) {
> +               ret = ENOSYS;
> +               goto error;
> +       }
> +
> +       ret = syscall_fn(regs->regs[4], regs->regs[5], regs->regs[6],
> +                        regs->regs[7], regs->regs[8], regs->regs[9]);
> +
> +       if (regs->regs[27])             /* return directly? */
> +               goto out;
> +
> +       regs->regs[7] = 0;              /* clear error flag */
> +       if (ret >= -EMAXERRNO - 1) {    /* error? */
> +               regs->regs[0] = nr;     /* save syscall number */
> +                                       /* for syscall restarting */
> +               ret = -ret;
> +               goto error;
> +       }
> +
> +       goto out;
> +
> +error:
> +       regs->regs[7] = 1;              /* set error flag */
> +
> +out:
> +       regs->regs[2] = ret;
> +       syscall_exit_to_user_mode(regs);
> +       return regs->regs[27];
> +}
> diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
> index 70e32de2bcaa..d9ae765e51f1 100644
> --- a/arch/mips/kernel/syscalls/syscall_n32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
> @@ -62,8 +62,8 @@
>  52     n32     socketpair                      sys_socketpair
>  53     n32     setsockopt                      sys_setsockopt
>  54     n32     getsockopt                      sys_getsockopt
> -55     n32     clone                           __sys_clone
> -56     n32     fork                            __sys_fork
> +55     n32     clone                           sys_clone
> +56     n32     fork                            sys_fork
>  57     n32     execve                          compat_sys_execve
>  58     n32     exit                            sys_exit
>  59     n32     wait4                           compat_sys_wait4
> @@ -207,7 +207,7 @@
>  196    n32     sched_getaffinity               compat_sys_sched_getaffinity
>  197    n32     cacheflush                      sys_cacheflush
>  198    n32     cachectl                        sys_cachectl
> -199    n32     sysmips                         __sys_sysmips
> +199    n32     sysmips                         sys_sysmips
>  200    n32     io_setup                        compat_sys_io_setup
>  201    n32     io_destroy                      sys_io_destroy
>  202    n32     io_getevents                    sys_io_getevents_time32
> @@ -373,7 +373,7 @@
>  432    n32     fsmount                         sys_fsmount
>  433    n32     fspick                          sys_fspick
>  434    n32     pidfd_open                      sys_pidfd_open
> -435    n32     clone3                          __sys_clone3
> +435    n32     clone3                          sys_clone3
>  436    n32     close_range                     sys_close_range
>  437    n32     openat2                         sys_openat2
>  438    n32     pidfd_getfd                     sys_pidfd_getfd
> diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
> index 1ca7bc337932..edec3e82d67a 100644
> --- a/arch/mips/kernel/syscalls/syscall_n64.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
> @@ -62,8 +62,8 @@
>  52     n64     socketpair                      sys_socketpair
>  53     n64     setsockopt                      sys_setsockopt
>  54     n64     getsockopt                      sys_getsockopt
> -55     n64     clone                           __sys_clone
> -56     n64     fork                            __sys_fork
> +55     n64     clone                           sys_clone
> +56     n64     fork                            sys_fork
>  57     n64     execve                          sys_execve
>  58     n64     exit                            sys_exit
>  59     n64     wait4                           sys_wait4
> @@ -207,7 +207,7 @@
>  196    n64     sched_getaffinity               sys_sched_getaffinity
>  197    n64     cacheflush                      sys_cacheflush
>  198    n64     cachectl                        sys_cachectl
> -199    n64     sysmips                         __sys_sysmips
> +199    n64     sysmips                         sys_sysmips
>  200    n64     io_setup                        sys_io_setup
>  201    n64     io_destroy                      sys_io_destroy
>  202    n64     io_getevents                    sys_io_getevents
> @@ -349,7 +349,7 @@
>  432    n64     fsmount                         sys_fsmount
>  433    n64     fspick                          sys_fspick
>  434    n64     pidfd_open                      sys_pidfd_open
> -435    n64     clone3                          __sys_clone3
> +435    n64     clone3                          sys_clone3
>  436    n64     close_range                     sys_close_range
>  437    n64     openat2                         sys_openat2
>  438    n64     pidfd_getfd                     sys_pidfd_getfd
> diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
> index a61c35edaa74..89a1f267da6a 100644
> --- a/arch/mips/kernel/syscalls/syscall_o32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
> @@ -9,7 +9,7 @@
>  #
>  0      o32     syscall                         sys_syscall                     sys32_syscall
>  1      o32     exit                            sys_exit
> -2      o32     fork                            __sys_fork
> +2      o32     fork                            sys_fork
>  3      o32     read                            sys_read
>  4      o32     write                           sys_write
>  5      o32     open                            sys_open                        compat_sys_open
> @@ -131,7 +131,7 @@
>  117    o32     ipc                             sys_ipc                         compat_sys_ipc
>  118    o32     fsync                           sys_fsync
>  119    o32     sigreturn                       sys_sigreturn                   sys32_sigreturn
> -120    o32     clone                           __sys_clone
> +120    o32     clone                           sys_clone
>  121    o32     setdomainname                   sys_setdomainname
>  122    o32     uname                           sys_newuname
>  123    o32     modify_ldt                      sys_ni_syscall
> @@ -160,7 +160,7 @@
>  146    o32     writev                          sys_writev
>  147    o32     cacheflush                      sys_cacheflush
>  148    o32     cachectl                        sys_cachectl
> -149    o32     sysmips                         __sys_sysmips
> +149    o32     sysmips                         sys_sysmips
>  150    o32     unused150                       sys_ni_syscall
>  151    o32     getsid                          sys_getsid
>  152    o32     fdatasync                       sys_fdatasync
> @@ -422,7 +422,7 @@
>  432    o32     fsmount                         sys_fsmount
>  433    o32     fspick                          sys_fspick
>  434    o32     pidfd_open                      sys_pidfd_open
> -435    o32     clone3                          __sys_clone3
> +435    o32     clone3                          sys_clone3
>  436    o32     close_range                     sys_close_range
>  437    o32     openat2                         sys_openat2
>  438    o32     pidfd_getfd                     sys_pidfd_getfd
> --
> 2.27.0
>

Feiyang Chen Oct. 14, 2021, 8:56 a.m. UTC | #3

On Thu, 14 Oct 2021 at 16:37, WANG Xuerui <[e-mail]> wrote:
>
> Hi Feiyang,
>
> On 2021/10/14 16:32, Feiyang Chen wrote:
> > Convert MIPS syscall to use the generic entry infrastructure from
> > kernel/entry/*.
> >
> > There are a few special things on MIPS:
> >
> > - There is one type of syscall on MIPS32 (scall32-o32) and three types
> > of syscalls on MIPS64 (scall64-o32, scall64-n32 and scall64-n64). Now
> > convert to C code to handle different types of syscalls.
> >
> > - For some special syscalls (e.g. fork, clone, clone3 and sysmips),
> > save_static_function() wrapper is used to save static registers. Now
> > SAVE_STATIC is used in handle_sys before calling do_syscall(), so the
> > save_static_function() wrapper can be removed.
> >
> > - For sigreturn/rt_sigreturn and sysmips, inline assembly is used to
> > jump to syscall_exit directly for skipping setting the error flag and
> > restoring all registers. Now use regs->regs[27] to mark whether to
> > handle the error flag and restore all registers in handle_sys, so these
> > functions can return normally as other architecture.
> >
> > Signed-off-by: Feiyang Chen <[e-mail]>
> > Signed-off-by: Yanteng Si <[e-mail]>
> > Reviewed-by: Huacai Chen <[e-mail]>
> > ---
> >  arch/mips/Kconfig                         |   1 +
> >  arch/mips/include/asm/entry-common.h      |  13 ++
> >  arch/mips/include/asm/ptrace.h            |   8 +-
> >  arch/mips/include/asm/sim.h               |  70 -------
> >  arch/mips/include/asm/syscall.h           |   5 +
> >  arch/mips/include/asm/thread_info.h       |  17 +-
> >  arch/mips/include/uapi/asm/ptrace.h       |   7 +-
> >  arch/mips/kernel/Makefile                 |  14 +-
> >  arch/mips/kernel/entry.S                  |  75 ++------
> >  arch/mips/kernel/linux32.c                |   1 -
> >  arch/mips/kernel/ptrace.c                 |  78 --------
> >  arch/mips/kernel/scall.S                  | 137 +++++++++++++
> >  arch/mips/kernel/scall32-o32.S            | 223 ----------------------
> >  arch/mips/kernel/scall64-n32.S            | 107 -----------
> >  arch/mips/kernel/scall64-n64.S            | 116 -----------
> >  arch/mips/kernel/scall64-o32.S            | 221 ---------------------
> >  arch/mips/kernel/signal.c                 |  37 ++--
> >  arch/mips/kernel/signal_n32.c             |  16 +-
> >  arch/mips/kernel/signal_o32.c             |  31 +--
> >  arch/mips/kernel/syscall.c                | 148 +++++++++++---
> >  arch/mips/kernel/syscalls/syscall_n32.tbl |   8 +-
> >  arch/mips/kernel/syscalls/syscall_n64.tbl |   8 +-
> >  arch/mips/kernel/syscalls/syscall_o32.tbl |   8 +-
> >  23 files changed, 354 insertions(+), 995 deletions(-)
> >  create mode 100644 arch/mips/include/asm/entry-common.h
> >  delete mode 100644 arch/mips/include/asm/sim.h
> >  create mode 100644 arch/mips/kernel/scall.S
> >  delete mode 100644 arch/mips/kernel/scall32-o32.S
> >  delete mode 100644 arch/mips/kernel/scall64-n32.S
> >  delete mode 100644 arch/mips/kernel/scall64-n64.S
> >  delete mode 100644 arch/mips/kernel/scall64-o32.S
> >
> > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > index 1291774a2fa5..debd125100ad 100644
> > --- a/arch/mips/Kconfig
> > +++ b/arch/mips/Kconfig
> > @@ -32,6 +32,7 @@ config MIPS
> >       select GENERIC_ATOMIC64 if !64BIT
> >       select GENERIC_CMOS_UPDATE
> >       select GENERIC_CPU_AUTOPROBE
> > +     select GENERIC_ENTRY
> >       select GENERIC_GETTIMEOFDAY
> >       select GENERIC_IOMAP
> >       select GENERIC_IRQ_PROBE
> > diff --git a/arch/mips/include/asm/entry-common.h b/arch/mips/include/asm/entry-common.h
> > new file mode 100644
> > index 000000000000..0fe2a098ded9
> > --- /dev/null
> > +++ b/arch/mips/include/asm/entry-common.h
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef ARCH_LOONGARCH_ENTRY_COMMON_H
> > +#define ARCH_LOONGARCH_ENTRY_COMMON_H
> Do you intend to say "MIPS"? ;-)

Hi, YunQiang, Xuerui,

Yes, I will fix it in the next version.

Thanks,
Feiyang

> > +
> > +#include <linux/sched.h>
> > +#include <linux/processor.h>
> > +
> > +static inline bool on_thread_stack(void)
> > +{
> > +     return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));
> > +}
> > +
> > +#endif

Patch

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1291774a2fa5..debd125100ad 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -32,6 +32,7 @@  config MIPS
 	select GENERIC_ATOMIC64 if !64BIT
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
+	select GENERIC_ENTRY
 	select GENERIC_GETTIMEOFDAY
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_PROBE
diff --git a/arch/mips/include/asm/entry-common.h b/arch/mips/include/asm/entry-common.h
new file mode 100644
index 000000000000..0fe2a098ded9
--- /dev/null
+++ b/arch/mips/include/asm/entry-common.h
@@ -0,0 +1,13 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_LOONGARCH_ENTRY_COMMON_H
+#define ARCH_LOONGARCH_ENTRY_COMMON_H
+
+#include <linux/sched.h>
+#include <linux/processor.h>
+
+static inline bool on_thread_stack(void)
+{
+	return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));
+}
+
+#endif
diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
index daf3cf244ea9..1b8f9d2ddc44 100644
--- a/arch/mips/include/asm/ptrace.h
+++ b/arch/mips/include/asm/ptrace.h
@@ -51,6 +51,11 @@  struct pt_regs {
 	unsigned long __last[0];
 } __aligned(8);
 
+static inline int regs_irqs_disabled(struct pt_regs *regs)
+{
+	return arch_irqs_disabled_flags(regs->cp0_status);
+}
+
 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 {
 	return regs->regs[29];
@@ -156,9 +161,6 @@  static inline long regs_return_value(struct pt_regs *regs)
 #define instruction_pointer(regs) ((regs)->cp0_epc)
 #define profile_pc(regs) instruction_pointer(regs)
 
-extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall);
-extern asmlinkage void syscall_trace_leave(struct pt_regs *regs);
-
 extern void die(const char *, struct pt_regs *) __noreturn;
 
 static inline void die_if_kernel(const char *str, struct pt_regs *regs)
diff --git a/arch/mips/include/asm/sim.h b/arch/mips/include/asm/sim.h
deleted file mode 100644
index 59f31a95facd..000000000000
--- a/arch/mips/include/asm/sim.h
+++ /dev/null
@@ -1,70 +0,0 @@ 
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1999, 2000, 2003 Ralf Baechle
- * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- */
-#ifndef _ASM_SIM_H
-#define _ASM_SIM_H
-
-
-#include <asm/asm-offsets.h>
-
-#define __str2(x) #x
-#define __str(x) __str2(x)
-
-#ifdef CONFIG_32BIT
-
-#define save_static_function(symbol)					\
-__asm__(								\
-	".text\n\t"							\
-	".globl\t__" #symbol "\n\t"					\
-	".align\t2\n\t"							\
-	".type\t__" #symbol ", @function\n\t"				\
-	".ent\t__" #symbol ", 0\n__"					\
-	#symbol":\n\t"							\
-	".frame\t$29, 0, $31\n\t"					\
-	"sw\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"	\
-	"sw\t$17,"__str(PT_R17)"($29)\n\t"				\
-	"sw\t$18,"__str(PT_R18)"($29)\n\t"				\
-	"sw\t$19,"__str(PT_R19)"($29)\n\t"				\
-	"sw\t$20,"__str(PT_R20)"($29)\n\t"				\
-	"sw\t$21,"__str(PT_R21)"($29)\n\t"				\
-	"sw\t$22,"__str(PT_R22)"($29)\n\t"				\
-	"sw\t$23,"__str(PT_R23)"($29)\n\t"				\
-	"sw\t$30,"__str(PT_R30)"($29)\n\t"				\
-	"j\t" #symbol "\n\t"						\
-	".end\t__" #symbol "\n\t"					\
-	".size\t__" #symbol",. - __" #symbol)
-
-#endif /* CONFIG_32BIT */
-
-#ifdef CONFIG_64BIT
-
-#define save_static_function(symbol)					\
-__asm__(								\
-	".text\n\t"							\
-	".globl\t__" #symbol "\n\t"					\
-	".align\t2\n\t"							\
-	".type\t__" #symbol ", @function\n\t"				\
-	".ent\t__" #symbol ", 0\n__"					\
-	#symbol":\n\t"							\
-	".frame\t$29, 0, $31\n\t"					\
-	"sd\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"	\
-	"sd\t$17,"__str(PT_R17)"($29)\n\t"				\
-	"sd\t$18,"__str(PT_R18)"($29)\n\t"				\
-	"sd\t$19,"__str(PT_R19)"($29)\n\t"				\
-	"sd\t$20,"__str(PT_R20)"($29)\n\t"				\
-	"sd\t$21,"__str(PT_R21)"($29)\n\t"				\
-	"sd\t$22,"__str(PT_R22)"($29)\n\t"				\
-	"sd\t$23,"__str(PT_R23)"($29)\n\t"				\
-	"sd\t$30,"__str(PT_R30)"($29)\n\t"				\
-	"j\t" #symbol "\n\t"						\
-	".end\t__" #symbol "\n\t"					\
-	".size\t__" #symbol",. - __" #symbol)
-
-#endif /* CONFIG_64BIT */
-
-#endif /* _ASM_SIM_H */
diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index 25fa651c937d..02ca0d659428 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -157,4 +157,9 @@  static inline int syscall_get_arch(struct task_struct *task)
 	return arch;
 }
 
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
+{
+	return false;
+}
+
 #endif	/* __ASM_MIPS_SYSCALL_H */
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 0b17aaa9e012..5a5237413065 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -29,7 +29,8 @@  struct thread_info {
 	__u32			cpu;		/* current CPU */
 	int			preempt_count;	/* 0 => preemptable, <0 => BUG */
 	struct pt_regs		*regs;
-	long			syscall;	/* syscall number */
+	unsigned long		syscall;	/* syscall number */
+	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 };
 
 /*
@@ -69,6 +70,8 @@  static inline struct thread_info *current_thread_info(void)
 	return __current_thread_info;
 }
 
+register unsigned long current_stack_pointer __asm__("$29");
+
 #endif /* !__ASSEMBLY__ */
 
 /* thread information allocation */
@@ -149,22 +152,10 @@  static inline struct thread_info *current_thread_info(void)
 #define _TIF_MSA_CTX_LIVE	(1<<TIF_MSA_CTX_LIVE)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
 
-#define _TIF_WORK_SYSCALL_ENTRY	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
-				 _TIF_SYSCALL_AUDIT | \
-				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)
-
-/* work to do in syscall_trace_leave() */
-#define _TIF_WORK_SYSCALL_EXIT	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
-				 _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_TRACEPOINT)
-
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		\
 	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_NOTIFY_RESUME |	\
 	 _TIF_UPROBE | _TIF_NOTIFY_SIGNAL)
-/* work to do on any return to u-space */
-#define _TIF_ALLWORK_MASK	(_TIF_NOHZ | _TIF_WORK_MASK |		\
-				 _TIF_WORK_SYSCALL_EXIT |		\
-				 _TIF_SYSCALL_TRACEPOINT)
 
 /*
  * We stash processor id into a COP0 register to retrieve it fast
diff --git a/arch/mips/include/uapi/asm/ptrace.h b/arch/mips/include/uapi/asm/ptrace.h
index f3c025445e45..27e2c85398bc 100644
--- a/arch/mips/include/uapi/asm/ptrace.h
+++ b/arch/mips/include/uapi/asm/ptrace.h
@@ -102,8 +102,9 @@  struct pt_watch_regs {
 	};
 };
 
-#define PTRACE_GET_WATCH_REGS	0xd0
-#define PTRACE_SET_WATCH_REGS	0xd1
-
+#define PTRACE_SYSEMU			0x1f
+#define PTRACE_SYSEMU_SINGLESTEP	0x20
+#define PTRACE_GET_WATCH_REGS		0xd0
+#define PTRACE_SET_WATCH_REGS		0xd1
 
 #endif /* _UAPI_ASM_PTRACE_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 814b3da30501..44875660f6ae 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -5,10 +5,10 @@ 
 
 extra-y		:= head.o vmlinux.lds
 
-obj-y		+= branch.o cmpxchg.o elf.o entry.o genex.o idle.o irq.o \
-		   process.o prom.o ptrace.o reset.o setup.o signal.o \
-		   syscall.o time.o topology.o traps.o unaligned.o watch.o \
-		   vdso.o cacheinfo.o
+obj-y		+= branch.o cacheinfo.o cmpxchg.o elf.o entry.o genex.o \
+		   idle.o irq.o process.o prom.o ptrace.o reset.o scall.o \
+		   setup.o signal.o syscall.o time.o topology.o traps.o \
+		   unaligned.o watch.o vdso.o
 
 ifdef CONFIG_CPU_R3K_TLB
 obj-y		+= cpu-r3k-probe.o
@@ -76,11 +76,9 @@  obj-$(CONFIG_IRQ_TXX9)		+= irq_txx9.o
 obj-$(CONFIG_IRQ_GT641XX)	+= irq-gt641xx.o
 
 obj-$(CONFIG_KPROBES)		+= kprobes.o
-obj-$(CONFIG_32BIT)		+= scall32-o32.o
-obj-$(CONFIG_64BIT)		+= scall64-n64.o
 obj-$(CONFIG_MIPS32_COMPAT)	+= linux32.o ptrace32.o signal32.o
-obj-$(CONFIG_MIPS32_N32)	+= scall64-n32.o signal_n32.o
-obj-$(CONFIG_MIPS32_O32)	+= scall64-o32.o signal_o32.o
+obj-$(CONFIG_MIPS32_N32)	+= signal_n32.o
+obj-$(CONFIG_MIPS32_O32)	+= signal_o32.o
 
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_PROC_FS)		+= proc.o
diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
index 4b896f5023ff..1a2aec9dab1b 100644
--- a/arch/mips/kernel/entry.S
+++ b/arch/mips/kernel/entry.S
@@ -72,49 +72,32 @@  FEXPORT(ret_from_kernel_thread)
 	jal	schedule_tail		# a0 = struct task_struct *prev
 	move	a0, s1
 	jal	s0
-	j	syscall_exit
+	move	a0, sp
+	jal	syscall_exit_to_user_mode
+
+	.set	noat
+	RESTORE_STATIC
+	RESTORE_SOME
+	RESTORE_SP_AND_RET
+	.set	at
 
 FEXPORT(ret_from_fork)
 	jal	schedule_tail		# a0 = struct task_struct *prev
-
-FEXPORT(syscall_exit)
-#ifdef CONFIG_DEBUG_RSEQ
 	move	a0, sp
-	jal	rseq_syscall
-#endif
-	local_irq_disable		# make sure need_resched and
-					# signals dont change between
-					# sampling and return
-	LONG_L	a2, TI_FLAGS($28)	# current->work
-	li	t0, _TIF_ALLWORK_MASK
-	and	t0, a2, t0
-	bnez	t0, syscall_exit_work
+	jal	syscall_exit_to_user_mode
 
-restore_all:				# restore full frame
 	.set	noat
-	RESTORE_TEMP
-	RESTORE_AT
 	RESTORE_STATIC
-restore_partial:		# restore partial frame
-#ifdef CONFIG_TRACE_IRQFLAGS
-	SAVE_STATIC
-	SAVE_AT
-	SAVE_TEMP
-	LONG_L	v0, PT_STATUS(sp)
-#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
-	and	v0, ST0_IEP
-#else
-	and	v0, ST0_IE
-#endif
-	beqz	v0, 1f
-	jal	trace_hardirqs_on
-	b	2f
-1:	jal	trace_hardirqs_off
-2:
+	RESTORE_SOME
+	RESTORE_SP_AND_RET
+	.set	at
+
+restore_all:				# restore full frame
+	.set	noat
 	RESTORE_TEMP
 	RESTORE_AT
 	RESTORE_STATIC
-#endif
+restore_partial:			# restore partial frame
 	RESTORE_SOME
 	RESTORE_SP_AND_RET
 	.set	at
@@ -143,32 +126,6 @@  work_notifysig:				# deal with pending signals and
 	jal	do_notify_resume	# a2 already loaded
 	j	resume_userspace_check
 
-FEXPORT(syscall_exit_partial)
-#ifdef CONFIG_DEBUG_RSEQ
-	move	a0, sp
-	jal	rseq_syscall
-#endif
-	local_irq_disable		# make sure need_resched doesn't
-					# change between and return
-	LONG_L	a2, TI_FLAGS($28)	# current->work
-	li	t0, _TIF_ALLWORK_MASK
-	and	t0, a2
-	beqz	t0, restore_partial
-	SAVE_STATIC
-syscall_exit_work:
-	LONG_L	t0, PT_STATUS(sp)		# returning to kernel mode?
-	andi	t0, t0, KU_USER
-	beqz	t0, resume_kernel
-	li	t0, _TIF_WORK_SYSCALL_EXIT
-	and	t0, a2			# a2 is preloaded with TI_FLAGS
-	beqz	t0, work_pending	# trace bit set?
-	local_irq_enable		# could let syscall_trace_leave()
-					# call schedule() instead
-	TRACE_IRQS_ON
-	move	a0, sp
-	jal	syscall_trace_leave
-	b	resume_userspace
-
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR5) || \
     defined(CONFIG_CPU_MIPSR6) || defined(CONFIG_MIPS_MT)
 
diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 6b61be486303..2b4b1fc1ff1b 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -38,7 +38,6 @@ 
 #include <net/scm.h>
 
 #include <asm/compat-signal.h>
-#include <asm/sim.h>
 #include <linux/uaccess.h>
 #include <asm/mmu_context.h>
 #include <asm/mman.h>
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index db7c5be1d4a3..04c08e41cfd3 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -46,9 +46,6 @@ 
 #include <asm/bootinfo.h>
 #include <asm/reg.h>
 
-#define CREATE_TRACE_POINTS
-#include <trace/events/syscalls.h>
-
 /*
  * Called by kernel/ptrace.c when detaching..
  *
@@ -1305,78 +1302,3 @@  long arch_ptrace(struct task_struct *child, long request,
  out:
 	return ret;
 }
-
-/*
- * Notification of system call entry/exit
- * - triggered by current->work.syscall_trace
- */
-asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
-{
-	user_exit();
-
-	current_thread_info()->syscall = syscall;
-
-	if (test_thread_flag(TIF_SYSCALL_TRACE)) {
-		if (tracehook_report_syscall_entry(regs))
-			return -1;
-		syscall = current_thread_info()->syscall;
-	}
-
-#ifdef CONFIG_SECCOMP
-	if (unlikely(test_thread_flag(TIF_SECCOMP))) {
-		int ret, i;
-		struct seccomp_data sd;
-		unsigned long args[6];
-
-		sd.nr = syscall;
-		sd.arch = syscall_get_arch(current);
-		syscall_get_arguments(current, regs, args);
-		for (i = 0; i < 6; i++)
-			sd.args[i] = args[i];
-		sd.instruction_pointer = KSTK_EIP(current);
-
-		ret = __secure_computing(&sd);
-		if (ret == -1)
-			return ret;
-		syscall = current_thread_info()->syscall;
-	}
-#endif
-
-	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
-		trace_sys_enter(regs, regs->regs[2]);
-
-	audit_syscall_entry(syscall, regs->regs[4], regs->regs[5],
-			    regs->regs[6], regs->regs[7]);
-
-	/*
-	 * Negative syscall numbers are mistaken for rejected syscalls, but
-	 * won't have had the return value set appropriately, so we do so now.
-	 */
-	if (syscall < 0)
-		syscall_set_return_value(current, regs, -ENOSYS, 0);
-	return syscall;
-}
-
-/*
- * Notification of system call entry/exit
- * - triggered by current->work.syscall_trace
- */
-asmlinkage void syscall_trace_leave(struct pt_regs *regs)
-{
-        /*
-	 * We may come here right after calling schedule_user()
-	 * or do_notify_resume(), in which case we can be in RCU
-	 * user mode.
-	 */
-	user_exit();
-
-	audit_syscall_exit(regs);
-
-	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
-		trace_sys_exit(regs, regs_return_value(regs));
-
-	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		tracehook_report_syscall_exit(regs, 0);
-
-	user_enter();
-}
diff --git a/arch/mips/kernel/scall.S b/arch/mips/kernel/scall.S
new file mode 100644
index 000000000000..fae8d99f0458
--- /dev/null
+++ b/arch/mips/kernel/scall.S
@@ -0,0 +1,137 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01, 02 by Ralf Baechle
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2001 MIPS Technologies, Inc.
+ * Copyright (C) 2004 Thiemo Seufer
+ * Copyright (C) 2014 Imagination Technologies Ltd.
+ */
+#include <linux/errno.h>
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/irqflags.h>
+#include <asm/mipsregs.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/asm-offsets.h>
+#include <asm/sysmips.h>
+#include <asm/thread_info.h>
+#include <asm/unistd.h>
+#include <asm/war.h>
+
+	.align	5
+NESTED(handle_sys, PT_SIZE, sp)
+	.set	noat
+	SAVE_SOME
+	SAVE_STATIC
+	CLI
+	.set	at
+
+	move	a0, sp
+	jal	do_syscall
+	beqz	v0, 1f				# restore all registers?
+	nop
+
+	.set	noat
+	RESTORE_TEMP
+	RESTORE_STATIC
+	RESTORE_AT
+1:	RESTORE_SOME
+	RESTORE_SP_AND_RET
+	.set	at
+	END(handle_sys)
+
+#ifdef CONFIG_32BIT
+LEAF(sys_syscall)
+	subu	t0, a0, __NR_O32_Linux		# check syscall number
+	sltiu	v0, t0, __NR_O32_Linux_syscalls
+	beqz	t0, einval			# do not recurse
+	sll	t1, t0, 2
+	beqz	v0, einval
+	lw	t2, sys_call_table(t1)		# syscall routine
+
+	move	a0, a1				# shift argument registers
+	move	a1, a2
+	move	a2, a3
+	lw	a3, 16(sp)
+	lw	t4, 20(sp)
+	lw	t5, 24(sp)
+	lw	t6, 28(sp)
+	sw	t4, 16(sp)
+	sw	t5, 20(sp)
+	sw	t6, 24(sp)
+	jr	t2
+	/* Unreached */
+
+einval: li	v0, -ENOSYS
+	jr	ra
+	END(sys_syscall)
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+	/*
+	 * For FPU affinity scheduling on MIPS MT processors, we need to
+	 * intercept sys_sched_xxxaffinity() calls until we get a proper hook
+	 * in kernel/sched/core.c.  Considered only temporary we only support
+	 * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
+	 * atm.
+	 */
+#define sys_sched_setaffinity	mipsmt_sys_sched_setaffinity
+#define sys_sched_getaffinity	mipsmt_sys_sched_getaffinity
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
+#define __SYSCALL(nr, entry) 	PTR entry
+	.align	2
+	.type	sys_call_table, @object
+EXPORT(sys_call_table)
+#include <asm/syscall_table_o32.h>
+#endif /* CONFIG_32BIT */
+
+#ifdef CONFIG_64BIT
+#ifdef CONFIG_MIPS32_O32
+LEAF(sys32_syscall)
+	subu	t0, a0, __NR_O32_Linux		# check syscall number
+	sltiu	v0, t0, __NR_O32_Linux_syscalls
+	beqz	t0, einval			# do not recurse
+	dsll	t1, t0, 3
+	beqz	v0, einval
+	ld	t2, sys32_call_table(t1)	# syscall routine
+
+	move	a0, a1				# shift argument registers
+	move	a1, a2
+	move	a2, a3
+	move	a3, a4
+	move	a4, a5
+	move	a5, a6
+	move	a6, a7
+	jr	t2
+	/* Unreached */
+
+einval: li	v0, -ENOSYS
+	jr	ra
+	END(sys32_syscall)
+
+#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
+#define __SYSCALL(nr, entry)	PTR entry
+	.align	3
+	.type	sys32_call_table,@object
+EXPORT(sys32_call_table)
+#include <asm/syscall_table_o32.h>
+#endif /* CONFIG_MIPS32_O32 */
+
+#ifdef CONFIG_MIPS32_N32
+#undef __SYSCALL
+#define __SYSCALL(nr, entry)	PTR entry
+	.align	3
+	.type	sysn32_call_table, @object
+EXPORT(sysn32_call_table)
+#include <asm/syscall_table_n32.h>
+#endif /* CONFIG_MIPS32_N32 */
+
+#undef __SYSCALL
+#define __SYSCALL(nr, entry)	PTR entry
+	.align	3
+	.type	sys_call_table, @object
+EXPORT(sys_call_table)
+#include <asm/syscall_table_n64.h>
+#endif /* CONFIG_64BIT */
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
deleted file mode 100644
index b1b2e106f711..000000000000
--- a/arch/mips/kernel/scall32-o32.S
+++ /dev/null
@@ -1,223 +0,0 @@ 
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1995-99, 2000- 02, 06 Ralf Baechle <[e-mail]>
- * Copyright (C) 2001 MIPS Technologies, Inc.
- * Copyright (C) 2004 Thiemo Seufer
- * Copyright (C) 2014 Imagination Technologies Ltd.
- */
-#include <linux/errno.h>
-#include <asm/asm.h>
-#include <asm/asmmacro.h>
-#include <asm/irqflags.h>
-#include <asm/mipsregs.h>
-#include <asm/regdef.h>
-#include <asm/stackframe.h>
-#include <asm/isadep.h>
-#include <asm/sysmips.h>
-#include <asm/thread_info.h>
-#include <asm/unistd.h>
-#include <asm/war.h>
-#include <asm/asm-offsets.h>
-
-	.align	5
-NESTED(handle_sys, PT_SIZE, sp)
-	.set	noat
-	SAVE_SOME
-	TRACE_IRQS_ON_RELOAD
-	STI
-	.set	at
-
-	lw	t1, PT_EPC(sp)		# skip syscall on return
-
-	addiu	t1, 4			# skip to next instruction
-	sw	t1, PT_EPC(sp)
-
-	sw	a3, PT_R26(sp)		# save a3 for syscall restarting
-
-	/*
-	 * More than four arguments.  Try to deal with it by copying the
-	 * stack arguments from the user stack to the kernel stack.
-	 * This Sucks (TM).
-	 */
-	lw	t0, PT_R29(sp)		# get old user stack pointer
-
-	/*
-	 * We intentionally keep the kernel stack a little below the top of
-	 * userspace so we don't have to do a slower byte accurate check here.
-	 */
-	addu	t4, t0, 32
-	bltz	t4, bad_stack		# -> sp is bad
-
-	/*
-	 * Ok, copy the args from the luser stack to the kernel stack.
-	 */
-
-	.set    push
-	.set    noreorder
-	.set	nomacro
-
-load_a4: user_lw(t5, 16(t0))		# argument #5 from usp
-load_a5: user_lw(t6, 20(t0))		# argument #6 from usp
-load_a6: user_lw(t7, 24(t0))		# argument #7 from usp
-load_a7: user_lw(t8, 28(t0))		# argument #8 from usp
-loads_done:
-
-	sw	t5, 16(sp)		# argument #5 to ksp
-	sw	t6, 20(sp)		# argument #6 to ksp
-	sw	t7, 24(sp)		# argument #7 to ksp
-	sw	t8, 28(sp)		# argument #8 to ksp
-	.set	pop
-
-	.section __ex_table,"a"
-	PTR	load_a4, bad_stack_a4
-	PTR	load_a5, bad_stack_a5
-	PTR	load_a6, bad_stack_a6
-	PTR	load_a7, bad_stack_a7
-	.previous
-
-	lw	t0, TI_FLAGS($28)	# syscall tracing enabled?
-	li	t1, _TIF_WORK_SYSCALL_ENTRY
-	and	t0, t1
-	bnez	t0, syscall_trace_entry # -> yes
-syscall_common:
-	subu	v0, v0, __NR_O32_Linux	# check syscall number
-	sltiu	t0, v0, __NR_O32_Linux_syscalls
-	beqz	t0, illegal_syscall
-
-	sll	t0, v0, 2
-	la	t1, sys_call_table
-	addu	t1, t0
-	lw	t2, (t1)		# syscall routine
-
-	beqz	t2, illegal_syscall
-
-	jalr	t2			# Do The Real Thing (TM)
-
-	li	t0, -EMAXERRNO - 1	# error?
-	sltu	t0, t0, v0
-	sw	t0, PT_R7(sp)		# set error flag
-	beqz	t0, 1f
-
-	lw	t1, PT_R2(sp)		# syscall number
-	negu	v0			# error
-	sw	t1, PT_R0(sp)		# save it for syscall restarting
-1:	sw	v0, PT_R2(sp)		# result
-
-o32_syscall_exit:
-	j	syscall_exit_partial
-
-/* ------------------------------------------------------------------------ */
-
-syscall_trace_entry:
-	SAVE_STATIC
-	move	a0, sp
-
-	/*
-	 * syscall number is in v0 unless we called syscall(__NR_###)
-	 * where the real syscall number is in a0
-	 */
-	move	a1, v0
-	subu	t2, v0,  __NR_O32_Linux
-	bnez	t2, 1f /* __NR_syscall at offset 0 */
-	lw	a1, PT_R4(sp)
-
-1:	jal	syscall_trace_enter
-
-	bltz	v0, 1f			# seccomp failed? Skip syscall
-
-	RESTORE_STATIC
-	lw	v0, PT_R2(sp)		# Restore syscall (maybe modified)
-	lw	a0, PT_R4(sp)		# Restore argument registers
-	lw	a1, PT_R5(sp)
-	lw	a2, PT_R6(sp)
-	lw	a3, PT_R7(sp)
-	j	syscall_common
-
-1:	j	syscall_exit
-
-/* ------------------------------------------------------------------------ */
-
-	/*
-	 * Our open-coded access area sanity test for the stack pointer
-	 * failed. We probably should handle this case a bit more drastic.
-	 */
-bad_stack:
-	li	v0, EFAULT
-	sw	v0, PT_R2(sp)
-	li	t0, 1				# set error flag
-	sw	t0, PT_R7(sp)
-	j	o32_syscall_exit
-
-bad_stack_a4:
-	li	t5, 0
-	b	load_a5
-
-bad_stack_a5:
-	li	t6, 0
-	b	load_a6
-
-bad_stack_a6:
-	li	t7, 0
-	b	load_a7
-
-bad_stack_a7:
-	li	t8, 0
-	b	loads_done
-
-	/*
-	 * The system call does not exist in this kernel
-	 */
-illegal_syscall:
-	li	v0, ENOSYS			# error
-	sw	v0, PT_R2(sp)
-	li	t0, 1				# set error flag
-	sw	t0, PT_R7(sp)
-	j	o32_syscall_exit
-	END(handle_sys)
-
-	LEAF(sys_syscall)
-	subu	t0, a0, __NR_O32_Linux	# check syscall number
-	sltiu	v0, t0, __NR_O32_Linux_syscalls
-	beqz	t0, einval		# do not recurse
-	sll	t1, t0, 2
-	beqz	v0, einval
-	lw	t2, sys_call_table(t1)		# syscall routine
-
-	move	a0, a1				# shift argument registers
-	move	a1, a2
-	move	a2, a3
-	lw	a3, 16(sp)
-	lw	t4, 20(sp)
-	lw	t5, 24(sp)
-	lw	t6, 28(sp)
-	sw	t4, 16(sp)
-	sw	t5, 20(sp)
-	sw	t6, 24(sp)
-	jr	t2
-	/* Unreached */
-
-einval: li	v0, -ENOSYS
-	jr	ra
-	END(sys_syscall)
-
-#ifdef CONFIG_MIPS_MT_FPAFF
-	/*
-	 * For FPU affinity scheduling on MIPS MT processors, we need to
-	 * intercept sys_sched_xxxaffinity() calls until we get a proper hook
-	 * in kernel/sched/core.c.  Considered only temporary we only support
-	 * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
-	 * atm.
-	 */
-#define sys_sched_setaffinity	mipsmt_sys_sched_setaffinity
-#define sys_sched_getaffinity	mipsmt_sys_sched_getaffinity
-#endif /* CONFIG_MIPS_MT_FPAFF */
-
-#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
-#define __SYSCALL(nr, entry) 	PTR entry
-	.align	2
-	.type	sys_call_table, @object
-EXPORT(sys_call_table)
-#include <asm/syscall_table_o32.h>
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
deleted file mode 100644
index f650c55a17dc..000000000000
--- a/arch/mips/kernel/scall64-n32.S
+++ /dev/null
@@ -1,107 +0,0 @@ 
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01 by Ralf Baechle
- * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- * Copyright (C) 2001 MIPS Technologies, Inc.
- */
-#include <linux/errno.h>
-#include <asm/asm.h>
-#include <asm/asmmacro.h>
-#include <asm/irqflags.h>
-#include <asm/mipsregs.h>
-#include <asm/regdef.h>
-#include <asm/stackframe.h>
-#include <asm/thread_info.h>
-#include <asm/unistd.h>
-
-#ifndef CONFIG_MIPS32_O32
-/* No O32, so define handle_sys here */
-#define handle_sysn32 handle_sys
-#endif
-
-	.align	5
-NESTED(handle_sysn32, PT_SIZE, sp)
-#ifndef CONFIG_MIPS32_O32
-	.set	noat
-	SAVE_SOME
-	TRACE_IRQS_ON_RELOAD
-	STI
-	.set	at
-#endif
-
-	dsubu	t0, v0, __NR_N32_Linux	# check syscall number
-	sltiu	t0, t0, __NR_N32_Linux_syscalls
-
-#ifndef CONFIG_MIPS32_O32
-	ld	t1, PT_EPC(sp)		# skip syscall on return
-	daddiu	t1, 4			# skip to next instruction
-	sd	t1, PT_EPC(sp)
-#endif
-	beqz	t0, not_n32_scall
-
-	sd	a3, PT_R26(sp)		# save a3 for syscall restarting
-
-	li	t1, _TIF_WORK_SYSCALL_ENTRY
-	LONG_L	t0, TI_FLAGS($28)	# syscall tracing enabled?
-	and	t0, t1, t0
-	bnez	t0, n32_syscall_trace_entry
-
-syscall_common:
-	dsll	t0, v0, 3		# offset into table
-	ld	t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0)
-
-	jalr	t2			# Do The Real Thing (TM)
-
-	li	t0, -EMAXERRNO - 1	# error?
-	sltu	t0, t0, v0
-	sd	t0, PT_R7(sp)		# set error flag
-	beqz	t0, 1f
-
-	ld	t1, PT_R2(sp)		# syscall number
-	dnegu	v0			# error
-	sd	t1, PT_R0(sp)		# save it for syscall restarting
-1:	sd	v0, PT_R2(sp)		# result
-
-	j	syscall_exit_partial
-
-/* ------------------------------------------------------------------------ */
-
-n32_syscall_trace_entry:
-	SAVE_STATIC
-	move	a0, sp
-	move	a1, v0
-	jal	syscall_trace_enter
-
-	bltz	v0, 1f			# seccomp failed? Skip syscall
-
-	RESTORE_STATIC
-	ld	v0, PT_R2(sp)		# Restore syscall (maybe modified)
-	ld	a0, PT_R4(sp)		# Restore argument registers
-	ld	a1, PT_R5(sp)
-	ld	a2, PT_R6(sp)
-	ld	a3, PT_R7(sp)
-	ld	a4, PT_R8(sp)
-	ld	a5, PT_R9(sp)
-
-	dsubu	t2, v0, __NR_N32_Linux	# check (new) syscall number
-	sltiu   t0, t2, __NR_N32_Linux_syscalls
-	beqz	t0, not_n32_scall
-
-	j	syscall_common
-
-1:	j	syscall_exit
-
-not_n32_scall:
-	/* This is not an n32 compatibility syscall, pass it on to
-	   the n64 syscall handlers.  */
-	j	handle_sys64
-
-	END(handle_sysn32)
-
-#define __SYSCALL(nr, entry)	PTR entry
-	.type	sysn32_call_table, @object
-EXPORT(sysn32_call_table)
-#include <asm/syscall_table_n32.h>
diff --git a/arch/mips/kernel/scall64-n64.S b/arch/mips/kernel/scall64-n64.S
deleted file mode 100644
index 5d7bfc65e4d0..000000000000
--- a/arch/mips/kernel/scall64-n64.S
+++ /dev/null
@@ -1,116 +0,0 @@ 
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1995, 96, 97, 98, 99, 2000, 01, 02 by Ralf Baechle
- * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- * Copyright (C) 2001 MIPS Technologies, Inc.
- */
-#include <linux/errno.h>
-#include <asm/asm.h>
-#include <asm/asmmacro.h>
-#include <asm/irqflags.h>
-#include <asm/mipsregs.h>
-#include <asm/regdef.h>
-#include <asm/stackframe.h>
-#include <asm/asm-offsets.h>
-#include <asm/sysmips.h>
-#include <asm/thread_info.h>
-#include <asm/unistd.h>
-#include <asm/war.h>
-
-#ifndef CONFIG_MIPS32_COMPAT
-/* Neither O32 nor N32, so define handle_sys here */
-#define handle_sys64 handle_sys
-#endif
-
-	.align	5
-NESTED(handle_sys64, PT_SIZE, sp)
-#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
-	/*
-	 * When 32-bit compatibility is configured scall_o32.S
-	 * already did this.
-	 */
-	.set	noat
-	SAVE_SOME
-	TRACE_IRQS_ON_RELOAD
-	STI
-	.set	at
-#endif
-
-#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
-	ld	t1, PT_EPC(sp)		# skip syscall on return
-	daddiu	t1, 4			# skip to next instruction
-	sd	t1, PT_EPC(sp)
-#endif
-
-	sd	a3, PT_R26(sp)		# save a3 for syscall restarting
-
-	li	t1, _TIF_WORK_SYSCALL_ENTRY
-	LONG_L	t0, TI_FLAGS($28)	# syscall tracing enabled?
-	and	t0, t1, t0
-	bnez	t0, syscall_trace_entry
-
-syscall_common:
-	dsubu	t2, v0, __NR_64_Linux
-	sltiu   t0, t2, __NR_64_Linux_syscalls
-	beqz	t0, illegal_syscall
-
-	dsll	t0, t2, 3		# offset into table
-	dla	t2, sys_call_table
-	daddu	t0, t2, t0
-	ld	t2, (t0)		# syscall routine
-	beqz	t2, illegal_syscall
-
-	jalr	t2			# Do The Real Thing (TM)
-
-	li	t0, -EMAXERRNO - 1	# error?
-	sltu	t0, t0, v0
-	sd	t0, PT_R7(sp)		# set error flag
-	beqz	t0, 1f
-
-	ld	t1, PT_R2(sp)		# syscall number
-	dnegu	v0			# error
-	sd	t1, PT_R0(sp)		# save it for syscall restarting
-1:	sd	v0, PT_R2(sp)		# result
-
-n64_syscall_exit:
-	j	syscall_exit_partial
-
-/* ------------------------------------------------------------------------ */
-
-syscall_trace_entry:
-	SAVE_STATIC
-	move	a0, sp
-	move	a1, v0
-	jal	syscall_trace_enter
-
-	bltz	v0, 1f			# seccomp failed? Skip syscall
-
-	RESTORE_STATIC
-	ld	v0, PT_R2(sp)		# Restore syscall (maybe modified)
-	ld	a0, PT_R4(sp)		# Restore argument registers
-	ld	a1, PT_R5(sp)
-	ld	a2, PT_R6(sp)
-	ld	a3, PT_R7(sp)
-	ld	a4, PT_R8(sp)
-	ld	a5, PT_R9(sp)
-	j	syscall_common
-
-1:	j	syscall_exit
-
-illegal_syscall:
-	/* This also isn't a 64-bit syscall, throw an error.  */
-	li	v0, ENOSYS			# error
-	sd	v0, PT_R2(sp)
-	li	t0, 1				# set error flag
-	sd	t0, PT_R7(sp)
-	j	n64_syscall_exit
-	END(handle_sys64)
-
-#define __SYSCALL(nr, entry)	PTR entry
-	.align	3
-	.type	sys_call_table, @object
-EXPORT(sys_call_table)
-#include <asm/syscall_table_n64.h>
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
deleted file mode 100644
index cedc8bd88804..000000000000
--- a/arch/mips/kernel/scall64-o32.S
+++ /dev/null
@@ -1,221 +0,0 @@ 
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1995 - 2000, 2001 by Ralf Baechle
- * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- * Copyright (C) 2001 MIPS Technologies, Inc.
- * Copyright (C) 2004 Thiemo Seufer
- *
- * Hairy, the userspace application uses a different argument passing
- * convention than the kernel, so we have to translate things from o32
- * to ABI64 calling convention.	 64-bit syscalls are also processed
- * here for now.
- */
-#include <linux/errno.h>
-#include <asm/asm.h>
-#include <asm/asmmacro.h>
-#include <asm/irqflags.h>
-#include <asm/mipsregs.h>
-#include <asm/regdef.h>
-#include <asm/stackframe.h>
-#include <asm/thread_info.h>
-#include <asm/unistd.h>
-#include <asm/sysmips.h>
-
-	.align	5
-NESTED(handle_sys, PT_SIZE, sp)
-	.set	noat
-	SAVE_SOME
-	TRACE_IRQS_ON_RELOAD
-	STI
-	.set	at
-	ld	t1, PT_EPC(sp)		# skip syscall on return
-
-	dsubu	t0, v0, __NR_O32_Linux	# check syscall number
-	sltiu	t0, t0, __NR_O32_Linux_syscalls
-	daddiu	t1, 4			# skip to next instruction
-	sd	t1, PT_EPC(sp)
-	beqz	t0, not_o32_scall
-#if 0
- SAVE_ALL
- move a1, v0
- ASM_PRINT("Scall %ld\n")
- RESTORE_ALL
-#endif
-
-	/* We don't want to stumble over broken sign extensions from
-	   userland. O32 does never use the upper half. */
-	sll	a0, a0, 0
-	sll	a1, a1, 0
-	sll	a2, a2, 0
-	sll	a3, a3, 0
-
-	sd	a3, PT_R26(sp)		# save a3 for syscall restarting
-
-	/*
-	 * More than four arguments.  Try to deal with it by copying the
-	 * stack arguments from the user stack to the kernel stack.
-	 * This Sucks (TM).
-	 *
-	 * We intentionally keep the kernel stack a little below the top of
-	 * userspace so we don't have to do a slower byte accurate check here.
-	 */
-	ld	t0, PT_R29(sp)		# get old user stack pointer
-	daddu	t1, t0, 32
-	bltz	t1, bad_stack
-
-load_a4: lw	a4, 16(t0)		# argument #5 from usp
-load_a5: lw	a5, 20(t0)		# argument #6 from usp
-load_a6: lw	a6, 24(t0)		# argument #7 from usp
-load_a7: lw	a7, 28(t0)		# argument #8 from usp
-loads_done:
-
-	.section __ex_table,"a"
-	PTR	load_a4, bad_stack_a4
-	PTR	load_a5, bad_stack_a5
-	PTR	load_a6, bad_stack_a6
-	PTR	load_a7, bad_stack_a7
-	.previous
-
-	li	t1, _TIF_WORK_SYSCALL_ENTRY
-	LONG_L	t0, TI_FLAGS($28)	# syscall tracing enabled?
-	and	t0, t1, t0
-	bnez	t0, trace_a_syscall
-
-syscall_common:
-	dsll	t0, v0, 3		# offset into table
-	ld	t2, (sys32_call_table - (__NR_O32_Linux * 8))(t0)
-
-	jalr	t2			# Do The Real Thing (TM)
-
-	li	t0, -EMAXERRNO - 1	# error?
-	sltu	t0, t0, v0
-	sd	t0, PT_R7(sp)		# set error flag
-	beqz	t0, 1f
-
-	ld	t1, PT_R2(sp)		# syscall number
-	dnegu	v0			# error
-	sd	t1, PT_R0(sp)		# save it for syscall restarting
-1:	sd	v0, PT_R2(sp)		# result
-
-o32_syscall_exit:
-	j	syscall_exit_partial
-
-/* ------------------------------------------------------------------------ */
-
-trace_a_syscall:
-	SAVE_STATIC
-	sd	a4, PT_R8(sp)		# Save argument registers
-	sd	a5, PT_R9(sp)
-	sd	a6, PT_R10(sp)
-	sd	a7, PT_R11(sp)		# For indirect syscalls
-
-	move	a0, sp
-	/*
-	 * absolute syscall number is in v0 unless we called syscall(__NR_###)
-	 * where the real syscall number is in a0
-	 * note: NR_syscall is the first O32 syscall but the macro is
-	 * only defined when compiling with -mabi=32 (CONFIG_32BIT)
-	 * therefore __NR_O32_Linux is used (4000)
-	 */
-	.set	push
-	.set	reorder
-	subu	t1, v0,  __NR_O32_Linux
-	move	a1, v0
-	bnez	t1, 1f /* __NR_syscall at offset 0 */
-	ld	a1, PT_R4(sp) /* Arg1 for __NR_syscall case */
-	.set	pop
-
-1:	jal	syscall_trace_enter
-
-	bltz	v0, 1f			# seccomp failed? Skip syscall
-
-	RESTORE_STATIC
-	ld	v0, PT_R2(sp)		# Restore syscall (maybe modified)
-	ld	a0, PT_R4(sp)		# Restore argument registers
-	ld	a1, PT_R5(sp)
-	ld	a2, PT_R6(sp)
-	ld	a3, PT_R7(sp)
-	ld	a4, PT_R8(sp)
-	ld	a5, PT_R9(sp)
-	ld	a6, PT_R10(sp)
-	ld	a7, PT_R11(sp)		# For indirect syscalls
-
-	dsubu	t0, v0, __NR_O32_Linux	# check (new) syscall number
-	sltiu	t0, t0, __NR_O32_Linux_syscalls
-	beqz	t0, not_o32_scall
-
-	j	syscall_common
-
-1:	j	syscall_exit
-
-/* ------------------------------------------------------------------------ */
-
-	/*
-	 * The stackpointer for a call with more than 4 arguments is bad.
-	 */
-bad_stack:
-	li	v0, EFAULT
-	sd	v0, PT_R2(sp)
-	li	t0, 1			# set error flag
-	sd	t0, PT_R7(sp)
-	j	o32_syscall_exit
-
-bad_stack_a4:
-	li	a4, 0
-	b	load_a5
-
-bad_stack_a5:
-	li	a5, 0
-	b	load_a6
-
-bad_stack_a6:
-	li	a6, 0
-	b	load_a7
-
-bad_stack_a7:
-	li	a7, 0
-	b	loads_done
-
-not_o32_scall:
-	/*
-	 * This is not an o32 compatibility syscall, pass it on
-	 * to the 64-bit syscall handlers.
-	 */
-#ifdef CONFIG_MIPS32_N32
-	j	handle_sysn32
-#else
-	j	handle_sys64
-#endif
-	END(handle_sys)
-
-LEAF(sys32_syscall)
-	subu	t0, a0, __NR_O32_Linux	# check syscall number
-	sltiu	v0, t0, __NR_O32_Linux_syscalls
-	beqz	t0, einval		# do not recurse
-	dsll	t1, t0, 3
-	beqz	v0, einval
-	ld	t2, sys32_call_table(t1)		# syscall routine
-
-	move	a0, a1			# shift argument registers
-	move	a1, a2
-	move	a2, a3
-	move	a3, a4
-	move	a4, a5
-	move	a5, a6
-	move	a6, a7
-	jr	t2
-	/* Unreached */
-
-einval: li	v0, -ENOSYS
-	jr	ra
-	END(sys32_syscall)
-
-#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
-#define __SYSCALL(nr, entry)	PTR entry
-	.align	3
-	.type	sys32_call_table,@object
-EXPORT(sys32_call_table)
-#include <asm/syscall_table_o32.h>
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index c9b2a75563e1..314a6ffa0e07 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -32,7 +32,6 @@ 
 #include <linux/bitops.h>
 #include <asm/cacheflush.h>
 #include <asm/fpu.h>
-#include <asm/sim.h>
 #include <asm/ucontext.h>
 #include <asm/cpu-features.h>
 #include <asm/war.h>
@@ -627,7 +626,7 @@  SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 #endif
 
 #ifdef CONFIG_TRAD_SIGNALS
-asmlinkage void sys_sigreturn(void)
+asmlinkage long sys_sigreturn(void)
 {
 	struct sigframe __user *frame;
 	struct pt_regs *regs;
@@ -649,22 +648,17 @@  asmlinkage void sys_sigreturn(void)
 	else if (sig)
 		force_sig(sig);
 
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-		"move\t$29, %0\n\t"
-		"j\tsyscall_exit"
-		: /* no outputs */
-		: "r" (regs));
-	/* Unreached */
+	regs->regs[0] = 0;	/* No syscall restarting */
+	regs->regs[27] = 1;	/* return directly */
+	return regs->regs[2];
 
 badframe:
 	force_sig(SIGSEGV);
+	return 0;
 }
 #endif /* CONFIG_TRAD_SIGNALS */
 
-asmlinkage void sys_rt_sigreturn(void)
+asmlinkage long sys_rt_sigreturn(void)
 {
 	struct rt_sigframe __user *frame;
 	struct pt_regs *regs;
@@ -686,21 +680,16 @@  asmlinkage void sys_rt_sigreturn(void)
 	else if (sig)
 		force_sig(sig);
 
+	regs->regs[0] = 0;	/* No syscall restarting */
 	if (restore_altstack(&frame->rs_uc.uc_stack))
 		goto badframe;
 
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-		"move\t$29, %0\n\t"
-		"j\tsyscall_exit"
-		: /* no outputs */
-		: "r" (regs));
-	/* Unreached */
+	regs->regs[27] = 1;	/* return directly */
+	return regs->regs[2];
 
 badframe:
 	force_sig(SIGSEGV);
+	return 0;
 }
 
 #ifdef CONFIG_TRAD_SIGNALS
@@ -852,11 +841,11 @@  static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	signal_setup_done(ret, ksig, 0);
 }
 
-static void do_signal(struct pt_regs *regs)
+void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
 {
 	struct ksignal ksig;
 
-	if (get_signal(&ksig)) {
+	if (has_signal && get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.	*/
 		handle_signal(&ksig, regs);
 		return;
@@ -904,7 +893,7 @@  asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 
 	/* deal with pending signal delivery */
 	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
-		do_signal(regs);
+		arch_do_signal_or_restart(regs, thread_info_flags & _TIF_SIGPENDING);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
 		tracehook_notify_resume(regs);
diff --git a/arch/mips/kernel/signal_n32.c b/arch/mips/kernel/signal_n32.c
index 7bd00fad61af..e282f14747d2 100644
--- a/arch/mips/kernel/signal_n32.c
+++ b/arch/mips/kernel/signal_n32.c
@@ -19,7 +19,6 @@ 
 #include <asm/asm.h>
 #include <asm/cacheflush.h>
 #include <asm/compat-signal.h>
-#include <asm/sim.h>
 #include <linux/uaccess.h>
 #include <asm/ucontext.h>
 #include <asm/fpu.h>
@@ -51,7 +50,7 @@  struct rt_sigframe_n32 {
 	struct ucontextn32 rs_uc;
 };
 
-asmlinkage void sysn32_rt_sigreturn(void)
+asmlinkage long sysn32_rt_sigreturn(void)
 {
 	struct rt_sigframe_n32 __user *frame;
 	struct pt_regs *regs;
@@ -73,21 +72,16 @@  asmlinkage void sysn32_rt_sigreturn(void)
 	else if (sig)
 		force_sig(sig);
 
+	regs->regs[0] = 0;	/* No syscall restarting */
 	if (compat_restore_altstack(&frame->rs_uc.uc_stack))
 		goto badframe;
 
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-		"move\t$29, %0\n\t"
-		"j\tsyscall_exit"
-		: /* no outputs */
-		: "r" (regs));
-	/* Unreached */
+	regs->regs[27] = 1;	/* return directly */
+	return regs->regs[2];
 
 badframe:
 	force_sig(SIGSEGV);
+	return 0;
 }
 
 static int setup_rt_frame_n32(void *sig_return, struct ksignal *ksig,
diff --git a/arch/mips/kernel/signal_o32.c b/arch/mips/kernel/signal_o32.c
index 299a7a28ca33..ea6d12dd15cc 100644
--- a/arch/mips/kernel/signal_o32.c
+++ b/arch/mips/kernel/signal_o32.c
@@ -17,7 +17,6 @@ 
 #include <asm/abi.h>
 #include <asm/compat-signal.h>
 #include <asm/dsp.h>
-#include <asm/sim.h>
 #include <asm/unistd.h>
 
 #include "signal-common.h"
@@ -151,7 +150,7 @@  static int setup_frame_32(void *sig_return, struct ksignal *ksig,
 	return 0;
 }
 
-asmlinkage void sys32_rt_sigreturn(void)
+asmlinkage long sys32_rt_sigreturn(void)
 {
 	struct rt_sigframe32 __user *frame;
 	struct pt_regs *regs;
@@ -173,21 +172,16 @@  asmlinkage void sys32_rt_sigreturn(void)
 	else if (sig)
 		force_sig(sig);
 
+	regs->regs[0] = 0;	/* No syscall restarting */
 	if (compat_restore_altstack(&frame->rs_uc.uc_stack))
 		goto badframe;
 
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-		"move\t$29, %0\n\t"
-		"j\tsyscall_exit"
-		: /* no outputs */
-		: "r" (regs));
-	/* Unreached */
+	regs->regs[27] = 1;	/* return directly */
+	return regs->regs[2];
 
 badframe:
 	force_sig(SIGSEGV);
+	return 0;
 }
 
 static int setup_rt_frame_32(void *sig_return, struct ksignal *ksig,
@@ -253,7 +247,7 @@  struct mips_abi mips_abi_32 = {
 };
 
 
-asmlinkage void sys32_sigreturn(void)
+asmlinkage long sys32_sigreturn(void)
 {
 	struct sigframe32 __user *frame;
 	struct pt_regs *regs;
@@ -275,16 +269,11 @@  asmlinkage void sys32_sigreturn(void)
 	else if (sig)
 		force_sig(sig);
 
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-		"move\t$29, %0\n\t"
-		"j\tsyscall_exit"
-		: /* no outputs */
-		: "r" (regs));
-	/* Unreached */
+	regs->regs[0] = 0;	/* No syscall restarting */
+	regs->regs[27] = 1;	/* return directly */
+	return regs->regs[2];
 
 badframe:
 	force_sig(SIGSEGV);
+	return 0;
 }
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 2afa3eef486a..2653f82a8c99 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -8,6 +8,7 @@ 
  * Copyright (C) 2001 MIPS Technologies, Inc.
  */
 #include <linux/capability.h>
+#include <linux/entry-common.h>
 #include <linux/errno.h>
 #include <linux/linkage.h>
 #include <linux/fs.h>
@@ -35,9 +36,9 @@ 
 #include <asm/cacheflush.h>
 #include <asm/asm-offsets.h>
 #include <asm/signal.h>
-#include <asm/sim.h>
 #include <asm/shmparam.h>
 #include <asm/sync.h>
+#include <asm/syscall.h>
 #include <asm/sysmips.h>
 #include <asm/switch_to.h>
 
@@ -79,10 +80,6 @@  SYSCALL_DEFINE6(mips_mmap2, unsigned long, addr, unsigned long, len,
 			       pgoff >> (PAGE_SHIFT - 12));
 }
 
-save_static_function(sys_fork);
-save_static_function(sys_clone);
-save_static_function(sys_clone3);
-
 SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
 {
 	struct thread_info *ti = task_thread_info(current);
@@ -182,28 +179,11 @@  static inline int mips_atomic_set(unsigned long addr, unsigned long new)
 		return err;
 
 	regs = current_pt_regs();
-	regs->regs[2] = old;
-	regs->regs[7] = 0;	/* No error */
-
-	/*
-	 * Don't let your children do this ...
-	 */
-	__asm__ __volatile__(
-	"	move	$29, %0						\n"
-	"	j	syscall_exit					\n"
-	: /* no outputs */
-	: "r" (regs));
-
-	/* unreached.  Honestly.  */
-	unreachable();
+	regs->regs[7] = 0;	/* no error */
+	regs->regs[27] = 1;	/* return directly */
+	return old;
 }
 
-/*
- * mips_atomic_set() normally returns directly via syscall_exit potentially
- * clobbering static registers, so be sure to preserve them.
- */
-save_static_function(sys_sysmips);
-
 SYSCALL_DEFINE3(sysmips, long, cmd, long, arg1, long, arg2)
 {
 	switch (cmd) {
@@ -249,3 +229,121 @@  asmlinkage void bad_stack(void)
 {
 	do_exit(SIGSEGV);
 }
+
+#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
+static inline int get_args(struct pt_regs *regs)
+{
+	int *usp = (int *)regs->regs[29];
+
+#ifdef CONFIG_MIPS32_O32
+	/*
+	 * Hairy, the userspace application uses a different argument passing
+	 * convention than the kernel, so we have to translate things from o32
+	 * to ABI64 calling convention.
+	 *
+	 * We don't want to stumble over broken sign extensions from userland.
+	 * O32 does never use the upper half.
+	 */
+	regs->regs[4] = (int)regs->regs[4];
+	regs->regs[5] = (int)regs->regs[5];
+	regs->regs[6] = (int)regs->regs[6];
+	regs->regs[7] = (int)regs->regs[7];
+#endif
+
+	/*
+	 * More than four arguments.  Try to deal with it by copying the
+	 * stack arguments from the user stack to the kernel stack.
+	 * This Sucks (TM).
+	 *
+	 * We intentionally keep the kernel stack a little below the top of
+	 * userspace so we don't have to do a slower byte accurate check here.
+	 */
+	if (!access_ok(usp, 32))
+		return -1;
+
+	get_user(regs->regs[8], usp + 4);
+	get_user(regs->regs[9], usp + 5);
+	get_user(regs->regs[10], usp + 6);
+	get_user(regs->regs[11], usp + 7);
+
+	return 0;
+}
+#endif
+
+typedef long (*sys_call_fn)(unsigned long, unsigned long,
+	unsigned long, unsigned long, unsigned long, unsigned long);
+
+long noinstr do_syscall(struct pt_regs *regs)
+{
+	unsigned long nr;
+	unsigned long ret;
+	sys_call_fn syscall_fn = NULL;
+
+	nr = regs->regs[2];
+	current_thread_info()->syscall = nr;
+	nr = syscall_enter_from_user_mode(regs, nr);
+
+	regs->cp0_epc += 4;		/* skip syscall on return */
+					/* skip to next instruction */
+	regs->regs[26] = regs->regs[7];	/* save a3 for syscall restarting */
+	regs->regs[27] = 0;		/* do not return directly */
+
+#ifdef CONFIG_32BIT
+	if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls) {
+		if (get_args(regs) < 0) {
+			ret = EFAULT;
+			goto error;
+		}
+		syscall_fn = (sys_call_fn)sys_call_table[nr - __NR_O32_Linux];
+	}
+#endif
+
+#ifdef CONFIG_MIPS32_O32
+	if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls) {
+		if (get_args(regs) < 0) {
+			ret = EFAULT;
+			goto error;
+		}
+		syscall_fn = (sys_call_fn)sys32_call_table[nr - __NR_O32_Linux];
+	}
+#endif
+
+#ifdef CONFIG_MIPS32_N32
+	if (nr >= __NR_N32_Linux && nr < __NR_N32_Linux + __NR_N32_Linux_syscalls)
+		syscall_fn = (sys_call_fn)sysn32_call_table[nr - __NR_N32_Linux];
+#endif
+
+#ifdef CONFIG_64BIT
+	if (nr >= __NR_64_Linux && nr < __NR_64_Linux + __NR_64_Linux_syscalls)
+		syscall_fn = (sys_call_fn)sys_call_table[nr - __NR_64_Linux];
+#endif
+
+	if (unlikely(!syscall_fn)) {
+		ret = ENOSYS;
+		goto error;
+	}
+
+	ret = syscall_fn(regs->regs[4], regs->regs[5], regs->regs[6],
+			 regs->regs[7], regs->regs[8], regs->regs[9]);
+
+	if (regs->regs[27])		/* return directly? */
+		goto out;
+
+	regs->regs[7] = 0;		/* clear error flag */
+	if (ret >= -EMAXERRNO - 1) {	/* error? */
+		regs->regs[0] = nr;	/* save syscall number */
+					/* for syscall restarting */
+		ret = -ret;
+		goto error;
+	}
+
+	goto out;
+
+error:
+	regs->regs[7] = 1;		/* set error flag */
+
+out:
+	regs->regs[2] = ret;
+	syscall_exit_to_user_mode(regs);
+	return regs->regs[27];
+}
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index 70e32de2bcaa..d9ae765e51f1 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -62,8 +62,8 @@ 
 52	n32	socketpair			sys_socketpair
 53	n32	setsockopt			sys_setsockopt
 54	n32	getsockopt			sys_getsockopt
-55	n32	clone				__sys_clone
-56	n32	fork				__sys_fork
+55	n32	clone				sys_clone
+56	n32	fork				sys_fork
 57	n32	execve				compat_sys_execve
 58	n32	exit				sys_exit
 59	n32	wait4				compat_sys_wait4
@@ -207,7 +207,7 @@ 
 196	n32	sched_getaffinity		compat_sys_sched_getaffinity
 197	n32	cacheflush			sys_cacheflush
 198	n32	cachectl			sys_cachectl
-199	n32	sysmips				__sys_sysmips
+199	n32	sysmips				sys_sysmips
 200	n32	io_setup			compat_sys_io_setup
 201	n32	io_destroy			sys_io_destroy
 202	n32	io_getevents			sys_io_getevents_time32
@@ -373,7 +373,7 @@ 
 432	n32	fsmount				sys_fsmount
 433	n32	fspick				sys_fspick
 434	n32	pidfd_open			sys_pidfd_open
-435	n32	clone3				__sys_clone3
+435	n32	clone3				sys_clone3
 436	n32	close_range			sys_close_range
 437	n32	openat2				sys_openat2
 438	n32	pidfd_getfd			sys_pidfd_getfd
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
index 1ca7bc337932..edec3e82d67a 100644
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -62,8 +62,8 @@ 
 52	n64	socketpair			sys_socketpair
 53	n64	setsockopt			sys_setsockopt
 54	n64	getsockopt			sys_getsockopt
-55	n64	clone				__sys_clone
-56	n64	fork				__sys_fork
+55	n64	clone				sys_clone
+56	n64	fork				sys_fork
 57	n64	execve				sys_execve
 58	n64	exit				sys_exit
 59	n64	wait4				sys_wait4
@@ -207,7 +207,7 @@ 
 196	n64	sched_getaffinity		sys_sched_getaffinity
 197	n64	cacheflush			sys_cacheflush
 198	n64	cachectl			sys_cachectl
-199	n64	sysmips				__sys_sysmips
+199	n64	sysmips				sys_sysmips
 200	n64	io_setup			sys_io_setup
 201	n64	io_destroy			sys_io_destroy
 202	n64	io_getevents			sys_io_getevents
@@ -349,7 +349,7 @@ 
 432	n64	fsmount				sys_fsmount
 433	n64	fspick				sys_fspick
 434	n64	pidfd_open			sys_pidfd_open
-435	n64	clone3				__sys_clone3
+435	n64	clone3				sys_clone3
 436	n64	close_range			sys_close_range
 437	n64	openat2				sys_openat2
 438	n64	pidfd_getfd			sys_pidfd_getfd
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index a61c35edaa74..89a1f267da6a 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -9,7 +9,7 @@ 
 #
 0	o32	syscall				sys_syscall			sys32_syscall
 1	o32	exit				sys_exit
-2	o32	fork				__sys_fork
+2	o32	fork				sys_fork
 3	o32	read				sys_read
 4	o32	write				sys_write
 5	o32	open				sys_open			compat_sys_open
@@ -131,7 +131,7 @@ 
 117	o32	ipc				sys_ipc				compat_sys_ipc
 118	o32	fsync				sys_fsync
 119	o32	sigreturn			sys_sigreturn			sys32_sigreturn
-120	o32	clone				__sys_clone
+120	o32	clone				sys_clone
 121	o32	setdomainname			sys_setdomainname
 122	o32	uname				sys_newuname
 123	o32	modify_ldt			sys_ni_syscall
@@ -160,7 +160,7 @@ 
 146	o32	writev				sys_writev
 147	o32	cacheflush			sys_cacheflush
 148	o32	cachectl			sys_cachectl
-149	o32	sysmips				__sys_sysmips
+149	o32	sysmips				sys_sysmips
 150	o32	unused150			sys_ni_syscall
 151	o32	getsid				sys_getsid
 152	o32	fdatasync			sys_fdatasync
@@ -422,7 +422,7 @@ 
 432	o32	fsmount				sys_fsmount
 433	o32	fspick				sys_fspick
 434	o32	pidfd_open			sys_pidfd_open
-435	o32	clone3				__sys_clone3
+435	o32	clone3				sys_clone3
 436	o32	close_range			sys_close_range
 437	o32	openat2				sys_openat2
 438	o32	pidfd_getfd			sys_pidfd_getfd