| Message ID | 20220921214439.1491510-8-stillson@rivosinc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v12,01/17] riscv: Rename __switch_to_aux -> fpu | expand |
On 9/21/22 14:43, Chris Stillson wrote: > From: Greentime Hu <greentime.hu@sifive.com> > > This patch adds task switch support for vector. It supports partial lazy > save and restore mechanism. It also supports all lengths of vlen. > > [guoren@linux.alibaba.com: First available porting to support vector > context switching] > [nick.knight@sifive.com: Rewrite vector.S to support dynamic vlen, xlen and > code refine] > [vincent.chen@sifive.com: Fix the might_sleep issue in vstate_save, > vstate_restore] > [andrew@sifive.com: Optimize task switch codes of vector] > [ruinland.tsai@sifive.com: Fix the arch_release_task_struct free wrong > datap issue] > > Suggested-by: Andrew Waterman <andrew@sifive.com> > Co-developed-by: Nick Knight <nick.knight@sifive.com> > Signed-off-by: Nick Knight <nick.knight@sifive.com> > Co-developed-by: Guo Ren <guoren@linux.alibaba.com> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > Co-developed-by: Vincent Chen <vincent.chen@sifive.com> > Signed-off-by: Vincent Chen <vincent.chen@sifive.com> > Co-developed-by: Ruinland Tsai <ruinland.tsai@sifive.com> > Signed-off-by: Ruinland Tsai <ruinland.tsai@sifive.com> > Signed-off-by: Greentime Hu <greentime.hu@sifive.com> > Reported-by: kernel test robot <lkp@intel.com> > Reported-by: kernel test robot <lkp@intel.com> > --- > arch/riscv/include/asm/switch_to.h | 66 ++++++++++++++++++++++++++++++ > arch/riscv/kernel/Makefile | 1 + > arch/riscv/kernel/process.c | 43 +++++++++++++++++++ > 3 files changed, 110 insertions(+) > > diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h > index df1aa589b7fd..527951c033d4 100644 > --- a/arch/riscv/include/asm/switch_to.h > +++ b/arch/riscv/include/asm/switch_to.h > @@ -7,11 +7,13 @@ > #define _ASM_RISCV_SWITCH_TO_H > > #include <linux/jump_label.h> > +#include <linux/slab.h> > #include <linux/sched/task_stack.h> > #include <asm/hwcap.h> > #include <asm/processor.h> > #include <asm/ptrace.h> > #include <asm/csr.h> > +#include <asm/asm-offsets.h> > > #ifdef CONFIG_FPU > extern void __fstate_save(struct task_struct *save_to); > @@ -68,6 +70,68 @@ static __always_inline bool has_fpu(void) { return false; } > #define __switch_to_fpu(__prev, __next) do { } while (0) > #endif > > +#ifdef CONFIG_VECTOR > +extern struct static_key_false cpu_hwcap_vector; > +static __always_inline bool has_vector(void) > +{ > + return static_branch_likely(&cpu_hwcap_vector); > +} > +extern unsigned long riscv_vsize; > +extern void __vstate_save(struct __riscv_v_state *save_to, void *datap); > +extern void __vstate_restore(struct __riscv_v_state *restore_from, void *datap); > + > +static inline void __vstate_clean(struct pt_regs *regs) > +{ > + regs->status = (regs->status & ~(SR_VS)) | SR_VS_CLEAN; > +} > + > +static inline void vstate_off(struct task_struct *task, > + struct pt_regs *regs) > +{ > + regs->status = (regs->status & ~SR_VS) | SR_VS_OFF; > +} > + > +static inline void vstate_save(struct task_struct *task, > + struct pt_regs *regs) > +{ > + if ((regs->status & SR_VS) == SR_VS_DIRTY) { > + struct __riscv_v_state *vstate = &(task->thread.vstate); > + > + __vstate_save(vstate, vstate->datap); > + __vstate_clean(regs); > + } > +} > + > +static inline void vstate_restore(struct task_struct *task, > + struct pt_regs *regs) > +{ > + if ((regs->status & SR_VS) != SR_VS_OFF) { > + struct __riscv_v_state *vstate = &(task->thread.vstate); > + > + __vstate_restore(vstate, vstate->datap); > + __vstate_clean(regs); > + } > +} > + > +static inline void __switch_to_vector(struct task_struct *prev, > + struct task_struct *next) > +{ > + struct pt_regs *regs; > + > + regs = task_pt_regs(prev); > + if (unlikely(regs->status & SR_SD)) > + vstate_save(prev, regs); > + vstate_restore(next, task_pt_regs(next)); > +} > + > +#else > +static __always_inline bool has_vector(void) { return false; } > +#define riscv_vsize (0) > +#define vstate_save(task, regs) do { } while (0) > +#define vstate_restore(task, regs) do { } while (0) > +#define __switch_to_vector(__prev, __next) do { } while (0) > +#endif All of this needs to be moved into vector.h for better containment. I would also wire in struct __riscv_v_state vstate in struct thread_struct in this patch. > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > index 33bb60a354cd..35752fb6d145 100644 > --- a/arch/riscv/kernel/Makefile > +++ b/arch/riscv/kernel/Makefile > @@ -55,6 +55,7 @@ obj-$(CONFIG_MMU) += vdso.o vdso/ > > obj-$(CONFIG_RISCV_M_MODE) += traps_misaligned.o > obj-$(CONFIG_FPU) += fpu.o > +obj-$(CONFIG_VECTOR) += vector.o This needs to go into last patch which adds Kconfig/Makefile enabling. > + > + if (has_vector()) { Would it make sense to add IS_ENABLED(CONFIG_VECTOR) inside this helper - would help compiler remove the codegen completely for !VECTOR but still having some build test coverage. Anyhow this is minor point and can be added later. > + struct __riscv_v_state *vstate = &(current->thread.vstate); > + > + /* Enable vector and allocate memory for vector registers. */ > + if (!vstate->datap) { > + vstate->datap = kzalloc(riscv_vsize, GFP_KERNEL); > + if (WARN_ON(!vstate->datap)) > + return; > + } > + regs->status |= SR_VS_INITIAL; > + > + /* > + * Restore the initial value to the vector register > + * before starting the user program. > + */ > + vstate_restore(current, regs); > + } > + ... > +#ifdef CONFIG_VECTOR > + /* Reset vector state */ > + vstate_off(current, task_pt_regs(current)); > + memset(¤t->thread.vstate, 0, RISCV_V_STATE_DATAP); > +#endif This doesn't check has_vector() as we want to unconditionally clean memory for security reasons ? > } > > int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) > { > fstate_save(src, task_pt_regs(src)); > *dst = *src; > + dst->thread.vstate.datap = NULL; has_vector() needed here ? > > +void arch_release_task_struct(struct task_struct *tsk) > +{ > + /* Free the vector context of datap. */ > + if (has_vector() && tsk->thread.vstate.datap) > + kfree(tsk->thread.vstate.datap); > +} > + > int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) > { > unsigned long clone_flags = args->flags; > @@ -175,7 +208,17 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) > p->thread.ra = (unsigned long)ret_from_kernel_thread; > p->thread.s[0] = (unsigned long)args->fn; > p->thread.s[1] = (unsigned long)args->fn_arg; > + p->thread.vstate.datap = NULL; > } else { > + /* Allocate the datap for the user process if datap is NULL */ > + if (has_vector() && !p->thread.vstate.datap) { > + void *datap = kzalloc(riscv_vsize, GFP_KERNEL); > + /* Failed to allocate memory. */ > + if (!datap) > + return -ENOMEM; > + p->thread.vstate.datap = datap; > + memset(&p->thread.vstate, 0, RISCV_V_STATE_DATAP); > + } > *childregs = *(current_pt_regs()); > if (usp) /* User fork */ > childregs->sp = usp;
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index df1aa589b7fd..527951c033d4 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -7,11 +7,13 @@ #define _ASM_RISCV_SWITCH_TO_H #include <linux/jump_label.h> +#include <linux/slab.h> #include <linux/sched/task_stack.h> #include <asm/hwcap.h> #include <asm/processor.h> #include <asm/ptrace.h> #include <asm/csr.h> +#include <asm/asm-offsets.h> #ifdef CONFIG_FPU extern void __fstate_save(struct task_struct *save_to); @@ -68,6 +70,68 @@ static __always_inline bool has_fpu(void) { return false; } #define __switch_to_fpu(__prev, __next) do { } while (0) #endif +#ifdef CONFIG_VECTOR +extern struct static_key_false cpu_hwcap_vector; +static __always_inline bool has_vector(void) +{ + return static_branch_likely(&cpu_hwcap_vector); +} +extern unsigned long riscv_vsize; +extern void __vstate_save(struct __riscv_v_state *save_to, void *datap); +extern void __vstate_restore(struct __riscv_v_state *restore_from, void *datap); + +static inline void __vstate_clean(struct pt_regs *regs) +{ + regs->status = (regs->status & ~(SR_VS)) | SR_VS_CLEAN; +} + +static inline void vstate_off(struct task_struct *task, + struct pt_regs *regs) +{ + regs->status = (regs->status & ~SR_VS) | SR_VS_OFF; +} + +static inline void vstate_save(struct task_struct *task, + struct pt_regs *regs) +{ + if ((regs->status & SR_VS) == SR_VS_DIRTY) { + struct __riscv_v_state *vstate = &(task->thread.vstate); + + __vstate_save(vstate, vstate->datap); + __vstate_clean(regs); + } +} + +static inline void vstate_restore(struct task_struct *task, + struct pt_regs *regs) +{ + if ((regs->status & SR_VS) != SR_VS_OFF) { + struct __riscv_v_state *vstate = &(task->thread.vstate); + + __vstate_restore(vstate, vstate->datap); + __vstate_clean(regs); + } +} + +static inline void __switch_to_vector(struct task_struct *prev, + struct task_struct *next) +{ + struct pt_regs *regs; + + regs = task_pt_regs(prev); + if (unlikely(regs->status & SR_SD)) + vstate_save(prev, regs); + vstate_restore(next, task_pt_regs(next)); +} + +#else +static __always_inline bool has_vector(void) { return false; } +#define riscv_vsize (0) +#define vstate_save(task, regs) do { } while (0) +#define vstate_restore(task, regs) do { } while (0) +#define __switch_to_vector(__prev, __next) do { } while (0) +#endif + extern struct task_struct *__switch_to(struct task_struct *, struct task_struct *); @@ -77,6 +141,8 @@ do { \ struct task_struct *__next = (next); \ if (has_fpu()) \ __switch_to_fpu(__prev, __next); \ + if (has_vector()) \ + __switch_to_vector(__prev, __next); \ ((last) = __switch_to(__prev, __next)); \ } while (0) diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 33bb60a354cd..35752fb6d145 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -55,6 +55,7 @@ obj-$(CONFIG_MMU) += vdso.o vdso/ obj-$(CONFIG_RISCV_M_MODE) += traps_misaligned.o obj-$(CONFIG_FPU) += fpu.o +obj-$(CONFIG_VECTOR) += vector.o obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += cpu_ops.o diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index ceb9ebab6558..e88a37fc77ed 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -124,6 +124,25 @@ void start_thread(struct pt_regs *regs, unsigned long pc, */ fstate_restore(current, regs); } + + if (has_vector()) { + struct __riscv_v_state *vstate = &(current->thread.vstate); + + /* Enable vector and allocate memory for vector registers. */ + if (!vstate->datap) { + vstate->datap = kzalloc(riscv_vsize, GFP_KERNEL); + if (WARN_ON(!vstate->datap)) + return; + } + regs->status |= SR_VS_INITIAL; + + /* + * Restore the initial value to the vector register + * before starting the user program. + */ + vstate_restore(current, regs); + } + regs->epc = pc; regs->sp = sp; @@ -148,15 +167,29 @@ void flush_thread(void) fstate_off(current, task_pt_regs(current)); memset(¤t->thread.fstate, 0, sizeof(current->thread.fstate)); #endif +#ifdef CONFIG_VECTOR + /* Reset vector state */ + vstate_off(current, task_pt_regs(current)); + memset(¤t->thread.vstate, 0, RISCV_V_STATE_DATAP); +#endif } int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { fstate_save(src, task_pt_regs(src)); *dst = *src; + dst->thread.vstate.datap = NULL; + return 0; } +void arch_release_task_struct(struct task_struct *tsk) +{ + /* Free the vector context of datap. */ + if (has_vector() && tsk->thread.vstate.datap) + kfree(tsk->thread.vstate.datap); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { unsigned long clone_flags = args->flags; @@ -175,7 +208,17 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.ra = (unsigned long)ret_from_kernel_thread; p->thread.s[0] = (unsigned long)args->fn; p->thread.s[1] = (unsigned long)args->fn_arg; + p->thread.vstate.datap = NULL; } else { + /* Allocate the datap for the user process if datap is NULL */ + if (has_vector() && !p->thread.vstate.datap) { + void *datap = kzalloc(riscv_vsize, GFP_KERNEL); + /* Failed to allocate memory. */ + if (!datap) + return -ENOMEM; + p->thread.vstate.datap = datap; + memset(&p->thread.vstate, 0, RISCV_V_STATE_DATAP); + } *childregs = *(current_pt_regs()); if (usp) /* User fork */ childregs->sp = usp;