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Wed, 22 Jan 2025 14:56:59 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2f7e6aaf3b4sm2301375a91.25.2025.01.22.14.56.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jan 2025 14:56:58 -0800 (PST) From: Charlie Jenkins Date: Wed, 22 Jan 2025 14:56:22 -0800 Subject: [PATCH 3/4] loongarch: entry: Migrate ret_from_fork() to C MIME-Version: 1.0 Message-Id: <20250122-riscv_optimize_entry-v1-3-4ee95559cfd0@rivosinc.com> References: <20250122-riscv_optimize_entry-v1-0-4ee95559cfd0@rivosinc.com> In-Reply-To: <20250122-riscv_optimize_entry-v1-0-4ee95559cfd0@rivosinc.com> To: Paul Walmsley , Palmer Dabbelt , Huacai Chen , WANG Xuerui , Thomas Gleixner , Peter Zijlstra , Andy Lutomirski , Alexandre Ghiti Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, Charlie Jenkins X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5559; i=charlie@rivosinc.com; h=from:subject:message-id; bh=IfDjpWzOkJ2hu8S0SjhggOry7IIgS+knXj7qp/i1XMU=; b=owGbwMvMwCXWx5hUnlvL8Y3xtFoSQ/rE8i1dL+OOSYp8qL2mJrSGk+0H5+f2Kp+Pe9jq1j479 X6Zw93yjlIWBjEuBlkxRRaeaw3MrXf0y46Klk2AmcPKBDKEgYtTACbS58XwP8BkwY7+lm9r70p9 PBS5f82H6nUbnypMbNbf1X3B77b6BXlGhvWh9sl8e+4IHvqc9LB/msHdqb4Hds7b5PnpRYe+W/a WgzwA X-Developer-Key: i=charlie@rivosinc.com; a=openpgp; fpr=7D834FF11B1D8387E61C776FFB10D1F27D6B1354 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250122_145659_693402_06679931 X-CRM114-Status: GOOD ( 11.93 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Loongarch is the only architecture that calls syscall_exit_to_user_mode() from asm. Move the call into C so that this function can be inlined across all architectures. Signed-off-by: Charlie Jenkins --- arch/loongarch/include/asm/switch_to.h | 8 ++++++++ arch/loongarch/kernel/entry.S | 22 ++++++++++----------- arch/loongarch/kernel/process.c | 36 ++++++++++++++++++++++++++++------ 3 files changed, 48 insertions(+), 18 deletions(-) diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h index 5b225aff3ba21aa06d0713bc8e73e1b941389630..a1c5576f1fd145670e13038bec6dd390486099ab 100644 --- a/arch/loongarch/include/asm/switch_to.h +++ b/arch/loongarch/include/asm/switch_to.h @@ -26,6 +26,14 @@ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next, struct thread_info *next_ti, void *sched_ra, void *sched_cfa); +void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev, + struct pt_regs *regs, + int (*fn)(void *), + void *fn_arg); + +void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev, + struct pt_regs *regs); + /* * For newly created kernel threads switch_to() will return to * ret_from_kernel_thread, newly created user threads to ret_from_fork. diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S index 48e7e34e355e83eae8165957ba2eac05a8bf17df..2abc29e573810e000f2fef4646ddca0dbb80eabe 100644 --- a/arch/loongarch/kernel/entry.S +++ b/arch/loongarch/kernel/entry.S @@ -77,24 +77,22 @@ SYM_CODE_START(handle_syscall) SYM_CODE_END(handle_syscall) _ASM_NOKPROBE(handle_syscall) -SYM_CODE_START(ret_from_fork) +SYM_CODE_START(ret_from_fork_asm) UNWIND_HINT_REGS - bl schedule_tail # a0 = struct task_struct *prev - move a0, sp - bl syscall_exit_to_user_mode + move a1, sp + bl ret_from_fork RESTORE_STATIC RESTORE_SOME RESTORE_SP_AND_RET -SYM_CODE_END(ret_from_fork) +SYM_CODE_END(ret_from_fork_asm) -SYM_CODE_START(ret_from_kernel_thread) +SYM_CODE_START(ret_from_kernel_thread_asm) UNWIND_HINT_REGS - bl schedule_tail # a0 = struct task_struct *prev - move a0, s1 - jirl ra, s0, 0 - move a0, sp - bl syscall_exit_to_user_mode + move a1, sp + move a2, s0 + move a3, s1 + bl ret_from_kernel_thread RESTORE_STATIC RESTORE_SOME RESTORE_SP_AND_RET -SYM_CODE_END(ret_from_kernel_thread) +SYM_CODE_END(ret_from_kernel_thread_asm) diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c index 6e58f65455c7ca3eae2e88ed852c8655a6701e5c..9bb069ef363fefed1f2115e6572b31c2b76bb414 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -47,6 +48,7 @@ #include #include #include +#include #include #include @@ -63,8 +65,12 @@ EXPORT_SYMBOL(__stack_chk_guard); unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; EXPORT_SYMBOL(boot_option_idle_override); -asmlinkage void ret_from_fork(void); -asmlinkage void ret_from_kernel_thread(void); +asmlinkage void restore_and_ret(void); +asmlinkage void ret_from_fork_asm(void); +void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev, + struct pt_regs *regs, + int (*fn)(void *), + void *fn_arg) void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) { @@ -138,6 +144,24 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } +void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev, + struct pt_regs *regs, + int (*fn)(void *), + void *fn_arg) +{ + schedule_tail(prev); + + fn(fn_arg); + + syscall_exit_to_user_mode(regs); +} + +void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev, struct pt_regs *regs) +{ + schedule_tail(prev); + syscall_exit_to_user_mode(regs); +} + /* * Copy architecture-specific thread state */ @@ -165,8 +189,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.reg03 = childksp; p->thread.reg23 = (unsigned long)args->fn; p->thread.reg24 = (unsigned long)args->fn_arg; - p->thread.reg01 = (unsigned long)ret_from_kernel_thread; - p->thread.sched_ra = (unsigned long)ret_from_kernel_thread; + p->thread.reg01 = (unsigned long)ret_from_kernel_thread_asm; + p->thread.sched_ra = (unsigned long)ret_from_kernel_thread_asm; memset(childregs, 0, sizeof(struct pt_regs)); childregs->csr_euen = p->thread.csr_euen; childregs->csr_crmd = p->thread.csr_crmd; @@ -182,8 +206,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) childregs->regs[3] = usp; p->thread.reg03 = (unsigned long) childregs; - p->thread.reg01 = (unsigned long) ret_from_fork; - p->thread.sched_ra = (unsigned long) ret_from_fork; + p->thread.reg01 = (unsigned long) ret_from_fork_asm; + p->thread.sched_ra = (unsigned long) ret_from_fork_asm; /* * New tasks lose permission to use the fpu. This accelerates context