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Wed, 05 Mar 2025 16:44:07 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22410a7f7efsm347085ad.132.2025.03.05.16.44.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Mar 2025 16:44:06 -0800 (PST) From: Charlie Jenkins Date: Wed, 05 Mar 2025 16:43:44 -0800 Subject: [PATCH v5 1/4] riscv: entry: Convert ret_from_fork() to C MIME-Version: 1.0 Message-Id: <20250305-riscv_optimize_entry-v5-1-6507b5dff3ce@rivosinc.com> References: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@rivosinc.com> In-Reply-To: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@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=3515; i=charlie@rivosinc.com; h=from:subject:message-id; bh=gaq/v9YuAdYAHAPq6G2li6XLwEhlQb1rcc0R86FQKSc=; b=owGbwMvMwCXWx5hUnlvL8Y3xtFoSQ/qJ95cmmFbUVL2sO39dKoPRMmj9pzsX2Qs+M8168p73+ VOJGWfbO0pZGMS4GGTFFFl4rjUwt97RLzsqWjYBZg4rE8gQBi5OAZhI7VFGhsfPeK/yBc58PmH/ xAU9hi8Wqni+fhxzylBn0evACz3GjdwMv9mKOK8wLMzQEsx4Ob15ef/Hi1oMOlvuvJux01vD0Td nMhcA 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-20250305_164408_100106_3E63E7E5 X-CRM114-Status: GOOD ( 11.74 ) 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 Move the main section of ret_from_fork() to C to allow inlining of syscall_exit_to_user_mode(). Signed-off-by: Charlie Jenkins Reviewed-by: Alexandre Ghiti --- arch/riscv/include/asm/asm-prototypes.h | 1 + arch/riscv/kernel/entry.S | 15 ++++++--------- arch/riscv/kernel/process.c | 14 ++++++++++++-- 3 files changed, 19 insertions(+), 11 deletions(-) diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index cd627ec289f163a630b73dd03dd52a6b28692997..733ff609778797001006c33bba9e3cc5b1f15387 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -52,6 +52,7 @@ DECLARE_DO_ERROR_INFO(do_trap_ecall_s); DECLARE_DO_ERROR_INFO(do_trap_ecall_m); DECLARE_DO_ERROR_INFO(do_trap_break); +asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs); asmlinkage void handle_bad_stack(struct pt_regs *regs); asmlinkage void do_page_fault(struct pt_regs *regs); asmlinkage void do_irq(struct pt_regs *regs); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 33a5a9f2a0d4e1eeccfb3621b9e518b88e1b0704..b2dc5e7c7b3a843fa4aa02eba2a911eb3ce31d1f 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -319,17 +319,14 @@ SYM_CODE_END(handle_kernel_stack_overflow) ASM_NOKPROBE(handle_kernel_stack_overflow) #endif -SYM_CODE_START(ret_from_fork) +SYM_CODE_START(ret_from_fork_asm) call schedule_tail - beqz s0, 1f /* not from kernel thread */ - /* Call fn(arg) */ - move a0, s1 - jalr s0 -1: - move a0, sp /* pt_regs */ - call syscall_exit_to_user_mode + move a0, s1 /* fn_arg */ + move a1, s0 /* fn */ + move a2, sp /* pt_regs */ + call ret_from_fork j ret_from_exception -SYM_CODE_END(ret_from_fork) +SYM_CODE_END(ret_from_fork_asm) #ifdef CONFIG_IRQ_STACKS /* diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 7c244de7718008947075357ea4502d56419d507c..7b0a0bfe29aec896c2bdd8976d855dd390de88d7 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -17,7 +17,9 @@ #include #include #include +#include +#include #include #include #include @@ -36,7 +38,7 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif -extern asmlinkage void ret_from_fork(void); +extern asmlinkage void ret_from_fork_asm(void); void noinstr arch_cpu_idle(void) { @@ -206,6 +208,14 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } +asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) +{ + if (unlikely(fn)) + fn(fn_arg); + + syscall_exit_to_user_mode(regs); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { unsigned long clone_flags = args->flags; @@ -242,7 +252,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.riscv_v_flags = 0; if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); - p->thread.ra = (unsigned long)ret_from_fork; + p->thread.ra = (unsigned long)ret_from_fork_asm; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; } From patchwork Thu Mar 6 00:43:45 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Charlie Jenkins X-Patchwork-Id: 14003677 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CA396C28B25 for ; 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Wed, 05 Mar 2025 16:44:08 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22410a7f7efsm347085ad.132.2025.03.05.16.44.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Mar 2025 16:44:08 -0800 (PST) From: Charlie Jenkins Date: Wed, 05 Mar 2025 16:43:45 -0800 Subject: [PATCH v5 2/4] riscv: entry: Split ret_from_fork() into user and kernel MIME-Version: 1.0 Message-Id: <20250305-riscv_optimize_entry-v5-2-6507b5dff3ce@rivosinc.com> References: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@rivosinc.com> In-Reply-To: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@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=4464; i=charlie@rivosinc.com; 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However that imposed a performance degradation. Partially reverting this commit to have ret_from_fork() split again results in a 1% increase on the number of times fork is able to be called per second. Signed-off-by: Charlie Jenkins --- arch/riscv/include/asm/asm-prototypes.h | 3 ++- arch/riscv/kernel/entry.S | 13 ++++++++++--- arch/riscv/kernel/process.c | 17 +++++++++++------ 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index 733ff609778797001006c33bba9e3cc5b1f15387..bfc8ea5f9319b19449ec59493b45b926df888832 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -52,7 +52,8 @@ DECLARE_DO_ERROR_INFO(do_trap_ecall_s); DECLARE_DO_ERROR_INFO(do_trap_ecall_m); DECLARE_DO_ERROR_INFO(do_trap_break); -asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs); +asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs); +asmlinkage void ret_from_fork_user(struct pt_regs *regs); asmlinkage void handle_bad_stack(struct pt_regs *regs); asmlinkage void do_page_fault(struct pt_regs *regs); asmlinkage void do_irq(struct pt_regs *regs); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index b2dc5e7c7b3a843fa4aa02eba2a911eb3ce31d1f..0fb338000c6dc0358742cd03497fa54b9e9d1aec 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -319,14 +319,21 @@ SYM_CODE_END(handle_kernel_stack_overflow) ASM_NOKPROBE(handle_kernel_stack_overflow) #endif -SYM_CODE_START(ret_from_fork_asm) +SYM_CODE_START(ret_from_fork_kernel_asm) call schedule_tail move a0, s1 /* fn_arg */ move a1, s0 /* fn */ move a2, sp /* pt_regs */ - call ret_from_fork + call ret_from_fork_kernel j ret_from_exception -SYM_CODE_END(ret_from_fork_asm) +SYM_CODE_END(ret_from_fork_kernel_asm) + +SYM_CODE_START(ret_from_fork_user_asm) + call schedule_tail + move a0, sp /* pt_regs */ + call ret_from_fork_user + j ret_from_exception +SYM_CODE_END(ret_from_fork_user_asm) #ifdef CONFIG_IRQ_STACKS /* diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 7b0a0bfe29aec896c2bdd8976d855dd390de88d7..485ec7a80a56097e8905cd6395af29633846b5c8 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -38,7 +38,8 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif -extern asmlinkage void ret_from_fork_asm(void); +extern asmlinkage void ret_from_fork_kernel_asm(void); +extern asmlinkage void ret_from_fork_user_asm(void); void noinstr arch_cpu_idle(void) { @@ -208,14 +209,18 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } -asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) +asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) { - if (unlikely(fn)) - fn(fn_arg); + fn(fn_arg); syscall_exit_to_user_mode(regs); } +asmlinkage void ret_from_fork_user(struct pt_regs *regs) +{ + syscall_exit_to_user_mode(regs); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { unsigned long clone_flags = args->flags; @@ -238,6 +243,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.s[0] = (unsigned long)args->fn; p->thread.s[1] = (unsigned long)args->fn_arg; + p->thread.ra = (unsigned long)ret_from_fork_kernel_asm; } else { *childregs = *(current_pt_regs()); /* Turn off status.VS */ @@ -247,12 +253,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) if (clone_flags & CLONE_SETTLS) childregs->tp = tls; childregs->a0 = 0; /* Return value of fork() */ - p->thread.s[0] = 0; + p->thread.ra = (unsigned long)ret_from_fork_user_asm; } p->thread.riscv_v_flags = 0; if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); - p->thread.ra = (unsigned long)ret_from_fork_asm; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; } From patchwork Thu Mar 6 00:43:46 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Charlie Jenkins X-Patchwork-Id: 14003678 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C3361C28B22 for ; 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Wed, 05 Mar 2025 16:44:10 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22410a7f7efsm347085ad.132.2025.03.05.16.44.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Mar 2025 16:44:09 -0800 (PST) From: Charlie Jenkins Date: Wed, 05 Mar 2025 16:43:46 -0800 Subject: [PATCH v5 3/4] LoongArch: entry: Migrate ret_from_fork() to C MIME-Version: 1.0 Message-Id: <20250305-riscv_optimize_entry-v5-3-6507b5dff3ce@rivosinc.com> References: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@rivosinc.com> In-Reply-To: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@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=5547; i=charlie@rivosinc.com; h=from:subject:message-id; bh=ji6jPR39ZKDby+guv8CCAiBLyKbpGz9Kynms9BH9fJU=; b=owGbwMvMwCXWx5hUnlvL8Y3xtFoSQ/qJ95ePTzBvvzPfOaKeK9gkZ6GPsf20tfcCnKo13u4KZ LworCLQUcrCIMbFICumyMJzrYG59Y5+2VHRsgkwc1iZQIYwcHEKwETSrjEyXF0Ud+RJZLCFOkfG I+4SH97LUxlbNP/rrNyTuuCCQeD5Gob/abeMBayufysUjl2cYcByfGvR7nPRXyd+OcZXxRJx4OZ 2HgA= 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-20250305_164410_956074_1609AD48 X-CRM114-Status: GOOD ( 10.56 ) 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/asm-prototypes.h | 8 +++++++ arch/loongarch/kernel/entry.S | 22 +++++++++---------- arch/loongarch/kernel/process.c | 33 +++++++++++++++++++++++------ 3 files changed, 45 insertions(+), 18 deletions(-) diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 51f224bcfc654228ae423e9a066b25b35102a5b9..704066b4f7368be15be960fadbcd6c2574bbf6c0 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -12,3 +12,11 @@ __int128_t __ashlti3(__int128_t a, int b); __int128_t __ashrti3(__int128_t a, int b); __int128_t __lshrti3(__int128_t a, int b); #endif + +asmlinkage void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev, + struct pt_regs *regs); + +asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev, + struct pt_regs *regs, + int (*fn)(void *), + void *fn_arg); 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..98bc60d7c550fcc0225e8452f81a7d6cd7888015 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -33,6 +34,7 @@ #include #include +#include #include #include #include @@ -47,6 +49,7 @@ #include #include #include +#include #include #include @@ -63,8 +66,9 @@ 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); +asmlinkage void ret_from_kernel_thread_asm(void); void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) { @@ -138,6 +142,23 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } +asmlinkage 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); +} + +asmlinkage 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); +} + /* * Copy architecture-specific thread state */ @@ -165,8 +186,8 @@ 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 +203,8 @@ 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. 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Wed, 05 Mar 2025 16:44:11 -0800 (PST) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22410a7f7efsm347085ad.132.2025.03.05.16.44.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Mar 2025 16:44:11 -0800 (PST) From: Charlie Jenkins Date: Wed, 05 Mar 2025 16:43:47 -0800 Subject: [PATCH v5 4/4] entry: Inline syscall_exit_to_user_mode() MIME-Version: 1.0 Message-Id: <20250305-riscv_optimize_entry-v5-4-6507b5dff3ce@rivosinc.com> References: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@rivosinc.com> In-Reply-To: <20250305-riscv_optimize_entry-v5-0-6507b5dff3ce@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=5141; i=charlie@rivosinc.com; h=from:subject:message-id; bh=j7ZO4FXV1Hf14yiJt7JLsFHCp0FLrXbd7xunBuFQ9j8=; b=owGbwMvMwCXWx5hUnlvL8Y3xtFoSQ/qJ95d9ndq3LQ44de6FoLjnP4Wflp+6lvkeeNEuvN8vl k/soW5mRykLgxgXg6yYIgvPtQbm1jv6ZUdFyybAzGFlAhnCwMUpABNRWMDIsEH+59MDmer/fzAU vvxYZjyFw/HQm6w1f54Er/xks8PGu5mRoa1Us0Hzc7CdgfrJc8aZ75wz9rt7hrUu4uo1/VOqxcH FAQA= 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-20250305_164412_643027_9C909E5B X-CRM114-Status: GOOD ( 14.66 ) 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 Architectures using the generic entry code can be optimized by having syscall_exit_to_user_mode inlined. Signed-off-by: Charlie Jenkins Reviewed-by: Alexandre Ghiti --- include/linux/entry-common.h | 43 ++++++++++++++++++++++++++++++++++++-- kernel/entry/common.c | 49 +------------------------------------------- 2 files changed, 42 insertions(+), 50 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index fc61d0205c97084acc89c8e45e088946f5e6d9b2..f94f3fdf15fc0091223cc9f7b823970302e67312 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -14,6 +14,7 @@ #include #include +#include /* * Define dummy _TIF work flags if not defined by the architecture or for @@ -366,6 +367,15 @@ static __always_inline void exit_to_user_mode(void) lockdep_hardirqs_on(CALLER_ADDR0); } +/** + * syscall_exit_work - Handle work before returning to user mode + * @regs: Pointer to current pt_regs + * @work: Current thread syscall work + * + * Do one-time syscall specific work. + */ +void syscall_exit_work(struct pt_regs *regs, unsigned long work); + /** * syscall_exit_to_user_mode_work - Handle work before returning to user mode * @regs: Pointer to currents pt_regs @@ -379,7 +389,30 @@ static __always_inline void exit_to_user_mode(void) * make the final state transitions. Interrupts must stay disabled between * return from this function and the invocation of exit_to_user_mode(). */ -void syscall_exit_to_user_mode_work(struct pt_regs *regs); +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +{ + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); + unsigned long nr = syscall_get_nr(current, regs); + + CT_WARN_ON(ct_state() != CT_STATE_KERNEL); + + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { + if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr)) + local_irq_enable(); + } + + rseq_syscall(regs); + + /* + * Do one-time syscall specific work. If these work items are + * enabled, we want to run them exactly once per syscall exit with + * interrupts enabled. + */ + if (unlikely(work & SYSCALL_WORK_EXIT)) + syscall_exit_work(regs, work); + local_irq_disable_exit_to_user(); + exit_to_user_mode_prepare(regs); +} /** * syscall_exit_to_user_mode - Handle work before returning to user mode @@ -410,7 +443,13 @@ void syscall_exit_to_user_mode_work(struct pt_regs *regs); * exit_to_user_mode(). This function is preferred unless there is a * compelling architectural reason to use the separate functions. */ -void syscall_exit_to_user_mode(struct pt_regs *regs); +static __always_inline void syscall_exit_to_user_mode(struct pt_regs *regs) +{ + instrumentation_begin(); + syscall_exit_to_user_mode_work(regs); + instrumentation_end(); + exit_to_user_mode(); +} /** * irqentry_enter_from_user_mode - Establish state before invoking the irq handler diff --git a/kernel/entry/common.c b/kernel/entry/common.c index e33691d5adf7aab4af54cf2bf8e5ef5bd6ad1424..f55e421fb196dd5f9d4e34dd85ae096c774cf879 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -146,7 +146,7 @@ static inline bool report_single_step(unsigned long work) return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; } -static void syscall_exit_work(struct pt_regs *regs, unsigned long work) +void syscall_exit_work(struct pt_regs *regs, unsigned long work) { bool step; @@ -173,53 +173,6 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long work) ptrace_report_syscall_exit(regs, step); } -/* - * Syscall specific exit to user mode preparation. Runs with interrupts - * enabled. - */ -static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) -{ - unsigned long work = READ_ONCE(current_thread_info()->syscall_work); - unsigned long nr = syscall_get_nr(current, regs); - - CT_WARN_ON(ct_state() != CT_STATE_KERNEL); - - if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { - if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr)) - local_irq_enable(); - } - - rseq_syscall(regs); - - /* - * Do one-time syscall specific work. If these work items are - * enabled, we want to run them exactly once per syscall exit with - * interrupts enabled. - */ - if (unlikely(work & SYSCALL_WORK_EXIT)) - syscall_exit_work(regs, work); -} - -static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs) -{ - syscall_exit_to_user_mode_prepare(regs); - local_irq_disable_exit_to_user(); - exit_to_user_mode_prepare(regs); -} - -void syscall_exit_to_user_mode_work(struct pt_regs *regs) -{ - __syscall_exit_to_user_mode_work(regs); -} - -__visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs) -{ - instrumentation_begin(); - __syscall_exit_to_user_mode_work(regs); - instrumentation_end(); - exit_to_user_mode(); -} - noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs) { enter_from_user_mode(regs);