[PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user

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* [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode()
@ 2025-01-28  5:33 Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 1/4] riscv: entry: Convert ret_from_fork() to C Charlie Jenkins
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Charlie Jenkins @ 2025-01-28  5:33 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Huacai Chen, WANG Xuerui,
	Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, loongarch, Charlie Jenkins

Similar to commit 221a164035fd ("entry: Move
syscall_enter_from_user_mode() to header file"), move
syscall_exit_to_user_mode() to the header file as well.

Testing was done with the byte-unixbench [1] syscall benchmark (which
calls getpid) and QEMU. On riscv I measured a 7.09246% improvement, on
x86 a 2.98843% improvement, on loongarch a 6.07954% improvement, and on
s390 a 11.1328% improvement.

Since this is on QEMU, I know these numbers are not perfect, but they
show a trend of general improvement across all architectures that use
the generic entry code.

[1] https://github.com/kdlucas/byte-unixbench

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
Changes in v4:
- I had messed up warning for ct_state() on rebase, correct that issue
- Link to v3: https://lore.kernel.org/r/20250124-riscv_optimize_entry-v3-0-869f36b9e43b@rivosinc.com

Changes in v3:
- Fixup comment to properly reflect args (Alex)
- Fix prototypes for loongarch (Huacai)
- Link to v2: https://lore.kernel.org/r/20250123-riscv_optimize_entry-v2-0-7c259492d508@rivosinc.com

Changes in v2:
- Fixup compilation issues for loongarch
- Fixup compilation issues with CONFIG_CONTEXT_TRACKING_USER
- Link to v1: https://lore.kernel.org/r/20250122-riscv_optimize_entry-v1-0-4ee95559cfd0@rivosinc.com

---
Charlie Jenkins (4):
      riscv: entry: Convert ret_from_fork() to C
      riscv: entry: Split ret_from_fork() into user and kernel
      LoongArch: entry: Migrate ret_from_fork() to C
      entry: Inline syscall_exit_to_user_mode()

 arch/loongarch/include/asm/asm-prototypes.h |  8 +++++
 arch/loongarch/kernel/entry.S               | 22 ++++++-------
 arch/loongarch/kernel/process.c             | 33 +++++++++++++++----
 arch/riscv/include/asm/asm-prototypes.h     |  2 ++
 arch/riscv/kernel/entry.S                   | 20 +++++++-----
 arch/riscv/kernel/process.c                 | 21 +++++++++++--
 include/linux/entry-common.h                | 43 +++++++++++++++++++++++--
 kernel/entry/common.c                       | 49 +----------------------------
 8 files changed, 119 insertions(+), 79 deletions(-)
---
base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04
change-id: 20240402-riscv_optimize_entry-583843420325
-- 
- Charlie


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^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH v4 1/4] riscv: entry: Convert ret_from_fork() to C
  2025-01-28  5:33 [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
@ 2025-01-28  5:33 ` Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 2/4] riscv: entry: Split ret_from_fork() into user and kernel Charlie Jenkins
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 6+ messages in thread
From: Charlie Jenkins @ 2025-01-28  5:33 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Huacai Chen, WANG Xuerui,
	Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, loongarch, Charlie Jenkins

Move the main section of ret_from_fork() to C to allow inlining of
syscall_exit_to_user_mode().

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 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 58b6482c2bf662bf5224ca50c8e21a68760a6b41..0d07e6d8f6b57beba438dbba5e8c74a014582bee 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -17,7 +17,9 @@
 #include <linux/ptrace.h>
 #include <linux/uaccess.h>
 #include <linux/personality.h>
+#include <linux/entry-common.h>
 
+#include <asm/asm-prototypes.h>
 #include <asm/unistd.h>
 #include <asm/processor.h>
 #include <asm/csr.h>
@@ -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())
 		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;
 }

-- 
2.43.0


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^ permalink raw reply related	[flat|nested] 6+ messages in thread

* [PATCH v4 2/4] riscv: entry: Split ret_from_fork() into user and kernel
  2025-01-28  5:33 [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 1/4] riscv: entry: Convert ret_from_fork() to C Charlie Jenkins
@ 2025-01-28  5:33 ` Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 3/4] LoongArch: entry: Migrate ret_from_fork() to C Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode() Charlie Jenkins
  3 siblings, 0 replies; 6+ messages in thread
From: Charlie Jenkins @ 2025-01-28  5:33 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Huacai Chen, WANG Xuerui,
	Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, loongarch, Charlie Jenkins

This function was unified into a single function in commit ab9164dae273
("riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork").
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 <charlie@rivosinc.com>
---
 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 0d07e6d8f6b57beba438dbba5e8c74a014582bee..5f15236cb526bd9fe61636ed372b4b76c94df946 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())
 		riscv_v_thread_alloc(p);
-	p->thread.ra = (unsigned long)ret_from_fork_asm;
 	p->thread.sp = (unsigned long)childregs; /* kernel sp */
 	return 0;
 }

-- 
2.43.0


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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* [PATCH v4 3/4] LoongArch: entry: Migrate ret_from_fork() to C
  2025-01-28  5:33 [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 1/4] riscv: entry: Convert ret_from_fork() to C Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 2/4] riscv: entry: Split ret_from_fork() into user and kernel Charlie Jenkins
@ 2025-01-28  5:33 ` Charlie Jenkins
  2025-01-28  5:33 ` [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode() Charlie Jenkins
  3 siblings, 0 replies; 6+ messages in thread
From: Charlie Jenkins @ 2025-01-28  5:33 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Huacai Chen, WANG Xuerui,
	Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, loongarch, Charlie Jenkins

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 <charlie@rivosinc.com>
---
 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 <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
+#include <linux/entry-common.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
@@ -33,6 +34,7 @@
 #include <linux/prctl.h>
 #include <linux/nmi.h>
 
+#include <asm/asm-prototypes.h>
 #include <asm/asm.h>
 #include <asm/bootinfo.h>
 #include <asm/cpu.h>
@@ -47,6 +49,7 @@
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/reg.h>
+#include <asm/switch_to.h>
 #include <asm/unwind.h>
 #include <asm/vdso.h>
 
@@ -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. This accelerates context

-- 
2.43.0


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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode()
  2025-01-28  5:33 [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
                   ` (2 preceding siblings ...)
  2025-01-28  5:33 ` [PATCH v4 3/4] LoongArch: entry: Migrate ret_from_fork() to C Charlie Jenkins
@ 2025-01-28  5:33 ` Charlie Jenkins
  2025-02-05  8:13   ` kernel test robot
  3 siblings, 1 reply; 6+ messages in thread
From: Charlie Jenkins @ 2025-01-28  5:33 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Huacai Chen, WANG Xuerui,
	Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, loongarch, Charlie Jenkins

Architectures using the generic entry code can be optimized by having
syscall_exit_to_user_mode inlined.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 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 <linux/kmsan.h>
 
 #include <asm/entry-common.h>
+#include <asm/syscall.h>
 
 /*
  * 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);

-- 
2.43.0


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^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode()
  2025-01-28  5:33 ` [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode() Charlie Jenkins
@ 2025-02-05  8:13   ` kernel test robot
  0 siblings, 0 replies; 6+ messages in thread
From: kernel test robot @ 2025-02-05  8:13 UTC (permalink / raw)
  To: Charlie Jenkins
  Cc: oe-lkp, lkp, linux-kernel, Paul Walmsley, Palmer Dabbelt,
	Huacai Chen, WANG Xuerui, Thomas Gleixner, Peter Zijlstra,
	Andy Lutomirski, Alexandre Ghiti, linux-riscv, loongarch,
	Charlie Jenkins, oliver.sang



Hello,

kernel test robot noticed a 1.9% improvement of stress-ng.seek.ops_per_sec on:


commit: c1bc35dd5bf6c7fa86a936a4fbe3b8d92fbf8641 ("[PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode()")
url: https://github.com/intel-lab-lkp/linux/commits/Charlie-Jenkins/riscv-entry-Convert-ret_from_fork-to-C/20250128-133636
patch link: https://lore.kernel.org/all/20250127-riscv_optimize_entry-v4-4-868cf7702dc9@rivosinc.com/
patch subject: [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode()

testcase: stress-ng
config: x86_64-rhel-9.4
compiler: gcc-12
test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory
parameters:

	nr_threads: 100%
	testtime: 60s
	test: seek
	cpufreq_governor: performance


In addition to that, the commit also has significant impact on the following tests:

+------------------+--------------------------------------------------------------------------------+
| testcase: change | stress-ng: stress-ng.context.swapcontext_calls_per_sec 1.9% improvement        |
| test machine     | 384 threads 2 sockets Intel(R) Xeon(R) 6972P (Granite Rapids) with 128G memory |
| test parameters  | cpufreq_governor=performance                                                   |
|                  | nr_threads=100%                                                                |
|                  | test=context                                                                   |
|                  | testtime=60s                                                                   |
+------------------+--------------------------------------------------------------------------------+




Details are as below:
-------------------------------------------------------------------------------------------------->


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250205/202502051555.85ae6844-lkp@intel.com

=========================================================================================
compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
  gcc-12/performance/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/lkp-icl-2sp8/seek/stress-ng/60s

commit: 
  37c1871b51 ("LoongArch: entry: Migrate ret_from_fork() to C")
  c1bc35dd5b ("entry: Inline syscall_exit_to_user_mode()")

37c1871b51766a66 c1bc35dd5bf6c7fa86a936a4fbe 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
    104886 ± 19%     +19.3%     125157 ± 17%  numa-meminfo.node1.Slab
      2583 ± 39%     +75.4%       4531 ± 40%  proc-vmstat.numa_hint_faults_local
    179842            +0.6%     180945        vmstat.system.in
    177.18            -2.6%     172.49        stress-ng.seek.nanosecs_per_seek
 1.223e+09            +1.9%  1.246e+09        stress-ng.seek.ops
  20376380            +1.9%   20771261        stress-ng.seek.ops_per_sec
      1.05 ± 20%    -100.0%       0.00        perf-sched.sch_delay.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
     13.11 ± 28%    -100.0%       0.00        perf-sched.sch_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      3.12 ± 21%    -100.0%       0.00        perf-sched.wait_and_delay.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      2785 ± 14%    -100.0%       0.00        perf-sched.wait_and_delay.count.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    836.20 ± 43%    -100.0%       0.00        perf-sched.wait_and_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      2.07 ± 27%    -100.0%       0.00        perf-sched.wait_time.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    834.79 ± 44%    -100.0%       0.00        perf-sched.wait_time.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      2.04            +3.4%       2.11        perf-stat.i.MPKI
 3.682e+08            +2.0%  3.754e+08        perf-stat.i.cache-misses
 4.637e+08            +1.8%  4.721e+08        perf-stat.i.cache-references
      1.23            +1.5%       1.25        perf-stat.i.cpi
    603.02            -1.9%     591.60        perf-stat.i.cycles-between-cache-misses
 1.798e+11            -1.4%  1.772e+11        perf-stat.i.instructions
      0.82            -1.4%       0.80        perf-stat.i.ipc
      3902            +1.8%       3972 ±  2%  perf-stat.i.minor-faults
      3902            +1.8%       3972 ±  2%  perf-stat.i.page-faults
      2.05            +3.4%       2.12        perf-stat.overall.MPKI
      1.23            +1.5%       1.25        perf-stat.overall.cpi
    602.25            -1.9%     590.74        perf-stat.overall.cycles-between-cache-misses
      0.81            -1.4%       0.80        perf-stat.overall.ipc
 3.623e+08            +1.9%  3.693e+08        perf-stat.ps.cache-misses
 4.562e+08            +1.8%  4.645e+08        perf-stat.ps.cache-references
 1.769e+11            -1.4%  1.743e+11        perf-stat.ps.instructions
      3826            +1.8%       3893 ±  2%  perf-stat.ps.minor-faults
      3826            +1.8%       3893 ±  2%  perf-stat.ps.page-faults
 1.085e+13            -2.0%  1.063e+13        perf-stat.total.instructions
     10.62 ±  2%      -0.6       10.02 ±  3%  perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.llseek.stress_run
      9.46 ±  2%      -0.5        8.94 ±  3%  perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.llseek.stress_run
      0.63            +0.0        0.66 ±  3%  perf-profile.calltrace.cycles-pp.x64_sys_call.do_syscall_64.entry_SYSCALL_64_after_hwframe.llseek
      1.61            +0.0        1.64        perf-profile.calltrace.cycles-pp.copy_page_from_iter_atomic.generic_perform_write.generic_file_write_iter.vfs_write.ksys_write
      2.78            +0.1        2.85        perf-profile.calltrace.cycles-pp.__filemap_get_folio.simple_write_begin.generic_perform_write.generic_file_write_iter.vfs_write
      2.94            +0.1        3.02        perf-profile.calltrace.cycles-pp.simple_write_begin.generic_perform_write.generic_file_write_iter.vfs_write.ksys_write
      8.58            +0.2        8.77        perf-profile.calltrace.cycles-pp.copy_page_to_iter.filemap_read.vfs_read.ksys_read.do_syscall_64
      8.37            +0.2        8.56        perf-profile.calltrace.cycles-pp._copy_to_iter.copy_page_to_iter.filemap_read.vfs_read.ksys_read
      8.96            +0.2        9.17        perf-profile.calltrace.cycles-pp.folio_unlock.simple_write_end.generic_perform_write.generic_file_write_iter.vfs_write
      9.53            +0.2        9.75        perf-profile.calltrace.cycles-pp.simple_write_end.generic_perform_write.generic_file_write_iter.vfs_write.ksys_write
     12.86            +0.3       13.15        perf-profile.calltrace.cycles-pp.filemap_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
     14.08            +0.3       14.42        perf-profile.calltrace.cycles-pp.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe.read
     15.98            +0.3       16.32        perf-profile.calltrace.cycles-pp.generic_perform_write.generic_file_write_iter.vfs_write.ksys_write.do_syscall_64
     19.18            +0.4       19.55        perf-profile.calltrace.cycles-pp.generic_file_write_iter.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
     20.30            +0.4       20.67        perf-profile.calltrace.cycles-pp.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
      7.39            -7.4        0.00        perf-profile.children.cycles-pp.syscall_exit_to_user_mode
     54.31            -0.7       53.60        perf-profile.children.cycles-pp.llseek
     56.77            -0.3       56.42        perf-profile.children.cycles-pp.do_syscall_64
     59.25            -0.3       58.95        perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
      0.12 ±  3%      +0.0        0.15 ± 13%  perf-profile.children.cycles-pp.generic_file_read_iter
      1.73            +0.0        1.77        perf-profile.children.cycles-pp.x64_sys_call
      1.97            +0.1        2.02        perf-profile.children.cycles-pp.filemap_get_entry
      2.84            +0.1        2.92        perf-profile.children.cycles-pp.__filemap_get_folio
      2.97            +0.1        3.05        perf-profile.children.cycles-pp.simple_write_begin
      6.98            +0.1        7.09        perf-profile.children.cycles-pp.entry_SYSRETQ_unsafe_stack
      1.96            +0.1        2.08 ±  5%  perf-profile.children.cycles-pp.stress_shim_lseek
      8.92            +0.1        9.06        perf-profile.children.cycles-pp.entry_SYSCALL_64
      8.40            +0.2        8.58        perf-profile.children.cycles-pp._copy_to_iter
      8.61            +0.2        8.80        perf-profile.children.cycles-pp.copy_page_to_iter
      8.97            +0.2        9.19        perf-profile.children.cycles-pp.folio_unlock
      9.57            +0.2        9.80        perf-profile.children.cycles-pp.simple_write_end
     19.10            +0.3       19.38        perf-profile.children.cycles-pp.read
     12.94            +0.3       13.24        perf-profile.children.cycles-pp.filemap_read
     25.30            +0.3       25.62        perf-profile.children.cycles-pp.write
     14.14            +0.3       14.48        perf-profile.children.cycles-pp.vfs_read
     16.12            +0.3       16.47        perf-profile.children.cycles-pp.generic_perform_write
     14.72            +0.4       15.08        perf-profile.children.cycles-pp.ksys_read
     19.25            +0.4       19.62        perf-profile.children.cycles-pp.generic_file_write_iter
     20.95            +0.4       21.33        perf-profile.children.cycles-pp.ksys_write
     20.40            +0.4       20.78        perf-profile.children.cycles-pp.vfs_write
      6.38            -6.4        0.00        perf-profile.self.cycles-pp.syscall_exit_to_user_mode
      0.63            +0.0        0.65        perf-profile.self.cycles-pp.__filemap_get_folio
      2.20            +0.0        2.23        perf-profile.self.cycles-pp.entry_SYSCALL_64
      2.45            +0.0        2.48        perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
      0.97            +0.0        1.00        perf-profile.self.cycles-pp.filemap_read
      1.51            +0.0        1.56        perf-profile.self.cycles-pp.x64_sys_call
      1.54            +0.0        1.59        perf-profile.self.cycles-pp.filemap_get_read_batch
      6.54            +0.1        6.64        perf-profile.self.cycles-pp.llseek
      6.74            +0.1        6.85        perf-profile.self.cycles-pp.entry_SYSRETQ_unsafe_stack
      8.35            +0.2        8.54        perf-profile.self.cycles-pp._copy_to_iter
      8.93            +0.2        9.14        perf-profile.self.cycles-pp.folio_unlock
      3.91            +6.1        9.96        perf-profile.self.cycles-pp.do_syscall_64


***************************************************************************************************
lkp-gnr-2ap2: 384 threads 2 sockets Intel(R) Xeon(R) 6972P (Granite Rapids) with 128G memory
=========================================================================================
compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
  gcc-12/performance/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/lkp-gnr-2ap2/context/stress-ng/60s

commit: 
  37c1871b51 ("LoongArch: entry: Migrate ret_from_fork() to C")
  c1bc35dd5b ("entry: Inline syscall_exit_to_user_mode()")

37c1871b51766a66 c1bc35dd5bf6c7fa86a936a4fbe 
---------------- --------------------------- 
         %stddev     %change         %stddev
             \          |                \  
    933000 ± 10%     +30.5%    1217543 ± 18%  proc-vmstat.pgfree
     40.25 ± 37%     +70.8%      68.75 ± 37%  sched_debug.cpu.nr_uninterruptible.max
 1.063e+08            +1.9%  1.083e+08        stress-ng.context.ops
   1771139            +1.9%    1805148        stress-ng.context.ops_per_sec
   4608060            +1.9%    4696809        stress-ng.context.swapcontext_calls_per_sec
      0.06 ± 24%    -100.0%       0.00        perf-sched.sch_delay.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      4.53 ± 59%    -100.0%       0.00        perf-sched.sch_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    217.64 ± 10%     -17.8%     178.86 ± 17%  perf-sched.wait_and_delay.avg.ms.pipe_read.vfs_read.ksys_read.do_syscall_64
      0.67 ± 83%    -100.0%       0.00        perf-sched.wait_and_delay.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
      3262 ±  3%    -100.0%       0.00        perf-sched.wait_and_delay.count.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    505.60 ± 97%    -100.0%       0.00        perf-sched.wait_and_delay.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    217.59 ± 10%     -18.1%     178.22 ± 17%  perf-sched.wait_time.avg.ms.pipe_read.vfs_read.ksys_read.do_syscall_64
      0.61 ± 91%    -100.0%       0.00        perf-sched.wait_time.avg.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
    502.72 ± 98%    -100.0%       0.00        perf-sched.wait_time.max.ms.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.[unknown]
 1.197e+11            -4.4%  1.145e+11        perf-stat.i.branch-instructions
      1.48            +0.1        1.57        perf-stat.i.branch-miss-rate%
 1.761e+09            +1.5%  1.788e+09        perf-stat.i.branch-misses
      2.06            +4.1%       2.15        perf-stat.i.cpi
 6.404e+11            -4.3%  6.129e+11        perf-stat.i.instructions
      0.49            -3.9%       0.47        perf-stat.i.ipc
      1.47            +0.1        1.56        perf-stat.overall.branch-miss-rate%
      2.06            +4.1%       2.15        perf-stat.overall.cpi
      0.48            -3.9%       0.47        perf-stat.overall.ipc
 1.178e+11            -4.4%  1.126e+11        perf-stat.ps.branch-instructions
 1.732e+09            +1.5%  1.758e+09        perf-stat.ps.branch-misses
   6.3e+11            -4.3%  6.029e+11        perf-stat.ps.instructions
 3.849e+13            -3.5%  3.716e+13        perf-stat.total.instructions
      6.12            -6.1        0.00        perf-profile.calltrace.cycles-pp.syscall_exit_to_user_mode.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
     33.80            -0.7       33.14        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.swapcontext
     31.62            -0.5       31.12        perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
     90.78            -0.3       90.49        perf-profile.calltrace.cycles-pp.swapcontext
      1.40            -0.1        1.30        perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.swapcontext
      1.44            -0.0        1.40        perf-profile.calltrace.cycles-pp.sigprocmask.__x64_sys_rt_sigprocmask.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
      0.57            +0.0        0.61        perf-profile.calltrace.cycles-pp.entry_SYSRETQ_unsafe_stack.swapcontext
      0.72            +0.0        0.77        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_safe_stack.swapcontext
      2.21            +0.1        2.28        perf-profile.calltrace.cycles-pp.stress_thread2
      2.20            +0.1        2.28        perf-profile.calltrace.cycles-pp.stress_thread3
      2.15            +0.1        2.24        perf-profile.calltrace.cycles-pp.stress_thread1
      7.38            +0.1        7.48        perf-profile.calltrace.cycles-pp._copy_to_user.__x64_sys_rt_sigprocmask.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
      8.90            +0.1        9.00        perf-profile.calltrace.cycles-pp._copy_from_user.__x64_sys_rt_sigprocmask.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
      1.26            +0.1        1.37        perf-profile.calltrace.cycles-pp.x64_sys_call.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
     21.14            +0.3       21.49        perf-profile.calltrace.cycles-pp.__x64_sys_rt_sigprocmask.do_syscall_64.entry_SYSCALL_64_after_hwframe.swapcontext
     22.96            +0.5       23.48        perf-profile.calltrace.cycles-pp.entry_SYSCALL_64.swapcontext
      6.45            -6.4        0.00        perf-profile.children.cycles-pp.syscall_exit_to_user_mode
     32.36            -0.7       31.64        perf-profile.children.cycles-pp.do_syscall_64
     34.18            -0.7       33.52        perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
     96.11            -0.1       96.00        perf-profile.children.cycles-pp.swapcontext
      1.59            -0.1        1.50        perf-profile.children.cycles-pp.syscall_return_via_sysret
      1.54            -0.0        1.51        perf-profile.children.cycles-pp.sigprocmask
      0.74            +0.1        0.79        perf-profile.children.cycles-pp.entry_SYSCALL_64_safe_stack
      1.72            +0.1        1.78        perf-profile.children.cycles-pp.stress_thread3
      1.70            +0.1        1.75        perf-profile.children.cycles-pp.stress_thread1
      1.72            +0.1        1.78        perf-profile.children.cycles-pp.stress_thread2
      7.64            +0.1        7.76        perf-profile.children.cycles-pp._copy_to_user
      1.44            +0.1        1.58        perf-profile.children.cycles-pp.x64_sys_call
      9.59            +0.2        9.74        perf-profile.children.cycles-pp._copy_from_user
      7.18            +0.2        7.35        perf-profile.children.cycles-pp.entry_SYSRETQ_unsafe_stack
     12.65            +0.3       12.92        perf-profile.children.cycles-pp.entry_SYSCALL_64
     21.19            +0.3       21.50        perf-profile.children.cycles-pp.__x64_sys_rt_sigprocmask
      5.45            -5.5        0.00        perf-profile.self.cycles-pp.syscall_exit_to_user_mode
      1.59            -0.1        1.50        perf-profile.self.cycles-pp.syscall_return_via_sysret
      1.39            -0.0        1.36        perf-profile.self.cycles-pp.sigprocmask
      2.32            +0.0        2.35        perf-profile.self.cycles-pp.entry_SYSCALL_64
      1.17            +0.0        1.20        perf-profile.self.cycles-pp.stress_thread3
      1.18            +0.0        1.21        perf-profile.self.cycles-pp.stress_thread2
      1.17            +0.0        1.20        perf-profile.self.cycles-pp.stress_thread1
      2.83            +0.0        2.87        perf-profile.self.cycles-pp.__x64_sys_rt_sigprocmask
      2.00            +0.1        2.05        perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
      0.73            +0.1        0.79        perf-profile.self.cycles-pp.entry_SYSCALL_64_safe_stack
      7.50            +0.1        7.62        perf-profile.self.cycles-pp._copy_to_user
      9.20            +0.1        9.34        perf-profile.self.cycles-pp._copy_from_user
      1.22            +0.1        1.37        perf-profile.self.cycles-pp.x64_sys_call
      6.99            +0.2        7.15        perf-profile.self.cycles-pp.entry_SYSRETQ_unsafe_stack
     49.94            +0.4       50.34        perf-profile.self.cycles-pp.swapcontext
      3.36            +5.2        8.51        perf-profile.self.cycles-pp.do_syscall_64





Disclaimer:
Results have been estimated based on internal Intel analysis and are provided
for informational purposes only. Any difference in system hardware or software
design or configuration may affect actual performance.


-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki


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2025-01-28  5:33 [PATCH v4 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user_mode() Charlie Jenkins
2025-01-28  5:33 ` [PATCH v4 1/4] riscv: entry: Convert ret_from_fork() to C Charlie Jenkins
2025-01-28  5:33 ` [PATCH v4 2/4] riscv: entry: Split ret_from_fork() into user and kernel Charlie Jenkins
2025-01-28  5:33 ` [PATCH v4 3/4] LoongArch: entry: Migrate ret_from_fork() to C Charlie Jenkins
2025-01-28  5:33 ` [PATCH v4 4/4] entry: Inline syscall_exit_to_user_mode() Charlie Jenkins
2025-02-05  8:13   ` kernel test robot

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