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Subject[PATCH v2 34/36] x86/entry: Use pt_regs_to_thread_info() in syscall entry tracing
Date
It generates simpler and faster code than current_thread_info().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/common.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 88966fbf7125..3d44c83f2769 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -30,6 +30,13 @@
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

+static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs)
+{
+ unsigned long top_of_stack =
+ (unsigned long)(regs + 1) + TOP_OF_KERNEL_STACK_PADDING;
+ return (struct thread_info *)(top_of_stack - THREAD_SIZE);
+}
+
#ifdef CONFIG_CONTEXT_TRACKING
/* Called on entry from user mode with IRQs off. */
__visible void enter_from_user_mode(void)
@@ -68,14 +75,14 @@ static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch)
*/
unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
{
+ struct thread_info *ti = pt_regs_to_thread_info(regs);
unsigned long ret = 0;
u32 work;

if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
BUG_ON(regs != task_pt_regs(current));

- work = ACCESS_ONCE(current_thread_info()->flags) &
- _TIF_WORK_SYSCALL_ENTRY;
+ work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;

#ifdef CONFIG_CONTEXT_TRACKING
/*
@@ -157,9 +164,9 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch,
unsigned long phase1_result)
{
+ struct thread_info *ti = pt_regs_to_thread_info(regs);
long ret = 0;
- u32 work = ACCESS_ONCE(current_thread_info()->flags) &
- _TIF_WORK_SYSCALL_ENTRY;
+ u32 work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;

if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
BUG_ON(regs != task_pt_regs(current));
@@ -211,13 +218,6 @@ long syscall_trace_enter(struct pt_regs *regs)
return syscall_trace_enter_phase2(regs, arch, phase1_result);
}

-static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs)
-{
- unsigned long top_of_stack =
- (unsigned long)(regs + 1) + TOP_OF_KERNEL_STACK_PADDING;
- return (struct thread_info *)(top_of_stack - THREAD_SIZE);
-}
-
/* Called with IRQs disabled. */
__visible void prepare_exit_to_usermode(struct pt_regs *regs)
{
--
2.4.3


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