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Message-ID: <tip-196bd485ee4f03ce4c690bfcf38138abfcd0a4bc@git.kernel.org>
Date: Fri, 29 Sep 2017 13:15:26 -0700
From: tip-bot for Andrey Ryabinin <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
luto@...nel.org, aryabinin@...tuozzo.com, tglx@...utronix.de,
hpa@...or.com, mingo@...nel.org, jpoimboe@...hat.com,
peterz@...radead.org
Subject: [tip:x86/urgent] x86/asm: Use register variable to get stack
pointer value
Commit-ID: 196bd485ee4f03ce4c690bfcf38138abfcd0a4bc
Gitweb: https://git.kernel.org/tip/196bd485ee4f03ce4c690bfcf38138abfcd0a4bc
Author: Andrey Ryabinin <aryabinin@...tuozzo.com>
AuthorDate: Fri, 29 Sep 2017 17:15:36 +0300
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 29 Sep 2017 19:39:44 +0200
x86/asm: Use register variable to get stack pointer value
Currently we use current_stack_pointer() function to get the value
of the stack pointer register. Since commit:
f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang")
... we have a stack register variable declared. It can be used instead of
current_stack_pointer() function which allows to optimize away some
excessive "mov %rsp, %<dst>" instructions:
-mov %rsp,%rdx
-sub %rdx,%rax
-cmp $0x3fff,%rax
-ja ffffffff810722fd <ist_begin_non_atomic+0x2d>
+sub %rsp,%rax
+cmp $0x3fff,%rax
+ja ffffffff810722fa <ist_begin_non_atomic+0x2a>
Remove current_stack_pointer(), rename __asm_call_sp to current_stack_pointer
and use it instead of the removed function.
Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20170929141537.29167-1-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/asm.h | 4 ++--
arch/x86/include/asm/thread_info.h | 11 -----------
arch/x86/kernel/irq_32.c | 6 +++---
arch/x86/kernel/traps.c | 2 +-
arch/x86/mm/tlb.c | 2 +-
5 files changed, 7 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 30c3c9a..b0dc91f 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -141,8 +141,8 @@
* gets set up by the containing function. If you forget to do this, objtool
* may print a "call without frame pointer save/setup" warning.
*/
-register unsigned long __asm_call_sp asm(_ASM_SP);
-#define ASM_CALL_CONSTRAINT "+r" (__asm_call_sp)
+register unsigned long current_stack_pointer asm(_ASM_SP);
+#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif
#endif /* _ASM_X86_ASM_H */
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 5161da1a..89e7eeb 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -158,17 +158,6 @@ struct thread_info {
*/
#ifndef __ASSEMBLY__
-static inline unsigned long current_stack_pointer(void)
-{
- unsigned long sp;
-#ifdef CONFIG_X86_64
- asm("mov %%rsp,%0" : "=g" (sp));
-#else
- asm("mov %%esp,%0" : "=g" (sp));
-#endif
- return sp;
-}
-
/*
* Walks up the stack frames to make sure that the specified object is
* entirely contained by a single stack frame.
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 1f38d9a..d4eb450 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -64,7 +64,7 @@ static void call_on_stack(void *func, void *stack)
static inline void *current_stack(void)
{
- return (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
+ return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
}
static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
@@ -88,7 +88,7 @@ static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
/* Save the next esp at the bottom of the stack */
prev_esp = (u32 *)irqstk;
- *prev_esp = current_stack_pointer();
+ *prev_esp = current_stack_pointer;
if (unlikely(overflow))
call_on_stack(print_stack_overflow, isp);
@@ -139,7 +139,7 @@ void do_softirq_own_stack(void)
/* Push the previous esp onto the stack */
prev_esp = (u32 *)irqstk;
- *prev_esp = current_stack_pointer();
+ *prev_esp = current_stack_pointer;
call_on_stack(__do_softirq, isp);
}
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 34ea365..67db4f4 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -142,7 +142,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
* from double_fault.
*/
BUG_ON((unsigned long)(current_top_of_stack() -
- current_stack_pointer()) >= THREAD_SIZE);
+ current_stack_pointer) >= THREAD_SIZE);
preempt_enable_no_resched();
}
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 93fe97c..49d9778 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -191,7 +191,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
* mapped in the new pgd, we'll double-fault. Forcibly
* map it.
*/
- unsigned int index = pgd_index(current_stack_pointer());
+ unsigned int index = pgd_index(current_stack_pointer);
pgd_t *pgd = next->pgd + index;
if (unlikely(pgd_none(*pgd)))
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