[PATCH for review] [82/145] x86_64: Don't use lock section for mutexes and semaphores

Andi Kleen
2006-08-10T20:06:40Z

r

Lock sections cannot be handled by the dwarf2 unwinder.

Disadvantage is a taken branch in the hot path.

Signed-off-by: Andi Kleen <ak@suse.de>

---
include/asm-x86_64/mutex.h | 20 ++++++--------------
include/asm-x86_64/semaphore.h | 40 ++++++++++++++--------------------------
include/asm-x86_64/spinlock.h | 13 ++++++-------
3 files changed, 26 insertions(+), 47 deletions(-)

Index: linux/include/asm-x86_64/mutex.h
===================================================================
--- linux.orig/include/asm-x86_64/mutex.h
+++ linux/include/asm-x86_64/mutex.h
@@ -25,13 +25,9 @@ do { \
\
__asm__ __volatile__( \
LOCK_PREFIX " decl (%%rdi) \n" \
- " js 2f \n" \
- "1: \n" \
- \
- LOCK_SECTION_START("") \
- "2: call "#fail_fn" \n" \
- " jmp 1b \n" \
- LOCK_SECTION_END \
+ " jns 1f \n" \
+ " call "#fail_fn" \n" \
+ "1:" \
\
:"=D" (dummy) \
: "D" (v) \
@@ -75,13 +71,9 @@ do { \
\
__asm__ __volatile__( \
LOCK_PREFIX " incl (%%rdi) \n" \
- " jle 2f \n" \
- "1: \n" \
- \
- LOCK_SECTION_START("") \
- "2: call "#fail_fn" \n" \
- " jmp 1b \n" \
- LOCK_SECTION_END \
+ " jg 1f \n" \
+ " call "#fail_fn" \n" \
+ "1: " \
\
:"=D" (dummy) \
: "D" (v) \
Index: linux/include/asm-x86_64/spinlock.h
===================================================================
--- linux.orig/include/asm-x86_64/spinlock.h
+++ linux/include/asm-x86_64/spinlock.h
@@ -20,16 +20,15 @@
(*(volatile signed int *)(&(x)->slock) <= 0)

#define __raw_spin_lock_string \
- "\n1:\t" \
+ "\n0:\t" \
"lock ; decl %0\n\t" \
- "js 2f\n" \
- LOCK_SECTION_START("") \
- "2:\t" \
+ "jns 2f\n" \
+ "1:\n\t" \
"rep;nop\n\t" \
"cmpl $0,%0\n\t" \
- "jle 2b\n\t" \
- "jmp 1b\n" \
- LOCK_SECTION_END
+ "jle 1b\n\t" \
+ "jmp 0b\n" \
+ "2:\t"

#define __raw_spin_lock_string_up \
"\n\tdecl %0"
Index: linux/include/asm-x86_64/semaphore.h
===================================================================
--- linux.orig/include/asm-x86_64/semaphore.h
+++ linux/include/asm-x86_64/semaphore.h
@@ -107,12 +107,9 @@ static inline void down(struct semaphore
__asm__ __volatile__(
"# atomic down operation\n\t"
LOCK_PREFIX "decl %0\n\t" /* --sem->count */
- "js 2f\n"
- "1:\n"
- LOCK_SECTION_START("")
- "2:\tcall __down_failed\n\t"
- "jmp 1b\n"
- LOCK_SECTION_END
+ "jns 1f\n\t"
+ "call __down_failed\n"
+ "1:"
:"=m" (sem->count)
:"D" (sem)
:"memory");
@@ -130,14 +127,11 @@ static inline int down_interruptible(str

__asm__ __volatile__(
"# atomic interruptible down operation\n\t"
+ "xorl %0,%0\n\t"
LOCK_PREFIX "decl %1\n\t" /* --sem->count */
- "js 2f\n\t"
- "xorl %0,%0\n"
- "1:\n"
- LOCK_SECTION_START("")
- "2:\tcall __down_failed_interruptible\n\t"
- "jmp 1b\n"
- LOCK_SECTION_END
+ "jns 2f\n\t"
+ "call __down_failed_interruptible\n"
+ "2:\n"
:"=a" (result), "=m" (sem->count)
:"D" (sem)
:"memory");
@@ -154,14 +148,11 @@ static inline int down_trylock(struct se

__asm__ __volatile__(
"# atomic interruptible down operation\n\t"
+ "xorl %0,%0\n\t"
LOCK_PREFIX "decl %1\n\t" /* --sem->count */
- "js 2f\n\t"
- "xorl %0,%0\n"
- "1:\n"
- LOCK_SECTION_START("")
- "2:\tcall __down_failed_trylock\n\t"
- "jmp 1b\n"
- LOCK_SECTION_END
+ "jns 2f\n\t"
+ "call __down_failed_trylock\n\t"
+ "2:\n"
:"=a" (result), "=m" (sem->count)
:"D" (sem)
:"memory","cc");
@@ -179,12 +170,9 @@ static inline void up(struct semaphore *
__asm__ __volatile__(
"# atomic up operation\n\t"
LOCK_PREFIX "incl %0\n\t" /* ++sem->count */
- "jle 2f\n"
- "1:\n"
- LOCK_SECTION_START("")
- "2:\tcall __up_wakeup\n\t"
- "jmp 1b\n"
- LOCK_SECTION_END
+ "jg 1f\n\t"
+ "call __up_wakeup\n"
+ "1:"
:"=m" (sem->count)
:"D" (sem)
:"memory");