lkml.org 
[lkml]   [2015]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:x86/asm] x86/asm: Always inline atomics
Commit-ID:  3462bd2adeadc49d9e126bca3b5536a3437a902d
Gitweb: http://git.kernel.org/tip/3462bd2adeadc49d9e126bca3b5536a3437a902d
Author: Hagen Paul Pfeifer <hagen@jauu.net>
AuthorDate: Mon, 20 Apr 2015 23:27:11 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 22 Apr 2015 08:14:41 +0200

x86/asm: Always inline atomics

During some code analysis I realized that atomic_add(), atomic_sub()
and friends are not necessarily inlined AND that each function
is defined multiple times:

atomic_inc: 544 duplicates
atomic_dec: 215 duplicates
atomic_dec_and_test: 107 duplicates
atomic64_inc: 38 duplicates
[...]

Each definition is exact equally, e.g.:

ffffffff813171b8 <atomic_add>:
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 01 3e lock add %edi,(%rsi)
5d pop %rbp
c3 retq

In turn each definition has one or more callsites (sure):

ffffffff81317c78: e8 3b f5 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a062: e8 51 d1 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a190: e8 23 d0 ff ff callq ffffffff813171b8 <atomic_add> [...]

The other way around would be to remove the static linkage - but
I prefer an enforced inlining here.

Before:
text data bss dec hex filename
81467393 19874720 20168704 121510817 73e1ba1 vmlinux.orig

After:
text data bss dec hex filename
81461323 19874720 20168704 121504747 73e03eb vmlinux.inlined

Yes, the inlining here makes the kernel even smaller! ;)

Linus further observed:

"I have this memory of having seen that before - the size
heuristics for gcc getting confused by inlining.
[...]

It might be a good idea to mark things that are basically just
wrappers around a single (or a couple of) asm instruction to be
always_inline."

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1429565231-4609-1-git-send-email-hagen@jauu.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/atomic.h | 16 ++++++++--------
arch/x86/include/asm/atomic64_64.h | 8 ++++----
2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 5e5cd12..75a9ee8 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -46,7 +46,7 @@ static inline void atomic_set(atomic_t *v, int i)
*
* Atomically adds @i to @v.
*/
-static inline void atomic_add(int i, atomic_t *v)
+static __always_inline void atomic_add(int i, atomic_t *v)
{
asm volatile(LOCK_PREFIX "addl %1,%0"
: "+m" (v->counter)
@@ -60,7 +60,7 @@ static inline void atomic_add(int i, atomic_t *v)
*
* Atomically subtracts @i from @v.
*/
-static inline void atomic_sub(int i, atomic_t *v)
+static __always_inline void atomic_sub(int i, atomic_t *v)
{
asm volatile(LOCK_PREFIX "subl %1,%0"
: "+m" (v->counter)
@@ -76,7 +76,7 @@ static inline void atomic_sub(int i, atomic_t *v)
* true if the result is zero, or false for all
* other cases.
*/
-static inline int atomic_sub_and_test(int i, atomic_t *v)
+static __always_inline int atomic_sub_and_test(int i, atomic_t *v)
{
GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e");
}
@@ -87,7 +87,7 @@ static inline int atomic_sub_and_test(int i, atomic_t *v)
*
* Atomically increments @v by 1.
*/
-static inline void atomic_inc(atomic_t *v)
+static __always_inline void atomic_inc(atomic_t *v)
{
asm volatile(LOCK_PREFIX "incl %0"
: "+m" (v->counter));
@@ -99,7 +99,7 @@ static inline void atomic_inc(atomic_t *v)
*
* Atomically decrements @v by 1.
*/
-static inline void atomic_dec(atomic_t *v)
+static __always_inline void atomic_dec(atomic_t *v)
{
asm volatile(LOCK_PREFIX "decl %0"
: "+m" (v->counter));
@@ -113,7 +113,7 @@ static inline void atomic_dec(atomic_t *v)
* returns true if the result is 0, or false for all other
* cases.
*/
-static inline int atomic_dec_and_test(atomic_t *v)
+static __always_inline int atomic_dec_and_test(atomic_t *v)
{
GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
}
@@ -152,7 +152,7 @@ static inline int atomic_add_negative(int i, atomic_t *v)
*
* Atomically adds @i to @v and returns @i + @v
*/
-static inline int atomic_add_return(int i, atomic_t *v)
+static __always_inline int atomic_add_return(int i, atomic_t *v)
{
return i + xadd(&v->counter, i);
}
@@ -191,7 +191,7 @@ static inline int atomic_xchg(atomic_t *v, int new)
* Atomically adds @a to @v, so long as @v was not already @u.
* Returns the old value of @v.
*/
-static inline int __atomic_add_unless(atomic_t *v, int a, int u)
+static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int c, old;
c = atomic_read(v);
diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
index f8d273e..b965f9e 100644
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -40,7 +40,7 @@ static inline void atomic64_set(atomic64_t *v, long i)
*
* Atomically adds @i to @v.
*/
-static inline void atomic64_add(long i, atomic64_t *v)
+static __always_inline void atomic64_add(long i, atomic64_t *v)
{
asm volatile(LOCK_PREFIX "addq %1,%0"
: "=m" (v->counter)
@@ -81,7 +81,7 @@ static inline int atomic64_sub_and_test(long i, atomic64_t *v)
*
* Atomically increments @v by 1.
*/
-static inline void atomic64_inc(atomic64_t *v)
+static __always_inline void atomic64_inc(atomic64_t *v)
{
asm volatile(LOCK_PREFIX "incq %0"
: "=m" (v->counter)
@@ -94,7 +94,7 @@ static inline void atomic64_inc(atomic64_t *v)
*
* Atomically decrements @v by 1.
*/
-static inline void atomic64_dec(atomic64_t *v)
+static __always_inline void atomic64_dec(atomic64_t *v)
{
asm volatile(LOCK_PREFIX "decq %0"
: "=m" (v->counter)
@@ -148,7 +148,7 @@ static inline int atomic64_add_negative(long i, atomic64_t *v)
*
* Atomically adds @i to @v and returns @i + @v
*/
-static inline long atomic64_add_return(long i, atomic64_t *v)
+static __always_inline long atomic64_add_return(long i, atomic64_t *v)
{
return i + xadd(&v->counter, i);
}

\
 
 \ /
  Last update: 2015-04-22 16:41    [W:0.113 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site