From 3462bd2adeadc49d9e126bca3b5536a3437a902d Mon Sep 17 00:00:00 2001 From: Hagen Paul Pfeifer Date: Mon, 20 Apr 2015 23:27:11 +0200 Subject: [PATCH] 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 : 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 [...] ffffffff8131a062: e8 51 d1 ff ff callq ffffffff813171b8 [...] ffffffff8131a190: e8 23 d0 ff ff callq ffffffff813171b8 [...] 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 Acked-by: Linus Torvalds Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1429565231-4609-1-git-send-email-hagen@jauu.net Signed-off-by: Ingo Molnar --- 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 5e5cd123fdfb..75a9ee8529f3 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 f8d273e18516..b965f9e03f2a 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); } -- 2.39.5