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Date: Wed, 11 Sep 2013 15:13:23 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...nel.org>, Andi Kleen <ak@...ux.intel.com>,
Peter Anvin <hpa@...or.com>,
Mike Galbraith <bitbucket@...ine.de>,
Thomas Gleixner <tglx@...utronix.de>,
Arjan van de Ven <arjan@...ux.intel.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 0/7] preempt_count rework -v2
On Tue, Sep 10, 2013 at 02:43:06PM -0700, Linus Torvalds wrote:
> That said, looking at your patch, I get the *very* strong feeling that
> we could make a macro that does all the repetitions for us, and then
> have a
>
> GENERATE_RMW(atomic_sub_and_test, LOCK_PREFIX "subl", "e", "")
The below seems to compile..
---
arch/x86/include/asm/atomic.h | 29 +--------
arch/x86/include/asm/atomic64_64.h | 28 +--------
arch/x86/include/asm/local.h | 28 +--------
arch/x86/include/asm/addcc.h | 115 +++++++++++++++++++++++++++++++++++++
4 files changed, 128 insertions(+), 72 deletions(-)
Index: linux-2.6/arch/x86/include/asm/atomic.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/atomic.h
+++ linux-2.6/arch/x86/include/asm/atomic.h
@@ -6,6 +6,7 @@
#include <asm/processor.h>
#include <asm/alternative.h>
#include <asm/cmpxchg.h>
+#include <asm/addcc.h>
/*
* Atomic operations that C can't guarantee us. Useful for
@@ -76,12 +77,7 @@ static inline void atomic_sub(int i, ato
*/
static inline int atomic_sub_and_test(int i, atomic_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
- : "+m" (v->counter), "=qm" (c)
- : "ir" (i) : "memory");
- return c;
+ GENERATE_ADDcc(v->counter, -i, LOCK_PREFIX, "e");
}
/**
@@ -118,12 +114,7 @@ static inline void atomic_dec(atomic_t *
*/
static inline int atomic_dec_and_test(atomic_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "decl %0; sete %1"
- : "+m" (v->counter), "=qm" (c)
- : : "memory");
- return c != 0;
+ GENERATE_ADDcc(v->counter, -1, LOCK_PREFIX, "e");
}
/**
@@ -136,12 +127,7 @@ static inline int atomic_dec_and_test(at
*/
static inline int atomic_inc_and_test(atomic_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "incl %0; sete %1"
- : "+m" (v->counter), "=qm" (c)
- : : "memory");
- return c != 0;
+ GENERATE_ADDcc(v->counter, 1, LOCK_PREFIX, "e");
}
/**
@@ -155,12 +141,7 @@ static inline int atomic_inc_and_test(at
*/
static inline int atomic_add_negative(int i, atomic_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
- : "+m" (v->counter), "=qm" (c)
- : "ir" (i) : "memory");
- return c;
+ GENERATE_ADDcc(v->counter, i, LOCK_PREFIX, "s");
}
/**
Index: linux-2.6/arch/x86/include/asm/atomic64_64.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/atomic64_64.h
+++ linux-2.6/arch/x86/include/asm/atomic64_64.h
@@ -72,12 +72,7 @@ static inline void atomic64_sub(long i,
*/
static inline int atomic64_sub_and_test(long i, atomic64_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "subq %2,%0; sete %1"
- : "=m" (v->counter), "=qm" (c)
- : "er" (i), "m" (v->counter) : "memory");
- return c;
+ GENERATE_ADDcc(v->counter, -i, LOCK_PREFIX, "e");
}
/**
@@ -116,12 +111,7 @@ static inline void atomic64_dec(atomic64
*/
static inline int atomic64_dec_and_test(atomic64_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "decq %0; sete %1"
- : "=m" (v->counter), "=qm" (c)
- : "m" (v->counter) : "memory");
- return c != 0;
+ GENERATE_ADDcc(v->counter, -1, LOCK_PREFIX, "e");
}
/**
@@ -134,12 +124,7 @@ static inline int atomic64_dec_and_test(
*/
static inline int atomic64_inc_and_test(atomic64_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "incq %0; sete %1"
- : "=m" (v->counter), "=qm" (c)
- : "m" (v->counter) : "memory");
- return c != 0;
+ GENERATE_ADDcc(v->counter, 1, LOCK_PREFIX, "e");
}
/**
@@ -153,12 +138,7 @@ static inline int atomic64_inc_and_test(
*/
static inline int atomic64_add_negative(long i, atomic64_t *v)
{
- unsigned char c;
-
- asm volatile(LOCK_PREFIX "addq %2,%0; sets %1"
- : "=m" (v->counter), "=qm" (c)
- : "er" (i), "m" (v->counter) : "memory");
- return c;
+ GENERATE_ADDcc(v->counter, i, LOCK_PREFIX, "s");
}
/**
Index: linux-2.6/arch/x86/include/asm/local.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/local.h
+++ linux-2.6/arch/x86/include/asm/local.h
@@ -52,12 +52,7 @@ static inline void local_sub(long i, loc
*/
static inline int local_sub_and_test(long i, local_t *l)
{
- unsigned char c;
-
- asm volatile(_ASM_SUB "%2,%0; sete %1"
- : "+m" (l->a.counter), "=qm" (c)
- : "ir" (i) : "memory");
- return c;
+ GENERATE_ADDcc(l->a.counter, -i, "", "e");
}
/**
@@ -70,12 +65,7 @@ static inline int local_sub_and_test(lon
*/
static inline int local_dec_and_test(local_t *l)
{
- unsigned char c;
-
- asm volatile(_ASM_DEC "%0; sete %1"
- : "+m" (l->a.counter), "=qm" (c)
- : : "memory");
- return c != 0;
+ GENERATE_ADDcc(l->a.counter, -1, "", "e");
}
/**
@@ -88,12 +78,7 @@ static inline int local_dec_and_test(loc
*/
static inline int local_inc_and_test(local_t *l)
{
- unsigned char c;
-
- asm volatile(_ASM_INC "%0; sete %1"
- : "+m" (l->a.counter), "=qm" (c)
- : : "memory");
- return c != 0;
+ GENERATE_ADDcc(l->a.counter, 1, "", "e");
}
/**
@@ -107,12 +92,7 @@ static inline int local_inc_and_test(loc
*/
static inline int local_add_negative(long i, local_t *l)
{
- unsigned char c;
-
- asm volatile(_ASM_ADD "%2,%0; sets %1"
- : "+m" (l->a.counter), "=qm" (c)
- : "ir" (i) : "memory");
- return c;
+ GENERATE_ADDcc(l->a.counter, i, "", "s");
}
/**
Index: linux-2.6/arch/x86/include/asm/addcc.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/x86/include/asm/addcc.h
@@ -0,0 +1,115 @@
+#ifndef _ASM_X86_ADDcc
+#define _ASM_X86_ADDcc
+
+extern void __bad_addcc_size(void);
+
+#ifdef CC_HAVE_ASM_GOTO
+
+#define GENERATE_ADDcc(var, val, lock, cc) \
+do { \
+ const int add_ID__ = (__builtin_constant_p(val) && \
+ ((val) == 1 || (val) == -1)) ? (val) : 0; \
+ \
+ switch (sizeof(var)) { \
+ case 4: \
+ if (add_ID__ == 1) { \
+ asm volatile goto(lock "incl %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var) \
+ : "memory" : cc_label); \
+ } else if (add_ID__ == -1) { \
+ asm volatile goto(lock "decl %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var) \
+ : "memory" : cc_label); \
+ } else { \
+ asm volatile goto(lock "addl %1, %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var), "er" (val) \
+ : "memory" : cc_label); \
+ } \
+ break; \
+ \
+ case 8: \
+ if (add_ID__ == 1) { \
+ asm volatile goto(lock "incq %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var) \
+ : "memory" : cc_label); \
+ } else if (add_ID__ == -1) { \
+ asm volatile goto(lock "decq %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var) \
+ : "memory" : cc_label); \
+ } else { \
+ asm volatile goto(lock "addq %1, %0;" \
+ "j" cc " %l[cc_label]" \
+ : : "m" (var), "er" (val) \
+ : "memory" : cc_label); \
+ } \
+ break; \
+ \
+ default: __bad_addcc_size(); \
+ } \
+ \
+ return 0; \
+cc_label: \
+ return 1; \
+} while (0)
+
+#else /* !CC_HAVE_ASM_GOTO */
+
+#define GENERATE_ADDcc(var, val, lock, cc) \
+do { \
+ const int add_ID__ = (__builtin_constant_p(val) && \
+ ((val) == 1 || (val) == -1)) ? (val) : 0; \
+ char c; \
+ \
+ switch (sizeof(var)) { \
+ case 4: \
+ if (add_ID__ == 1) { \
+ asm volatile (lock "incl %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : : "memory"); \
+ } else if (add_ID__ == -1) { \
+ asm volatile (lock "decl %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : : "memory"); \
+ } else { \
+ asm volatile (lock "addl %2, %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : "er" (val) : "memory"); \
+ } \
+ break; \
+ \
+ case 8: \
+ if (add_ID__ == 1) { \
+ asm volatile (lock "incq %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : : "memory"); \
+ } else if (add_ID__ == -1) { \
+ asm volatile (lock "decq %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : : "memory"); \
+ } else { \
+ asm volatile (lock "addq %2, %0;" \
+ "set" cc " %1" \
+ : "+m" (var), "=qm" (c) \
+ : "er" (val) : "memory"); \
+ } \
+ break; \
+ \
+ default: __bad_addcc_size(); \
+ } \
+ \
+ return c != 0; \
+} while (0)
+
+#endif /* CC_HAVE_ASM_GOTO */
+
+#endif /* _ASM_X86_ADDcc */
--
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