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Message-ID: <20090217104734.GB25856@jurassic.park.msu.ru>
Date: Tue, 17 Feb 2009 13:47:34 +0300
From: Ivan Kokshaysky <ink@...assic.park.msu.ru>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Richard Henderson <rth@...ddle.net>, linux-kernel@...r.kernel.org
Subject: [PATCH] alpha: xchg/cmpxchg cleanup and fixes
- "_local" versions of xchg/cmpxchg functions duplicate code
of non-local ones (quite a few pages of assembler), except
memory barriers. We can generate these two variants from a
single header file using simple macros;
- convert xchg macro back to inline function using always_inline
attribute;
- use proper argument types for cmpxchg_u8/u16 functions
to fix a problem with negative arguments.
Signed-off-by: Ivan Kokshaysky <ink@...assic.park.msu.ru>
---
arch/alpha/include/asm/system.h | 547 ++++-----------------------------------
arch/alpha/include/asm/xchg.h | 258 ++++++++++++++++++
2 files changed, 308 insertions(+), 497 deletions(-)
diff --git a/arch/alpha/include/asm/system.h b/arch/alpha/include/asm/system.h
index afe20fa..5aa40cc 100644
--- a/arch/alpha/include/asm/system.h
+++ b/arch/alpha/include/asm/system.h
@@ -309,518 +309,71 @@ extern int __min_ipl;
#define tbia() __tbi(-2, /* no second argument */)
/*
- * Atomic exchange.
- * Since it can be used to implement critical sections
- * it must clobber "memory" (also for interrupts in UP).
+ * Atomic exchange routines.
*/
-static inline unsigned long
-__xchg_u8(volatile char *m, unsigned long val)
-{
- unsigned long ret, tmp, addr64;
-
- __asm__ __volatile__(
- " andnot %4,7,%3\n"
- " insbl %1,%4,%1\n"
- "1: ldq_l %2,0(%3)\n"
- " extbl %2,%4,%0\n"
- " mskbl %2,%4,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%3)\n"
- " beq %2,2f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
- : "r" ((long)m), "1" (val) : "memory");
-
- return ret;
-}
-
-static inline unsigned long
-__xchg_u16(volatile short *m, unsigned long val)
-{
- unsigned long ret, tmp, addr64;
-
- __asm__ __volatile__(
- " andnot %4,7,%3\n"
- " inswl %1,%4,%1\n"
- "1: ldq_l %2,0(%3)\n"
- " extwl %2,%4,%0\n"
- " mskwl %2,%4,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%3)\n"
- " beq %2,2f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
- : "r" ((long)m), "1" (val) : "memory");
-
- return ret;
-}
-
-static inline unsigned long
-__xchg_u32(volatile int *m, unsigned long val)
-{
- unsigned long dummy;
-
- __asm__ __volatile__(
- "1: ldl_l %0,%4\n"
- " bis $31,%3,%1\n"
- " stl_c %1,%2\n"
- " beq %1,2f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (val), "=&r" (dummy), "=m" (*m)
- : "rI" (val), "m" (*m) : "memory");
-
- return val;
-}
-
-static inline unsigned long
-__xchg_u64(volatile long *m, unsigned long val)
-{
- unsigned long dummy;
-
- __asm__ __volatile__(
- "1: ldq_l %0,%4\n"
- " bis $31,%3,%1\n"
- " stq_c %1,%2\n"
- " beq %1,2f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (val), "=&r" (dummy), "=m" (*m)
- : "rI" (val), "m" (*m) : "memory");
+#define __ASM__MB
+#define ____xchg(type, args...) __xchg ## type ## _local(args)
+#define ____cmpxchg(type, args...) __cmpxchg ## type ## _local(args)
+#include <asm/xchg.h>
- return val;
-}
-
-/* This function doesn't exist, so you'll get a linker error
- if something tries to do an invalid xchg(). */
-extern void __xchg_called_with_bad_pointer(void);
-
-#define __xchg(ptr, x, size) \
-({ \
- unsigned long __xchg__res; \
- volatile void *__xchg__ptr = (ptr); \
- switch (size) { \
- case 1: __xchg__res = __xchg_u8(__xchg__ptr, x); break; \
- case 2: __xchg__res = __xchg_u16(__xchg__ptr, x); break; \
- case 4: __xchg__res = __xchg_u32(__xchg__ptr, x); break; \
- case 8: __xchg__res = __xchg_u64(__xchg__ptr, x); break; \
- default: __xchg_called_with_bad_pointer(); __xchg__res = x; \
- } \
- __xchg__res; \
-})
-
-#define xchg(ptr,x) \
- ({ \
- __typeof__(*(ptr)) _x_ = (x); \
- (__typeof__(*(ptr))) __xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \
+#define xchg_local(ptr,x) \
+ ({ \
+ __typeof__(*(ptr)) _x_ = (x); \
+ (__typeof__(*(ptr))) __xchg_local((ptr), (unsigned long)_x_, \
+ sizeof(*(ptr))); \
})
-static inline unsigned long
-__xchg_u8_local(volatile char *m, unsigned long val)
-{
- unsigned long ret, tmp, addr64;
-
- __asm__ __volatile__(
- " andnot %4,7,%3\n"
- " insbl %1,%4,%1\n"
- "1: ldq_l %2,0(%3)\n"
- " extbl %2,%4,%0\n"
- " mskbl %2,%4,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%3)\n"
- " beq %2,2f\n"
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
- : "r" ((long)m), "1" (val) : "memory");
-
- return ret;
-}
-
-static inline unsigned long
-__xchg_u16_local(volatile short *m, unsigned long val)
-{
- unsigned long ret, tmp, addr64;
-
- __asm__ __volatile__(
- " andnot %4,7,%3\n"
- " inswl %1,%4,%1\n"
- "1: ldq_l %2,0(%3)\n"
- " extwl %2,%4,%0\n"
- " mskwl %2,%4,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%3)\n"
- " beq %2,2f\n"
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
- : "r" ((long)m), "1" (val) : "memory");
-
- return ret;
-}
-
-static inline unsigned long
-__xchg_u32_local(volatile int *m, unsigned long val)
-{
- unsigned long dummy;
-
- __asm__ __volatile__(
- "1: ldl_l %0,%4\n"
- " bis $31,%3,%1\n"
- " stl_c %1,%2\n"
- " beq %1,2f\n"
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (val), "=&r" (dummy), "=m" (*m)
- : "rI" (val), "m" (*m) : "memory");
-
- return val;
-}
-
-static inline unsigned long
-__xchg_u64_local(volatile long *m, unsigned long val)
-{
- unsigned long dummy;
-
- __asm__ __volatile__(
- "1: ldq_l %0,%4\n"
- " bis $31,%3,%1\n"
- " stq_c %1,%2\n"
- " beq %1,2f\n"
- ".subsection 2\n"
- "2: br 1b\n"
- ".previous"
- : "=&r" (val), "=&r" (dummy), "=m" (*m)
- : "rI" (val), "m" (*m) : "memory");
-
- return val;
-}
-
-#define __xchg_local(ptr, x, size) \
-({ \
- unsigned long __xchg__res; \
- volatile void *__xchg__ptr = (ptr); \
- switch (size) { \
- case 1: __xchg__res = __xchg_u8_local(__xchg__ptr, x); break; \
- case 2: __xchg__res = __xchg_u16_local(__xchg__ptr, x); break; \
- case 4: __xchg__res = __xchg_u32_local(__xchg__ptr, x); break; \
- case 8: __xchg__res = __xchg_u64_local(__xchg__ptr, x); break; \
- default: __xchg_called_with_bad_pointer(); __xchg__res = x; \
- } \
- __xchg__res; \
-})
-
-#define xchg_local(ptr,x) \
- ({ \
- __typeof__(*(ptr)) _x_ = (x); \
- (__typeof__(*(ptr))) __xchg_local((ptr), (unsigned long)_x_, \
- sizeof(*(ptr))); \
+#define cmpxchg_local(ptr, o, n) \
+ ({ \
+ __typeof__(*(ptr)) _o_ = (o); \
+ __typeof__(*(ptr)) _n_ = (n); \
+ (__typeof__(*(ptr))) __cmpxchg_local((ptr), (unsigned long)_o_, \
+ (unsigned long)_n_, \
+ sizeof(*(ptr))); \
})
-/*
- * Atomic compare and exchange. Compare OLD with MEM, if identical,
- * store NEW in MEM. Return the initial value in MEM. Success is
- * indicated by comparing RETURN with OLD.
- *
- * The memory barrier should be placed in SMP only when we actually
- * make the change. If we don't change anything (so if the returned
- * prev is equal to old) then we aren't acquiring anything new and
- * we don't need any memory barrier as far I can tell.
- */
-
-#define __HAVE_ARCH_CMPXCHG 1
-
-static inline unsigned long
-__cmpxchg_u8(volatile char *m, long old, long new)
-{
- unsigned long prev, tmp, cmp, addr64;
-
- __asm__ __volatile__(
- " andnot %5,7,%4\n"
- " insbl %1,%5,%1\n"
- "1: ldq_l %2,0(%4)\n"
- " extbl %2,%5,%0\n"
- " cmpeq %0,%6,%3\n"
- " beq %3,2f\n"
- " mskbl %2,%5,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%4)\n"
- " beq %2,3f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
- : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-
- return prev;
-}
-
-static inline unsigned long
-__cmpxchg_u16(volatile short *m, long old, long new)
-{
- unsigned long prev, tmp, cmp, addr64;
-
- __asm__ __volatile__(
- " andnot %5,7,%4\n"
- " inswl %1,%5,%1\n"
- "1: ldq_l %2,0(%4)\n"
- " extwl %2,%5,%0\n"
- " cmpeq %0,%6,%3\n"
- " beq %3,2f\n"
- " mskwl %2,%5,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%4)\n"
- " beq %2,3f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
- : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-
- return prev;
-}
-
-static inline unsigned long
-__cmpxchg_u32(volatile int *m, int old, int new)
-{
- unsigned long prev, cmp;
-
- __asm__ __volatile__(
- "1: ldl_l %0,%5\n"
- " cmpeq %0,%3,%1\n"
- " beq %1,2f\n"
- " mov %4,%1\n"
- " stl_c %1,%2\n"
- " beq %1,3f\n"
-#ifdef CONFIG_SMP
- " mb\n"
-#endif
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r"(prev), "=&r"(cmp), "=m"(*m)
- : "r"((long) old), "r"(new), "m"(*m) : "memory");
-
- return prev;
-}
+#define cmpxchg64_local(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg_local((ptr), (o), (n)); \
+ })
-static inline unsigned long
-__cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new)
-{
- unsigned long prev, cmp;
-
- __asm__ __volatile__(
- "1: ldq_l %0,%5\n"
- " cmpeq %0,%3,%1\n"
- " beq %1,2f\n"
- " mov %4,%1\n"
- " stq_c %1,%2\n"
- " beq %1,3f\n"
#ifdef CONFIG_SMP
- " mb\n"
+#undef __ASM__MB
+#define __ASM__MB "\tmb\n"
#endif
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r"(prev), "=&r"(cmp), "=m"(*m)
- : "r"((long) old), "r"(new), "m"(*m) : "memory");
-
- return prev;
-}
-
-/* This function doesn't exist, so you'll get a linker error
- if something tries to do an invalid cmpxchg(). */
-extern void __cmpxchg_called_with_bad_pointer(void);
-
-static __always_inline unsigned long
-__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
-{
- switch (size) {
- case 1:
- return __cmpxchg_u8(ptr, old, new);
- case 2:
- return __cmpxchg_u16(ptr, old, new);
- case 4:
- return __cmpxchg_u32(ptr, old, new);
- case 8:
- return __cmpxchg_u64(ptr, old, new);
- }
- __cmpxchg_called_with_bad_pointer();
- return old;
-}
-
-#define cmpxchg(ptr, o, n) \
- ({ \
- __typeof__(*(ptr)) _o_ = (o); \
- __typeof__(*(ptr)) _n_ = (n); \
- (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
- (unsigned long)_n_, sizeof(*(ptr))); \
+#undef ____xchg
+#undef ____cmpxchg
+#define ____xchg(type, args...) __xchg ##type(args)
+#define ____cmpxchg(type, args...) __cmpxchg ##type(args)
+#include <asm/xchg.h>
+
+#define xchg(ptr,x) \
+ ({ \
+ __typeof__(*(ptr)) _x_ = (x); \
+ (__typeof__(*(ptr))) __xchg((ptr), (unsigned long)_x_, \
+ sizeof(*(ptr))); \
})
-#define cmpxchg64(ptr, o, n) \
- ({ \
- BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
- cmpxchg((ptr), (o), (n)); \
- })
-
-static inline unsigned long
-__cmpxchg_u8_local(volatile char *m, long old, long new)
-{
- unsigned long prev, tmp, cmp, addr64;
-
- __asm__ __volatile__(
- " andnot %5,7,%4\n"
- " insbl %1,%5,%1\n"
- "1: ldq_l %2,0(%4)\n"
- " extbl %2,%5,%0\n"
- " cmpeq %0,%6,%3\n"
- " beq %3,2f\n"
- " mskbl %2,%5,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%4)\n"
- " beq %2,3f\n"
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
- : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-
- return prev;
-}
-
-static inline unsigned long
-__cmpxchg_u16_local(volatile short *m, long old, long new)
-{
- unsigned long prev, tmp, cmp, addr64;
-
- __asm__ __volatile__(
- " andnot %5,7,%4\n"
- " inswl %1,%5,%1\n"
- "1: ldq_l %2,0(%4)\n"
- " extwl %2,%5,%0\n"
- " cmpeq %0,%6,%3\n"
- " beq %3,2f\n"
- " mskwl %2,%5,%2\n"
- " or %1,%2,%2\n"
- " stq_c %2,0(%4)\n"
- " beq %2,3f\n"
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
- : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-
- return prev;
-}
-
-static inline unsigned long
-__cmpxchg_u32_local(volatile int *m, int old, int new)
-{
- unsigned long prev, cmp;
-
- __asm__ __volatile__(
- "1: ldl_l %0,%5\n"
- " cmpeq %0,%3,%1\n"
- " beq %1,2f\n"
- " mov %4,%1\n"
- " stl_c %1,%2\n"
- " beq %1,3f\n"
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r"(prev), "=&r"(cmp), "=m"(*m)
- : "r"((long) old), "r"(new), "m"(*m) : "memory");
-
- return prev;
-}
-
-static inline unsigned long
-__cmpxchg_u64_local(volatile long *m, unsigned long old, unsigned long new)
-{
- unsigned long prev, cmp;
-
- __asm__ __volatile__(
- "1: ldq_l %0,%5\n"
- " cmpeq %0,%3,%1\n"
- " beq %1,2f\n"
- " mov %4,%1\n"
- " stq_c %1,%2\n"
- " beq %1,3f\n"
- "2:\n"
- ".subsection 2\n"
- "3: br 1b\n"
- ".previous"
- : "=&r"(prev), "=&r"(cmp), "=m"(*m)
- : "r"((long) old), "r"(new), "m"(*m) : "memory");
-
- return prev;
-}
-
-static __always_inline unsigned long
-__cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
- int size)
-{
- switch (size) {
- case 1:
- return __cmpxchg_u8_local(ptr, old, new);
- case 2:
- return __cmpxchg_u16_local(ptr, old, new);
- case 4:
- return __cmpxchg_u32_local(ptr, old, new);
- case 8:
- return __cmpxchg_u64_local(ptr, old, new);
- }
- __cmpxchg_called_with_bad_pointer();
- return old;
-}
-#define cmpxchg_local(ptr, o, n) \
- ({ \
- __typeof__(*(ptr)) _o_ = (o); \
- __typeof__(*(ptr)) _n_ = (n); \
- (__typeof__(*(ptr))) __cmpxchg_local((ptr), (unsigned long)_o_, \
- (unsigned long)_n_, sizeof(*(ptr))); \
+#define cmpxchg(ptr, o, n) \
+ ({ \
+ __typeof__(*(ptr)) _o_ = (o); \
+ __typeof__(*(ptr)) _n_ = (n); \
+ (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
+ (unsigned long)_n_, sizeof(*(ptr)));\
})
-#define cmpxchg64_local(ptr, o, n) \
- ({ \
- BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
- cmpxchg_local((ptr), (o), (n)); \
+
+#define cmpxchg64(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg((ptr), (o), (n)); \
})
+#undef __ASM__MB
+#undef ____cmpxchg
+
+#define __HAVE_ARCH_CMPXCHG 1
#endif /* __ASSEMBLY__ */
diff --git a/arch/alpha/include/asm/xchg.h b/arch/alpha/include/asm/xchg.h
new file mode 100644
index 0000000..beba1b8
--- /dev/null
+++ b/arch/alpha/include/asm/xchg.h
@@ -0,0 +1,258 @@
+#ifndef __ALPHA_SYSTEM_H
+#error Do not include xchg.h directly!
+#else
+/*
+ * xchg/xchg_local and cmpxchg/cmpxchg_local share the same code
+ * except that local version do not have the expensive memory barrier.
+ * So this file is included twice from asm/system.h.
+ */
+
+/*
+ * Atomic exchange.
+ * Since it can be used to implement critical sections
+ * it must clobber "memory" (also for interrupts in UP).
+ */
+
+static inline unsigned long
+____xchg(_u8, volatile char *m, unsigned long val)
+{
+ unsigned long ret, tmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %4,7,%3\n"
+ " insbl %1,%4,%1\n"
+ "1: ldq_l %2,0(%3)\n"
+ " extbl %2,%4,%0\n"
+ " mskbl %2,%4,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%3)\n"
+ " beq %2,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
+ : "r" ((long)m), "1" (val) : "memory");
+
+ return ret;
+}
+
+static inline unsigned long
+____xchg(_u16, volatile short *m, unsigned long val)
+{
+ unsigned long ret, tmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %4,7,%3\n"
+ " inswl %1,%4,%1\n"
+ "1: ldq_l %2,0(%3)\n"
+ " extwl %2,%4,%0\n"
+ " mskwl %2,%4,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%3)\n"
+ " beq %2,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
+ : "r" ((long)m), "1" (val) : "memory");
+
+ return ret;
+}
+
+static inline unsigned long
+____xchg(_u32, volatile int *m, unsigned long val)
+{
+ unsigned long dummy;
+
+ __asm__ __volatile__(
+ "1: ldl_l %0,%4\n"
+ " bis $31,%3,%1\n"
+ " stl_c %1,%2\n"
+ " beq %1,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (val), "=&r" (dummy), "=m" (*m)
+ : "rI" (val), "m" (*m) : "memory");
+
+ return val;
+}
+
+static inline unsigned long
+____xchg(_u64, volatile long *m, unsigned long val)
+{
+ unsigned long dummy;
+
+ __asm__ __volatile__(
+ "1: ldq_l %0,%4\n"
+ " bis $31,%3,%1\n"
+ " stq_c %1,%2\n"
+ " beq %1,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (val), "=&r" (dummy), "=m" (*m)
+ : "rI" (val), "m" (*m) : "memory");
+
+ return val;
+}
+
+/* This function doesn't exist, so you'll get a linker error
+ if something tries to do an invalid xchg(). */
+extern void __xchg_called_with_bad_pointer(void);
+
+static __always_inline unsigned long
+____xchg(, volatile void *ptr, unsigned long x, int size)
+{
+ switch (size) {
+ case 1:
+ return ____xchg(_u8, ptr, x);
+ case 2:
+ return ____xchg(_u16, ptr, x);
+ case 4:
+ return ____xchg(_u32, ptr, x);
+ case 8:
+ return ____xchg(_u64, ptr, x);
+ }
+ __xchg_called_with_bad_pointer();
+ return x;
+}
+
+/*
+ * Atomic compare and exchange. Compare OLD with MEM, if identical,
+ * store NEW in MEM. Return the initial value in MEM. Success is
+ * indicated by comparing RETURN with OLD.
+ *
+ * The memory barrier should be placed in SMP only when we actually
+ * make the change. If we don't change anything (so if the returned
+ * prev is equal to old) then we aren't acquiring anything new and
+ * we don't need any memory barrier as far I can tell.
+ */
+
+static inline unsigned long
+____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new)
+{
+ unsigned long prev, tmp, cmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %5,7,%4\n"
+ " insbl %1,%5,%1\n"
+ "1: ldq_l %2,0(%4)\n"
+ " extbl %2,%5,%0\n"
+ " cmpeq %0,%6,%3\n"
+ " beq %3,2f\n"
+ " mskbl %2,%5,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%4)\n"
+ " beq %2,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
+ : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new)
+{
+ unsigned long prev, tmp, cmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %5,7,%4\n"
+ " inswl %1,%5,%1\n"
+ "1: ldq_l %2,0(%4)\n"
+ " extwl %2,%5,%0\n"
+ " cmpeq %0,%6,%3\n"
+ " beq %3,2f\n"
+ " mskwl %2,%5,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%4)\n"
+ " beq %2,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
+ : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u32, volatile int *m, int old, int new)
+{
+ unsigned long prev, cmp;
+
+ __asm__ __volatile__(
+ "1: ldl_l %0,%5\n"
+ " cmpeq %0,%3,%1\n"
+ " beq %1,2f\n"
+ " mov %4,%1\n"
+ " stl_c %1,%2\n"
+ " beq %1,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r"(prev), "=&r"(cmp), "=m"(*m)
+ : "r"((long) old), "r"(new), "m"(*m) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new)
+{
+ unsigned long prev, cmp;
+
+ __asm__ __volatile__(
+ "1: ldq_l %0,%5\n"
+ " cmpeq %0,%3,%1\n"
+ " beq %1,2f\n"
+ " mov %4,%1\n"
+ " stq_c %1,%2\n"
+ " beq %1,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r"(prev), "=&r"(cmp), "=m"(*m)
+ : "r"((long) old), "r"(new), "m"(*m) : "memory");
+
+ return prev;
+}
+
+/* This function doesn't exist, so you'll get a linker error
+ if something tries to do an invalid cmpxchg(). */
+extern void __cmpxchg_called_with_bad_pointer(void);
+
+static __always_inline unsigned long
+____cmpxchg(, volatile void *ptr, unsigned long old, unsigned long new,
+ int size)
+{
+ switch (size) {
+ case 1:
+ return ____cmpxchg(_u8, ptr, old, new);
+ case 2:
+ return ____cmpxchg(_u16, ptr, old, new);
+ case 4:
+ return ____cmpxchg(_u32, ptr, old, new);
+ case 8:
+ return ____cmpxchg(_u64, ptr, old, new);
+ }
+ __cmpxchg_called_with_bad_pointer();
+ return old;
+}
+
+#endif
--
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