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Subject[patch 21/28] Add cmpxchg_local to ppc
Add a local processor version of cmpxchg for ppc.

Implements __cmpxchg_u32_local and uses it for 32 bits cmpxchg_local.
It uses the non NMI safe cmpxchg_local_generic for 1, 2 and 8 bytes
cmpxchg_local.

From: Gunnar Larisch <gl@denx.de>
From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Gunnar Larisch <gl@denx.de>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: clameter@sgi.com
CC: benh@kernel.crashing.org
---
include/asm-ppc/system.h | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)
Index: linux-2.6-lttng/include/asm-ppc/system.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-ppc/system.h 2007-08-07 14:31:51.000000000 -0400
+++ linux-2.6-lttng/include/asm-ppc/system.h 2007-08-07 15:03:51.000000000 -0400
@@ -208,12 +208,34 @@ __cmpxchg_u32(volatile unsigned int *p,
return prev;
}

+static __inline__ unsigned long
+__cmpxchg_u32_local(volatile unsigned int *p, unsigned int old,
+ unsigned int new)
+{
+ unsigned int prev;
+
+ __asm__ __volatile__ ("\n\
+1: lwarx %0,0,%2 \n\
+ cmpw 0,%0,%3 \n\
+ bne 2f \n"
+ PPC405_ERR77(0,%2)
+" stwcx. %4,0,%2 \n\
+ bne- 1b\n"
+"2:"
+ : "=&r" (prev), "=m" (*p)
+ : "r" (p), "r" (old), "r" (new), "m" (*p)
+ : "cc", "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 __inline__ unsigned long
-__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new,
+ unsigned int size)
{
switch (size) {
case 4:
@@ -235,6 +257,31 @@ __cmpxchg(volatile void *ptr, unsigned l
(unsigned long)_n_, sizeof(*(ptr))); \
})

+#include <asm-generic/cmpxchg-local.h>
+
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+ unsigned long old,
+ unsigned long new, int size)
+{
+ switch (size) {
+ case 4:
+ return __cmpxchg_u32_local(ptr, old, new);
+ default:
+ return __cmpxchg_local_generic(ptr, old, new, size);
+ }
+
+ return old;
+}
+
+/*
+ * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
+ * them available.
+ */
+#define cmpxchg_local(ptr,o,n) \
+ (__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr)))
+#define cmpxchg64_local(ptr,o,n) __cmpxchg64_local_generic((ptr), (o), (n))
+
#define arch_align_stack(x) (x)

#endif /* __KERNEL__ */
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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