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authorPaul Burton <paul.burton@imgtec.com>2017-06-09 17:26:35 -0700
committerRalf Baechle <ralf@linux-mips.org>2017-06-29 02:42:24 +0200
commit77299db802d4a7ae43f7ca246adbff0420bc9f5a (patch)
tree85d2b250525303fc2e96bba1e43152ca889d3b70 /arch/mips/include
parent5154f3b4194910a4216866e7535c37e5bcb17800 (diff)
MIPS: cmpxchg: Use __compiletime_error() for bad cmpxchg() pointers
Our cmpxchg() implementation relies upon generating a call to a function which doesn't really exist (__cmpxchg_called_with_bad_pointer) to create a link failure in cases where cmpxchg() is called with a pointer to a value of an unsupported size. The __compiletime_error macro can be used to decorate a function such that a call to it generates a compile-time, rather than a link-time, error. This patch uses __compiletime_error to cause bad cmpxchg() calls to error out at compile time rather than link time, allowing errors to occur more quickly & making it easier to spot where the problem comes from. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16350/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include')
-rw-r--r--arch/mips/include/asm/cmpxchg.h13
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
index a19359649b60..ee0214e00ab1 100644
--- a/arch/mips/include/asm/cmpxchg.h
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -137,10 +137,17 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
})
/*
- * This function doesn't exist, so you'll get a linker error
- * if something tries to do an invalid cmpxchg().
+ * This function doesn't exist, so if it is called you'll either:
+ *
+ * - Get an error at compile-time due to __compiletime_error, if supported by
+ * your compiler.
+ *
+ * or:
+ *
+ * - Get an error at link-time due to the call to the missing function.
*/
-extern void __cmpxchg_called_with_bad_pointer(void);
+extern void __cmpxchg_called_with_bad_pointer(void)
+ __compiletime_error("Bad argument size for cmpxchg");
#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier) \
({ \