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| author | Paul Burton <paul.burton@imgtec.com> | 2017-06-10 03:26:35 +0300 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-06-29 03:42:24 +0300 |
| commit | 77299db802d4a7ae43f7ca246adbff0420bc9f5a (patch) | |
| tree | 85d2b250525303fc2e96bba1e43152ca889d3b70 | |
| parent | 5154f3b4194910a4216866e7535c37e5bcb17800 (diff) | |
| download | linux-77299db802d4a7ae43f7ca246adbff0420bc9f5a.tar.xz | |
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>
| -rw-r--r-- | arch/mips/include/asm/cmpxchg.h | 13 |
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) \ ({ \ |