diff options
| author | Paul Burton <paul.burton@imgtec.com> | 2017-06-09 17:26:36 -0700 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-06-29 02:42:24 +0200 |
| commit | d15dc68c1143e249c36612c15bf4e930637b47c3 (patch) | |
| tree | 3d15ad84f49c8d9735298f4f4915dd7a5e7f69d3 /arch/mips/include/asm | |
| parent | 77299db802d4a7ae43f7ca246adbff0420bc9f5a (diff) | |
MIPS: cmpxchg: Error out on unsupported xchg() calls
xchg() has up until now simply returned the x parameter in cases where
it is called with a pointer to a value of an unsupported size. This will
often cause the calling code to hit a failure path, presuming that the
value of x differs from the content of the memory pointed at by ptr, but
we can do better by producing a compile-time or link-time error such
that unsupported calls to xchg() are detectable earlier than runtime.
This patch does this in the same was as is already done for cmpxchg(),
using a call to a missing function annotated with __compiletime_error().
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16351/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm')
| -rw-r--r-- | arch/mips/include/asm/cmpxchg.h | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h index ee0214e00ab1..fe652c3e5d8c 100644 --- a/arch/mips/include/asm/cmpxchg.h +++ b/arch/mips/include/asm/cmpxchg.h @@ -24,6 +24,21 @@ # define __scbeqz "beqz" #endif +/* + * These functions doesn't exist, so if they are 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) + __compiletime_error("Bad argument size for cmpxchg"); +extern unsigned long __xchg_called_with_bad_pointer(void) + __compiletime_error("Bad argument size for xchg"); + #define __xchg_asm(ld, st, m, val) \ ({ \ __typeof(*(m)) __ret; \ @@ -89,9 +104,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz return __xchg_u32(ptr, x); case 8: return __xchg_u64(ptr, x); + default: + return __xchg_called_with_bad_pointer(); } - - return x; } #define xchg(ptr, x) \ @@ -136,19 +151,6 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz __ret; \ }) -/* - * 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) - __compiletime_error("Bad argument size for cmpxchg"); - #define __cmpxchg(ptr, old, new, pre_barrier, post_barrier) \ ({ \ __typeof__(ptr) __ptr = (ptr); \ |