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authorRichard Henderson <rth@twiddle.net>2012-03-24 21:31:25 +0100
committerRichard Henderson <rth@twiddle.net>2012-09-21 22:02:15 +0200
commit62724cc5ebd7fb9113f156cbc0d2bb5e3cb0a9ae (patch)
tree264a6d37e963318a07ab782c7aea863c7578167e
parentcfb75cb9807463ebe18b127096b48b5d0db1ce03 (diff)
linux-user: Use memcpy in get_user/put_user.
When host and target have differing alignment rules, using a cast and direct memory operation can result in SIGBUS. Use memcpy instead, which the compiler will happily optimize when alignment is satisfied. Signed-off-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--linux-user/qemu.h47
1 files changed, 15 insertions, 32 deletions
diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 69b27d7146..fc4cc00b9f 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -289,46 +289,29 @@ static inline int access_ok(int type, abi_ulong addr, abi_ulong size)
* struct has been locked - usually with lock_user_struct().
*/
#define __put_user(x, hptr)\
-({\
+({ __typeof(*hptr) pu_ = (x);\
switch(sizeof(*hptr)) {\
- case 1:\
- *(uint8_t *)(hptr) = (uint8_t)(typeof(*hptr))(x);\
- break;\
- case 2:\
- *(uint16_t *)(hptr) = tswap16((uint16_t)(typeof(*hptr))(x));\
- break;\
- case 4:\
- *(uint32_t *)(hptr) = tswap32((uint32_t)(typeof(*hptr))(x));\
- break;\
- case 8:\
- *(uint64_t *)(hptr) = tswap64((typeof(*hptr))(x));\
- break;\
- default:\
- abort();\
+ case 1: break;\
+ case 2: pu_ = tswap16(pu_); break; \
+ case 4: pu_ = tswap32(pu_); break; \
+ case 8: pu_ = tswap64(pu_); break; \
+ default: abort();\
}\
+ memcpy(hptr, &pu_, sizeof(pu_)); \
0;\
})
#define __get_user(x, hptr) \
-({\
+({ __typeof(*hptr) gu_; \
+ memcpy(&gu_, hptr, sizeof(gu_)); \
switch(sizeof(*hptr)) {\
- case 1:\
- x = (typeof(*hptr))*(uint8_t *)(hptr);\
- break;\
- case 2:\
- x = (typeof(*hptr))tswap16(*(uint16_t *)(hptr));\
- break;\
- case 4:\
- x = (typeof(*hptr))tswap32(*(uint32_t *)(hptr));\
- break;\
- case 8:\
- x = (typeof(*hptr))tswap64(*(uint64_t *)(hptr));\
- break;\
- default:\
- /* avoid warning */\
- x = 0;\
- abort();\
+ case 1: break; \
+ case 2: gu_ = tswap16(gu_); break; \
+ case 4: gu_ = tswap32(gu_); break; \
+ case 8: gu_ = tswap64(gu_); break; \
+ default: abort();\
}\
+ (x) = gu_; \
0;\
})