Commit 62724cc5 authored by Richard Henderson's avatar Richard Henderson
Browse files

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: default avatarRichard Henderson <rth@twiddle.net>
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parent cfb75cb9

linux-user/qemu.h

+15 −32
Original line number Diff line number Diff line
@@ -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;\

})