The previous formuation with multiple assignments to __typeof(*hptr) falls down when hptr is qualified const. E.g. with const struct S *p, p->f is also qualified const.
With this formulation, there's no assignment to any local variable. Signed-off-by: Richard Henderson <r...@twiddle.net> --- linux-user/qemu.h | 50 ++++++++++++++++++++------------------------------ 1 file changed, 20 insertions(+), 30 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index fc4cc00..39b2c9c 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -284,36 +284,26 @@ static inline int access_ok(int type, abi_ulong addr, abi_ulong size) (type == VERIFY_READ) ? PAGE_READ : (PAGE_READ | PAGE_WRITE)) == 0; } -/* NOTE __get_user and __put_user use host pointers and don't check access. */ -/* These are usually used to access struct data members once the - * struct has been locked - usually with lock_user_struct(). - */ -#define __put_user(x, hptr)\ -({ __typeof(*hptr) pu_ = (x);\ - switch(sizeof(*hptr)) {\ - 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: break; \ - case 2: gu_ = tswap16(gu_); break; \ - case 4: gu_ = tswap32(gu_); break; \ - case 8: gu_ = tswap64(gu_); break; \ - default: abort();\ - }\ - (x) = gu_; \ - 0;\ -}) +/* NOTE __get_user and __put_user use host pointers and don't check access. + These are usually used to access struct data members once the struct has + been locked - usually with lock_user_struct. */ +#define __put_user(x, hptr) \ +(*(hptr) = \ + __builtin_choose_expr(sizeof(*(hptr)) == 1, (uint8_t)(x), \ + __builtin_choose_expr(sizeof(*(hptr)) == 2, tswap16((uint16_t)(x)), \ + __builtin_choose_expr(sizeof(*(hptr)) == 4, tswap32((uint32_t)(x)), \ + __builtin_choose_expr(sizeof(*(hptr)) == 8, tswap64((uint64_t)(x)), \ + abort())))), \ + 0) + +#define __get_user(x, hptr) \ +((x) = \ + __builtin_choose_expr(sizeof(*(hptr)) == 1, *(hptr), \ + __builtin_choose_expr(sizeof(*(hptr)) == 2, tswap16(*(hptr)), \ + __builtin_choose_expr(sizeof(*(hptr)) == 4, tswap32(*(hptr)), \ + __builtin_choose_expr(sizeof(*(hptr)) == 8, tswap64(*(hptr)), \ + abort())))), \ + 0) /* put_user()/get_user() take a guest address and check access */ /* These are usually used to access an atomic data type, such as an int, -- 1.7.11.4