• Christophe Leroy's avatar
    powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9 · 592bbe9c
    Christophe Leroy authored
    GCC 4.9 sometimes fails to build with "m<>" constraint in
    inline assembly.
    
      CC      lib/iov_iter.o
    In file included from ./arch/powerpc/include/asm/cmpxchg.h:6:0,
                     from ./arch/powerpc/include/asm/atomic.h:11,
                     from ./include/linux/atomic.h:7,
                     from ./include/linux/crypto.h:15,
                     from ./include/crypto/hash.h:11,
                     from lib/iov_iter.c:2:
    lib/iov_iter.c: In function 'iovec_from_user.part.30':
    ./arch/powerpc/include/asm/uaccess.h:287:2: error: 'asm' operand has impossible constraints
      __asm__ __volatile__(    \
      ^
    ./include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
     # define unlikely(x) __builtin_expect(!!(x), 0)
                                              ^
    ./arch/powerpc/include/asm/uaccess.h:583:34: note: in expansion of macro 'unsafe_op_wrap'
     #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                      ^
    ./arch/powerpc/include/asm/uaccess.h:329:10: note: in expansion of macro '__get_user_asm'
      case 4: __get_user_asm(x, (u32 __user *)ptr, retval, "lwz"); break; \
              ^
    ./arch/powerpc/include/asm/uaccess.h:363:3: note: in expansion of macro '__get_user_size_allowed'
       __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
       ^
    ./arch/powerpc/include/asm/uaccess.h:100:2: note: in expansion of macro '__get_user_nocheck'
      __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
      ^
    ./arch/powerpc/include/asm/uaccess.h:583:49: note: in expansion of macro '__get_user_allowed'
     #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                                     ^
    lib/iov_iter.c:1663:3: note: in expansion of macro 'unsafe_get_user'
       unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
       ^
    make[1]: *** [scripts/Makefile.build:283: lib/iov_iter.o] Error 1
    
    Define a UPD_CONSTR macro that is "<>" by default and
    only "" with GCC prior to GCC 5.
    
    Fixes: fcf1f268 ("powerpc/uaccess: Add pre-update addressing to __put_user_asm_goto()")
    Fixes: 2f279eeb ("powerpc/uaccess: Add pre-update addressing to __get_user_asm() and __put_user_asm()")
    Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
    Acked-by: default avatarSegher Boessenkool <segher@kernel.crashing.org>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/212d3bc4a52ca71523759517bb9c61f7e477c46a.1603179582.git.christophe.leroy@csgroup.eu
    592bbe9c
asm-const.h 671 Bytes