x86: drop bogus "cc" clobber from __try_cmpxchg_user_asm()

commit 1df931d95f4dc1c11db1123e85d4e08156e46ef9 upstream.

As noted (and fixed) a couple of times in the past, "=@cc<cond>" outputs
and clobbering of "cc" don't work well together. The compiler appears to
mean to reject such, but doesn't - in its upstream form - quite manage
to yet for "cc". Furthermore two similar macros don't clobber "cc", and
clobbering "cc" is pointless in asm()-s for x86 anyway - the compiler
always assumes status flags to be clobbered there.

Fixes: 989b5db215a2 ("x86/uaccess: Implement macros for CMPXCHG on user addresses")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Message-Id: <485c0c0b-a3a7-0b7c-5264-7d00c01de032@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 2f4c9c168b11d893c629ee6e50850dd227edb78c..ab5e577373093561c20c218a7bdd31303ad74a56 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -471,7 +471,7 @@ do {                                                                        \
                       [ptr] "+m" (*_ptr),                              \
                       [old] "+a" (__old)                               \
                     : [new] ltype (__new)                              \
-                    : "memory", "cc");                                 \
+                    : "memory");                                       \
        if (unlikely(__err))                                            \
                goto label;                                             \
        if (unlikely(!success))                                         \