[PATCH 5.10 072/122] x86: drop bogus "cc" clobber from __try_cmpxchg_user_asm()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2024-02-27 14:30:03
Also in:
linux-patches
5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jan Beulich <redacted>
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 <redacted>
Message-Id: [off-list ref]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/uaccess.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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)) \