This is a note to let you know that I've just added the patch titled
x86: drop bogus "cc" clobber from __try_cmpxchg_user_asm()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-drop-bogus-cc-clobber-from-__try_cmpxchg_user_asm.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1df931d95f4dc1c11db1123e85d4e08156e46ef9 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@xxxxxxxx>
Date: Tue, 7 Jun 2022 17:00:53 +0200
Subject: x86: drop bogus "cc" clobber from __try_cmpxchg_user_asm()
From: Jan Beulich <jbeulich@xxxxxxxx>
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@xxxxxxxx>
Message-Id: <485c0c0b-a3a7-0b7c-5264-7d00c01de032@xxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)) \
Patches currently in stable-queue which might be from jbeulich@xxxxxxxx are
queue-5.10/x86-drop-bogus-cc-clobber-from-__try_cmpxchg_user_asm.patch
