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

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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: 989b5db215 ("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>
This commit is contained in:
Jan Beulich 2022-06-07 17:00:53 +02:00 committed by Paolo Bonzini
parent cf4a8693d9
commit 1df931d95f
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/uaccess.h
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@ -439,7 +439,7 @@ do { \
[ptr] "+m" (*_ptr), \ [ptr] "+m" (*_ptr), \
[old] "+a" (__old) \ [old] "+a" (__old) \
: [new] ltype (__new) \ : [new] ltype (__new) \
: "memory", "cc"); \ : "memory"); \
if (unlikely(__err)) \ if (unlikely(__err)) \
goto label; \ goto label; \
if (unlikely(!success)) \ if (unlikely(!success)) \