diff options
| author | Jan Beulich <JBeulich@suse.com> | 2018-02-19 07:49:12 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-02-20 09:33:39 +0100 |
| commit | 700b7c5409c3e9da279fbea78cf28a78fbc176cd (patch) | |
| tree | 005f64cec96d3ff3b7b05f2c26c5903f5a9c004b /arch/x86/include/asm/refcount.h | |
| parent | 3b3a9268bba62b35a29bafe0931715b1725fdf26 (diff) | |
x86/asm: Improve how GEN_*_SUFFIXED_RMWcc() specify clobbers
Commit:
df3405245a ("x86/asm: Add suffix macro for GEN_*_RMWcc()")
... introduced "suffix" RMWcc operations, adding bogus clobber specifiers:
For one, on x86 there's no point explicitly clobbering "cc".
In fact, with GCC properly fixed, this results in an overlap being detected by
the compiler between outputs and clobbers.
Furthermore it seems bad practice to me to have clobber specification
and use of the clobbered register(s) disconnected - it should rather be
at the invocation place of that GEN_{UN,BIN}ARY_SUFFIXED_RMWcc() macros
that the clobber is specified which this particular invocation needs.
Drop the "cc" clobber altogether and move the "cx" one to refcount.h.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5A8AF1F802000078001A91E1@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/refcount.h')
| -rw-r--r-- | arch/x86/include/asm/refcount.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/refcount.h b/arch/x86/include/asm/refcount.h index 4e44250e7d0d..d65171120e90 100644 --- a/arch/x86/include/asm/refcount.h +++ b/arch/x86/include/asm/refcount.h @@ -67,13 +67,13 @@ static __always_inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) { GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, "er", i, "%0", e); + r->refs.counter, "er", i, "%0", e, "cx"); } static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r) { GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, "%0", e); + r->refs.counter, "%0", e, "cx"); } static __always_inline __must_check |