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700b7c5409
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>
57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_RMWcc
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#define _ASM_X86_RMWcc
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#define __CLOBBERS_MEM(clb...) "memory", ## clb
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#if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO)
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/* Use asm goto */
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#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \
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do { \
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asm_volatile_goto (fullop "; j" #cc " %l[cc_label]" \
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: : [counter] "m" (var), ## __VA_ARGS__ \
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: clobbers : cc_label); \
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return 0; \
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cc_label: \
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return 1; \
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} while (0)
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#define __BINARY_RMWcc_ARG " %1, "
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#else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
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/* Use flags output or a set instruction */
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#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \
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do { \
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bool c; \
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asm volatile (fullop CC_SET(cc) \
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: [counter] "+m" (var), CC_OUT(cc) (c) \
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: __VA_ARGS__ : clobbers); \
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return c; \
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} while (0)
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#define __BINARY_RMWcc_ARG " %2, "
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#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
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#define GEN_UNARY_RMWcc(op, var, arg0, cc) \
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__GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM())
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#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc, clobbers...)\
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__GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc, \
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__CLOBBERS_MEM(clobbers))
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#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \
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__GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc, \
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__CLOBBERS_MEM(), vcon (val))
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#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc, \
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clobbers...) \
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__GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc, \
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__CLOBBERS_MEM(clobbers), vcon (val))
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#endif /* _ASM_X86_RMWcc */
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