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2d12c6fb78
ANNOTATE_IGNORE_ALTERNATIVE adds additional noise to the code generated by CLAC/STAC alternatives, hurting readability for those whose read uaccess-related code generation on a regular basis. Remove the annotation specifically for the "NOP patched with CLAC/STAC" case in favor of a manual check. Leave the other uses of that annotation in place as they're less common and more difficult to detect. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/fc972ba4995d826fcfb8d02733a14be8d670900b.1744098446.git.jpoimboe@kernel.org
73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Supervisor Mode Access Prevention support
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*
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* Copyright (C) 2012 Intel Corporation
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* Author: H. Peter Anvin <hpa@linux.intel.com>
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*/
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#ifndef _ASM_X86_SMAP_H
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#define _ASM_X86_SMAP_H
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#include <asm/nops.h>
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#include <asm/cpufeatures.h>
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#include <asm/alternative.h>
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#ifdef __ASSEMBLER__
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#define ASM_CLAC \
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ALTERNATIVE "", "clac", X86_FEATURE_SMAP
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#define ASM_STAC \
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ALTERNATIVE "", "stac", X86_FEATURE_SMAP
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#else /* __ASSEMBLER__ */
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static __always_inline void clac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative("", "clac", X86_FEATURE_SMAP);
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}
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static __always_inline void stac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative("", "stac", X86_FEATURE_SMAP);
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}
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static __always_inline unsigned long smap_save(void)
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{
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unsigned long flags;
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asm volatile ("# smap_save\n\t"
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ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
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"", "pushf; pop %0; clac",
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X86_FEATURE_SMAP)
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: "=rm" (flags) : : "memory", "cc");
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return flags;
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}
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static __always_inline void smap_restore(unsigned long flags)
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{
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asm volatile ("# smap_restore\n\t"
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ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
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"", "push %0; popf",
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X86_FEATURE_SMAP)
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: : "g" (flags) : "memory", "cc");
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}
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/* These macros can be used in asm() statements */
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#define ASM_CLAC \
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ALTERNATIVE("", "clac", X86_FEATURE_SMAP)
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#define ASM_STAC \
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ALTERNATIVE("", "stac", X86_FEATURE_SMAP)
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#define ASM_CLAC_UNSAFE \
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ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "clac", X86_FEATURE_SMAP)
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#define ASM_STAC_UNSAFE \
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ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "stac", X86_FEATURE_SMAP)
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#endif /* __ASSEMBLER__ */
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#endif /* _ASM_X86_SMAP_H */
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