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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. */
#ifndef _ASM_X86_NOSPEC_H
#define _ASM_X86_NOSPEC_H
#include <asm/alternative.h>
/* Allow to insert a read memory barrier into conditionals */
static always_inline bool barrier_nospec_true(void)
{
#ifdef CONFIG_SPECULATIVE_HARDEN_BRANCH
alternative("lfence #nospec-true", "", X86_FEATURE_SC_NO_BRANCH_HARDEN);
#endif
return true;
}
static always_inline bool barrier_nospec_false(void)
{
#ifdef CONFIG_SPECULATIVE_HARDEN_BRANCH
alternative("lfence #nospec-false", "", X86_FEATURE_SC_NO_BRANCH_HARDEN);
#endif
return false;
}
/* Allow to protect evaluation of conditionals with respect to speculation */
static always_inline bool evaluate_nospec(bool condition)
{
if ( condition )
return barrier_nospec_true();
else
return barrier_nospec_false();
}
/* Allow to block speculative execution in generic code */
static always_inline void block_speculation(void)
{
barrier_nospec_true();
}
#endif /* _ASM_X86_NOSPEC_H */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* indent-tabs-mode: nil
* End:
*/
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