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Peter Zijlstra
25e73b7e3f
It was reported that under certain circumstances GCC emits ENDBR
instructions for _THIS_IP_ usage. Specifically, when it appears at the
start of a basic block -- but not elsewhere.
Since _THIS_IP_ is never used for control flow, these ENDBR
instructions are completely superfluous. Override the _THIS_IP_
definition for x86_64 to avoid this.
Less ENDBR instructions is better.
Fixes: 156ff4a544 ("x86/ibt: Base IBT bits")
Reported-by: David Kaplan <[email protected]>
Reviewed-by: Andrew Cooper <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
14 lines
346 B
C
14 lines
346 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_INSTRUCTION_POINTER_H
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#define _LINUX_INSTRUCTION_POINTER_H
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#include <asm/linkage.h>
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#define _RET_IP_ (unsigned long)__builtin_return_address(0)
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#ifndef _THIS_IP_
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#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
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#endif
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#endif /* _LINUX_INSTRUCTION_POINTER_H */
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