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arm64: Add a BTI landing pad to .mcount

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The .mcount function needs a BTI branch target. As we can't rely on
asm.h being included use the hint version of a "bti c" instruction.
This is a nop when BTI is not supported or not used.

Reviewed by:	markj
Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D42230
This commit is contained in:
Andrew Turner 2023-10-16 15:34:19 +01:00
parent 5270cc9757
commit 0590ed0967
1 changed files with 2 additions and 0 deletions
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2
sys/arm64/include/profile.h
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@ -68,6 +68,8 @@ static void _mcount
" .globl .mcount \n" \
" .mcount: \n" \
" .cfi_startproc \n" \
/* Allow this to work with BTI, see BTI_C in asm.h */ \
" hint #34 \n" \
/* Load the caller return address as frompc */ \
" ldr x0, [x29, #8] \n" \
/* Use our return address as selfpc */ \