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arm64: Add macro version of the BTI instruction

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BTI is only available from v8.5 so we need to encode it using HINT in
generic code and for older toolchains. Add an assembler macro based on
one written by Mark Rutland which lets us use the mnemonic and update
the existing users.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20211214152714.2380849-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Brown 2021-12-14 15:27:12 +00:00 committed by Catalin Marinas
parent 580b536b50
commit 9be34be87c
3 changed files with 16 additions and 11 deletions
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10
arch/arm64/crypto/aes-modes.S
View File

@ -363,15 +363,15 @@ ST5( mov v4.16b, vctr.16b )
adr x16, 1f
sub x16, x16, x12, lsl #3
br x16
hint 34 // bti c
bti c
mov v0.d[0], vctr.d[0]
hint 34 // bti c
bti c
mov v1.d[0], vctr.d[0]
hint 34 // bti c
bti c
mov v2.d[0], vctr.d[0]
hint 34 // bti c
bti c
mov v3.d[0], vctr.d[0]
ST5( hint 34 )
ST5( bti c )
ST5( mov v4.d[0], vctr.d[0] )
1: b 2f
.previous

10
arch/arm64/include/asm/assembler.h
View File

@ -790,6 +790,16 @@ alternative_endif
.Lnoyield_\@:
.endm
/*
* Branch Target Identifier (BTI)
*/
.macro bti, targets
.equ .L__bti_targets_c, 34
.equ .L__bti_targets_j, 36
.equ .L__bti_targets_jc,38
hint #.L__bti_targets_\targets
.endm
/*
* This macro emits a program property note section identifying
* architecture features which require special handling, mainly for

7
arch/arm64/include/asm/linkage.h
View File

@ -6,12 +6,7 @@
#if defined(CONFIG_ARM64_BTI_KERNEL) && defined(__aarch64__)
/*
* Since current versions of gas reject the BTI instruction unless we
* set the architecture version to v8.5 we use the hint instruction
* instead.
*/
#define BTI_C hint 34 ;
#define BTI_C bti c ;
/*
* When using in-kernel BTI we need to ensure that PCS-conformant assembly