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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Mark Brown <broonie@kernel.org>
Subject: [PATCH v4 1/3] arm64: Add macro version of the BTI instruction
Date: Tue, 14 Dec 2021 15:27:12 +0000	[thread overview]
Message-ID: <20211214152714.2380849-2-broonie@kernel.org> (raw)
In-Reply-To: <20211214152714.2380849-1-broonie@kernel.org>

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>
---
 arch/arm64/crypto/aes-modes.S      | 10 +++++-----
 arch/arm64/include/asm/assembler.h | 10 ++++++++++
 arch/arm64/include/asm/linkage.h   |  7 +------
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S
index b495de22bb38..ff01f0167ba2 100644
--- a/arch/arm64/crypto/aes-modes.S
+++ b/arch/arm64/crypto/aes-modes.S
@@ -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
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 136d13f3d6e9..e8bd0af0141c 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -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
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index 9906541a6861..c5d0c11d7709 100644
--- a/arch/arm64/include/asm/linkage.h
+++ b/arch/arm64/include/asm/linkage.h
@@ -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
-- 
2.30.2


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  reply	other threads:[~2021-12-14 15:29 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-14 15:27 [PATCH v4 0/3] arm64: BTI cleanups Mark Brown
2021-12-14 15:27 ` Mark Brown [this message]
2021-12-14 15:27 ` [PATCH v4 2/3] arm64: Unconditionally override SYM_FUNC macros Mark Brown
2021-12-14 15:27 ` [PATCH v4 3/3] arm64: Use BTI C directly and unconditionally Mark Brown
2021-12-14 15:35   ` Ard Biesheuvel
2021-12-14 15:59 ` [PATCH v4 0/3] arm64: BTI cleanups Mark Rutland
2021-12-14 19:16 ` Catalin Marinas

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