arm64: Add macro version of the BTI instruction

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>

diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S
index b495de2..ff01f01 100644 (file)
--- 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 136d13f..e8bd0af 100644 (file)
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -791,6 +791,16 @@ alternative_endif
        .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
  * use in assembly files included in the VDSO.

diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index 9906541..c5d0c11 100644 (file)
--- 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