From a46cec12f4a53ee5113f42b327cbb8d4cda074d2 Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@arm.com>
Date: Fri, 24 Jul 2020 10:41:31 +0100
Subject: [PATCH] arm64: Reserve HWCAP2_MTE as (1 << 18)
While MTE is not supported in the upstream kernel yet, add a comment
that HWCAP2_MTE as (1 << 18) is reserved. Glibc makes use of it for the
resolving (ifunc) of the MTE-safe string routines.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/hwcap.h | 1 +
arch/arm64/include/uapi/asm/hwcap.h | 1 +
arch/arm64/kernel/cpuinfo.c | 1 +
3 files changed, 3 insertions(+)
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index d683bcbf1e7c0..22f73fe090309 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -95,6 +95,7 @@
#define KERNEL_HWCAP_DGH __khwcap2_feature(DGH)
#define KERNEL_HWCAP_RNG __khwcap2_feature(RNG)
#define KERNEL_HWCAP_BTI __khwcap2_feature(BTI)
+/* reserved for KERNEL_HWCAP_MTE __khwcap2_feature(MTE) */
/*
* This yields a mask that user programs can use to figure out what
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index 2d6ba1c2592ed..912162f735298 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -74,5 +74,6 @@
#define HWCAP2_DGH (1 << 15)
#define HWCAP2_RNG (1 << 16)
#define HWCAP2_BTI (1 << 17)
+/* reserved for HWCAP2_MTE (1 << 18) */
#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 86637466daa85..393c6fb1f1cb4 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -93,6 +93,7 @@ static const char *const hwcap_str[] = {
"dgh",
"rng",
"bti",
+ /* reserved for "mte" */
NULL
};
--
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