[PATCH v2 7/7] arm64: Add compat hwcap SSBS

From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Amit Daniel Kachhap <amit.kachhap@arm.com>
Subject: [PATCH v2 7/7] arm64: Add compat hwcap SSBS
Date: Wed, 11 Jan 2023 11:07:06 +0530	[thread overview]
Message-ID: <20230111053706.13994-8-amit.kachhap@arm.com> (raw)
In-Reply-To: <20230111053706.13994-1-amit.kachhap@arm.com>

This hwcap was added for 32-bit native arm kernel by commit fea53546be57
("ARM: 9274/1: Add hwcap for Speculative Store Bypassing Safe") and hence
the corresponding changes added in 32-bit compat arm64 for similar user
interfaces.

Speculative Store Bypass Safe is a feature(FEAT_SSBS) present in
AArch32/AArch64 state for Armv8 and can be identified by PFR2.SSBS
identification register. This hwcap is already advertised in native arm64
kernel.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
 arch/arm64/include/asm/hwcap.h | 1 +
 arch/arm64/kernel/cpufeature.c | 3 ++-
 arch/arm64/kernel/cpuinfo.c    | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index f2bcf4255f97..2f539a3e3d3a 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -44,6 +44,7 @@
 #define COMPAT_HWCAP2_SHA2	(1 << 3)
 #define COMPAT_HWCAP2_CRC32	(1 << 4)
 #define COMPAT_HWCAP2_SB	(1 << 5)
+#define COMPAT_HWCAP2_SSBS	(1 << 6)
 
 #ifndef __ASSEMBLY__
 #include <linux/log2.h>
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 8adbafbdf1da..d54c2a003435 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -562,7 +562,7 @@ static const struct arm64_ftr_bits ftr_id_pfr1[] = {
 };
 
 static const struct arm64_ftr_bits ftr_id_pfr2[] = {
-	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_EL1_SSBS_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_EL1_SSBS_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_EL1_CSV3_SHIFT, 4, 0),
 	ARM64_FTR_END,
 };
@@ -2878,6 +2878,7 @@ static const struct arm64_cpu_capabilities compat_elf_hwcaps[] = {
 	HWCAP_CAP(SYS_ID_ISAR6_EL1, ID_ISAR6_EL1_SB_SHIFT, 4, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SB),
 	HWCAP_CAP(SYS_ID_ISAR6_EL1, ID_ISAR6_EL1_BF16_SHIFT, 4, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP, COMPAT_HWCAP_ASIMDBF16),
 	HWCAP_CAP(SYS_ID_ISAR6_EL1, ID_ISAR6_EL1_I8MM_SHIFT, 4, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP, COMPAT_HWCAP_I8MM),
+	HWCAP_CAP(SYS_ID_PFR2_EL1, ID_PFR2_EL1_SSBS_SHIFT, 4, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SSBS),
 #endif
 	{},
 };
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index d2b41f2544f5..876cd96c73ea 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -162,6 +162,7 @@ static const char *const compat_hwcap2_str[] = {
 	[COMPAT_KERNEL_HWCAP2(SHA2)]	= "sha2",
 	[COMPAT_KERNEL_HWCAP2(CRC32)]	= "crc32",
 	[COMPAT_KERNEL_HWCAP2(SB)]	= "sb",
+	[COMPAT_KERNEL_HWCAP2(SSBS)]	= "ssbs",
 };
 #endif /* CONFIG_COMPAT */
 
-- 
2.17.1


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