[PATCH v11 17/39] arm64/hwcap: Add hwcap for GCS

Mark Brown
2024-08-22T01:19:33Z

Provide a hwcap to enable userspace to detect support for GCS.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/arch/arm64/elf_hwcaps.rst | 2 ++
arch/arm64/include/asm/hwcap.h | 1 +
arch/arm64/include/uapi/asm/hwcap.h | 1 +
arch/arm64/kernel/cpufeature.c | 3 +++
arch/arm64/kernel/cpuinfo.c | 1 +
5 files changed, 8 insertions(+)

diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index 448c1664879b..cf87be078f33 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -365,6 +365,8 @@ HWCAP2_SME_SF8DP2
HWCAP2_SME_SF8DP4
Functionality implied by ID_AA64SMFR0_EL1.SF8DP4 == 0b1.

+HWCAP2_GCS
+ Functionality implied by ID_AA64PFR1_EL1.GCS == 0b1

4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 4edd3b61df11..fd7e162e7e39 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -157,6 +157,7 @@
#define KERNEL_HWCAP_SME_SF8FMA __khwcap2_feature(SME_SF8FMA)
#define KERNEL_HWCAP_SME_SF8DP4 __khwcap2_feature(SME_SF8DP4)
#define KERNEL_HWCAP_SME_SF8DP2 __khwcap2_feature(SME_SF8DP2)
+#define KERNEL_HWCAP_GCS __khwcap2_feature(GCS)

/*
* 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 285610e626f5..328fb7843e2f 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -122,5 +122,6 @@
#define HWCAP2_SME_SF8FMA (1UL << 60)
#define HWCAP2_SME_SF8DP4 (1UL << 61)
#define HWCAP2_SME_SF8DP2 (1UL << 62)
+#define HWCAP2_GCS (1UL << 63)

#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 315bd7be1106..e3e8290a4447 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2994,6 +2994,9 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(ID_AA64ZFR0_EL1, I8MM, IMP, CAP_HWCAP, KERNEL_HWCAP_SVEI8MM),
HWCAP_CAP(ID_AA64ZFR0_EL1, F32MM, IMP, CAP_HWCAP, KERNEL_HWCAP_SVEF32MM),
HWCAP_CAP(ID_AA64ZFR0_EL1, F64MM, IMP, CAP_HWCAP, KERNEL_HWCAP_SVEF64MM),
+#endif
+#ifdef CONFIG_ARM64_GCS
+ HWCAP_CAP(ID_AA64PFR1_EL1, GCS, IMP, CAP_HWCAP, KERNEL_HWCAP_GCS),
#endif
HWCAP_CAP(ID_AA64PFR1_EL1, SSBS, SSBS2, CAP_HWCAP, KERNEL_HWCAP_SSBS),
#ifdef CONFIG_ARM64_BTI
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 09eeaa24d456..2f539e3101ee 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -143,6 +143,7 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_SME_SF8FMA] = "smesf8fma",
[KERNEL_HWCAP_SME_SF8DP4] = "smesf8dp4",
[KERNEL_HWCAP_SME_SF8DP2] = "smesf8dp2",
+ [KERNEL_HWCAP_GCS] = "gcs",
};

#ifdef CONFIG_COMPAT

--
2.39.2