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Message-Id: <20211017124225.3018098-18-maz@kernel.org>
Date: Sun, 17 Oct 2021 13:42:25 +0100
From: Marc Zyngier <maz@...nel.org>
To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Will Deacon <will@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Shier <pshier@...gle.com>,
Raghavendra Rao Ananta <rananta@...gle.com>,
Ricardo Koller <ricarkol@...gle.com>,
Oliver Upton <oupton@...gle.com>,
Catalin Marinas <catalin.marinas@....com>,
Linus Walleij <linus.walleij@...aro.org>,
kernel-team@...roid.com
Subject: [PATCH v4 17/17] arm64: Add HWCAP for self-synchronising virtual counter
Since userspace can make use of the CNTVSS_EL0 instruction, expose
it via a HWCAP.
Suggested-by: Will Deacon <will@...nel.org>
Acked-by: Will Deacon <will@...nel.org>
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
Documentation/arm64/cpu-feature-registers.rst | 12 ++++++++++--
Documentation/arm64/elf_hwcaps.rst | 4 ++++
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 +
6 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst
index 328e0c454fbd..9f9b8fd06089 100644
--- a/Documentation/arm64/cpu-feature-registers.rst
+++ b/Documentation/arm64/cpu-feature-registers.rst
@@ -235,7 +235,15 @@ infrastructure:
| DPB | [3-0] | y |
+------------------------------+---------+---------+
- 6) ID_AA64MMFR2_EL1 - Memory model feature register 2
+ 6) ID_AA64MMFR0_EL1 - Memory model feature register 0
+
+ +------------------------------+---------+---------+
+ | Name | bits | visible |
+ +------------------------------+---------+---------+
+ | ECV | [63-60] | y |
+ +------------------------------+---------+---------+
+
+ 7) ID_AA64MMFR2_EL1 - Memory model feature register 2
+------------------------------+---------+---------+
| Name | bits | visible |
@@ -243,7 +251,7 @@ infrastructure:
| AT | [35-32] | y |
+------------------------------+---------+---------+
- 7) ID_AA64ZFR0_EL1 - SVE feature ID register 0
+ 8) ID_AA64ZFR0_EL1 - SVE feature ID register 0
+------------------------------+---------+---------+
| Name | bits | visible |
diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst
index ec1a5a63c1d0..af106af8e1c0 100644
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -247,6 +247,10 @@ HWCAP2_MTE
Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0010, as described
by Documentation/arm64/memory-tagging-extension.rst.
+HWCAP2_ECV
+
+ Functionality implied by ID_AA64MMFR0_EL1.ECV == 0b0001.
+
4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 8c129db8232a..b100e0055eab 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -105,6 +105,7 @@
#define KERNEL_HWCAP_RNG __khwcap2_feature(RNG)
#define KERNEL_HWCAP_BTI __khwcap2_feature(BTI)
#define KERNEL_HWCAP_MTE __khwcap2_feature(MTE)
+#define KERNEL_HWCAP_ECV __khwcap2_feature(ECV)
/*
* 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 b8f41aa234ee..7b23b16f21ce 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -75,5 +75,6 @@
#define HWCAP2_RNG (1 << 16)
#define HWCAP2_BTI (1 << 17)
#define HWCAP2_MTE (1 << 18)
+#define HWCAP2_ECV (1 << 19)
#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 26b11ce8fff6..97ed37c6ce5e 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -279,7 +279,7 @@ static const struct arm64_ftr_bits ftr_id_aa64zfr0[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64mmfr0[] = {
- ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_ECV_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_ECV_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_FGT_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_EXS_SHIFT, 4, 0),
/*
@@ -2457,6 +2457,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
#ifdef CONFIG_ARM64_MTE
HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_MTE_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_MTE, CAP_HWCAP, KERNEL_HWCAP_MTE),
#endif /* CONFIG_ARM64_MTE */
+ HWCAP_CAP(SYS_ID_AA64MMFR0_EL1, ID_AA64MMFR0_ECV_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ECV),
{},
};
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 87731fea5e41..6e27b759056a 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -94,6 +94,7 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_RNG] = "rng",
[KERNEL_HWCAP_BTI] = "bti",
[KERNEL_HWCAP_MTE] = "mte",
+ [KERNEL_HWCAP_ECV] = "ecv",
};
#ifdef CONFIG_COMPAT
--
2.30.2
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