From: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Armv8.7 introduces single-copy atomic 64-byte loads and stores
instructions and its variants named under FEAT_{LS64, LS64_V}.
These features are identified by ID_AA64ISAR1_EL1.LS64 and the
use of such instructions in userspace (EL0) can be trapped. In
order to support the use of corresponding instructions in userspace:
- Make ID_AA64ISAR1_EL1.LS64 visbile to userspace
- Add identifying and enabling in the cpufeature list
- Expose these support of these features to userspace through HWCAP3
and cpuinfo
Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
---
Documentation/arch/arm64/booting.rst | 12 ++++++
Documentation/arch/arm64/elf_hwcaps.rst | 6 +++
arch/arm64/include/asm/hwcap.h | 2 +
arch/arm64/include/uapi/asm/hwcap.h | 2 +
arch/arm64/kernel/cpufeature.c | 51 +++++++++++++++++++++++++
arch/arm64/kernel/cpuinfo.c | 2 +
arch/arm64/tools/cpucaps | 2 +
7 files changed, 77 insertions(+)
diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst
index 2f666a7c303c..471cb6633a7e 100644
--- a/Documentation/arch/arm64/booting.rst
+++ b/Documentation/arch/arm64/booting.rst
@@ -545,6 +545,18 @@ Before jumping into the kernel, the following conditions must be met:
- MDCR_EL3.TPM (bit 6) must be initialized to 0b0
+ For CPUs support for 64-byte loads and stores without status (FEAT_LS64):
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+ - HCRX_EL2.EnALS (bit 1) must be initialised to 0b1.
+
+ For CPUs support for 64-byte loads and stores with status (FEAT_LS64_V):
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+ - HCRX_EL2.EnASR (bit 2) must be initialised to 0b1.
+
The requirements described above for CPU mode, caches, MMUs, architected
timers, coherency and system registers apply to all CPUs. All CPUs must
enter the kernel in the same exception level. Where the values documented
diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index f58ada4d6cb2..bbb257a5a0b0 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -441,6 +441,12 @@ HWCAP3_MTE_FAR
HWCAP3_MTE_STORE_ONLY
Functionality implied by ID_AA64PFR2_EL1.MTESTOREONLY == 0b0001.
+HWCAP3_LS64
+ Functionality implied by ID_AA64ISAR1_EL1.LS64 == 0b0001.
+
+HWCAP3_LS64_V
+ Functionality implied by ID_AA64ISAR1_EL1.LS64 == 0b0010.
+
4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 13f94c8ddfc0..61c841c31e97 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -178,6 +178,8 @@
#define __khwcap3_feature(x) (const_ilog2(HWCAP3_ ## x) + 128)
#define KERNEL_HWCAP_MTE_FAR __khwcap3_feature(MTE_FAR)
#define KERNEL_HWCAP_MTE_STORE_ONLY __khwcap3_feature(MTE_STORE_ONLY)
+#define KERNEL_HWCAP_LS64 __khwcap3_feature(LS64)
+#define KERNEL_HWCAP_LS64_V __khwcap3_feature(LS64_V)
/*
* 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 72c78468b806..86f37b680023 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -145,5 +145,7 @@
*/
#define HWCAP3_MTE_FAR (1UL << 0)
#define HWCAP3_MTE_STORE_ONLY (1UL << 1)
+#define HWCAP3_LS64 (1UL << 2)
+#define HWCAP3_LS64_V (1UL << 3)
#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9ad065f15f1d..6f60685fd78a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -238,6 +238,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
+ ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_EL1_LS64_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_EL1_XS_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_EL1_I8MM_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_EL1_DGH_SHIFT, 4, 0),
@@ -2327,6 +2328,38 @@ static void cpu_enable_e0pd(struct arm64_cpu_capabilities const *cap)
}
#endif /* CONFIG_ARM64_E0PD */
+static bool has_ls64(const struct arm64_cpu_capabilities *entry, int __unused)
+{
+ u64 ls64;
+
+ ls64 = cpuid_feature_extract_field(__read_sysreg_by_encoding(entry->sys_reg),
+ entry->field_pos, entry->sign);
+
+ if (ls64 == ID_AA64ISAR1_EL1_LS64_NI ||
+ ls64 > ID_AA64ISAR1_EL1_LS64_LS64_ACCDATA)
+ return false;
+
+ if (entry->capability == ARM64_HAS_LS64 &&
+ ls64 >= ID_AA64ISAR1_EL1_LS64_LS64)
+ return true;
+
+ if (entry->capability == ARM64_HAS_LS64_V &&
+ ls64 >= ID_AA64ISAR1_EL1_LS64_LS64_V)
+ return true;
+
+ return false;
+}
+
+static void cpu_enable_ls64(struct arm64_cpu_capabilities const *cap)
+{
+ sysreg_clear_set(sctlr_el1, SCTLR_EL1_EnALS, SCTLR_EL1_EnALS);
+}
+
+static void cpu_enable_ls64_v(struct arm64_cpu_capabilities const *cap)
+{
+ sysreg_clear_set(sctlr_el1, SCTLR_EL1_EnASR, SCTLR_EL1_EnASR);
+}
+
#ifdef CONFIG_ARM64_PSEUDO_NMI
static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
int scope)
@@ -3131,6 +3164,22 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = has_cpuid_feature,
ARM64_CPUID_FIELDS(ID_AA64PFR2_EL1, GCIE, IMP)
},
+ {
+ .desc = "LS64",
+ .capability = ARM64_HAS_LS64,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_ls64,
+ .cpu_enable = cpu_enable_ls64,
+ ARM64_CPUID_FIELDS(ID_AA64ISAR1_EL1, LS64, LS64)
+ },
+ {
+ .desc = "LS64_V",
+ .capability = ARM64_HAS_LS64_V,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_ls64,
+ .cpu_enable = cpu_enable_ls64_v,
+ ARM64_CPUID_FIELDS(ID_AA64ISAR1_EL1, LS64, LS64_V)
+ },
{},
};
@@ -3250,6 +3299,8 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(ID_AA64ISAR1_EL1, BF16, EBF16, CAP_HWCAP, KERNEL_HWCAP_EBF16),
HWCAP_CAP(ID_AA64ISAR1_EL1, DGH, IMP, CAP_HWCAP, KERNEL_HWCAP_DGH),
HWCAP_CAP(ID_AA64ISAR1_EL1, I8MM, IMP, CAP_HWCAP, KERNEL_HWCAP_I8MM),
+ HWCAP_CAP(ID_AA64ISAR1_EL1, LS64, LS64, CAP_HWCAP, KERNEL_HWCAP_LS64),
+ HWCAP_CAP(ID_AA64ISAR1_EL1, LS64, LS64_V, CAP_HWCAP, KERNEL_HWCAP_LS64_V),
HWCAP_CAP(ID_AA64ISAR2_EL1, LUT, IMP, CAP_HWCAP, KERNEL_HWCAP_LUT),
HWCAP_CAP(ID_AA64ISAR3_EL1, FAMINMAX, IMP, CAP_HWCAP, KERNEL_HWCAP_FAMINMAX),
HWCAP_CAP(ID_AA64MMFR2_EL1, AT, IMP, CAP_HWCAP, KERNEL_HWCAP_USCAT),
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index ba834909a28b..e1ccec7a509f 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -81,6 +81,8 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_PACA] = "paca",
[KERNEL_HWCAP_PACG] = "pacg",
[KERNEL_HWCAP_GCS] = "gcs",
+ [KERNEL_HWCAP_LS64] = "ls64",
+ [KERNEL_HWCAP_LS64_V] = "ls64_v",
[KERNEL_HWCAP_DCPODP] = "dcpodp",
[KERNEL_HWCAP_SVE2] = "sve2",
[KERNEL_HWCAP_SVEAES] = "sveaes",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index ef0b7946f5a4..c4b38311e8b1 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -44,6 +44,8 @@ HAS_HCX
HAS_LDAPR
HAS_LPA2
HAS_LSE_ATOMICS
+HAS_LS64
+HAS_LS64_V
HAS_MOPS
HAS_NESTED_VIRT
HAS_BBML2_NOABORT
--
2.24.0
