From 43994d824e8443263dc98b151e6326bf677be52e Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 31 Oct 2017 15:51:19 +0000 Subject: [PATCH] arm64/sve: Detect SVE and activate runtime support This patch enables detection of hardware SVE support via the cpufeatures framework, and reports its presence to the kernel and userspace via the new ARM64_SVE cpucap and HWCAP_SVE hwcap respectively. Userspace can also detect SVE using ID_AA64PFR0_EL1, using the cpufeatures MRS emulation. When running on hardware that supports SVE, this enables runtime kernel support for SVE, and allows user tasks to execute SVE instructions and make of the of the SVE-specific user/kernel interface extensions implemented by this series. Signed-off-by: Dave Martin Reviewed-by: Suzuki K Poulose Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- Documentation/arm64/cpu-feature-registers.txt | 6 +++++- Documentation/arm64/elf_hwcaps.txt | 4 ++++ arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/include/asm/cpufeature.h | 3 ++- arch/arm64/include/uapi/asm/hwcap.h | 1 + arch/arm64/kernel/cpufeature.c | 17 +++++++++++++++++ arch/arm64/kernel/cpuinfo.c | 1 + arch/arm64/kernel/entry.S | 7 ++++--- 8 files changed, 36 insertions(+), 6 deletions(-) diff --git a/Documentation/arm64/cpu-feature-registers.txt b/Documentation/arm64/cpu-feature-registers.txt index 011ddfc1e570..bd9b3faab2c4 100644 --- a/Documentation/arm64/cpu-feature-registers.txt +++ b/Documentation/arm64/cpu-feature-registers.txt @@ -142,7 +142,11 @@ infrastructure: x--------------------------------------------------x | Name | bits | visible | |--------------------------------------------------| - | RES0 | [63-28] | n | + | RES0 | [63-36] | n | + |--------------------------------------------------| + | SVE | [35-32] | y | + |--------------------------------------------------| + | RES0 | [31-28] | n | |--------------------------------------------------| | GIC | [27-24] | n | |--------------------------------------------------| diff --git a/Documentation/arm64/elf_hwcaps.txt b/Documentation/arm64/elf_hwcaps.txt index 0ba180522e3c..89edba12a9e0 100644 --- a/Documentation/arm64/elf_hwcaps.txt +++ b/Documentation/arm64/elf_hwcaps.txt @@ -154,3 +154,7 @@ HWCAP_ASIMDDP HWCAP_SHA512 Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0002. + +HWCAP_SVE + + Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001. diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 8da621627d7c..2ff7c5e8efab 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -40,7 +40,8 @@ #define ARM64_WORKAROUND_858921 19 #define ARM64_WORKAROUND_CAVIUM_30115 20 #define ARM64_HAS_DCPOP 21 +#define ARM64_SVE 22 -#define ARM64_NCAPS 22 +#define ARM64_NCAPS 23 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9b27e8c10086..ac67cfc2585a 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -273,7 +273,8 @@ static inline bool system_uses_ttbr0_pan(void) static inline bool system_supports_sve(void) { - return false; + return IS_ENABLED(CONFIG_ARM64_SVE) && + cpus_have_const_cap(ARM64_SVE); } /* diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h index a4bad90a3fa3..622941098779 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -41,5 +41,6 @@ #define HWCAP_SM4 (1 << 19) #define HWCAP_ASIMDDP (1 << 20) #define HWCAP_SHA512 (1 << 21) +#define HWCAP_SVE (1 << 22) #endif /* _UAPI__ASM_HWCAP_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 036ad9d1b442..4cb2782f55a1 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -145,6 +145,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = { }; static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { + ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0), S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI), S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_FP_SHIFT, 4, ID_AA64PFR0_FP_NI), @@ -948,6 +949,19 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .min_field_value = 1, }, #endif +#ifdef CONFIG_ARM64_SVE + { + .desc = "Scalable Vector Extension", + .capability = ARM64_SVE, + .def_scope = SCOPE_SYSTEM, + .sys_reg = SYS_ID_AA64PFR0_EL1, + .sign = FTR_UNSIGNED, + .field_pos = ID_AA64PFR0_SVE_SHIFT, + .min_field_value = ID_AA64PFR0_SVE, + .matches = has_cpuid_feature, + .enable = sve_kernel_enable, + }, +#endif /* CONFIG_ARM64_SVE */ {}, }; @@ -985,6 +999,9 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = { HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_JSCVT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_JSCVT), HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_FCMA), HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_LRCPC), +#ifdef CONFIG_ARM64_SVE + HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, HWCAP_SVE), +#endif {}, }; diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index 58da504be36e..1e2554543506 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -75,6 +75,7 @@ static const char *const hwcap_str[] = { "sm4", "asimddp", "sha512", + "sve", NULL }; diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index a989e234dc32..6d14b8f29b5f 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -867,9 +867,10 @@ el0_svc: mov wscno, w8 // syscall number in w8 mov wsc_nr, #__NR_syscalls -#ifndef CONFIG_ARM64_SVE +#ifdef CONFIG_ARM64_SVE +alternative_if_not ARM64_SVE b el0_svc_naked -#else +alternative_else_nop_endif tbz x16, #TIF_SVE, el0_svc_naked // Skip unless TIF_SVE set: bic x16, x16, #_TIF_SVE // discard SVE state str x16, [tsk, #TSK_TI_FLAGS] @@ -884,7 +885,7 @@ el0_svc: mrs x9, cpacr_el1 bic x9, x9, #CPACR_EL1_ZEN_EL0EN // disable SVE for el0 msr cpacr_el1, x9 // synchronised by eret to el0 -#endif /* CONFIG_ARM64_SVE */ +#endif el0_svc_naked: // compat entry point stp x0, xscno, [sp, #S_ORIG_X0] // save the original x0 and syscall number -- 2.11.0