diff options
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 18 | ||||
| -rw-r--r-- | arch/arm64/kernel/fpsimd.c | 44 |
2 files changed, 40 insertions, 22 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index fb828f8c49e3..c493fa582a19 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1580,14 +1580,6 @@ static bool has_no_hw_prefetch(const struct arm64_cpu_capabilities *entry, int _ MIDR_CPU_VAR_REV(1, MIDR_REVISION_MASK)); } -static bool has_no_fpsimd(const struct arm64_cpu_capabilities *entry, int __unused) -{ - u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); - - return cpuid_feature_extract_signed_field(pfr0, - ID_AA64PFR0_EL1_FP_SHIFT) < 0; -} - static bool has_cache_idc(const struct arm64_cpu_capabilities *entry, int scope) { @@ -2398,11 +2390,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = { ARM64_CPUID_FIELDS(ID_AA64PFR0_EL1, CSV3, IMP) }, { - /* FP/SIMD is not implemented */ - .capability = ARM64_HAS_NO_FPSIMD, - .type = ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE, - .min_field_value = 0, - .matches = has_no_fpsimd, + .capability = ARM64_HAS_FPSIMD, + .type = ARM64_CPUCAP_SYSTEM_FEATURE, + .matches = has_cpuid_feature, + .cpu_enable = cpu_enable_fpsimd, + ARM64_CPUID_FIELDS(ID_AA64PFR0_EL1, FP, IMP) }, #ifdef CONFIG_ARM64_PMEM { diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 45ea9cabbaa4..d286bcfc3f41 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1520,8 +1520,17 @@ void do_sme_acc(unsigned long esr, struct pt_regs *regs) */ void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs) { - /* TODO: implement lazy context saving/restoring */ - WARN_ON(1); + /* Even if we chose not to use FPSIMD, the hardware could still trap: */ + if (!system_supports_fpsimd()) { + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); + return; + } + + /* + * When FPSIMD is enabled, we should never take a trap unless something + * has gone very wrong. + */ + BUG(); } /* @@ -1762,13 +1771,23 @@ void fpsimd_bind_state_to_cpu(struct cpu_fp_state *state) void fpsimd_restore_current_state(void) { /* - * For the tasks that were created before we detected the absence of - * FP/SIMD, the TIF_FOREIGN_FPSTATE could be set via fpsimd_thread_switch(), - * e.g, init. This could be then inherited by the children processes. - * If we later detect that the system doesn't support FP/SIMD, - * we must clear the flag for all the tasks to indicate that the - * FPSTATE is clean (as we can't have one) to avoid looping for ever in - * do_notify_resume(). + * TIF_FOREIGN_FPSTATE is set on the init task and copied by + * arch_dup_task_struct() regardless of whether FP/SIMD is detected. + * Thus user threads can have this set even when FP/SIMD hasn't been + * detected. + * + * When FP/SIMD is detected, begin_new_exec() will set + * TIF_FOREIGN_FPSTATE via flush_thread() -> fpsimd_flush_thread(), + * and fpsimd_thread_switch() will set TIF_FOREIGN_FPSTATE when + * switching tasks. We detect FP/SIMD before we exec the first user + * process, ensuring this has TIF_FOREIGN_FPSTATE set and + * do_notify_resume() will call fpsimd_restore_current_state() to + * install the user FP/SIMD context. + * + * When FP/SIMD is not detected, nothing else will clear or set + * TIF_FOREIGN_FPSTATE prior to the first return to userspace, and + * we must clear TIF_FOREIGN_FPSTATE to avoid do_notify_resume() + * looping forever calling fpsimd_restore_current_state(). */ if (!system_supports_fpsimd()) { clear_thread_flag(TIF_FOREIGN_FPSTATE); @@ -2101,6 +2120,13 @@ static inline void fpsimd_hotplug_init(void) static inline void fpsimd_hotplug_init(void) { } #endif +void cpu_enable_fpsimd(const struct arm64_cpu_capabilities *__always_unused p) +{ + unsigned long enable = CPACR_EL1_FPEN_EL1EN | CPACR_EL1_FPEN_EL0EN; + write_sysreg(read_sysreg(CPACR_EL1) | enable, CPACR_EL1); + isb(); +} + /* * FP/SIMD support code initialisation. */ |