diff options
| -rw-r--r-- | arch/arm64/include/asm/cache.h | 40 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 27 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 15 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpuinfo.c | 10 |
4 files changed, 87 insertions, 5 deletions
diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h index 5ee5bca8c24b..13dd42c3ad4e 100644 --- a/arch/arm64/include/asm/cache.h +++ b/arch/arm64/include/asm/cache.h @@ -40,6 +40,15 @@ #define L1_CACHE_SHIFT (6) #define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT) + +#define CLIDR_LOUU_SHIFT 27 +#define CLIDR_LOC_SHIFT 24 +#define CLIDR_LOUIS_SHIFT 21 + +#define CLIDR_LOUU(clidr) (((clidr) >> CLIDR_LOUU_SHIFT) & 0x7) +#define CLIDR_LOC(clidr) (((clidr) >> CLIDR_LOC_SHIFT) & 0x7) +#define CLIDR_LOUIS(clidr) (((clidr) >> CLIDR_LOUIS_SHIFT) & 0x7) + /* * Memory returned by kmalloc() may be used for DMA, so we must make * sure that all such allocations are cache aligned. Otherwise, @@ -84,6 +93,37 @@ static inline int cache_line_size(void) return cwg ? 4 << cwg : ARCH_DMA_MINALIGN; } +/* + * Read the effective value of CTR_EL0. + * + * According to ARM ARM for ARMv8-A (ARM DDI 0487C.a), + * section D10.2.33 "CTR_EL0, Cache Type Register" : + * + * CTR_EL0.IDC reports the data cache clean requirements for + * instruction to data coherence. + * + * 0 - dcache clean to PoU is required unless : + * (CLIDR_EL1.LoC == 0) || (CLIDR_EL1.LoUIS == 0 && CLIDR_EL1.LoUU == 0) + * 1 - dcache clean to PoU is not required for i-to-d coherence. + * + * This routine provides the CTR_EL0 with the IDC field updated to the + * effective state. + */ +static inline u32 __attribute_const__ read_cpuid_effective_cachetype(void) +{ + u32 ctr = read_cpuid_cachetype(); + + if (!(ctr & BIT(CTR_IDC_SHIFT))) { + u64 clidr = read_sysreg(clidr_el1); + + if (CLIDR_LOC(clidr) == 0 || + (CLIDR_LOUIS(clidr) == 0 && CLIDR_LOUU(clidr) == 0)) + ctr |= BIT(CTR_IDC_SHIFT); + } + + return ctr; +} + #endif /* __ASSEMBLY__ */ #endif diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index cde948991d68..3deb01c6ed49 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -68,11 +68,32 @@ static bool has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry, int scope) { - u64 mask = arm64_ftr_reg_ctrel0.strict_mask;; + u64 mask = arm64_ftr_reg_ctrel0.strict_mask; + u64 sys = arm64_ftr_reg_ctrel0.sys_val & mask; + u64 ctr_raw, ctr_real; WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible()); - return (read_cpuid_cachetype() & mask) != - (arm64_ftr_reg_ctrel0.sys_val & mask); + + /* + * We want to make sure that all the CPUs in the system expose + * a consistent CTR_EL0 to make sure that applications behaves + * correctly with migration. + * + * If a CPU has CTR_EL0.IDC but does not advertise it via CTR_EL0 : + * + * 1) It is safe if the system doesn't support IDC, as CPU anyway + * reports IDC = 0, consistent with the rest. + * + * 2) If the system has IDC, it is still safe as we trap CTR_EL0 + * access on this CPU via the ARM64_HAS_CACHE_IDC capability. + * + * So, we need to make sure either the raw CTR_EL0 or the effective + * CTR_EL0 matches the system's copy to allow a secondary CPU to boot. + */ + ctr_raw = read_cpuid_cachetype() & mask; + ctr_real = read_cpuid_effective_cachetype() & mask; + + return (ctr_real != sys) && (ctr_raw != sys); } static void diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index ba16bb7762ca..af50064dea51 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -861,11 +861,23 @@ static bool has_cache_idc(const struct arm64_cpu_capabilities *entry, if (scope == SCOPE_SYSTEM) ctr = arm64_ftr_reg_ctrel0.sys_val; else - ctr = read_cpuid_cachetype(); + ctr = read_cpuid_effective_cachetype(); return ctr & BIT(CTR_IDC_SHIFT); } +static void cpu_emulate_effective_ctr(const struct arm64_cpu_capabilities *__unused) +{ + /* + * If the CPU exposes raw CTR_EL0.IDC = 0, while effectively + * CTR_EL0.IDC = 1 (from CLIDR values), we need to trap accesses + * to the CTR_EL0 on this CPU and emulate it with the real/safe + * value. + */ + if (!(read_cpuid_cachetype() & BIT(CTR_IDC_SHIFT))) + sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0); +} + static bool has_cache_dic(const struct arm64_cpu_capabilities *entry, int scope) { @@ -1282,6 +1294,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .capability = ARM64_HAS_CACHE_IDC, .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = has_cache_idc, + .cpu_enable = cpu_emulate_effective_ctr, }, { .desc = "Instruction cache invalidation not required for I/D coherence", diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index dce971f2c167..bcc2831399cb 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -325,7 +325,15 @@ static void cpuinfo_detect_icache_policy(struct cpuinfo_arm64 *info) static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info) { info->reg_cntfrq = arch_timer_get_cntfrq(); - info->reg_ctr = read_cpuid_cachetype(); + /* + * Use the effective value of the CTR_EL0 than the raw value + * exposed by the CPU. CTR_E0.IDC field value must be interpreted + * with the CLIDR_EL1 fields to avoid triggering false warnings + * when there is a mismatch across the CPUs. Keep track of the + * effective value of the CTR_EL0 in our internal records for + * acurate sanity check and feature enablement. + */ + info->reg_ctr = read_cpuid_effective_cachetype(); info->reg_dczid = read_cpuid(DCZID_EL0); info->reg_midr = read_cpuid_id(); info->reg_revidr = read_cpuid(REVIDR_EL1); |