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| author | James Morse <james.morse@arm.com> | 2022-09-09 17:59:38 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2022-09-16 15:23:50 +0100 |
| commit | 1bdb0fbb2e27c51a6f311867726462c983a1d9ee (patch) | |
| tree | 729c45d634d041e7e6e9a306d91c6692011664a9 /arch/arm64/kernel/cpu_errata.c | |
| parent | 445c953e4a84b2942bdb5c0b5aff571c903680fe (diff) | |
| download | linux-1bdb0fbb2e27c51a6f311867726462c983a1d9ee.tar.bz2 | |
arm64: errata: remove BF16 HWCAP due to incorrect result on Cortex-A510
Cortex-A510's erratum #2658417 causes two BF16 instructions to return the
wrong result in rare circumstances when a pair of A510 CPUs are using
shared neon hardware.
The two instructions affected are BFMMLA and VMMLA, support for these is
indicated by the BF16 HWCAP. Remove it on affected platforms.
Signed-off-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20220909165938.3931307-4-james.morse@arm.com
[catalin.marinas@arm.com: add revision to the Kconfig help; remove .type]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/cpu_errata.c')
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 53b973b6059f..58ca4f6b25d6 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -121,6 +121,22 @@ cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused) sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCI, 0); } +static DEFINE_RAW_SPINLOCK(reg_user_mask_modification); +static void __maybe_unused +cpu_clear_bf16_from_user_emulation(const struct arm64_cpu_capabilities *__unused) +{ + struct arm64_ftr_reg *regp; + + regp = get_arm64_ftr_reg(SYS_ID_AA64ISAR1_EL1); + if (!regp) + return; + + raw_spin_lock(®_user_mask_modification); + if (regp->user_mask & ID_AA64ISAR1_EL1_BF16_MASK) + regp->user_mask &= ~ID_AA64ISAR1_EL1_BF16_MASK; + raw_spin_unlock(®_user_mask_modification); +} + #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \ .matches = is_affected_midr_range, \ .midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max) @@ -692,6 +708,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, }, #endif +#ifdef CONFIG_ARM64_ERRATUM_2658417 + { + .desc = "ARM erratum 2658417", + .capability = ARM64_WORKAROUND_2658417, + /* Cortex-A510 r0p0 - r1p1 */ + ERRATA_MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1), + MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)), + .cpu_enable = cpu_clear_bf16_from_user_emulation, + }, +#endif { } }; |