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Date: Tue, 9 Oct 2018 14:47:07 +0100 From: Suzuki K Poulose <suzuki.poulose@....com> To: linux-arm-kernel@...ts.infradead.org Cc: linux-kernel@...r.kernel.org, catalin.marinas@....com, will.deacon@....com, mark.rutland@....com, pelcan@...eaurora.org, shankerd@...eaurora.org, suzuki.poulose@....com Subject: [PATCH v2 3/3] arm64: cpufeature: Trap CTR_EL0 access only where it is necessary When there is a mismatch in the CTR_EL0 field, we trap access to CTR from EL0 on all CPUs to expose the safe value. However, we could skip trapping on a CPU which matches the safe value. Cc: Mark Rutland <mark.rutland@....com> Cc: Will Deacon <will.deacon@....com> Cc: Catalin Marinas <catalin.marinas@....com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com> --- arch/arm64/kernel/cpu_errata.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 3deb01c6ed49..9af8df96ec49 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -99,7 +99,12 @@ has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry, static void cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *__unused) { - sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0); + u64 mask = arm64_ftr_reg_ctrel0.strict_mask; + + /* Trap CTR_EL0 access on this CPU, only if it has a mismatch */ + if ((read_cpuid_cachetype() & mask) != + (arm64_ftr_reg_ctrel0.sys_val & mask)) + sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0); } atomic_t arm64_el2_vector_last_slot = ATOMIC_INIT(-1); -- 2.19.0
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