[PATCH 4.9 16/43] arm64: arch_timer: Add workaround for ARM erratum 1188873

Greg Kroah-Hartman
2022-04-06T19:31:03Z

From: Marc Zyngier <marc.zyngier@arm.com>

commit 95b861a4a6d94f64d5242605569218160ebacdbe upstream.

When running on Cortex-A76, a timer access from an AArch32 EL0
task may end up with a corrupted value or register. The workaround for
this is to trap these accesses at EL1/EL2 and execute them there.

This only affects versions r0p0, r1p0 and r2p0 of the CPU.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/Kconfig | 12 ++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/include/asm/cputype.h | 2 ++
arch/arm64/kernel/cpu_errata.c | 8 ++++++++
drivers/clocksource/arm_arch_timer.c | 15 +++++++++++++++
5 files changed, 39 insertions(+), 1 deletion(-)

--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -441,6 +441,18 @@ config ARM64_ERRATUM_1024718

If unsure, say Y.

+config ARM64_ERRATUM_1188873
+ bool "Cortex-A76: MRC read following MRRC read of specific Generic Timer in AArch32 might give incorrect result"
+ default y
+ help
+ This option adds work arounds for ARM Cortex-A76 erratum 1188873
+
+ Affected Cortex-A76 cores (r0p0, r1p0, r2p0) could cause
+ register corruption when accessing the timer registers from
+ AArch32 userspace.
+
+ If unsure, say Y.
+
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -38,7 +38,8 @@
#define ARM64_HARDEN_BRANCH_PREDICTOR 17
#define ARM64_SSBD 18
#define ARM64_MISMATCHED_CACHE_TYPE 19
+#define ARM64_WORKAROUND_1188873 20

-#define ARM64_NCAPS 20
+#define ARM64_NCAPS 21

#endif /* __ASM_CPUCAPS_H */
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -85,6 +85,7 @@
#define ARM_CPU_PART_CORTEX_A75 0xD0A
#define ARM_CPU_PART_CORTEX_A35 0xD04
#define ARM_CPU_PART_CORTEX_A55 0xD05
+#define ARM_CPU_PART_CORTEX_A76 0xD0B

#define APM_CPU_PART_POTENZA 0x000

@@ -102,6 +103,7 @@
#define MIDR_CORTEX_A75 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A75)
#define MIDR_CORTEX_A35 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A35)
#define MIDR_CORTEX_A55 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A55)
+#define MIDR_CORTEX_A76 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A76)
#define MIDR_THUNDERX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX)
#define MIDR_THUNDERX_81XX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX_81XX)
#define MIDR_CAVIUM_THUNDERX2 MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX2)
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -533,6 +533,14 @@ const struct arm64_cpu_capabilities arm6
.matches = has_ssbd_mitigation,
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_1188873
+ {
+ /* Cortex-A76 r0p0 to r2p0 */
+ .desc = "ARM erratum 1188873",
+ .capability = ARM64_WORKAROUND_1188873,
+ ERRATA_MIDR_RANGE(MIDR_CORTEX_A76, 0, 0, 2, 0),
+ },
+#endif
{
}
};
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -130,6 +130,13 @@ static u64 notrace fsl_a008585_read_cntv
}
#endif

+#ifdef CONFIG_ARM64_ERRATUM_1188873
+static u64 notrace arm64_1188873_read_cntvct_el0(void)
+{
+ return read_sysreg(cntvct_el0);
+}
+#endif
+
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL;
EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);
@@ -148,6 +155,14 @@ static const struct arch_timer_erratum_w
.read_cntvct_el0 = fsl_a008585_read_cntvct_el0,
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_1188873
+ {
+ .match_type = ate_match_local_cap_id,
+ .id = (void *)ARM64_WORKAROUND_1188873,
+ .desc = "ARM erratum 1188873",
+ .read_cntvct_el0 = arm64_1188873_read_cntvct_el0,
+ },
+#endif
};

typedef bool (*ate_match_fn_t)(const struct arch_timer_erratum_workaround *,