[stable:PATCH v4.14.274 01/27] arm64: arch_timer: Add workaround for ARM erratum 1188873

James Morse
2022-03-31T18:34:35Z

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>
---
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(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e76f74874a42..85310128a65e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -458,6 +458,18 @@ 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
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 2f8bd0388905..626e895dc008 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -45,7 +45,8 @@
#define ARM64_SSBD 25
#define ARM64_MISMATCHED_CACHE_TYPE 26
#define ARM64_SSBS 27
+#define ARM64_WORKAROUND_1188873 28

-#define ARM64_NCAPS 28
+#define ARM64_NCAPS 29

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index b23456035eac..e862f1f56ad7 100644
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -87,6 +87,7 @@
#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

@@ -112,6 +113,7 @@
#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_THUNDERX_83XX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX_83XX)
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 7d15f4cb6393..d75c4f4144f4 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -712,6 +712,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.matches = has_ssbd_mitigation,
.midr_range_list = arm64_ssb_cpus,
},
+#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
{
}
};
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 2c5913057b87..439a4d005812 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -298,6 +298,13 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
}
#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
DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *,
timer_unstable_counter_workaround);
@@ -381,6 +388,14 @@ static const struct arch_timer_erratum_workaround ool_workarounds[] = {
.read_cntvct_el0 = arm64_858921_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 *,
--
2.30.2