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arm64: errata: Add detection for TRBE write to out-of-range

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Arm Neoverse-N2 and Cortex-A710 cores are affected by an erratum where
the trbe, under some circumstances, might write upto 64bytes to an
address after the Limit as programmed by the TRBLIMITR_EL1.LIMIT.
This might -
  - Corrupt a page in the ring buffer, which may corrupt trace from a
    previous session, consumed by userspace.
  - Hit the guard page at the end of the vmalloc area and raise a fault.

To keep the handling simpler, we always leave the last page from the
range, which TRBE is allowed to write. This can be achieved by ensuring
that we always have more than a PAGE worth space in the range, while
calculating the LIMIT for TRBE. And then the LIMIT pointer can be
adjusted to leave the PAGE (TRBLIMITR.LIMIT -= PAGE_SIZE), out of the
TRBE range while enabling it. This makes sure that the TRBE will only
write to an area within its allowed limit (i.e, [head-head+size]) and
we do not have to handle address faults within the driver.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20211019163153.3692640-5-suzuki.poulose@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Suzuki K Poulose 2021-10-19 17:31:42 +01:00 • committed by Will Deacon
parent fa82d0b4b8
commit 8d81b2a38d
4 changed files with 66 additions and 0 deletions
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20
arch/arm64/kernel/cpu_errata.c
View file

@ -364,6 +364,18 @@ static const struct midr_range tsb_flush_fail_cpus[] = {
};
#endif /* CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE */
#ifdef CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
static struct midr_range trbe_write_out_of_range_cpus[] = {
#ifdef CONFIG_ARM64_ERRATUM_2253138
MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
#endif
#ifdef CONFIG_ARM64_ERRATUM_2224489
MIDR_ALL_VERSIONS(MIDR_CORTEX_A710),
#endif
{},
};
#endif /* CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE */
const struct arm64_cpu_capabilities arm64_errata[] = {
#ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
{
@ -577,6 +589,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.capability = ARM64_WORKAROUND_TSB_FLUSH_FAILURE,
ERRATA_MIDR_RANGE_LIST(tsb_flush_fail_cpus),
},
#endif
#ifdef CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
{
.desc = "ARM erratum 2253138 or 2224489",
.capability = ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE,
.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
CAP_MIDR_RANGE_LIST(trbe_write_out_of_range_cpus),
},
#endif
{
}