On 05/01/2022 05:05, Anshuman Khandual wrote:
TRBE implementations affected by Arm erratum #1902691 might corrupt trace
data or deadlock, when it's being written into the memory. Workaround this
problem in the driver, by preventing TRBE initialization on affected cpus.
This adds a new cpu errata in arm64 errata framework and also updates TRBE
driver as required.
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Suzuki Poulose <suzuki.poulose@xxxxxxx>
Cc: coresight@xxxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
Documentation/arm64/silicon-errata.rst | 2 ++
arch/arm64/Kconfig | 16 ++++++++++++++++
arch/arm64/kernel/cpu_errata.c | 9 +++++++++
arch/arm64/tools/cpucaps | 1 +
drivers/hwtracing/coresight/coresight-trbe.c | 12 ++++++++++++
5 files changed, 40 insertions(+)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index e0ef3e9a4b8b..50018f60c4d4 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -56,6 +56,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A510 | #2038923 | ARM64_ERRATUM_2038923 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A510 | #1902691 | ARM64_ERRATUM_1902691 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 026e34fb6fad..1ea5c3b4aac0 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -819,6 +819,22 @@ config ARM64_ERRATUM_2038923
If unsure, say Y.
+config ARM64_ERRATUM_1902691
+ bool "Cortex-A510: 1902691: workaround TRBE trace corruption"
+ depends on CORESIGHT_TRBE
+ default y
+ help
+ This option adds the workaround for ARM Cortex-A510 erratum 1902691.
+
+ Affected Cortex-A510 core might cause trace data corruption, when being written
+ into the memory. Effectively TRBE is broken and hence cannot be used to capture
+ trace data.
+
+ Work around this problem in the driver by just preventing TRBE initialization on
+ affected cpus.
+
+ If unsure, say Y.
+
It might be better to add :
"The firmware must have disabled the access to TRBE for the kernel on
such implementations. This will cover the kernel for any firmware that
doesn't do this already"
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 60b0c1f1d912..a3336dfb5a8a 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -615,6 +615,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
/* Cortex-A510 r0p0 - r0p2 */
ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2)
},
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_1902691
+ {
+ .desc = "ARM erratum 1902691",
+ .capability = ARM64_WORKAROUND_1902691,
+
+ /* Cortex-A510 r0p0 - r0p1 */
+ ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 1)
+ },
#endif
{
}
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 45a06d36d080..e7719e8f18de 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -57,6 +57,7 @@ WORKAROUND_1508412
WORKAROUND_1542419
WORKAROUND_2064142
WORKAROUND_2038923
+WORKAROUND_1902691
WORKAROUND_TRBE_OVERWRITE_FILL_MODE
WORKAROUND_TSB_FLUSH_FAILURE
WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 0689c6dab96d..b9b4e34fac15 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -93,12 +93,14 @@ struct trbe_buf {
#define TRBE_WORKAROUND_WRITE_OUT_OF_RANGE 1
#define TRBE_WORKAROUND_SYSREG_WRITE_FAILURE 2
#define TRBE_WORKAROUND_CORRUPTION_WITH_ENABLE 3
+#define TRBE_IS_BROKEN 4
static int trbe_errata_cpucaps[] = {
[TRBE_WORKAROUND_OVERWRITE_FILL_MODE] = ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE,
[TRBE_WORKAROUND_WRITE_OUT_OF_RANGE] = ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE,
[TRBE_WORKAROUND_SYSREG_WRITE_FAILURE] = ARM64_WORKAROUND_2064142,
[TRBE_WORKAROUND_CORRUPTION_WITH_ENABLE] = ARM64_WORKAROUND_2038923,
+ [TRBE_IS_BROKEN] = ARM64_WORKAROUND_1902691,
-1, /* Sentinel, must be the last entry */
};
@@ -181,6 +183,11 @@ static inline bool trbe_may_corrupt_with_enable(struct trbe_cpudata *cpudata)
return trbe_has_erratum(cpudata, TRBE_WORKAROUND_CORRUPTION_WITH_ENABLE);
}
+static inline bool trbe_is_broken(struct trbe_cpudata *cpudata)
+{
+ return trbe_has_erratum(cpudata, TRBE_IS_BROKEN);
+}
+
static int trbe_alloc_node(struct perf_event *event)
{
if (event->cpu == -1)
@@ -1291,6 +1298,11 @@ static void arm_trbe_probe_cpu(void *info)
*/
trbe_check_errata(cpudata);
+ if (trbe_is_broken(cpudata)) {
+ pr_err("TRBE might corrupt the trace on cpu %d\n", cpu);
It may be better to say:
"Disabling TRBE on CPU%d due to erratum"
Otherwise looks good to me.
Suzuki
