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Date: Wed, 5 Jan 2022 10:35:58 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-arm-kernel@...ts.infradead.org
Cc: Anshuman Khandual <anshuman.khandual@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Suzuki Poulose <suzuki.poulose@....com>,
coresight@...ts.linaro.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] coresight: trbe: Work around the invalid prohibited states
TRBE implementations affected by Arm erratum #2038923 might get TRBE into
an inconsistent view on whether trace is prohibited within the CPU. As a
result, the trace buffer or trace buffer state might be corrupted. This
happens after TRBE buffer has been enabled by setting TRBLIMITR_EL1.E,
followed by just a single context synchronization event before execution
changes from a context, in which trace is prohibited to one where it isn't,
or vice versa. In these mentioned conditions, the view of whether trace is
prohibited is inconsistent between parts of the CPU, and the trace buffer
or the trace buffer state might be corrupted.
Work around this problem in the TRBE driver by preventing an inconsistent
view of whether the trace is prohibited or not based on TRBLIMITR_EL1.E by
immediately following a change to TRBLIMITR_EL1.E with at least one ISB
instruction before an ERET, or two ISB instructions if no ERET is to take
place. This adds a new cpu errata in arm64 errata framework and also
updates TRBE driver as required.
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Suzuki Poulose <suzuki.poulose@....com>
Cc: coresight@...ts.linaro.org
Cc: linux-doc@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
Documentation/arm64/silicon-errata.rst | 2 +
arch/arm64/Kconfig | 23 ++++++++++
arch/arm64/kernel/cpu_errata.c | 9 ++++
arch/arm64/tools/cpucaps | 1 +
drivers/hwtracing/coresight/coresight-trbe.c | 47 +++++++++++++++-----
5 files changed, 72 insertions(+), 10 deletions(-)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index c9b30e6c2b6c..e0ef3e9a4b8b 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -54,6 +54,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A510 | #2064142 | ARM64_ERRATUM_2064142 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A510 | #2038923 | ARM64_ERRATUM_2038923 |
++----------------+-----------------+-----------------+-----------------------------+
| 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 2105b68d88db..026e34fb6fad 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -796,6 +796,29 @@ config ARM64_ERRATUM_2064142
If unsure, say Y.
+config ARM64_ERRATUM_2038923
+ bool "Cortex-A510: 2038923: workaround TRBE corruption with enable"
+ depends on CORESIGHT_TRBE
+ default y
+ help
+ This option adds the workaround for ARM Cortex-A510 erratum 2038923.
+
+ Affected Cortex-A510 core might cause an inconsistent view on whether trace is
+ prohibited within the CPU. As a result, the trace buffer or trace buffer state
+ might be corrupted. This happens after TRBE buffer has been enabled by setting
+ TRBLIMITR_EL1.E, followed by just a single context synchronization event before
+ execution changes from a context, in which trace is prohibited to one where it
+ isn't, or vice versa. In these mentioned conditions, the view of whether trace
+ is prohibited is inconsistent between parts of the CPU, and the trace buffer or
+ the trace buffer state might be corrupted.
+
+ Work around this in the driver by preventing an inconsistent view of whether the
+ trace is prohibited or not based on TRBLIMITR_EL1.E by immediately following a
+ change to TRBLIMITR_EL1.E with at least one ISB instruction before an ERET, or
+ two ISB instructions if no ERET is to take place.
+
+ If unsure, say Y.
+
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 cbb7d5a9aee7..60b0c1f1d912 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -607,6 +607,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2)
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_2038923
+ {
+ .desc = "ARM erratum 2038923",
+ .capability = ARM64_WORKAROUND_2038923,
+
+ /* Cortex-A510 r0p0 - r0p2 */
+ ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2)
+ },
+#endif
{
}
};
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index fca3cb329e1d..45a06d36d080 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -56,6 +56,7 @@ WORKAROUND_1463225
WORKAROUND_1508412
WORKAROUND_1542419
WORKAROUND_2064142
+WORKAROUND_2038923
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 ec24b62b2cec..0689c6dab96d 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -92,11 +92,13 @@ struct trbe_buf {
#define TRBE_WORKAROUND_OVERWRITE_FILL_MODE 0
#define TRBE_WORKAROUND_WRITE_OUT_OF_RANGE 1
#define TRBE_WORKAROUND_SYSREG_WRITE_FAILURE 2
+#define TRBE_WORKAROUND_CORRUPTION_WITH_ENABLE 3
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,
-1, /* Sentinel, must be the last entry */
};
@@ -174,6 +176,11 @@ static inline bool trbe_may_fail_sysreg_write(struct trbe_cpudata *cpudata)
return trbe_has_erratum(cpudata, TRBE_WORKAROUND_SYSREG_WRITE_FAILURE);
}
+static inline bool trbe_may_corrupt_with_enable(struct trbe_cpudata *cpudata)
+{
+ return trbe_has_erratum(cpudata, TRBE_WORKAROUND_CORRUPTION_WITH_ENABLE);
+}
+
static int trbe_alloc_node(struct perf_event *event)
{
if (event->cpu == -1)
@@ -187,6 +194,30 @@ static inline void trbe_drain_buffer(void)
dsb(nsh);
}
+static inline void set_trbe_enabled(struct trbe_cpudata *cpudata)
+{
+ u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
+
+ /*
+ * Enable the TRBE without clearing LIMITPTR which
+ * might be required for fetching the buffer limits.
+ */
+ trblimitr |= TRBLIMITR_ENABLE;
+ write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1);
+
+ /* Synchronize the TRBE enable event */
+ isb();
+
+ /*
+ * Errata affected TRBE implementation will need an additional
+ * context synchronization in order to prevent an inconsistent
+ * TRBE prohibited region view on the CPU which could possibly
+ * corrupt the TRBE buffer or the TRBE state.
+ */
+ if (trbe_may_corrupt_with_enable(cpudata))
+ isb();
+}
+
static inline void set_trbe_disabled(struct trbe_cpudata *cpudata)
{
u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
@@ -555,9 +586,10 @@ static void clr_trbe_status(void)
write_sysreg_s(trbsr, SYS_TRBSR_EL1);
}
-static void set_trbe_limit_pointer_enabled(unsigned long addr)
+static void set_trbe_limit_pointer_enabled(struct trbe_buf *buf)
{
u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
+ unsigned long addr = buf->trbe_limit;
WARN_ON(!IS_ALIGNED(addr, (1UL << TRBLIMITR_LIMIT_SHIFT)));
WARN_ON(!IS_ALIGNED(addr, PAGE_SIZE));
@@ -586,11 +618,8 @@ static void set_trbe_limit_pointer_enabled(unsigned long addr)
TRBLIMITR_TRIG_MODE_SHIFT;
trblimitr |= (addr & PAGE_MASK);
- trblimitr |= TRBLIMITR_ENABLE;
write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1);
-
- /* Synchronize the TRBE enable event */
- isb();
+ set_trbe_enabled(buf->cpudata);
}
static void trbe_enable_hw(struct trbe_buf *buf)
@@ -608,7 +637,7 @@ static void trbe_enable_hw(struct trbe_buf *buf)
* till now before enabling the TRBE.
*/
isb();
- set_trbe_limit_pointer_enabled(buf->trbe_limit);
+ set_trbe_limit_pointer_enabled(buf);
}
static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *handle,
@@ -1013,16 +1042,14 @@ static int arm_trbe_disable(struct coresight_device *csdev)
static void trbe_handle_spurious(struct perf_output_handle *handle)
{
- u64 limitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
+ struct trbe_buf *buf = etm_perf_sink_config(handle);
/*
* If the IRQ was spurious, simply re-enable the TRBE
* back without modifying the buffer parameters to
* retain the trace collected so far.
*/
- limitr |= TRBLIMITR_ENABLE;
- write_sysreg_s(limitr, SYS_TRBLIMITR_EL1);
- isb();
+ set_trbe_enabled(buf->cpudata);
}
static int trbe_handle_overflow(struct perf_output_handle *handle)
--
2.25.1
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