arm64: errata: Add detection for TRBE trace data corruption

TRBE implementations affected by Arm erratum #1902691 might corrupt trace
data or deadlock, when it's being written into the memory. So effectively
TRBE is broken and hence cannot be used to capture trace data. This adds
a new errata ARM64_ERRATUM_1902691 in arm64 errata framework.

Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Suzuki Poulose <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Suzuki K Poulose <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mathieu Poirier <[email protected]>

Author: Anshuman Khandual

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        |

arch/arm64/Kconfig

@@ -819,6 +819,24 @@ config ARM64_ERRATUM_2038923
 
 	  If unsure, say Y.
 
+config ARM64_ERRATUM_1902691
+	bool "Cortex-A510: 1902691: workaround TRBE trace corruption"
+	depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in
+	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. 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.
+
+	  If unsure, say Y.
+
 config CAVIUM_ERRATUM_22375
 	bool "Cavium erratum 22375, 24313"
 	default y

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
 	{
 	}

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