arm64: cpufeature: List early Cortex-A510 parts as having broken dbm

Versions of Cortex-A510 before r0p3 are affected by a hardware erratum
where the hardware update of the dirty bit is not correctly ordered.

Add these cpus to the cpu_has_broken_dbm list.

Signed-off-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20220125154040.549272-3-james.morse@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Documentation/arm64/silicon-errata.rst

@@ -98,6 +98,8 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A77      | #1508412        | ARM64_ERRATUM_1508412       |
 +----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2051678        | ARM64_ERRATUM_2051678       |
++----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A710     | #2119858        | ARM64_ERRATUM_2119858       |
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A710     | #2054223        | ARM64_ERRATUM_2054223       |

arch/arm64/Kconfig

@@ -670,6 +670,16 @@ config ARM64_ERRATUM_1508412
 config ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE
 	bool
 
+config ARM64_ERRATUM_2051678
+	bool "Cortex-A510: 2051678: disable Hardware Update of the page table dirty bit"
+	help
+	  This options adds the workaround for ARM Cortex-A510 erratum ARM64_ERRATUM_2051678.
+	  Affected Coretex-A510 might not respect the ordering rules for
+	  hardware update of the page table's dirty bit. The workaround
+	  is to not enable the feature on affected CPUs.
+
+	  If unsure, say Y.
+
 config ARM64_ERRATUM_2119858
 	bool "Cortex-A710/X2: 2119858: workaround TRBE overwriting trace data in FILL mode"
 	default y

arch/arm64/kernel/cpufeature.c

@@ -1645,6 +1645,9 @@ static bool cpu_has_broken_dbm(void)
 		MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
 		/* Kryo4xx Silver (rdpe => r1p0) */
 		MIDR_REV(MIDR_QCOM_KRYO_4XX_SILVER, 0xd, 0xe),
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_2051678
+		MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2),
 #endif
 		{},
 	};