arm64: cpufeature: add feature for CRC32 instructions

to #26730415

commit 86d0dd34eafffbc76a81aba6ae2d71927d3835a8 upstream.

Add a CRC32 feature bit and wire it up to the CPU id register so we
will be able to use alternatives patching for CRC32 operations.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

[ Rongwei: fixed conflicts ]
Signed-off-by: NRongwei Wang <rongwei.wang@linux.alibaba.com>
Acked-by: NZou Cao <zoucao@linux.alibaba.com>

arch/arm64/include/asm/cpucaps.h

@@ -53,7 +53,8 @@
 #define ARM64_HAS_STAGE2_FWB			32
 #define ARM64_WORKAROUND_1463225		33
 #define ARM64_SSBS				34
+#define ARM64_HAS_CRC32			35
 
-#define ARM64_NCAPS				35
+#define ARM64_NCAPS				36
 
 #endif /* __ASM_CPUCAPS_H */

arch/arm64/kernel/cpufeature.c

@@ -1338,6 +1338,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.cpu_enable = cpu_enable_ssbs,
 	},
 #endif
+	{
+		.desc = "CRC32 instructions",
+		.capability = ARM64_HAS_CRC32,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64ISAR0_EL1,
+		.field_pos = ID_AA64ISAR0_CRC32_SHIFT,
+		.min_field_value = 1,
+	},
 	{},
 };