arm64: add FEAT_LSE128 HWCAP

Add HWCAP for FEAT_LSE128 (128-bit Atomic instructions).
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20231003124544.858804-2-joey.gouly@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

Documentation/arch/arm64/elf_hwcaps.rst

@@ -314,6 +314,9 @@ HWCAP2_SVE_B16B16
 HWCAP2_LRCPC3
     Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0011.
 
+HWCAP2_LSE128
+    Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0011.
+
 4. Unused AT_HWCAP bits
 -----------------------
 

arch/arm64/include/asm/hwcap.h

@@ -141,6 +141,7 @@
 #define KERNEL_HWCAP_HBC		__khwcap2_feature(HBC)
 #define KERNEL_HWCAP_SVE_B16B16		__khwcap2_feature(SVE_B16B16)
 #define KERNEL_HWCAP_LRCPC3		__khwcap2_feature(LRCPC3)
+#define KERNEL_HWCAP_LSE128		__khwcap2_feature(LSE128)
 
 /*
  * This yields a mask that user programs can use to figure out what

arch/arm64/include/uapi/asm/hwcap.h

@@ -106,5 +106,6 @@
 #define HWCAP2_HBC		(1UL << 44)
 #define HWCAP2_SVE_B16B16	(1UL << 45)
 #define HWCAP2_LRCPC3		(1UL << 46)
+#define HWCAP2_LSE128		(1UL << 47)
 
 #endif /* _UAPI__ASM_HWCAP_H */

arch/arm64/kernel/cpufeature.c

@@ -2789,6 +2789,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
 	HWCAP_CAP(ID_AA64ISAR0_EL1, SHA2, SHA512, CAP_HWCAP, KERNEL_HWCAP_SHA512),
 	HWCAP_CAP(ID_AA64ISAR0_EL1, CRC32, IMP, CAP_HWCAP, KERNEL_HWCAP_CRC32),
 	HWCAP_CAP(ID_AA64ISAR0_EL1, ATOMIC, IMP, CAP_HWCAP, KERNEL_HWCAP_ATOMICS),
+	HWCAP_CAP(ID_AA64ISAR0_EL1, ATOMIC, FEAT_LSE128, CAP_HWCAP, KERNEL_HWCAP_LSE128),
 	HWCAP_CAP(ID_AA64ISAR0_EL1, RDM, IMP, CAP_HWCAP, KERNEL_HWCAP_ASIMDRDM),
 	HWCAP_CAP(ID_AA64ISAR0_EL1, SHA3, IMP, CAP_HWCAP, KERNEL_HWCAP_SHA3),
 	HWCAP_CAP(ID_AA64ISAR0_EL1, SM3, IMP, CAP_HWCAP, KERNEL_HWCAP_SM3),

arch/arm64/kernel/cpuinfo.c

@@ -129,6 +129,7 @@ static const char *const hwcap_str[] = {
 	[KERNEL_HWCAP_HBC]		= "hbc",
 	[KERNEL_HWCAP_SVE_B16B16]	= "sveb16b16",
 	[KERNEL_HWCAP_LRCPC3]		= "lrcpc3",
+	[KERNEL_HWCAP_LSE128]		= "lse128",
 };
 
 #ifdef CONFIG_COMPAT

arch/arm64/tools/sysreg

@@ -1239,6 +1239,7 @@ EndEnum
 UnsignedEnum	23:20	ATOMIC
 	0b0000	NI
 	0b0010	IMP
+	0b0011	FEAT_LSE128
 EndEnum
 UnsignedEnum	19:16	CRC32
 	0b0000	NI