arm64: Expose FRINT capabilities to userspace

ARMv8.5 introduces the FRINT series of instructions for rounding floating
point numbers to integers. Provide a capability to userspace in order to
allow applications to determine if the system supports these instructions.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Documentation/arm64/elf_hwcaps.txt

@@ -227,6 +227,10 @@ HWCAP_PACG
     ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
     Documentation/arm64/pointer-authentication.txt.
 
+HWCAP2_FRINT
+
+    Functionality implied by ID_AA64ISAR1_EL1.FRINTTS == 0b0001.
+
 
 4. Unused AT_HWCAP bits
 -----------------------

arch/arm64/include/asm/hwcap.h

@@ -96,6 +96,7 @@
 #define KERNEL_HWCAP_SVESHA3		__khwcap2_feature(SVESHA3)
 #define KERNEL_HWCAP_SVESM4		__khwcap2_feature(SVESM4)
 #define KERNEL_HWCAP_FLAGM2		__khwcap2_feature(FLAGM2)
+#define KERNEL_HWCAP_FRINT		__khwcap2_feature(FRINT)
 
 /*
  * This yields a mask that user programs can use to figure out what

arch/arm64/include/asm/sysreg.h

@@ -560,6 +560,7 @@
 
 /* id_aa64isar1 */
 #define ID_AA64ISAR1_SB_SHIFT		36
+#define ID_AA64ISAR1_FRINTTS_SHIFT	32
 #define ID_AA64ISAR1_GPI_SHIFT		28
 #define ID_AA64ISAR1_GPA_SHIFT		24
 #define ID_AA64ISAR1_LRCPC_SHIFT	20

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

@@ -64,5 +64,6 @@
 #define HWCAP2_SVESHA3		(1 << 5)
 #define HWCAP2_SVESM4		(1 << 6)
 #define HWCAP2_FLAGM2		(1 << 7)
+#define HWCAP2_FRINT		(1 << 8)
 
 #endif /* _UAPI__ASM_HWCAP_H */

arch/arm64/kernel/cpufeature.c

@@ -1640,6 +1640,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
 	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FCMA),
 	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_LRCPC),
 	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_ILRCPC),
+	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FRINTTS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FRINT),
 	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_SB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SB),
 	HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_USCAT),
 #ifdef CONFIG_ARM64_SVE

arch/arm64/kernel/cpuinfo.c

@@ -93,6 +93,7 @@ static const char *const hwcap_str[] = {
 	"svesha3",
 	"svesm4",
 	"flagm2",
+	"frint",
 	NULL
 };