arm64/hwcap: Support FEAT_EBF16

The v9.2 feature FEAT_EBF16 provides support for an extended BFloat16 mode.
Allow userspace to discover system support for this feature by adding a
hwcap for it.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220707103632.12745-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst
index 3d116fb536c538a58d1fbc2db25c1dde29004ef6..31fc10b833dd06eb61c6b8b3801cda9b8cd9ddba 100644 (file)
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -301,6 +301,10 @@ HWCAP2_WFXT
 
     Functionality implied by ID_AA64ISAR2_EL1.WFXT == 0b0010.
 
+HWCAP2_EBF16
+
+    Functionality implied by ID_AA64ISAR1_EL1.BF16 == 0b0010.
+
 4. Unused AT_HWCAP bits
 -----------------------
 

diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 9b5fdc114f8cead66b0a73aed9fd19c662439aae..cef4ae7a3d8b1f7191dd310e6ffd17b10555baec 100644 (file)
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -118,6 +118,7 @@
 #define KERNEL_HWCAP_SME_F32F32                __khwcap2_feature(SME_F32F32)
 #define KERNEL_HWCAP_SME_FA64          __khwcap2_feature(SME_FA64)
 #define KERNEL_HWCAP_WFXT              __khwcap2_feature(WFXT)
+#define KERNEL_HWCAP_EBF16             __khwcap2_feature(EBF16)
 
 /*
  * This yields a mask that user programs can use to figure out what

diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index fd7577cf8e77d6ec52d4035e38a33dff4f2142fe..1ad2568a2569f481d1cb52042c4c5e7f70f4935f 100644 (file)
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -91,5 +91,6 @@
 #define HWCAP2_SME_F32F32      (1 << 29)
 #define HWCAP2_SME_FA64                (1 << 30)
 #define HWCAP2_WFXT            (1UL << 31)
+#define HWCAP2_EBF16           (1UL << 32)
 
 #endif /* _UAPI__ASM_HWCAP_H */

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c7be49f33bb006dcfd8774ecb5bef49fbc268094..e27107655610a27fe1cf65e02c45ba067d1f7a8a 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2641,6 +2641,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FRINTTS_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FRINT),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_SB_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SB),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_BF16_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_BF16),
+       HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_BF16_SHIFT, 4, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_EBF16),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DGH_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DGH),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_I8MM_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_I8MM),
        HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_USCAT),

diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 8eff0a34ffd47547e0f3684a6b79745764e25d44..2ca131243c3059348cd6870be6b8a2a9659a0678 100644 (file)
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -107,6 +107,7 @@ static const char *const hwcap_str[] = {
        [KERNEL_HWCAP_SME_F32F32]       = "smef32f32",
        [KERNEL_HWCAP_SME_FA64]         = "smefa64",
        [KERNEL_HWCAP_WFXT]             = "wfxt",
+       [KERNEL_HWCAP_EBF16]            = "ebf16",
 };
 
 #ifdef CONFIG_COMPAT