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[5/8] ARM: vfp: Add hwcap for FEAT_AA32BF16

Message ID 20221026055001.12986-6-amit.kachhap@arm.com (mailing list archive)
State New, archived
Headers show
Series ARM: Expose Armv8 AArch32 features via hwcap | expand

Commit Message

Amit Daniel Kachhap Oct. 26, 2022, 5:49 a.m. UTC 
Advanced SIMD BFloat16 (FEAT_AA32BF16) is a feature present in AArch32
state for Armv8 and is represented by ISAR6.BF16 identification register.

This feature denotes the presence of VCVT, VCVTB, VCVTT, VDOT, VFMAB,
VFMAT and VMMLA instructions and hence adding a hwcap will enable the
userspace to check it before trying to use those instructions.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
 arch/arm/include/uapi/asm/hwcap.h | 1 +
 arch/arm/kernel/setup.c           | 1 +
 arch/arm/vfp/vfpmodule.c          | 6 ++++++
 3 files changed, 8 insertions(+)
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Patch

diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 3d168d4f2a51..14e260e2d6d0 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h
@@ -32,6 +32,7 @@ 
 #define HWCAP_ASIMDHP	(1 << 23)
 #define HWCAP_ASIMDDP	(1 << 24)
 #define HWCAP_ASIMDFHM	(1 << 25)
+#define HWCAP_ASIMDBF16	(1 << 26)
 
 /*
  * HWCAP2 flags - for elf_hwcap2 (in kernel) and AT_HWCAP2
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 5e8bf2d5e516..231d885ad4b5 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1253,6 +1253,7 @@  static const char *hwcap_str[] = {
 	"asimdhp",
 	"asimddp",
 	"asimdfhm",
+	"asimdbf16",
 	NULL
 };
 
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 404c4f901132..ff574cb8a0b9 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -851,6 +851,12 @@  static int __init vfp_init(void)
 		 */
 		if (cpuid_feature_extract_field(isar6, 8) == 0x1)
 			elf_hwcap |= HWCAP_ASIMDFHM;
+		/*
+		 * Check for the presence of Advanced SIMD Bfloat16
+		 * floating point instructions.
+		 */
+		if (cpuid_feature_extract_field(isar6, 20) == 0x1)
+			elf_hwcap |= HWCAP_ASIMDBF16;
 
 	/* Extract the architecture version on pre-cpuid scheme */
 	} else {