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[4/8] ARM: vfp: Add hwcap for FEAT_FHM

Message ID 20221026055001.12986-5-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 
Floating-point half-precision multiplication (FHM) is a feature present
in AArch32 state for Armv8 and is represented by ISAR6.FHM identification
register.

This feature denotes the presence of VFMAL and VMFSL 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(+)
diff mbox series

Patch

diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 64f3608e6f1b..3d168d4f2a51 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h
@@ -31,6 +31,7 @@ 
 #define HWCAP_FPHP	(1 << 22)
 #define HWCAP_ASIMDHP	(1 << 23)
 #define HWCAP_ASIMDDP	(1 << 24)
+#define HWCAP_ASIMDFHM	(1 << 25)
 
 /*
  * 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 c55ff1110152..5e8bf2d5e516 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1252,6 +1252,7 @@  static const char *hwcap_str[] = {
 	"fphp",
 	"asimdhp",
 	"asimddp",
+	"asimdfhm",
 	NULL
 };
 
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 70f1e0f4eece..404c4f901132 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -845,6 +845,12 @@  static int __init vfp_init(void)
 		isar6 = read_cpuid_ext(CPUID_EXT_ISAR6);
 		if (cpuid_feature_extract_field(isar6, 4) == 0x1)
 			elf_hwcap |= HWCAP_ASIMDDP;
+		/*
+		 * Check for the presence of Advanced SIMD Floating point
+		 * half-precision multiplication instructions.
+		 */
+		if (cpuid_feature_extract_field(isar6, 8) == 0x1)
+			elf_hwcap |= HWCAP_ASIMDFHM;
 
 	/* Extract the architecture version on pre-cpuid scheme */
 	} else {