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ARM: 9270/1: vfp: Add hwcap for FEAT_FHM

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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.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Amit Daniel Kachhap 2022-11-17 06:37:21 +01:00 committed by Russell King (Oracle)
parent 62ea0d873a
commit ce4835497c
3 changed files with 8 additions and 0 deletions
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1
arch/arm/include/uapi/asm/hwcap.h
View File

@ -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

1
arch/arm/kernel/setup.c
View File

@ -1252,6 +1252,7 @@ static const char *hwcap_str[] = {
"fphp",
"asimdhp",
"asimddp",
"asimdfhm",
NULL
};

6
arch/arm/vfp/vfpmodule.c
View File

@ -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 {