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

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>

diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 64f3608e6f1bf68294fb0520a2d55eb0aa1a1e23..3d168d4f2a51e48fceb9b72b7fd10fc406062a19 100644 (file)
--- 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 9841b897d476c78d3969689f805e4a54fc488cf0..d88c1326f529a98eca63b5c3a0891dc07423fb9e 100644 (file)
--- 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 70f1e0f4eece8da01887a928a79b5bd954bd4d06..404c4f9011329300038c499f22f7ce50e0e169d8 100644 (file)
--- 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 {