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arm64: Expose ARMv8.5 CondM capability to userspace 

ARMv8.5 adds new instructions XAFLAG and AXFLAG to translate the
representation of the results of floating point comparisons between the
native ARM format and an alternative format used by some software. Add
a hwcap allowing userspace to determine if they are present, since we
referred to earlier CondM extensions as FLAGM call these extensions
FLAGM2.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Brown 2019-06-18 19:10:54 +01:00 committed by Catalin Marinas
parent 8049672bb1
commit 1201937491
5 changed files with 8 additions and 0 deletions
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4
Documentation/arm64/elf_hwcaps.txt
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@ -207,6 +207,10 @@ HWCAP_FLAGM
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001.
HWCAP2_FLAGM2
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0010.
HWCAP_SSBS
Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.

1
arch/arm64/include/asm/hwcap.h
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@ -95,6 +95,7 @@
#define KERNEL_HWCAP_SVEBITPERM __khwcap2_feature(SVEBITPERM)
#define KERNEL_HWCAP_SVESHA3 __khwcap2_feature(SVESHA3)
#define KERNEL_HWCAP_SVESM4 __khwcap2_feature(SVESM4)
#define KERNEL_HWCAP_FLAGM2 __khwcap2_feature(FLAGM2)
/*
* This yields a mask that user programs can use to figure out what

1
arch/arm64/include/uapi/asm/hwcap.h
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@ -63,5 +63,6 @@
#define HWCAP2_SVEBITPERM (1 << 4)
#define HWCAP2_SVESHA3 (1 << 5)
#define HWCAP2_SVESM4 (1 << 6)
#define HWCAP2_FLAGM2 (1 << 7)
#endif /* _UAPI__ASM_HWCAP_H */

1
arch/arm64/kernel/cpufeature.c
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@ -1628,6 +1628,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_DP_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDDP),
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_FHM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDFHM),
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FLAGM),
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_FLAGM2),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_FP),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FPHP),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_ASIMD),

1
arch/arm64/kernel/cpuinfo.c
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@ -92,6 +92,7 @@ static const char *const hwcap_str[] = {
"svebitperm",
"svesha3",
"svesm4",
"flagm2",
NULL
};