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From: Joey Gouly <joey.gouly@arm.com>
To: <linux-arm-kernel@lists.infradead.org>
Cc: <nd@arm.com>, <alexandru.elisei@arm.com>,
	<catalin.marinas@arm.com>, <corbet@lwn.net>,
	<james.morse@arm.com>, <joey.gouly@arm.com>, <maz@kernel.org>,
	<reijiw@google.com>, <suzuki.poulose@arm.com>, <will@kernel.org>
Subject: [PATCH v1 0/3] arm64: Add two HWCAPs for Arm v8.7 FP behaviour
Date: Wed, 1 Dec 2021 12:05:55 +0000	[thread overview]
Message-ID: <20211201120558.9140-1-joey.gouly@arm.com> (raw)

This series adds new HWCAPs for two Arm v8.7 features:
  - FEAT_AFP: Alternate floating-point behavior for specific
    floating point instructions.
  - FEAT_RPRES: Increased precision of Reciprocal Estimate and
    Reciprocal Square Root Estimate from an 8-bit mantissa to a
    12-bit mantissa.

These features can be enabled by userspace by setting some new bits
in FPCR. These new bits are FPCR.{NEP, AH, FIZ}. Since these must be
explicitly enabled by userspace, this should not affect existing
applications.

This has been tested with:
  - FVP: combinations of both features, including mismatched CPUs
  - qemu: regression test, neither feature is supported
  - juno: regression test, neither feature is supported

Joey Gouly (3):
  arm64: cpufeature: add HWCAP for FEAT_AFP
  arm64: add ID_AA64ISAR2_EL1 sys register
  arm64: cpufeature: add HWCAP for FEAT_RPRES

 Documentation/arm64/cpu-feature-registers.rst | 17 +++++++++++++++++
 Documentation/arm64/elf_hwcaps.rst            |  8 ++++++++
 arch/arm64/include/asm/cpu.h                  |  1 +
 arch/arm64/include/asm/hwcap.h                |  2 ++
 arch/arm64/include/asm/sysreg.h               | 11 +++++++++++
 arch/arm64/include/uapi/asm/hwcap.h           |  2 ++
 arch/arm64/kernel/cpufeature.c                | 13 +++++++++++++
 arch/arm64/kernel/cpuinfo.c                   |  3 +++
 arch/arm64/kvm/sys_regs.c                     |  2 +-
 9 files changed, 58 insertions(+), 1 deletion(-)

-- 
2.17.1


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             reply	other threads:[~2021-12-01 12:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-01 12:05 Joey Gouly [this message]
2021-12-01 12:05 ` [PATCH v1 1/3] arm64: cpufeature: add HWCAP for FEAT_AFP Joey Gouly
2021-12-01 12:05 ` [PATCH v1 2/3] arm64: add ID_AA64ISAR2_EL1 sys register Joey Gouly
2021-12-01 16:23   ` Marc Zyngier
2021-12-01 12:05 ` [PATCH v1 3/3] arm64: cpufeature: add HWCAP for FEAT_RPRES Joey Gouly

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