arm64: HWCAP: add support for AT_HWCAP2
authorAndrew Murray <andrew.murray@arm.com>
Tue, 9 Apr 2019 09:52:40 +0000 (10:52 +0100)
committerWill Deacon <will.deacon@arm.com>
Tue, 16 Apr 2019 15:27:12 +0000 (16:27 +0100)
commitaaba098fe6ce594ae6f963dc041be6307e499f19
tree619d471f27d373e460f251afacddc19889dafe5c
parenta823c35ff2eda73046cc1847326071de350fceda
arm64: HWCAP: add support for AT_HWCAP2

As we will exhaust the first 32 bits of AT_HWCAP let's start
exposing AT_HWCAP2 to userspace to give us up to 64 caps.

Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we
prefer to expand into AT_HWCAP2 in order to provide a consistent
view to userspace between ILP32 and LP64. However internal to the
kernel we prefer to continue to use the full space of elf_hwcap.

To reduce complexity and allow for future expansion, we now
represent hwcaps in the kernel as ordinals and use a
KERNEL_HWCAP_ prefix. This allows us to support automatic feature
based module loading for all our hwcaps.

We introduce cpu_set_feature to set hwcaps which complements the
existing cpu_have_feature helper. These helpers allow us to clean
up existing direct uses of elf_hwcap and reduce any future effort
required to move beyond 64 caps.

For convenience we also introduce cpu_{have,set}_named_feature which
makes use of the cpu_feature macro to allow providing a hwcap name
without a {KERNEL_}HWCAP_ prefix.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
[will: use const_ilog2() and tweak documentation]
Signed-off-by: Will Deacon <will.deacon@arm.com>
15 files changed:
Documentation/arm64/elf_hwcaps.txt
arch/arm64/crypto/aes-ce-ccm-glue.c
arch/arm64/crypto/aes-neonbs-glue.c
arch/arm64/crypto/chacha-neon-glue.c
arch/arm64/crypto/crct10dif-ce-glue.c
arch/arm64/crypto/ghash-ce-glue.c
arch/arm64/crypto/nhpoly1305-neon-glue.c
arch/arm64/crypto/sha256-glue.c
arch/arm64/include/asm/cpufeature.h
arch/arm64/include/asm/hwcap.h
arch/arm64/include/uapi/asm/hwcap.h
arch/arm64/kernel/cpufeature.c
arch/arm64/kernel/cpuinfo.c
arch/arm64/kernel/fpsimd.c
drivers/clocksource/arm_arch_timer.c