[PATCH v2 0/5] arm64: advertise availability of CRC and crypto instructions

[Ard Biesheuvel]

@Russell, Nico,

Care to share your opinion on this alternative approach to allocating
hwcap feature bits for the ARMv8 Crypto Extensions for 32-bit ARM?

Regards,
Ard.


On 23 December 2013 15:06, Ard Biesheuvel <ard.biesheuvel at linaro.org> wrote:
> This series is a followup to the patch that was recently merged by Catalin that
> allocates hwcaps bits for CRC and Crypto Extensions instructions so userland can
> discover whether the current CPU has any of those capabilities.
>
> Patch #1 enables ARM support for the ELF_HWCAP2/AT_HWCAP2 ELF auxv entry that
> was recently added to the kernel and glibc (2.18). It extends the feature bit
> space to 64 bits (on 32-bit architectures)
>
> Patch #2 adds generic support for ELF_HWCAP2/AT_HWCAP2 to the 32-bit ELF compat
> mode for 64-bit architectures.
>
> Patch #3 adds support for ELF_HWCAP2/AT_HWCAP2 to arm64's 32-bit ELF compat mode
>
> Patch #4 allocates the HWCAP2 bits in the arch/arm tree. This is necessary
> because 32-bit ARM binaries can execute both under ARM and under arm64 kernels,
> so there should be agreement about the meaning of feature bits, even if the ARM
> kernel has no support yet for ARMv8 32-bit only hardware (such as ARMv8-R)
>
> Patch #5 advertises the CRC and Crypto Extensions to 32-bit ELF binaries running
> under an arm64 kernel.
>
> v2 changes:
> - omitted 2 arm64 specific patches that have already been merged by Catalin
> - move ARM feature bits to HWCAP2
>
> Ard Biesheuvel (5):
>   ARM: add support for AT_HWCAP2 ELF auxv entry
>   binfmt_elf: add ELF_HWCAP2 to compat auxv entries
>   arm64: add AT_HWCAP2 support for 32-bit compat
>   ARM: introduce HWCAP2 feature bits for ARMv8 Crypto Extensions
>   arm64: advertise ARMv8 extensions to 32-bit compat ELF binaries
>
>  arch/arm/include/asm/hwcap.h      |  3 ++-
>  arch/arm/include/uapi/asm/hwcap.h |  9 +++++++++
>  arch/arm/kernel/setup.c           | 16 ++++++++++++++++
>  arch/arm64/include/asm/hwcap.h    |  9 ++++++++-
>  arch/arm64/kernel/setup.c         | 33 +++++++++++++++++++++++++++++++++
>  fs/compat_binfmt_elf.c            |  5 +++++
>  6 files changed, 73 insertions(+), 2 deletions(-)
>
> --
> 1.8.3.2
>