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Message-ID: <CAKv+Gu_o1TEDUYPzUCV1x6D79saUyLdJb1L59GDPwD393CzynQ@mail.gmail.com>
Date: Tue, 7 Jan 2014 10:22:41 +0100
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: Russell King - ARM Linux <linux@....linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
viro@...iv.linux.org.uk, Nicolas Pitre <nico@...aro.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH v2 0/5] arm64: advertise availability of CRC and crypto instructions
@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@...aro.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
>
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