From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Tue, 3 Mar 2015 14:43:01 +0100 Subject: [PATCH] ARM: advertise availability of v8 Crypto instructions In-Reply-To: <1425054991-29951-1-git-send-email-ard.biesheuvel@linaro.org> References: <1425054991-29951-1-git-send-email-ard.biesheuvel@linaro.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 27 February 2015 at 17:36, Ard Biesheuvel wrote: > When running the 32-bit ARM kernel on ARMv8 capable bare metal (e.g., > 32-bit Android userland and kernel on a Cortex-A53), or as a KVM guest > on a 64-bit host, we should advertise the availability of the Crypto > instructions, so that userland libraries such as OpenSSL may use them. > (Support for the v8 Crypto instructions in the 32-bit build was added > to OpenSSL more than six months ago) > > This adds the ID feature bit detection, and sets elf_hwcap2 accordingly. > > Signed-off-by: Ard Biesheuvel > --- > arch/arm/kernel/setup.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index e55408e96559..8d4cb1c1c9ac 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -393,6 +393,22 @@ static void __init cpuid_init_hwcaps(void) > vmsa = (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xf) >> 0; > if (vmsa >= 5) > elf_hwcap |= HWCAP_LPAE; > + > + /* check for supported v8 Crypto instructions on non v7-M CPUs */ Perhaps this should be 'on v7+ (non v7-M) CPUs' > + if (cpu_architecture() == CPU_ARCH_ARMv7) { @Russell: any thoughts on this? Currently, v8 CPUs are identified as CPU_ARCH_ARMv7, and there is no point in performing this test on other architectures (including v7-M) > + unsigned int id = read_cpuid_ext(CPUID_EXT_ISAR5); > + > + switch ((id >> 4) & 0xf) { > + case 2: elf_hwcap2 |= HWCAP2_PMULL; > + case 1: elf_hwcap2 |= HWCAP2_AES; > + } > + if (((id >> 8) & 0xf) == 1) > + elf_hwcap2 |= HWCAP2_SHA1; > + if (((id >> 12) & 0xf) == 1) > + elf_hwcap2 |= HWCAP2_SHA2; > + if (((id >> 16) & 0xf) == 1) > + elf_hwcap2 |= HWCAP2_CRC32; > + } > } > > static void __init elf_hwcap_fixup(void) > -- > 1.8.3.2 >