@@ -375,7 +375,7 @@ void __init early_print(const char *str, ...)
static void __init cpuid_init_hwcaps(void)
{
- unsigned int divide_instrs, vmsa;
+ unsigned int divide_instrs, vmsa, features, block;
if (cpu_architecture() < CPU_ARCH_ARMv7)
return;
@@ -393,6 +393,37 @@ static void __init cpuid_init_hwcaps(void)
vmsa = (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xf) >> 0;
if (vmsa >= 5)
elf_hwcap |= HWCAP_LPAE;
+
+ /*
+ * ID_ISAR5 contains 4-bit wide signed feature blocks.
+ * The blocks we test below represent incremental functionality
+ * for non-negative values. Negative values are reserved.
+ */
+ features = read_cpuid_ext(ID_ISAR5);
+ block = (features >> 4) & 0xf;
+ if (!(block & 0x8)) {
+ switch (block) {
+ default:
+ case 2:
+ elf_hwcap2 |= HWCAP2_PMULL;
+ case 1:
+ elf_hwcap2 |= HWCAP2_AES;
+ case 0:
+ break;
+ }
+ }
+
+ block = (features >> 8) & 0xf;
+ if (block && !(block & 0x8))
+ elf_hwcap2 |= HWCAP2_SHA1;
+
+ block = (features >> 12) & 0xf;
+ if (block && !(block & 0x8))
+ elf_hwcap2 |= HWCAP2_SHA2;
+
+ block = (features >> 16) & 0xf;
+ if (block && !(block & 0x8))
+ elf_hwcap2 |= HWCAP2_CRC32;
}
static void __init elf_hwcap_fixup(void)
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 <ard.biesheuvel@linaro.org> --- v3: - reuse logic from arm64 kernel: the feature blocks are signed quantities that represent incremental functionality for non-negative values. v2: - drop redundant architecture check -> accessing ID_ISAR5 should be safe even on v7-M, and even if we don't expect to find crypto features there arch/arm/kernel/setup.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-)