From aaba098fe6ce594ae6f963dc041be6307e499f19 Mon Sep 17 00:00:00 2001 From: Andrew Murray Date: Tue, 9 Apr 2019 10:52:40 +0100 Subject: 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 [will: use const_ilog2() and tweak documentation] Signed-off-by: Will Deacon --- arch/arm64/include/uapi/asm/hwcap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm64/include/uapi') diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h index 5f0750c2199c..453b45af80b7 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -18,7 +18,7 @@ #define _UAPI__ASM_HWCAP_H /* - * HWCAP flags - for elf_hwcap (in kernel) and AT_HWCAP + * HWCAP flags - for AT_HWCAP */ #define HWCAP_FP (1 << 0) #define HWCAP_ASIMD (1 << 1) -- cgit