From e14f1db7a61f016d74393ca9e8fc49a91d27f603 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 27 Jul 2015 12:58:23 -0700 Subject: [PATCH] MIPS: AT_HWCAP aux vector infrastructure In order for userland to determine whether various features are safe to use, it will need to know both that the hardware supports those features and that the kernel is recent enough & configured appropriately to support them. For example under the O32 modeless FP proposal the dynamic linker & ifunc resolvers will need this information. The kernel is the only thing in a position to know availability accurately, so the kernel needs to provide the information to userland. This patch introduces the infrastructure to provide the AT_HWCAP aux vector to userland in order to provide that information. It also defines the 2 currently specified flags, which indicate MIPSr6 & MSA support. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Cc: Guenter Roeck Cc: Matthew Fortune Cc: Kees Cook Cc: Huacai Chen Cc: Maciej W. Rozycki Cc: Alex Smith Cc: linux-kernel@vger.kernel.org Cc: Leonid Yegoshin Cc: Markos Chandras Cc: Ingo Molnar Patchwork: https://patchwork.linux-mips.org/patch/10797/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/elf.h | 4 +++- arch/mips/include/uapi/asm/hwcap.h | 8 ++++++++ arch/mips/kernel/cpu-probe.c | 3 +++ 3 files changed, 14 insertions(+), 1 deletion(-) create mode 100644 arch/mips/include/uapi/asm/hwcap.h diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h index f19e890b99d2..53b26933b12c 100644 --- a/arch/mips/include/asm/elf.h +++ b/arch/mips/include/asm/elf.h @@ -382,7 +382,9 @@ do { \ instruction set this cpu supports. This could be done in userspace, but it's not easy, and we've already done it here. */ -#define ELF_HWCAP (0) +#define ELF_HWCAP (elf_hwcap) +extern unsigned int elf_hwcap; +#include /* * This yields a string that ld.so will use to load implementation diff --git a/arch/mips/include/uapi/asm/hwcap.h b/arch/mips/include/uapi/asm/hwcap.h new file mode 100644 index 000000000000..c7484a7ca686 --- /dev/null +++ b/arch/mips/include/uapi/asm/hwcap.h @@ -0,0 +1,8 @@ +#ifndef _UAPI_ASM_HWCAP_H +#define _UAPI_ASM_HWCAP_H + +/* HWCAP flags */ +#define HWCAP_MIPS_R6 (1 << 0) +#define HWCAP_MIPS_MSA (1 << 1) + +#endif /* _UAPI_ASM_HWCAP_H */ diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index 987036761fb6..b6c1feed8b7b 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -32,6 +32,9 @@ #include #include +/* Hardware capabilities */ +unsigned int elf_hwcap __read_mostly; + /* * Get the FPU Implementation/Revision. */ -- 2.34.1