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authorPaul Burton <paul.burton@imgtec.com>2015-07-27 22:58:23 +0300
committerRalf Baechle <ralf@linux-mips.org>2015-09-03 13:07:59 +0300
commite14f1db7a61f016d74393ca9e8fc49a91d27f603 (patch)
tree42c39860145a108787727893e220c98813290aa0
parentbf82cb30c7e58b3a9742f0a45962ebdf51befac7 (diff)
downloadlinux-e14f1db7a61f016d74393ca9e8fc49a91d27f603.tar.xz
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 <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Guenter Roeck <linux@roeck-us.net> Cc: Matthew Fortune <matthew.fortune@imgtec.com> Cc: Kees Cook <keescook@chromium.org> Cc: Huacai Chen <chenhc@lemote.com> Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: Alex Smith <alex@alex-smith.me.uk> Cc: linux-kernel@vger.kernel.org Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Cc: Ingo Molnar <mingo@kernel.org> Patchwork: https://patchwork.linux-mips.org/patch/10797/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/include/asm/elf.h4
-rw-r--r--arch/mips/include/uapi/asm/hwcap.h8
-rw-r--r--arch/mips/kernel/cpu-probe.c3
3 files changed, 14 insertions, 1 deletions
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 <asm/hwcap.h>
/*
* 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 <asm/spram.h>
#include <asm/uaccess.h>
+/* Hardware capabilities */
+unsigned int elf_hwcap __read_mostly;
+
/*
* Get the FPU Implementation/Revision.
*/