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authorTony Luck <tony.luck@intel.com>2016-09-01 21:39:33 +0300
committerThomas Gleixner <tglx@linutronix.de>2016-09-05 12:47:31 +0300
commit9a6fb28a355d2609ace4dab4e6425442c647894d (patch)
tree7c66135ce9e31daa18d5486e17c2f44ab3cfefd5 /arch/x86/include/asm/string_64.h
parent3637efb00864f465baebd49464e58319fd295b65 (diff)
downloadlinux-9a6fb28a355d2609ace4dab4e6425442c647894d.tar.xz
x86/mce: Improve memcpy_mcsafe()
Use the mcsafe_key defined in the previous patch to make decisions on which copy function to use. We can't use the FEATURE bit any more because PCI quirks run too late to affect the patching of code. So we use a static key. Turn memcpy_mcsafe() into an inline function to make life easier for callers. The assembly code that actually does the copy is now named memcpy_mcsafe_unrolled() Signed-off-by: Tony Luck <tony.luck@intel.com> Acked-by: Borislav Petkov <bp@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Boris Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/bfde2fc774e94f53d91b70a4321c85a0d33e7118.1472754712.git.tony.luck@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/include/asm/string_64.h')
-rw-r--r--arch/x86/include/asm/string_64.h16
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 877a1dfbf770..a164862d77e3 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -79,6 +79,7 @@ int strcmp(const char *cs, const char *ct);
#define memset(s, c, n) __memset(s, c, n)
#endif
+__must_check int memcpy_mcsafe_unrolled(void *dst, const void *src, size_t cnt);
DECLARE_STATIC_KEY_FALSE(mcsafe_key);
/**
@@ -89,10 +90,23 @@ DECLARE_STATIC_KEY_FALSE(mcsafe_key);
* @cnt: number of bytes to copy
*
* Low level memory copy function that catches machine checks
+ * We only call into the "safe" function on systems that can
+ * actually do machine check recovery. Everyone else can just
+ * use memcpy().
*
* Return 0 for success, -EFAULT for fail
*/
-int memcpy_mcsafe(void *dst, const void *src, size_t cnt);
+static __always_inline __must_check int
+memcpy_mcsafe(void *dst, const void *src, size_t cnt)
+{
+#ifdef CONFIG_X86_MCE
+ if (static_branch_unlikely(&mcsafe_key))
+ return memcpy_mcsafe_unrolled(dst, src, cnt);
+ else
+#endif
+ memcpy(dst, src, cnt);
+ return 0;
+}
#endif /* __KERNEL__ */