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authorAndi Kleen <ak@linux.intel.com>2015-10-23 01:07:20 +0300
committerIngo Molnar <mingo@kernel.org>2015-11-23 11:58:24 +0300
commit10013ebb5d7856c243541870f4e62fed68253e88 (patch)
treecdbb1182419f3dc05b3414a2abcca9f59d7c1268 /arch/x86/include/asm/uaccess.h
parent8c2accc8ca0be9cd8119ca439038243dfc8fcd0d (diff)
downloadlinux-10013ebb5d7856c243541870f4e62fed68253e88.tar.xz
x86: Add an inlined __copy_from_user_nmi() variant
Add a inlined __ variant of copy_from_user_nmi. The inlined variant allows the user to: - batch the access_ok() check for multiple accesses - avoid having a pagefault_disable/enable() on every access if the caller already ensures disabled page faults due to its context. - get all the optimizations in copy_*_user() for small constant sized transfers It is just a define to __copy_from_user_inatomic(). Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1445551641-13379-1-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
-rw-r--r--arch/x86/include/asm/uaccess.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 09b1b0ab94b7..660458af425d 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -745,5 +745,14 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
#undef __copy_from_user_overflow
#undef __copy_to_user_overflow
+/*
+ * We rely on the nested NMI work to allow atomic faults from the NMI path; the
+ * nested NMI paths are careful to preserve CR2.
+ *
+ * Caller must use pagefault_enable/disable, or run in interrupt context,
+ * and also do a uaccess_ok() check
+ */
+#define __copy_from_user_nmi __copy_from_user_inatomic
+
#endif /* _ASM_X86_UACCESS_H */