From 10013ebb5d7856c243541870f4e62fed68253e88 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 22 Oct 2015 15:07:20 -0700 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1445551641-13379-1-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/uaccess.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 09b1b0a..660458a 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 */ -- 2.7.4