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Message-Id: <1445551641-13379-1-git-send-email-andi@firstfloor.org> Date: Thu, 22 Oct 2015 15:07:20 -0700 From: Andi Kleen <andi@...stfloor.org> To: peterz@...radead.org Cc: mingo@...nel.org, linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com> Subject: [PATCH 1/2] x86: Add a __copy_from_user_nmi From: Andi Kleen <ak@...ux.intel.com> 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@...ux.intel.com> --- 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 a8df874..1d0766c 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 */ -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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