From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f176.google.com (mail-yk0-f176.google.com [209.85.160.176]) by kanga.kvack.org (Postfix) with ESMTP id 8A95B6B0003 for ; Tue, 5 Jan 2016 23:42:56 -0500 (EST) Received: by mail-yk0-f176.google.com with SMTP id k129so282420269yke.0 for ; Tue, 05 Jan 2016 20:42:56 -0800 (PST) Received: from mail-yk0-x22f.google.com (mail-yk0-x22f.google.com. [2607:f8b0:4002:c07::22f]) by mx.google.com with ESMTPS id b137si58644638ywe.363.2016.01.05.20.42.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 Jan 2016 20:42:55 -0800 (PST) Received: by mail-yk0-x22f.google.com with SMTP id x67so304722719ykd.2 for ; Tue, 05 Jan 2016 20:42:55 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <5b0243c5df825ad0841f4bb5584cd15d3f013f09.1451952351.git.tony.luck@intel.com> References: <5b0243c5df825ad0841f4bb5584cd15d3f013f09.1451952351.git.tony.luck@intel.com> Date: Tue, 5 Jan 2016 20:42:55 -0800 Message-ID: Subject: Re: [PATCH v7 3/3] x86, mce: Add __mcsafe_copy() From: Dan Williams Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Tony Luck Cc: Ingo Molnar , Borislav Petkov , Andrew Morton , Andy Lutomirski , "Elliott, Robert (Persistent Memory)" , "linux-kernel@vger.kernel.org" , Linux MM , linux-nvdimm , X86 ML On Thu, Dec 31, 2015 at 11:43 AM, Tony Luck wrote: > Make use of the EXTABLE_FAULT exception table entries. This routine > returns a structure to indicate the result of the copy: > > struct mcsafe_ret { > u64 trapnr; > u64 remain; > }; > > If the copy is successful, then both 'trapnr' and 'remain' are zero. > > If we faulted during the copy, then 'trapnr' will say which type > of trap (X86_TRAP_PF or X86_TRAP_MC) and 'remain' says how many > bytes were not copied. > > Signed-off-by: Tony Luck > --- > arch/x86/Kconfig | 10 +++ > arch/x86/include/asm/string_64.h | 10 +++ > arch/x86/kernel/x8664_ksyms_64.c | 4 ++ > arch/x86/lib/memcpy_64.S | 136 +++++++++++++++++++++++++++++++++++++++ > 4 files changed, 160 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 96d058a87100..42d26b4d1ec4 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1001,6 +1001,16 @@ config X86_MCE_INJECT > If you don't know what a machine check is and you don't do kernel > QA it is safe to say n. > > +config MCE_KERNEL_RECOVERY > + bool "Recovery from machine checks in special kernel memory copy functions" > + default n > + depends on X86_MCE && X86_64 > + ---help--- > + This option provides a new memory copy function mcsafe_memcpy() > + that is annotated to allow the machine check handler to return > + to an alternate code path to return an error to the caller instead > + of crashing the system. Say yes if you have a driver that uses this. > + > config X86_THERMAL_VECTOR > def_bool y > depends on X86_MCE_INTEL > diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h > index ff8b9a17dc4b..16a8f0e56e4a 100644 > --- a/arch/x86/include/asm/string_64.h > +++ b/arch/x86/include/asm/string_64.h > @@ -78,6 +78,16 @@ int strcmp(const char *cs, const char *ct); > #define memset(s, c, n) __memset(s, c, n) > #endif > > +#ifdef CONFIG_MCE_KERNEL_RECOVERY > +struct mcsafe_ret { > + u64 trapnr; > + u64 remain; > +}; Can we move this definition outside of the CONFIG_MCE_KERNEL_RECOVERY ifdef guard? On a test integration branch the kbuild robot caught the following: In file included from include/linux/pmem.h:21:0, from drivers/acpi/nfit.c:22: arch/x86/include/asm/pmem.h: In function 'arch_memcpy_from_pmem': >> arch/x86/include/asm/pmem.h:55:21: error: storage size of 'ret' isn't known struct mcsafe_ret ret; ^ >> arch/x86/include/asm/pmem.h:57:9: error: implicit declaration of function '__mcsafe_copy' [-Werror=implicit-function-declaration] ret = __mcsafe_copy(dst, (void __force *) src, n); ^ >> arch/x86/include/asm/pmem.h:55:21: warning: unused variable 'ret' [-Wunused-variable] struct mcsafe_ret ret; ^ cc1: some warnings being treated as errors vim +55 arch/x86/include/asm/pmem.h 49 } 50 51 static inline int arch_memcpy_from_pmem(void *dst, const void __pmem *src, 52 size_t n) 53 { 54 if (IS_ENABLED(CONFIG_MCE_KERNEL_RECOVERY)) { > 55 struct mcsafe_ret ret; 56 > 57 ret = __mcsafe_copy(dst, (void __force *) src, n); 58 if (ret.remain) 59 return -EIO; 60 return 0; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org