From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752285AbcAFHGq (ORCPT ); Wed, 6 Jan 2016 02:06:46 -0500 Received: from mga14.intel.com ([192.55.52.115]:18156 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751341AbcAFHGn convert rfc822-to-8bit (ORCPT ); Wed, 6 Jan 2016 02:06:43 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,528,1444719600"; d="scan'208";a="854428051" From: "Luck, Tony" To: "Williams, Dan J" CC: Ingo Molnar , Borislav Petkov , "Andrew Morton" , Andy Lutomirski , "Elliott, Robert (Persistent Memory)" , "linux-kernel@vger.kernel.org" , Linux MM , linux-nvdimm , X86 ML Subject: Re: [PATCH v7 3/3] x86, mce: Add __mcsafe_copy() Thread-Topic: [PATCH v7 3/3] x86, mce: Add __mcsafe_copy() Thread-Index: AQHRSDy66NEfYZb+9UOC/6DNKpLA+p7uERxU Date: Wed, 6 Jan 2016 07:06:41 +0000 Message-ID: References: <5b0243c5df825ad0841f4bb5584cd15d3f013f09.1451952351.git.tony.luck@intel.com>, In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org You were heading towards: ld: undefined __mcsafe_copy since that is also inside the #ifdef. Weren't you going to "select" this? I'm seriously wondering whether the ifdef still makes sense. Now I don't have an extra exception table and routines to sort/search/fixup, it doesn't seem as useful as it was a few iterations ago. Sent from my iPhone > On Jan 5, 2016, at 20:43, Dan Williams wrote: > >> 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;