From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 92A386B0003 for ; Wed, 6 Jan 2016 02:06:44 -0500 (EST) Received: by mail-pa0-f44.google.com with SMTP id yy13so136241211pab.3 for ; Tue, 05 Jan 2016 23:06:44 -0800 (PST) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTP id 4si12931995pfa.245.2016.01.05.23.06.43 for ; Tue, 05 Jan 2016 23:06:43 -0800 (PST) From: "Luck, Tony" Subject: Re: [PATCH v7 3/3] x86, mce: Add __mcsafe_copy() Date: Wed, 6 Jan 2016 07:06:41 +0000 Message-ID: References: <5b0243c5df825ad0841f4bb5584cd15d3f013f09.1451952351.git.tony.luck@intel.com>, In-Reply-To: Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: 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 You were heading towards: ld: undefined __mcsafe_copy since that is also inside the #ifdef.=20 Weren't you going to "select" this? I'm seriously wondering whether the ifdef still makes sense. Now I don't ha= ve an extra exception table and routines to sort/search/fixup, it doesn't s= eem as useful as it was a few iterations ago. Sent from my iPhone > On Jan 5, 2016, at 20:43, Dan Williams wrote: >=20 >> 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: >>=20 >> struct mcsafe_ret { >> u64 trapnr; >> u64 remain; >> }; >>=20 >> If the copy is successful, then both 'trapnr' and 'remain' are zero. >>=20 >> 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. >>=20 >> 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(+) >>=20 >> 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 kern= el >> QA it is safe to say n. >>=20 >> +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 ins= tead >> + 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/str= ing_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 >>=20 >> +#ifdef CONFIG_MCE_KERNEL_RECOVERY >> +struct mcsafe_ret { >> + u64 trapnr; >> + u64 remain; >> +}; >=20 > 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: >=20 > 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 k= nown > struct mcsafe_ret ret; > ^ >>> arch/x86/include/asm/pmem.h:57:9: error: implicit declaration of functi= on '__mcsafe_copy' [-Werror=3Dimplicit-function-declaration] > ret =3D __mcsafe_copy(dst, (void __force *) src, n); > ^ >>> arch/x86/include/asm/pmem.h:55:21: warning: unused variable 'ret' [-Wun= used-variable] > struct mcsafe_ret ret; > ^ > cc1: some warnings being treated as errors >=20 > vim +55 arch/x86/include/asm/pmem.h >=20 > 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 =3D __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