From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f54.google.com (mail-wm0-f54.google.com [74.125.82.54]) by kanga.kvack.org (Postfix) with ESMTP id 073FD82FD8 for ; Sun, 27 Dec 2015 01:57:28 -0500 (EST) Received: by mail-wm0-f54.google.com with SMTP id l126so232680781wml.1 for ; Sat, 26 Dec 2015 22:57:27 -0800 (PST) Received: from mail-wm0-x22d.google.com (mail-wm0-x22d.google.com. [2a00:1450:400c:c09::22d]) by mx.google.com with ESMTPS id cz5si66421576wjb.186.2015.12.26.22.57.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 26 Dec 2015 22:57:26 -0800 (PST) Received: by mail-wm0-x22d.google.com with SMTP id l126so238990646wml.1 for ; Sat, 26 Dec 2015 22:57:26 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <20151224214632.GF4128@pd.tnic> <20151225114937.GA862@pd.tnic> <5FBC1CF1-095B-466D-85D6-832FBFA98364@intel.com> <20151226103252.GA21988@pd.tnic> Date: Sat, 26 Dec 2015 22:57:26 -0800 Message-ID: Subject: Re: [PATCHV5 3/3] x86, ras: Add __mcsafe_copy() function to recover from machine checks From: Tony Luck Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Borislav Petkov , linux-nvdimm , X86 ML , "elliott@hpe.com" , "linux-mm@kvack.org" , Andrew Morton , "Williams, Dan J" , Ingo Molnar , "linux-kernel@vger.kernel.org" On Sat, Dec 26, 2015 at 6:16 PM, Andy Lutomirski wrote: >>> We could make one of them 31-bits (since even an "allyesconfig" kernel >>> is still much smaller than a gigabyte) to free a bit for a flag. But there >>> are those external tools to pre-sort exception tables that would all >>> need to be fixed too. > > Wait, why? The external tools sort by source address, and we'd > squeeze the flag into the target address, no? I was thinking that we'd need to recompute the fixup when we move the entry to its new sorted location. So that: ex_fixup_addr(const struct exception_table_entry *x) { return (unsigned long)&x->fixup + x->fixup; } will get the right value. Maybe this would still work out if the fixup is a 31-bit value plus a flag, but the external tool thinks it is a 32-bit value? I'd have to ponder that. -Tony -- 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