From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751380AbeDMSpa (ORCPT ); Fri, 13 Apr 2018 14:45:30 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:45384 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750984AbeDMSp1 (ORCPT ); Fri, 13 Apr 2018 14:45:27 -0400 Date: Fri, 13 Apr 2018 19:45:23 +0100 From: Dave Martin To: Linus Torvalds Cc: Russell King - ARM Linux , Linux Kernel Mailing List , "Dmitry V. Levin" , "Eric W. Biederman" , sparclinux , ppc-dev , linux-arm-kernel Subject: Re: sparc/ppc/arm compat siginfo ABI regressions: sending SIGFPE via kill() returns wrong values in si_pid and si_uid Message-ID: <20180413184522.GD16308@e103592.cambridge.arm.com> References: <20180412124928.GA29458@altlinux.org> <20180412131404.GE16141@n2100.armlinux.org.uk> <20180412172051.GK16141@n2100.armlinux.org.uk> <20180413094211.GN16141@n2100.armlinux.org.uk> <20180413170827.GB16308@e103592.cambridge.arm.com> <20180413175407.GO16141@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 13, 2018 at 11:23:36AM -0700, Linus Torvalds wrote: > On Fri, Apr 13, 2018 at 10:54 AM, Russell King - ARM Linux > wrote: > > > > FPE_FLTINV means "floating point invalid operation". Does it really > > cover the case where hardware has failed, or is it intended to cover > > the case where userspace did something wrong and asked for an invalid > > operation from the FP hardware? > > Note that the number of people who actually look at the si_code is > approximately zero. > > But the ones that _do_ check the si_code are certainly not going to > check it against a new code that they don't know about. > > I suspect that if you start searching for FLT_xyz occurrences in code, > approximately 100% of them are from the kernel code that generates > them, not from any actual users. > > So I'd be very surprised if you can find *anybody* who cares about > that exact value (with the possible exceptions of test-suites). > > Sadly, google code-search is no more. It was useful for things like that. I've found https://codesearch.debian.net/ useful for digging into this kind of question, though it tends to throw up a lot of false positives. Most uses I've seen do nothing more than use the FPE_xyz value to format diagnostic messages while dying. I struggled to find code that made a meaningful functional decision based on the value, though that's not proof... Cheers ---Dave