From: Dave Martin <Dave.Martin@arm•com>
To: Linus Torvalds <torvalds@linux-foundation•org>
Cc: Russell King - ARM Linux <linux@armlinux•org.uk>,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
"Dmitry V. Levin" <ldv@altlinux•org>,
"Eric W. Biederman" <ebiederm@xmission•com>,
sparclinux <sparclinux@vger•kernel.org>,
ppc-dev <linuxppc-dev@lists•ozlabs.org>,
linux-arm-kernel <linux-arm-kernel@lists•infradead.org>
Subject: Re: sparc/ppc/arm compat siginfo ABI regressions: sending SIGFPE via kill() returns wrong values in si_pid and si_uid
Date: Fri, 13 Apr 2018 19:45:23 +0100 [thread overview]
Message-ID: <20180413184522.GD16308@e103592.cambridge.arm.com> (raw)
In-Reply-To: <CA+55aFyya6B9_aq8ZSrZT-S-BGbpbDgFvDff5z8upDirpcoiHA@mail.gmail.com>
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
> <linux@armlinux•org.uk> 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
next prev parent reply other threads:[~2018-04-13 18:45 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-09 15:22 ppc compat v4.16 regression: sending SIGTRAP or SIGFPE via kill() returns wrong values in si_pid and si_uid Dmitry V. Levin
2018-04-12 1:34 ` sparc/ppc/arm compat siginfo ABI regressions: sending " Dmitry V. Levin
2018-04-12 1:45 ` Linus Torvalds
2018-04-12 9:58 ` Russell King - ARM Linux
2018-04-12 11:03 ` Dmitry V. Levin
2018-04-12 12:19 ` Russell King - ARM Linux
2018-04-12 12:49 ` Dmitry V. Levin
2018-04-12 13:14 ` Russell King - ARM Linux
2018-04-12 16:50 ` Linus Torvalds
2018-04-12 17:20 ` Russell King - ARM Linux
2018-04-12 17:22 ` Linus Torvalds
2018-04-13 9:42 ` Russell King - ARM Linux
2018-04-13 16:33 ` Linus Torvalds
2018-04-13 17:08 ` Dave Martin
2018-04-13 17:54 ` Russell King - ARM Linux
2018-04-13 18:23 ` Linus Torvalds
2018-04-13 18:45 ` Dave Martin [this message]
2018-04-13 19:53 ` Linus Torvalds
2018-04-15 13:12 ` Russell King - ARM Linux
2018-04-15 15:22 ` Eric W. Biederman
2018-04-15 15:56 ` [RFC PATCH 0/3] Dealing with the aliases of SI_USER Eric W. Biederman
2018-04-15 15:57 ` [RFC PATCH 1/3] signal: Ensure every siginfo we send has all bits initialized Eric W. Biederman
2018-04-17 13:23 ` Dave Martin
2018-04-17 19:37 ` Eric W. Biederman
2018-04-18 12:47 ` Dave Martin
2018-04-18 14:22 ` Eric W. Biederman
2018-04-19 8:26 ` Dave Martin
2018-04-15 15:58 ` [RFC PATCH 2/3] signal: Reduce copy_siginfo_to_user to just copy_to_user Eric W. Biederman
2018-04-15 15:59 ` [RFC PATCH 3/3] signal: Stop special casing TRAP_FIXME and FPE_FIXME in siginfo_layout Eric W. Biederman
2018-04-15 18:16 ` [RFC PATCH 0/3] Dealing with the aliases of SI_USER Linus Torvalds
2018-04-16 2:03 ` Eric W. Biederman
2018-04-18 17:58 ` Eric W. Biederman
2018-04-19 9:28 ` Dave Martin
2018-04-19 14:40 ` Eric W. Biederman
2018-04-13 18:35 ` sparc/ppc/arm compat siginfo ABI regressions: sending SIGFPE via kill() returns wrong values in si_pid and si_uid Dave Martin
2018-04-13 18:50 ` Russell King - ARM Linux
2018-04-13 18:56 ` Dave Martin
2018-04-12 17:35 ` Dmitry V. Levin
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