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From: "trippels at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/59644] [4.9 Regression] r206243 miscompiles Linux kernel
Date: Mon, 06 Jan 2014 09:17:00 -0000 [thread overview]
Message-ID: <bug-59644-4-aQ7yFDsPVY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-59644-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59644
--- Comment #13 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #12)
> (In reply to Markus Trippelsdorf from comment #11)
> > (In reply to Jakub Jelinek from comment #10)
> > > If you have time, could you please try to bisect manually which of the 4
> > > functions matters for the bootstrap failure?
> > > Compile printk.s with both compilers and apply by hand only portions of the
> > > diff that are for individual routines?
> >
> > Yes. I will try this later.
> > In the meantime I've found out that drivers/acpi/acpica/utxferror.c also
> > gets miscompiled. If I replace this two object files with good ones and
> > relink the kernel, everything runs fine (under qemu)...
> >
> > utxferror shows the same pattern as seen in printk.
>
> It is undestandable the patch changes how most/all stdarg functions are
> compiled in the kernel, the question is why the kernel cares in certain
> cases. Do you get some OOPS in the utxferror case or also silent hang
> without being able to tell what is going on? In ACPI case, I'd guess if the
> routine calls into BIOS that the BIOS (or whatever qemu uses instead of
> BIOS) might assume 16-byte stack alignment which is part of the ABI, but the
> kernel intentionally only guarantees 8-byte stack alignment.
It's also a silent hang in the utxferror case. In both cases the kernel
just executes the halt loop in early_idt_handler:
0xffffffff81a81165 <+69>: hlt
=> 0xffffffff81a81166 <+70>: jmp 0xffffffff81a81165
<early_idt_handler+69>
next prev parent reply other threads:[~2014-01-06 9:17 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-30 23:03 [Bug tree-optimization/59644] New: " trippels at gcc dot gnu.org
2013-12-30 23:43 ` [Bug tree-optimization/59644] " jakub at gcc dot gnu.org
2013-12-31 8:17 ` trippels at gcc dot gnu.org
2013-12-31 8:18 ` trippels at gcc dot gnu.org
2013-12-31 8:19 ` trippels at gcc dot gnu.org
2013-12-31 8:20 ` trippels at gcc dot gnu.org
2013-12-31 8:26 ` trippels at gcc dot gnu.org
2013-12-31 11:47 ` jakub at gcc dot gnu.org
2013-12-31 13:03 ` trippels at gcc dot gnu.org
2014-01-06 8:21 ` trippels at gcc dot gnu.org
2014-01-06 8:48 ` trippels at gcc dot gnu.org
2014-01-06 9:08 ` jakub at gcc dot gnu.org
2014-01-06 9:17 ` trippels at gcc dot gnu.org [this message]
2014-01-06 9:26 ` jakub at gcc dot gnu.org
2014-01-06 9:36 ` trippels at gcc dot gnu.org
2014-01-06 10:00 ` trippels at gcc dot gnu.org
2014-01-06 10:04 ` trippels at gcc dot gnu.org
2014-01-06 10:09 ` hjl.tools at gmail dot com
2014-01-06 10:12 ` jakub at gcc dot gnu.org
2014-01-06 10:21 ` trippels at gcc dot gnu.org
2014-01-06 11:28 ` jakub at gcc dot gnu.org
2014-01-06 11:55 ` jakub at gcc dot gnu.org
2014-01-06 13:39 ` [Bug target/59644] " jakub at gcc dot gnu.org
2014-01-06 21:38 ` jakub at gcc dot gnu.org
2014-01-06 21:39 ` jakub at gcc dot gnu.org
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