linux-kernel - Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from

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Message-ID: <20170714194248.6n7rw5ln6luhnz3l@treble>
Date:   Fri, 14 Jul 2017 14:42:48 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Mike Galbraith <efault@....de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ilia Mirkin <imirkin@...m.mit.edu>,
        LKML <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Ben Skeggs <bskeggs@...hat.com>, jeyu@...nel.org
Subject: Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP:
 drm_calc_vbltimestamp_from_scanoutpos+335

On Fri, Jul 14, 2017 at 06:33:01PM +0200, Mike Galbraith wrote:
> On Fri, 2017-07-14 at 18:10 +0200, Peter Zijlstra wrote:
> > On Fri, Jul 14, 2017 at 05:58:18PM +0200, Mike Galbraith wrote:
> > > On Fri, 2017-07-14 at 17:50 +0200, Peter Zijlstra wrote:
> > 
> > > > Urgh, is for some mysterious reason the __bug_table section of modules
> > > > ending up in RO memory?
> > > > 
> > > > I forever get lost in that link magic :/
> > > 
> > > +1
> > > 
> > > drm.ko
> > >  20 __bug_table   00000630  0000000000000000  0000000000000000  0004bff3  2**0
> > >                   CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
> > > vmlinux
> > >  15 __bug_table   0000ba84  ffffffff81af26c0  0000000001af26c0  00cf26c0  2**0
> > >                   CONTENTS, ALLOC, LOAD, READONLY, DATA
> > > 
> > > Danged if I know... um um RELOC business mucks things up?
> > 
> > Argh, it shouldn't be READONLY for vmlinux either, but apparently that
> > is working for mysterious reasons.
> > 
> > Some architectures were in fact complaining that I broke that, and hence
> > patch:
> > 
> > b5effd3815cc ("debug: Fix __bug_table[] in arch linker scripts")
> > 
> > I think we need professional help with this linking stuff, but who to
> > ask?
> 
> Andy Lutomirski?

Does this fix it?


diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 39e702d..aa6b202 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -35,7 +35,7 @@
 #define _BUG_FLAGS(ins, flags)						\
 do {									\
 	asm volatile("1:\t" ins "\n"					\
-		     ".pushsection __bug_table,\"a\"\n"			\
+		     ".pushsection __bug_table,\"aw\"\n"		\
 		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
 		     "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"	\
 		     "\t.word %c1"        "\t# bug_entry::line\n"	\
@@ -52,7 +52,7 @@ do {									\
 #define _BUG_FLAGS(ins, flags)						\
 do {									\
 	asm volatile("1:\t" ins "\n"					\
-		     ".pushsection __bug_table,\"a\"\n"			\
+		     ".pushsection __bug_table,\"aw\"\n"		\
 		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
 		     "\t.word %c0"        "\t# bug_entry::flags\n"	\
 		     "\t.org 2b+%c1\n"					\