Re: [bisected] 2.6.29-rc1 Firefox crashing on page load

[Justin Madru <jdm64@gawab.com>]

Hiroshi Shimamoto wrote:
> Justin Madru wrote:
>> Ok, finally bisected the bug, but the commit isn't related to networking!
>> I did: git revert 4217458dafaa57d8e26a46f5d05ab8c53cf64191
>> on current git and that fixed the bug.
>>
>> By the way, how do I undo my git revert, so I'm back to a pristine tree?
>> I want to drop my changes - the revert.
>> Also how do I find the commit that merged/pulled in this commit?
>>
>> commit 4217458dafaa57d8e26a46f5d05ab8c53cf64191
>> Author: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
>> Date: Fri Dec 5 17:17:09 2008 -0800
>>
>> x86: signal: change type of paramter for sys_rt_sigreturn()
>>
>> Impact: cleanup on 32-bit
>>
>> Peter pointed this parameter can be changed.
>>
>> Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
>> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>
> Hi,
> thanks for reporting.
>
> I'm not sure why this commit affects.
> Can you check vmlinux? size, objdump, etc.
> On my environment, the generated code looks same.
>
> Thanks,
> Hiroshi
>
I tried to do an objdump but it gave an error. How am I suppose to do an 
objdump?

$ objdump -x /boot/vmlinuz-2.6.29-rc2-git
objdump: /boot/vmlinuz-2.6.29-rc2-git: File format not recognized
$ readelf -a /boot/vmlinuz-2.6.29-rc2-git
readelf: Error: Unable to seek to 0xc031f2eb for section headers
readelf: Error: Not an ELF file - it has the wrong magic bytes at the start
$ ls -la /boot/vmlinuz-2.6.29-rc2-git
-rw-r--r-- 1 root root 2286480 2009-01-19 18:44 /boot/vmlinuz-2.6.29-rc2-git

Anyways, I've uploaded the extracted data.tar.gz file from the kernel 
deb file created when I
build a kernel (I use ubuntu and make-kpkg). The archive includes the 
kernel, config, system.map
and modules that I used. The files can be found at 
http://jdserver.homelinux.org/bugreports/002/
There are 2 files: data-norevert.tar.bz2 is a build without the revert, 
data-revert.tar.bz2 has the revert.

I think peter annema might have have a reason why it's crashing firefox.
If sizeof(struct pt_regs) != sizeof(unsigned long) the the stack could 
become
unbalanced if other code is not expecting a struct pt_regs.

Peter Annema wrote:
> > #ifdef CONFIG_X86_32
> > -asmlinkage int sys_rt_sigreturn(unsigned long __unused)
> > +asmlinkage int sys_rt_sigreturn(struct pt_regs regs)
> > {
> > - struct pt_regs *regs = (struct pt_regs *)&__unused;
> > -
> > - return do_rt_sigreturn(regs);
> > + return do_rt_sigreturn(&regs);
> > }
>
> Is sizeof(struct pt_regs) different from sizeof(unsigned long)? If so, 
> is some
> code somewhere messing with the stack and not expecting a struct 
> pt_regs to have
> been put on it?

Justin Madru