2004-10-24 23:01:40

by Daniel Jacobowitz

[permalink] [raw]
Subject: Unwind information fix for the vsyscall DSO

When working on GDB support I found a typo. I assume the comment is
correct. If you step to this particular instruction and backtrace, GDB gets
lost.

I haven't tested the fixed version yet, but I'm pretty confident in this
patch :-) Please apply.

--- arch/i386/kernel/vsyscall-sysenter.S.orig 2004-04-05 21:21:20.000000000 -0400
+++ arch/i386/kernel/vsyscall-sysenter.S 2004-10-24 18:50:54.000000000 -0400
@@ -84,7 +84,7 @@
.byte 0x04 /* DW_CFA_advance_loc4 */
.long .Lpop_ebp-.Lenter_kernel
.byte 0x0e /* DW_CFA_def_cfa_offset */
- .byte 0x12 /* RA at offset 12 now */
+ .byte 0x0c /* RA at offset 12 now */
.byte 0xc5 /* DW_CFA_restore %ebp */
.byte 0x04 /* DW_CFA_advance_loc4 */
.long .Lpop_edx-.Lpop_ebp


--
Daniel Jacobowitz


2004-10-24 23:27:20

by Linus Torvalds

[permalink] [raw]
Subject: Re: Unwind information fix for the vsyscall DSO



On Sun, 24 Oct 2004, Daniel Jacobowitz wrote:
>
> When working on GDB support I found a typo. I assume the comment is
> correct. If you step to this particular instruction and backtrace, GDB gets
> lost.
>
> I haven't tested the fixed version yet, but I'm pretty confident in this
> patch :-) Please apply.

The patch looks obvious, but I'd still like to see a "yeah, I tested it
now, and yes, gdb DTRT after the fix.."

Linus

2004-10-25 02:26:52

by Daniel Jacobowitz

[permalink] [raw]
Subject: Re: Unwind information fix for the vsyscall DSO

On Sun, Oct 24, 2004 at 04:27:13PM -0700, Linus Torvalds wrote:
>
>
> On Sun, 24 Oct 2004, Daniel Jacobowitz wrote:
> >
> > When working on GDB support I found a typo. I assume the comment is
> > correct. If you step to this particular instruction and backtrace, GDB gets
> > lost.
> >
> > I haven't tested the fixed version yet, but I'm pretty confident in this
> > patch :-) Please apply.
>
> The patch looks obvious, but I'd still like to see a "yeah, I tested it
> now, and yes, gdb DTRT after the fix.."

It looks good, but it triggered a related bug in GDB and 2.6.10-rc1
locked up while I was debugging that. I'll get back to you once I can
test it.

--
Daniel Jacobowitz