Re: [Patches] [patch] Fix for debug/tst-backtrace{5, 6} failure of 32-bit libc on 64-bit host

[Paul Pluzhnikov <ppluzhnikov@xxxxxxxxxx>]

On Mon, Feb 20, 2012 at 1:43 PM, Paul Pluzhnikov <ppluzhnikov@xxxxxxxxxx> wrote:

> debug/tst-backtrace6:
>
> Obtained backtrace with 7 functions
> Function 0: /build32/debug/tst-backtrace6(handle_signal+0x1a) [0x804910a]
> Function 1: linux-gate.so.1(__kernel_sigreturn+0) [0x55579400]
> Function 2: /build32/debug/tst-backtrace6(noreturn_func+0) [0x80493e0]
> Function 3: /build32/debug/tst-backtrace6() [0x80494d2]
> Function 4: /build32/debug/tst-backtrace6(fn+0x2a) [0x804941a]
> Function 5: /build32/debug/tst-backtrace6(fn+0x2a) [0x804941a]
> Function 6: /build32/debug/tst-backtrace6() [0x80494ef]
> Failure on line 96
>
> This failure is due to GCC laying out fn code like so:
>
>
> (gdb) x/3i 0x080494c8
>   0x80494c8 <fn+216>:  call   0x8048dcc <_exit@plt>
>   0x80494cd <fn+221>:  call   0x80493e0 <noreturn_func>
>   0x80494d2:   lea    0x0(%esi,%eiz,1),%esi                <<< no name "padding"

I see that Joseph already saw this failure:

Subject: Re: [Patches] Add more backtrace tests
From: "Joseph S. Myers" <joseph@xxxxxxxxxxxxxxxx>
Date: Thu, 8 Dec 2011 23:03:44 +0000 (UTC)

JSM> This one does fail for x86_64 (with GCC 4.6), unlike the previous ones; it
JSM> looks like it may be a real problem with the unwind info there.

I believe my diagnosis is correct, and unwind info is not the problem here
(at least for my version of gcc-4.7).

Thanks,
-- 
Paul Pluzhnikov
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