Re: [PATCH 0/4] 'catch syscall' feature

[Michael Snyder <msnyder@vmware.com>]

Hi Sergio,

What source tree or snapshot is your diff taken from?
I tried applying it to current cvs, and got a lot of
failures and fuzzes.

Sérgio Durigan Júnior wrote:
> Hello guys,
> 
> As this is my first "serious" patch to GDB, I'm sure there will be a lot
> of mistakes in it :-). Anyway, I hope this adds something useful to the
> program.
> 
> The purpose of this patch is to implement a new feature in GDB called
> "catch syscall". In this first moment, the feature should look something
> like the 'strace' utility, but less "capable" (it still can't, for
> example, get the syscall arguments and return code - although, the way I
> see, this would be easy to do).
> 
> With this feature, you can start over you GDB and tell it to start
> catching syscalls in the inferior. Whenever a syscall is called (or
> returns), GDB stops and tell you the name of it. You can also ask GDB to
> "filter" the syscalls so that you'll only see calls/returns from that
> specific syscall.
> 
> For now the feature is only implemented for PPC32 and PPC64, but in a
> future not so distant I intend to send patches for x86 and x86_64 too.
> 
> I've tried to organize the code the best way I could, and I've
> extensively used the codes for "catch fork", "catch exec" and "catch
> unload" as an example. I'd be glad if you could give some opinions about
> the way I did it :-).
> 
> I've also splitted the patch into 4 logical "sequences", that are
> organized in this way:
> 
> - First part implements the architecture-independent part of the
> feature.
> - Second part implements the architecture-dependent (PPC32 and PPC64)
> part of the feature.
> - Third part refers to the documentation.
> - Fourth part brings the testcase.
> 
> Unfortunately, if one applies the patch and compiles GDB for PPC64, it
> doesn't work properly. This is due to a bug which we have found that
> makes the inferior segfault when there is a breakpoint inserted at its
> entrypoint (AT_ENTRY). Luis Machado is taking a closer look into this
> issue, so I think he'll have a solution soon :-).
> 
> Special thanks goes to Thiago Bauermann, Luis Machado and Carlos Seo,
> who helped me a lot with my never-ending questions about GDB.
> 
> Regards,
> 
> --
> Sérgio Durigan Júnior
> Linux on Power Toolchain - Software Engineer
> Linux Technology Center - LTC
> IBM Brazil
> 
>