[Ltrace-devel] 3 patches for ltrace - fixes "armhf" target

[Petr Machata]

Greg Alexander <ltracedeb at galexander.org> writes:

> Thanks, I got the git tree now.  I am surprised how far ahead of
> debian-unstable it is.

You might want to consider rebasing to 0.7.2 in Debian.  That is fairly
stable version in my opinion, which finally supports threads, fully
understands parameter passing convention, and allows tracing not only
the main binary, but libraries as well.  It doesn't however support ARM.
See below for that.

> The build problem and syscall tracing have both already been fixed. :)

Great, glad to hear that.

> The PTRACE_SINGLESTEP issue remains:
>   26753 couldn't continue when handling __libc_start_main (0x9e88) at 0x9e88

Please take a look at the branch pmachata/arm.  We actually have a full
instruction decoding logic for software singlestepping now, ported from
GDB.

Your idea of trying PTRACE_SINGLESTEP first is appealing.  Some ARM
devices reportedly are capable of hardware singlestepping, but I don't
know if the Linux kernel supports that at all, and if yes, whether
there's a way to detect that you run on such hardware.  Unfortunately we
can't simply try PTRACE_SINGLESTEP, as older kernels did their own
emulation, which was unreliable, and we want to avoid using that.

Thanks,
PM