labath abandoned this revision.
================
Comment at: source/Plugins/Process/Linux/NativeRegisterContextLinux.cpp:53
@@ -22,2 +52,3 @@
+
NativeRegisterContextLinux::NativeRegisterContextLinux(NativeThreadProtocol
&native_thread,
uint32_t
concrete_frame_idx,
----------------
nitesh.jain wrote:
> labath wrote:
> > jaydeep wrote:
> > > We have tried executing ptrace(NT_PRSTATUS) on MIPS with 3.18. It is able
> > > to detect the arch correctly (64->64 and 64->32). However with 3.10 it
> > > fails with EIO. Is there any fallback method when ptrace(NT_PRSTATUS)
> > > fails?
> > Thanks for checking that out.
> >
> > This makes things a bit tricky. We *could* fallback to the "parse the
> > executable ELF" method of getting the architecture, but that would make
> > this patch a bit pointless, as that is what I am trying to remove in the
> > first place. I suppose we could make the fallback mips-only, but that will
> > not be too ideal either.
> >
> > I don't know about any other fallbacks. It would be interesting to know how
> > strace does that. I've tried looking at strace source code, but I could not
> > make much out of it. Do you know if a single strace binary is capable of
> > correctly tracing both 32- and 64-bit processes? If so, could you try
> > running the following experiment for me:
> > - create a simple c file that does a sleep(1) and exits
> > - compile 32- and 64-bit versions of the executable
> > - execute the following commands:
> > ```
> > strace -o /tmp/32.txt -- strace -o /dev/null -- a.out.32
> > strace -o /tmp/64.txt -- strace -o /dev/null -- a.out.64
> > ```
> >
> > Could you send me the outputs (32.txt, 64.txt). Maybe I'll be able to
> > figure something out from that.
> >
> > If that does not work, I may have to abandon this.
> >
> > thanks.
> // 32 bit ELF
> gcc-4.9 -g -O0 -mabi=64 -mips64r2 simple.c -o a.out.64
>
> // 64 bit ELF
> gcc-4.9 -g -O0 -mabi=32 -mips32r2 simple.c -o a.out.32
>
> // Strace for 32 and 64 bit
> strace -o /tmp/64.txt -- strace -o /dev/null -- ./a.out.64
> strace -o /tmp/32.txt -- strace -o /dev/null -- ./a.out.32
>
>
> // File command output for both file
>
> a.out.64: ELF 64-bit LSB executable, MIPS, MIPS64 rel2 version 1 (SYSV),
> dynamically linked, interpreter /lib64/ld.so.1,
> BuildID[sha1]=6e0f92a8abee292b4b6462d79ec0420a3d8aaad0, for GNU/Linux 2.6.32,
> not stripped
>
> a.out.32: ELF 32-bit LSB executable, MIPS, MIPS32 rel2 version 1, dynamically
> linked, interpreter /lib/ld.so.1, for GNU/Linux 2.6.32,
> BuildID[sha1]=c4e09148526975f777e3e70bec85868616d3ce94, not stripped
>
>
> {F1978053}
>
> {F1978054}
Thank you for helping me investigate this. I've been thinking about it a lot,
and I don't see any other way to get around this limitation at the moment. I
think we'll have to abandon this approach for now.
http://reviews.llvm.org/D20368
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