ARM prologue parsing support for Thumb-2 instructions?

Ulrich Weigand uweigand@de.ibm.com
Fri Jul 16 17:03:00 GMT 2010


Hello,

in testing GDB on an armv7l-linux-gnueabi board running Ubuntu Maverick
I noticed serious problems with getting backtraces out of system libraries.

Looking into this, it turns out that arm_analyze_prologue appears to have
no support at all for decoding Thumb-2 instructions.  (There is some
support for Thumb-2 in arm_skip_prologue, but not for unwinding.)

Since Thumb-2 is the default code generation option on this system, this 
makes it just about impossible to backtrace out of any code that does not
come with debug information.

Now I was wondering whether I'm missing something here ...  Is this really
just something that's simply missing?  If so, do you know whether anybody
is currently working on adding this support?  Otherwise, I could give it
a try.

Thanks,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com



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