Re: [PATCH] gdbserver gnu/linux: stepping over breakpoint

[Pedro Alves <palves@redhat.com>]

On 04/09/2015 04:06 PM, Yao Qi wrote:
> Pedro Alves <palves@redhat.com> writes:
> 
>> even reached.  The test isn't even threaded.  It sounds like
>> gdbserver is trying to step over the breakpoint at "foo"?  Didn't
>> gdb itself step over it?  How come that was reached in gdbserver?
>> Did we mishandle the breakpoint's reference count in gdbserver?
> 
> Shouldn't GDBserver step over breakpoint when the target side condition
> is false?

Oh, this is stepping past an hardware breakpoint, not software
breakpoint.  Yes, GDBserver should be stepping past such
breakpoints.  But, given GDBserver's software single-step
support is really really really really too simple:

/* We only place breakpoints in empty marker functions, and thread locking
   is outside of the function.  So rather than importing software single-step,
   we can just run until exit.  */
static CORE_ADDR
arm_reinsert_addr (void)
{
  struct regcache *regcache = get_thread_regcache (current_thread, 1);
  unsigned long pc;
  collect_register_by_name (regcache, "lr", &pc);
  return pc;
}

... we should probably disable target side conditions on software
single-step gdbserver ports.  E.g., try "si" through this function:

   void
   function ()
   {
     i = 0;
     i = 0; // set cond breakpoint that evals false here
     i = 0;
   }

I'd guess the "si" over the breakpoint ends in the caller
of "function"...

Thanks,
Pedro Alves