inconsistent sigtramp code in mips target

inconsistent sigtramp code in mips target

[Kevin Nomura]

gdb 6.0, file gdb/mips-tdep.c, function mips_find_saved_regs:

There are calls to "set_reg_offset" in a loop, followed by
some individual calls after the loop.  The latter have
no effect if the register was processed in the loop
(see the code for set_reg_offset).  SP_REGNUM is like this,
but PC_REGNUM is not, because of the particular values of
these constants (ugh).


  if ((get_frame_type (fci) == SIGTRAMP_FRAME))
    {
      for (ireg = 0; ireg < MIPS_NUMREGS; ireg++)
        {
          CORE_ADDR reg_position = (get_frame_base (fci) + SIGFRAME_REGSAVE_OFF
                                    + ireg * SIGFRAME_REG_SIZE);
          set_reg_offset (saved_regs, ireg, reg_position);
        }
      for (ireg = 0; ireg < MIPS_NUMREGS; ireg++)
        {
          CORE_ADDR reg_position = (get_frame_base (fci)
                                    + SIGFRAME_FPREGSAVE_OFF
                                    + ireg * SIGFRAME_REG_SIZE);
          set_reg_offset (saved_regs, FP0_REGNUM + ireg, reg_position);
        }

      set_reg_offset (saved_regs, PC_REGNUM, get_frame_base (fci) + SIGFRAME_PC_OFF);
      /* SP_REGNUM, contains the value and not the address.  */
      set_reg_offset (saved_regs, SP_REGNUM, get_frame_base (fci));
      return;
    }


The logical patch would be to move the special cases up front,
but I have no way to test this out (no access to a MIPS UNIX
platform).

On the other hand this isn't purely academic.  I came across this
because I need to define a custom sigtramp frame for our own
MIPS embedded platform.  It was baffling for a while that my
modification to the SP_REGNUM override had no effect.

Re: inconsistent sigtramp code in mips target

[Andrew Cagney]

> The logical patch would be to move the special cases up front,
> but I have no way to test this out (no access to a MIPS UNIX
> platform).
> 
> On the other hand this isn't purely academic.  I came across this
> because I need to define a custom sigtramp frame for our own
> MIPS embedded platform.  It was baffling for a while that my
> modification to the SP_REGNUM override had no effect.

Rather than the MIPS, check the x86 family for how to add a custom 
sigtramp handler (ex, i386_sigtramp_frame_sniffer).  Hopefully the new 
mechanism is less baffling - the current MIPS code is not a good reference.

Andrew

Re: inconsistent sigtramp code in mips target

[Daniel Jacobowitz]

On Wed, Oct 29, 2003 at 05:27:40PM -0500, Andrew Cagney wrote:
> >The logical patch would be to move the special cases up front,
> >but I have no way to test this out (no access to a MIPS UNIX
> >platform).
> >
> >On the other hand this isn't purely academic.  I came across this
> >because I need to define a custom sigtramp frame for our own
> >MIPS embedded platform.  It was baffling for a while that my
> >modification to the SP_REGNUM override had no effect.
> 
> Rather than the MIPS, check the x86 family for how to add a custom 
> sigtramp handler (ex, i386_sigtramp_frame_sniffer).  Hopefully the new 
> mechanism is less baffling - the current MIPS code is not a good reference.

But since he's got a MIPS target, the frame sniffers won't help him at
all, will they?  They can't be used until the MIPS is converted.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

Re: inconsistent sigtramp code in mips target

[Kevin Nomura]

On Wed, Oct 29, 2003 at 05:30:01PM -0500, Daniel Jacobowitz wrote:
> On Wed, Oct 29, 2003 at 05:27:40PM -0500, Andrew Cagney wrote:
> > >The logical patch would be to move the special cases up front,
> > >but I have no way to test this out (no access to a MIPS UNIX
> > >platform).
> > >
> > >On the other hand this isn't purely academic.  I came across this
> > >because I need to define a custom sigtramp frame for our own
> > >MIPS embedded platform.  It was baffling for a while that my
> > >modification to the SP_REGNUM override had no effect.
> > 
> > Rather than the MIPS, check the x86 family for how to add a custom 
> > sigtramp handler (ex, i386_sigtramp_frame_sniffer).  Hopefully the new 
> > mechanism is less baffling - the current MIPS code is not a good reference.
> 
> But since he's got a MIPS target, the frame sniffers won't help him at
> all, will they?  They can't be used until the MIPS is converted.

Right.  I used the new framework for i386, and am puzzling it out
for Alpha.  MIPS is a horse of a different colour and required
breaking encapsulation entirely by hacking 
frame.c:deprecated_update_frame_base_hack() in addition to the
above.

Re: inconsistent sigtramp code in mips target

[Andrew Cagney]

> On Wed, Oct 29, 2003 at 05:27:40PM -0500, Andrew Cagney wrote:
> 
>> >The logical patch would be to move the special cases up front,
>> >but I have no way to test this out (no access to a MIPS UNIX
>> >platform).
>> >
>> >On the other hand this isn't purely academic.  I came across this
>> >because I need to define a custom sigtramp frame for our own
>> >MIPS embedded platform.  It was baffling for a while that my
>> >modification to the SP_REGNUM override had no effect.
> 
>> 
>> Rather than the MIPS, check the x86 family for how to add a custom 
>> sigtramp handler (ex, i386_sigtramp_frame_sniffer).  Hopefully the new 
>> mechanism is less baffling - the current MIPS code is not a good reference.
> 
> 
> But since he's got a MIPS target, the frame sniffers won't help him at
> all, will they?  They can't be used until the MIPS is converted.

Looks like Kevin may have drawn the short straw.

Andrew