[RFA] Testing REGISTER_NAME in mips-linux-nat.c
Daniel Jacobowitz
drow@mvista.com
Mon Jul 7 18:09:00 GMT 2003
On Sat, Jun 28, 2003 at 02:36:31PM -0400, Daniel Jacobowitz wrote:
> On Fri, Jun 27, 2003 at 03:31:18PM -0400, Andrew Cagney wrote:
> > >A recent change to mips_register_name to return a empty string for
> > >register numbers < NUM_REGS is causing problems with the native mips
> > >linux port. The change in mips_register_name is:
> >
> > Arrgh, they keep turning up :-(
> >
> > > + /* Map [NUM_REGS .. 2*NUM_REGS) onto the raw registers, but then
> > > + don't make the raw register names visible. */
> > > + int rawnum = regno % NUM_REGS;
> > > + if (regno < NUM_REGS)
> > > + return "";
> > >
> > >Now for example when mips_linux_cannot_fetch_register() is called with
> > >regno == PC_REGNUM, it will return 1 and reading of the PC will return
> > >zero as the PC value.
> > >
> > >I think this is the correct patch, but I'm not 100% sure. Perhaps we
> > >can just eliminate the REGISTER_NAME check completely.
> >
> > The assertion:
> >
> > gdb_assert (regno >= 0 && regno < NUM_REGS);
> >
> > holds so, yes, eliminating REGISTER_NAME would make sense.
>
> Take a look at MIPS_REGISTER_NAMES in tm-mips.h, which is the generic
> registers. Note lots of empty (unnamed) entries in there - we can't
> fetch or store those. That's what the check is trying to avoid.
>
> I don't think Fred's patch is right either, because this function
> shouldn't even be called for regno > NUM_REGS, so it just disables the
> check. I think the right thing to do is either (ugh!) to call
> REGISTER_NAME (regno + NUM_REGS), or to switch to an inclusive list of
> available registers. Which is easier, and cleaner.
>
> Fred, my mips-linux box is offline at the moment, so I can't test this.
> Could you try the attached patch and let me know if it works?
>
> I think I'm going to try to get my own breed of automated testing
> going to cover this...
>
> > Hmm, how come this doesn't just use PTRACE_GETREGS?
>
> Because mips-linux doesn't implement that yet.
>
> --
> Daniel Jacobowitz
> MontaVista Software Debian GNU/Linux Developer
>
> 2003-06-28 Daniel Jacobowitz <drow@mvista.com>
>
> * mips-linux-nat.c (mips_linux_cannot_fetch_register)
> (mips_linux_cannot_store_register): List supported instead of
> unsupported registers.
I've checked this in everywhere.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
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