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Re: [RFA] Testing REGISTER_NAME in mips-linux-nat.c
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.
Index: mips-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-linux-nat.c,v
retrieving revision 1.4
diff -u -p -r1.4 mips-linux-nat.c
--- mips-linux-nat.c 30 Oct 2002 04:10:06 -0000 1.4
+++ mips-linux-nat.c 28 Jun 2003 18:34:04 -0000
@@ -1,6 +1,6 @@
/* Native-dependent code for GNU/Linux on MIPS processors.
- Copyright 2001, 2002 Free Software Foundation, Inc.
+ Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of GDB.
@@ -29,31 +29,42 @@
int
mips_linux_cannot_fetch_register (int regno)
{
- if (REGISTER_NAME (regno)[0] == 0)
- return 1;
- if (regno == PS_REGNUM)
- return 1;
- else if (regno == ZERO_REGNUM)
- return 1;
- else
+ if (regno > ZERO_REGNUM && regno < ZERO_REGNUM + 32)
return 0;
+ else if (regno >= FP0_REGNUM && regno <= FP0_REGNUM + 32)
+ return 0;
+
+ switch (regno)
+ {
+ case LO_REGNUM:
+ case HI_REGNUM:
+ case BADVADDR_REGNUM:
+ case CAUSE_REGNUM:
+ case PC_REGNUM:
+ case FCRCS_REGNUM:
+ case FCRIR_REGNUM:
+ return 0;
+ }
+
+ return 1;
}
int
mips_linux_cannot_store_register (int regno)
{
- if (REGISTER_NAME (regno)[0] == 0)
- return 1;
- if (regno == PS_REGNUM)
- return 1;
- else if (regno == ZERO_REGNUM)
- return 1;
- else if (regno == BADVADDR_REGNUM)
- return 1;
- else if (regno == CAUSE_REGNUM)
- return 1;
- else if (regno == FCRIR_REGNUM)
- return 1;
- else
+ if (regno > ZERO_REGNUM && regno < ZERO_REGNUM + 32)
return 0;
+ else if (regno >= FP0_REGNUM && regno <= FP0_REGNUM + 32)
+ return 0;
+
+ switch (regno)
+ {
+ case LO_REGNUM:
+ case HI_REGNUM:
+ case PC_REGNUM:
+ case FCRCS_REGNUM:
+ return 0;
+ }
+
+ return 1;
}