Re: [PATCH] Fix hppa_linux_sigtramp_frame_unwind_cache

["Randolph Chung" <randolph@tausq.org>]

Hrm, this worries me.

The sigcontext structure looks like this:

struct sigcontext {
    unsigned long sc_flags;
    unsigned long sc_gr[32];
    unsigned long long sc_fr[32];
    unsigned long sc_iasq[2];
    unsigned long sc_iaoq[2];
    unsigned long sc_sar;
};

I am positive that when I wrote this the structure got padded between
sc_gr and sc_fr to keep the unsigned long long at a 8-byte boundary.
If this has changed now that means we've introduced a silent ABI
change....

The SAR stuff looks ok. I'm not very sure about restoring the IPSW either.

randolph


On Sat, Sep 13, 2008 at 4:57 PM, John David Anglin
<dave@hiauly1.hia.nrc.ca> wrote:
> The main fix in this patch is to remove the pad increment of scptr.  As
> far as I know, there is no pad field in the sigcontext struct between the
> general registers and the floating point registers.
>
> I also recorded the PSW and SAR registers.  It might be a mistake to record
> the PSW value, but I believe the SAR register definitely needs to be recorded.
>
> Somewhat tested on hppa-linux but the gdb testsuite crashes 2.6.19.22.
>
> Ok?
>
> Dave
> --
> J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
> National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)
>
> 2008-09-13  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
>
>        * hppa-linux-tdep.c (hppa_linux_sigtramp_frame_unwind_cache): Record
>        HPPA_IPSW_REGNUM and HPPA_SAR_REGNUM values.  Remove pad increment.
>
> Index: hppa-linux-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/hppa-linux-tdep.c,v
> retrieving revision 1.31
> diff -u -3 -p -r1.31 hppa-linux-tdep.c
> --- hppa-linux-tdep.c   21 Aug 2008 13:19:18 -0000      1.31
> +++ hppa-linux-tdep.c   13 Sep 2008 22:51:35 -0000
> @@ -227,7 +229,8 @@ hppa_linux_sigtramp_frame_unwind_cache (
>   /* Skip sc_flags.  */
>   scptr += 4;
>
> -  /* GR[0] is the psw, we don't restore that.  */
> +  /* GR[0] is the psw.  */
> +  info->saved_regs[HPPA_IPSW_REGNUM].addr = scptr;
>   scptr += 4;
>
>   /* General registers.  */
> @@ -237,9 +240,6 @@ hppa_linux_sigtramp_frame_unwind_cache (
>       scptr += 4;
>     }
>
> -  /* Pad.  */
> -  scptr += 4;
> -
>   /* FP regs; FP0-3 are not restored.  */
>   scptr += (8 * 4);
>
> @@ -262,6 +262,9 @@ hppa_linux_sigtramp_frame_unwind_cache (
>   info->saved_regs[HPPA_PCOQ_TAIL_REGNUM].addr = scptr;
>   scptr += 4;
>
> +  info->saved_regs[HPPA_SAR_REGNUM].addr = scptr;
> +  scptr += 4;
> +
>   info->base = get_frame_register_unsigned (this_frame, HPPA_SP_REGNUM);
>
>   return info;
>