Re: [PATCH] AArch64 pauth: Fix internal error when target supports extra regs

[Koudai Iwahori <koudai@google.com>]

Hi Luis,

It worked, thank you!
I'm using OpenOCD. OpenOCD provides registers like ELR_EL1.



On Tue, Oct 4, 2022 at 5:27 PM Luis Machado <luis.machado@arm.com> wrote:

> Hi,
>
> This should be addressed by
> https://sourceware.org/pipermail/gdb-patches/2022-October/192272.html.
>
> Could you please give it a try? It was pushed yesterday.
>
> Out of curiosity, are you using user-mode QEMU? You mentioned extra
> registers, and those are usually
> provided by emulators.
>
> On 9/28/22 03:50, Koudai Iwahori via Gdb-patches wrote:
> > GDB crashes in aarch64_pseudo_register_type() when target supports pauth
> > and extra registers.
> > When the target supports pauth, GDB keeps a pseudo register `RA_STATE`
> > and aarch64_gdbarch_tdep::ra_sign_state_regnum has the integer index of
> > the register.
> > aarch64_gdbarch_tdep::ra_sign_state_regnum is initialized to
> > (# of reg) + (# of pseudo reg) right after GDB checking if the target
> > supports the core/fpu/sve registers.
> > However, the number of registers is updated in tdesc_use_registers() if
> > the target can provide extra registers.
> > In such cases, ra_sign_state_regnum does not have the right value and
> > internal_error() in aarch64_pseudo_register_type() fires.
> > I added ra_sign_state_pseudo_regnum field to aarch64_gdbarch_tdep for
> > storing the pseudo register number and added get_ra_sign_state_regnum
> > member function.
> > ---
> >   gdb/aarch64-tdep.c | 23 ++++++++++++-----------
> >   gdb/aarch64-tdep.h |  8 +++++++-
> >   2 files changed, 19 insertions(+), 12 deletions(-)
> >
> > diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
> > index 7229b53838e..87335ad22ae 100644
> > --- a/gdb/aarch64-tdep.c
> > +++ b/gdb/aarch64-tdep.c
> > @@ -254,7 +254,8 @@ aarch64_frame_unmask_lr (aarch64_gdbarch_tdep *tdep,
> >   {
> >     if (tdep->has_pauth ()
> >         && frame_unwind_register_unsigned (this_frame,
> > -                                      tdep->ra_sign_state_regnum))
> > +                                      tdep->get_ra_sign_state_regnum (
> > +                                             get_frame_arch
> (this_frame))))
> >       {
> >         int cmask_num = AARCH64_PAUTH_CMASK_REGNUM
> (tdep->pauth_reg_base);
> >         CORE_ADDR cmask = frame_unwind_register_unsigned (this_frame,
> cmask_num);
> > @@ -542,7 +543,7 @@ aarch64_analyze_prologue (struct gdbarch *gdbarch,
> >
> >         if (tdep->has_pauth () && cache != nullptr)
> >           {
> > -           int regnum = tdep->ra_sign_state_regnum;
> > +           int regnum = tdep->get_ra_sign_state_regnum (gdbarch);
> >             cache->saved_regs[regnum].set_value (ra_state_val);
> >           }
> >       }
> > @@ -882,7 +883,7 @@ aarch64_analyze_prologue_test (void)
> >
> >         if (tdep->has_pauth ())
> >       {
> > -       int regnum = tdep->ra_sign_state_regnum;
> > +       int regnum = tdep->get_ra_sign_state_regnum (gdbarch);
> >         SELF_CHECK (cache.saved_regs[regnum].is_value ());
> >       }
> >       }
> > @@ -1137,7 +1138,8 @@ aarch64_prologue_prev_register (struct frame_info
> *this_frame,
> >         lr = frame_unwind_register_unsigned (this_frame,
> AARCH64_LR_REGNUM);
> >
> >         if (tdep->has_pauth ()
> > -       && cache->saved_regs[tdep->ra_sign_state_regnum].is_value ())
> > +       && cache->saved_regs[tdep->get_ra_sign_state_regnum (gdbarch)]
> > +             .is_value ())
> >       lr = aarch64_frame_unmask_lr (tdep, this_frame, lr);
> >
> >         return frame_unwind_got_constant (this_frame, prev_regnum, lr);
> > @@ -1344,7 +1346,7 @@ aarch64_dwarf2_frame_init_reg (struct gdbarch
> *gdbarch, int regnum,
> >     /* Init pauth registers.  */
> >     if (tdep->has_pauth ())
> >       {
> > -      if (regnum == tdep->ra_sign_state_regnum)
> > +      if (regnum == tdep->get_ra_sign_state_regnum (gdbarch))
> >       {
> >         /* Initialize RA_STATE to zero.  */
> >         reg->how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
> > @@ -2255,7 +2257,7 @@ aarch64_dwarf_reg_to_regnum (struct gdbarch
> *gdbarch, int reg)
> >     if (tdep->has_pauth ())
> >       {
> >         if (reg == AARCH64_DWARF_RA_SIGN_STATE)
> > -     return tdep->ra_sign_state_regnum;
> > +     return tdep->get_ra_sign_state_regnum (gdbarch);
> >       }
> >
> >     return -1;
> > @@ -2662,7 +2664,7 @@ aarch64_pseudo_register_name (struct gdbarch
> *gdbarch, int regnum)
> >     /* RA_STATE is used for unwinding only.  Do not assign it a name -
> this
> >        prevents it from being read by methods such as
> >        mi_cmd_trace_frame_collected.  */
> > -  if (tdep->has_pauth () && regnum == tdep->ra_sign_state_regnum)
> > +  if (tdep->has_pauth () && p_regnum ==
> tdep->ra_sign_state_pseudo_regnum)
> >       return "";
> >
> >     internal_error (__FILE__, __LINE__,
> > @@ -2698,7 +2700,7 @@ aarch64_pseudo_register_type (struct gdbarch
> *gdbarch, int regnum)
> >         && p_regnum < AARCH64_SVE_V0_REGNUM + AARCH64_V_REGS_NUM)
> >       return aarch64_vnv_type (gdbarch);
> >
> > -  if (tdep->has_pauth () && regnum == tdep->ra_sign_state_regnum)
> > +  if (tdep->has_pauth () && p_regnum ==
> tdep->ra_sign_state_pseudo_regnum)
> >       return builtin_type (gdbarch)->builtin_uint64;
> >
> >     internal_error (__FILE__, __LINE__,
> > @@ -2732,7 +2734,7 @@ aarch64_pseudo_register_reggroup_p (struct gdbarch
> *gdbarch, int regnum,
> >          && p_regnum < AARCH64_SVE_V0_REGNUM + AARCH64_V_REGS_NUM)
> >       return group == all_reggroup || group == vector_reggroup;
> >     /* RA_STATE is used for unwinding only.  Do not assign it to any
> groups.  */
> > -  if (tdep->has_pauth () && regnum == tdep->ra_sign_state_regnum)
> > +  if (tdep->has_pauth () && p_regnum ==
> tdep->ra_sign_state_pseudo_regnum)
> >       return 0;
> >
> >     return group == all_reggroup;
> > @@ -3598,8 +3600,7 @@ aarch64_gdbarch_init (struct gdbarch_info info,
> struct gdbarch_list *arches)
> >     tdep->jb_elt_size = 8;
> >     tdep->vq = vq;
> >     tdep->pauth_reg_base = first_pauth_regnum;
> > -  tdep->ra_sign_state_regnum = (feature_pauth == NULL) ? -1
> > -                             : ra_sign_state_offset + num_regs;
> > +  tdep->ra_sign_state_pseudo_regnum = ra_sign_state_offset;
> >     tdep->mte_reg_base = first_mte_regnum;
> >     tdep->tls_regnum = tls_regnum;
> >
> > diff --git a/gdb/aarch64-tdep.h b/gdb/aarch64-tdep.h
> > index d8513023c37..acb69b2dc40 100644
> > --- a/gdb/aarch64-tdep.h
> > +++ b/gdb/aarch64-tdep.h
> > @@ -94,7 +94,13 @@ struct aarch64_gdbarch_tdep : gdbarch_tdep_base
> >     }
> >
> >     int pauth_reg_base = 0;
> > -  int ra_sign_state_regnum = 0;
> > +  int ra_sign_state_pseudo_regnum = -1;
> > +
> > +  int get_ra_sign_state_regnum (gdbarch *gdbarch) const
> > +  {
> > +    gdb_assert (ra_sign_state_pseudo_regnum >= 0);
> > +    return ra_sign_state_pseudo_regnum + gdbarch_num_regs (gdbarch);
> > +  }
> >
> >     /* Returns true if the target supports pauth.  */
> >     bool has_pauth () const
>
>