----- Original Message -----
> On Fri, Dec 18, 2015 at 11:55:07PM +0100, Andrew Jones wrote:
> > compat user mode prstatus already just works, almost. This missing
> > pieces are that pt_regs->sp and pt_regs->fp are not in their usual
> > locations. We need to pull them out of their architecturally mapped
> > general purpose registers.
> > ---
> > arm64.c | 42 ++++++++++++++++++++++++++++++++++--------
> > 1 file changed, 34 insertions(+), 8 deletions(-)
> >
> > diff --git a/arm64.c b/arm64.c
> > index 183e768498fe8..3a82d20cdd465 100644
> > --- a/arm64.c
> > +++ b/arm64.c
> > @@ -993,6 +993,25 @@ arm64_stackframe_init(void)
> > #define PSR_MODE_EL3h 0x0000000d
> > #define PSR_MODE_MASK 0x0000000f
> >
> > +/* Architecturally defined mapping between AArch32 and AArch64 registers
> > */
> > +#define compat_usr(x) regs[(x)]
> > +#define compat_fp regs[11]
> > +#define compat_sp regs[13]
> > +#define compat_lr regs[14]
> > +
> > +#define user_mode(ptregs) \
> > + (((ptregs)->pstate & PSR_MODE_MASK) == PSR_MODE_EL0t)
> > +
> > +#define compat_user_mode(ptregs) \
> > + (((ptregs)->pstate & (PSR_MODE32_BIT | PSR_MODE_MASK)) == \
> > + (PSR_MODE32_BIT | PSR_MODE_EL0t))
> > +
> > +#define user_stack_pointer(ptregs) \
> > + (!compat_user_mode(ptregs) ? (ptregs)->sp : (ptregs)->compat_sp)
> > +
> > +#define user_frame_pointer(ptregs) \
> > + (!compat_user_mode(ptregs) ? (ptregs)->regs[29] : (ptregs)->compat_fp)
> > +
> > static int
> > arm64_is_kernel_exception_frame(struct bt_info *bt, ulong stkptr)
> > {
> > @@ -1340,21 +1359,28 @@ arm64_get_dumpfile_stackframe(struct bt_info *bt,
> > struct arm64_stackframe *frame
> > struct machine_specific *ms = machdep->machspec;
> > struct arm64_pt_regs *ptregs;
> >
> > - if (!ms->panic_task_regs ||
> > - (!ms->panic_task_regs[bt->tc->processor].sp &&
> > - !ms->panic_task_regs[bt->tc->processor].pc)) {
> > + if (!ms->panic_task_regs || !ms->panic_task_regs[bt->tc->processor].pc)
> > {
>
> Hi Dave,
>
> I'm having second thoughts about keeping the
> !ms->panic_task_regs[bt->tc->processor].pc test. pc being zero sounds
> like a good reason to crash, or a potential status of a pc after a crash.
> I don't think we should be too hasty to reject the rest of the registers.
> Is there anyway we can relax the sanity checking, but still keep the crash
> utility happy?
>
> Thanks,
> drew
Hi Drew,
OK, refresh my mind -- I'm not sure what the reasoning behind the patch snippet
above?
Originally the code checked whether *both* the sp and pc are NULL, and if so,
returns
BT_REGS_NOT_FOUD (which seems fair to me). Your patch stops checking for a
NULL sp, but
still checks for a NULL pc. In this QEMU dump, the patch doesn't really
accomplish anything,
since both incoming registers are non-NULL (albeit with a sp pointing to
16-bytes below the
top of the stack). It seems like we could leave it as-is.
Dave
> > bt->flags |= BT_REGS_NOT_FOUND;
> > return FALSE;
> > }
> >
> > ptregs = &ms->panic_task_regs[bt->tc->processor];
> > - frame->sp = ptregs->sp;
> > frame->pc = ptregs->pc;
> > - frame->fp = ptregs->regs[29];
> > -
> > - if (!is_kernel_text(frame->pc) &&
> > - in_user_stack(bt->tc->task, frame->sp))
> > + if (user_mode(ptregs)) {
> > + frame->sp = user_stack_pointer(ptregs);
> > + frame->fp = user_frame_pointer(ptregs);
> > + if (is_kernel_text(frame->pc) ||
> > + !in_user_stack(bt->tc->task, frame->sp)) {
> > + error(WARNING, "Corrupt prstatus? pstate=0x%lx, but no
> > user frame
> > found\n",
> > +
> > ptregs->pstate);
> > + bt->flags |= BT_REGS_NOT_FOUND;
> > + return FALSE;
> > + }
> > bt->flags |= BT_USER_SPACE;
> > + } else {
> > + frame->sp = ptregs->sp;
> > + frame->fp = ptregs->regs[29];
> > + }
> >
> > if (arm64_in_kdump_text(bt, frame))
> > bt->flags |= BT_KDUMP_ADJUST;
> > --
> > 1.8.3.1
> >
> > --
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> > Crash-utility@redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
>
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