[Crash-utility] [PATCH] ppc64: rework bt command

[Dave Anderson]

Hi Hari,

Can you check the original bugzilla w/respect to a task running
in user space when the crash occurs?

Thanks,
  Dave


----- Original Message -----
> 
> 
> ----- Original Message -----
> > Commit 3db3d3992d78 was aimed at making 'bt' work for dumpfiles saved
> > with fadump but it introduced a bit of unwarranted complexity in 'bt'
> > command processing. Rework 'bt' command processing for PPC64 arch to
> > make it a little less compilated and also, print symbols for NIP and
> > LR registers on exception frames.
> > 
> > Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
> 
> Thanks, Hari.  As we discussed in the related bugzilla, this looks good.
> Queued for crash-7.2.4:
> 
>   https://github.com/crash-utility/crash/commit/5fe78861ea1589084f6a2956a6ff63677c9269e1
> 
> Dave
> 
> 
>   
> > ---
> >  ppc64.c |  140
> >  +++++++++++++++++++++++++++++++++++++++++++++------------------
> >  1 file changed, 99 insertions(+), 41 deletions(-)
> > 
> > diff --git a/ppc64.c b/ppc64.c
> > index f5d0dac..03fecd3 100644
> > --- a/ppc64.c
> > +++ b/ppc64.c
> > @@ -2093,15 +2093,10 @@ ppc64_print_stack_entry(int frame,
> >  					lr);
> >  				return;
> >  			}
> > -			if (req->pc != lr) {
> > -				fprintf(fp, "\n%s[Link Register] ",
> > -					frame < 10 ? " " : "");
> > -				fprintf(fp, "[%lx] %s at %lx",
> > -					req->sp, lrname, lr);
> > -			}
> >  			req->ra = lr;
> >  		}
> > -		if (!req->name || STREQ(req->name,lrname))
> > +		if (!req->name || STREQ(req->name, lrname) ||
> > +		    !is_kernel_text(req->pc))
> >  			fprintf(fp, "  (unreliable)");
> >  		
> >  		fprintf(fp, "\n");
> > @@ -2219,6 +2214,22 @@ ppc64_print_regs(struct ppc64_pt_regs *regs)
> >          fprintf(fp, "    Syscall Result: %016lx\n", regs->result);
> >  }
> >  
> > +static void ppc64_print_nip_lr(struct ppc64_pt_regs *regs, int print_lr)
> > +{
> > +	char buf[BUFSIZE];
> > +	char *sym_buf;
> > +
> > +	sym_buf = value_to_symstr(regs->nip, buf, 0);
> > +	if (sym_buf[0] != NULLCHAR)
> > +		fprintf(fp, " [NIP  : %s]\n", sym_buf);
> > +
> > +	if (print_lr) {
> > +		sym_buf = value_to_symstr(regs->link, buf, 0);
> > +		if (sym_buf[0] != NULLCHAR)
> > +			fprintf(fp, " [LR   : %s]\n", sym_buf);
> > +	}
> > +}
> > +
> >  /*
> >   * Print the exception frame information
> >   */
> > @@ -2231,6 +2242,59 @@ ppc64_print_eframe(char *efrm_str, struct
> > ppc64_pt_regs *regs,
> >  
> >  	fprintf(fp, " %s [%lx] exception frame:\n", efrm_str, regs->trap);
> >  	ppc64_print_regs(regs);
> > +	ppc64_print_nip_lr(regs, 1);
> > +}
> > +
> > +/*
> > + * For vmcore typically saved with KDump or FADump, get SP and IP values
> > + * from the saved ptregs.
> > + */
> > +static int
> > +ppc64_vmcore_stack_frame(struct bt_info *bt_in, ulong *nip, ulong *ksp)
> > +{
> > +	struct ppc64_pt_regs *pt_regs;
> > +	unsigned long unip;
> > +
> > +	pt_regs = (struct ppc64_pt_regs *)bt_in->machdep;
> > +	if (!pt_regs || !pt_regs->gpr[1]) {
> > +		/*
> > +		 * Not collected regs. May be the corresponding CPU not
> > +		 * responded to an IPI in case of KDump OR f/w has not
> > +		 * not provided the register info in case of FADump.
> > +		 */
> > +		fprintf(fp, "%0lx: GPR1 register value (SP) was not saved\n",
> > +			bt_in->task);
> > +		return FALSE;
> > +	}
> > +	*ksp = pt_regs->gpr[1];
> > +	if (IS_KVADDR(*ksp)) {
> > +		readmem(*ksp+16, KVADDR, &unip, sizeof(ulong), "Regs NIP value",
> > +			FAULT_ON_ERROR);
> > +		*nip = unip;
> > +	} else {
> > +		if (IN_TASK_VMA(bt_in->task, *ksp))
> > +			fprintf(fp, "%0lx: Task is running in user space\n",
> > +				bt_in->task);
> > +		else
> > +			fprintf(fp, "%0lx: Invalid Stack Pointer %0lx\n",
> > +				bt_in->task, *ksp);
> > +		*nip = pt_regs->nip;
> > +	}
> > +
> > +	if (bt_in->flags &&
> > +	((BT_TEXT_SYMBOLS|BT_TEXT_SYMBOLS_PRINT|BT_TEXT_SYMBOLS_NOPRINT)))
> > +		return TRUE;
> > +
> > +	/*
> > +	 * Print the collected regs for the active task
> > +	 */
> > +	ppc64_print_regs(pt_regs);
> > +	if (!IS_KVADDR(*ksp))
> > +		return FALSE;
> > +
> > +	ppc64_print_nip_lr(pt_regs, (unip != pt_regs->link) ? 1 : 0);
> > +
> > +	return TRUE;
> >  }
> >  
> >  /*
> > @@ -2239,7 +2303,7 @@ ppc64_print_eframe(char *efrm_str, struct
> > ppc64_pt_regs
> > *regs,
> >  static int
> >  ppc64_get_dumpfile_stack_frame(struct bt_info *bt_in, ulong *nip, ulong
> >  *ksp)
> >  {
> > -	int i;
> > +	int i, ret, panic_task;
> >  	char *sym;
> >  	ulong *up;
> >  	struct bt_info bt_local, *bt;
> > @@ -2251,11 +2315,29 @@ ppc64_get_dumpfile_stack_frame(struct bt_info
> > *bt_in,
> > ulong *nip, ulong *ksp)
> >  	struct ppc64_pt_regs *pt_regs;
> >  	struct syment *sp;
> >  
> > -        bt = &bt_local;
> > -        BCOPY(bt_in, bt, sizeof(struct bt_info));
> > -        ms = machdep->machspec;
> > +	bt = &bt_local;
> > +	BCOPY(bt_in, bt, sizeof(struct bt_info));
> > +	ms = machdep->machspec;
> > +	ur_nip = ur_ksp = 0;
> > +
> > +	panic_task = tt->panic_task == bt->task ? TRUE : FALSE;
> >  
> >  	check_hardirq = check_softirq = tt->flags & IRQSTACKS ? TRUE : FALSE;
> > +	if (panic_task && bt->machdep) {
> > +		pt_regs = (struct ppc64_pt_regs *)bt->machdep;
> > +		ur_nip = pt_regs->nip;
> > +		ur_ksp = pt_regs->gpr[1];
> > +	} else if ((pc->flags & KDUMP) ||
> > +		   ((pc->flags & DISKDUMP) &&
> > +		    (*diskdump_flags & KDUMP_CMPRS_LOCAL))) {
> > +		/*
> > +		 * For the KDump or FADump vmcore, use SP and IP values
> > +		 * that are saved in ptregs.
> > +		 */
> > +		ret = ppc64_vmcore_stack_frame(bt_in, nip, ksp);
> > +		if (ret)
> > +			return TRUE;
> > +	}
> >  
> >  	if (bt->task != tt->panic_task) {
> >  		char cpu_frozen = FALSE;
> > @@ -2385,38 +2467,14 @@ retry:
> >  		check_intrstack = FALSE;
> >  		goto retry;
> >  	}
> > -
> >  	/*
> > -	 * We didn't find what we were looking for, so try to use
> > -	 * the SP and IP values saved in ptregs.
> > +	 *  We didn't find what we were looking for, so just use what was
> > +	 *  passed in the ELF header.
> >  	 */
> > -	pt_regs = (struct ppc64_pt_regs *)bt_in->machdep;
> > -	if (!pt_regs || !pt_regs->gpr[1]) {
> > -		/*
> > -		 * Not collected regs. May be the corresponding CPU did not
> > -		 * respond to an IPI.
> > -		 */
> > -		if (CRASHDEBUG(1))
> > -			fprintf(fp, "%0lx: GPR1(SP) register value not saved\n",
> > -				bt_in->task);
> > -	} else {
> > -		*ksp = pt_regs->gpr[1];
> > -		if (IS_KVADDR(*ksp)) {
> > -			readmem(*ksp+16, KVADDR, nip, sizeof(ulong),
> > -				"Regs NIP value", FAULT_ON_ERROR);
> > -			ppc64_print_regs(pt_regs);
> > -			return TRUE;
> > -		} else {
> > -			if (IN_TASK_VMA(bt_in->task, *ksp))
> > -				fprintf(fp, "%0lx: Task is running in user space\n",
> > -					bt_in->task);
> > -			else
> > -				fprintf(fp, "%0lx: Invalid Stack Pointer %0lx\n",
> > -					bt_in->task, *ksp);
> > -			*nip = pt_regs->nip;
> > -			ppc64_print_regs(pt_regs);
> > -			return FALSE;
> > -		}
> > +	if (ur_nip && ur_ksp) {
> > +		*nip = ur_nip;
> > +		*ksp = ur_ksp;
> > +		return TRUE;
> >  	}
> >  
> >          console("ppc64_get_dumpfile_stack_frame: cannot find SP for panic
> >          task\n");
> > 
> > 
>