commit 5fe78861ea1589084f6a2956a6ff63677c9269e1

Author: Dave Anderson <anderson@redhat.com>

Date:   Fri Sep 7 16:05:52 2018 -0400

    Commit 3db3d3992d781c1e42587d2d2bf81e785408e0c2 in crash-7.1.8 was

    aimed at making the PPC64 "bt" command work for dumpfiles saved

    with the FADUMP facility, but it introduced a bit of unwarranted

    complexity in "bt" command processing.  Reworked the "bt" command

    processing for PPC64 arch to make it a little less compilated and

    also to print symbols for NIP and LR registers in exception frames.

    Without the patch, "bt" on non-panic active tasks may fail with

    the message "bt: invalid kernel virtual address: <address>

    type: Regs NIP value".

    (hbathini@linux.ibm.com)

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");