ppc64: still allow to move on if the emergency stacks info fails to i…

…nitialize

Currently crash will fail and then exit, if the initialization of
the emergency stacks information fails. In real customer environments,
sometimes, a vmcore may be partially damaged, although such vmcores
are rare. For example:

  # ./crash ../3.10.0-1127.18.2.el7.ppc64le/vmcore ../3.10.0-1127.18.2.el7.ppc64le/vmlinux  -s
  crash: invalid kernel virtual address: 38  type: "paca->emergency_sp"
  #

Lets try to keep loading vmcore if such issues happen, so call
the readmem() with the RETURN_ON_ERROR instead of FAULT_ON_ERROR,
which allows the crash move on.

Reported-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>

ppc64.c

@@ -1224,13 +1224,13 @@ ppc64_init_paca_info(void)
 		ulong paca_loc;
 
 		readmem(symbol_value("paca_ptrs"), KVADDR, &paca_loc, sizeof(void *),
-			"paca double pointer", FAULT_ON_ERROR);
+			"paca double pointer", RETURN_ON_ERROR);
 		readmem(paca_loc, KVADDR, paca_ptr, sizeof(void *) * kt->cpus,
-			"paca pointers", FAULT_ON_ERROR);
+			"paca pointers", RETURN_ON_ERROR);
 	} else if (symbol_exists("paca") &&
 		   (get_symbol_type("paca", NULL, NULL) == TYPE_CODE_PTR)) {
 		readmem(symbol_value("paca"), KVADDR, paca_ptr, sizeof(void *) * kt->cpus,
-			"paca pointers", FAULT_ON_ERROR);
+			"paca pointers", RETURN_ON_ERROR);
 	} else {
 		free(paca_ptr);
 		return;
@@ -1245,7 +1245,7 @@ ppc64_init_paca_info(void)
 		for (i = 0; i < kt->cpus; i++)
 			readmem(paca_ptr[i] + offset, KVADDR, &ms->emergency_sp[i],
 				sizeof(void *), "paca->emergency_sp",
-				FAULT_ON_ERROR);
+				RETURN_ON_ERROR);
 	}
 
 	if (MEMBER_EXISTS("paca_struct", "nmi_emergency_sp")) {
@@ -1256,7 +1256,7 @@ ppc64_init_paca_info(void)
 		for (i = 0; i < kt->cpus; i++)
 			readmem(paca_ptr[i] + offset, KVADDR, &ms->nmi_emergency_sp[i],
 				sizeof(void *), "paca->nmi_emergency_sp",
-				FAULT_ON_ERROR);
+				RETURN_ON_ERROR);
 	}
 
 	if (MEMBER_EXISTS("paca_struct", "mc_emergency_sp")) {
@@ -1267,7 +1267,7 @@ ppc64_init_paca_info(void)
 		for (i = 0; i < kt->cpus; i++)
 			readmem(paca_ptr[i] + offset, KVADDR, &ms->mc_emergency_sp[i],
 				sizeof(void *), "paca->mc_emergency_sp",
-				FAULT_ON_ERROR);
+				RETURN_ON_ERROR);
 	}
 
 	free(paca_ptr);
@@ -1947,7 +1947,7 @@ ppc64_in_emergency_stack(int cpu, ulong addr, bool verbose)
 	if (cpu < 0  || cpu >= kt->cpus)
 		return NONE_STACK;
 
-	if (ms->emergency_sp) {
+	if (ms->emergency_sp && IS_KVADDR(ms->emergency_sp[cpu])) {
 		top = ms->emergency_sp[cpu];
 		base =  top - STACKSIZE();
 		if (addr >= base && addr < top) {
@@ -1957,7 +1957,7 @@ ppc64_in_emergency_stack(int cpu, ulong addr, bool verbose)
 		}
 	}
 
-	if (ms->nmi_emergency_sp) {
+	if (ms->nmi_emergency_sp && IS_KVADDR(ms->nmi_emergency_sp[cpu])) {
 		top = ms->nmi_emergency_sp[cpu];
 		base = top - STACKSIZE();
 		if (addr >= base && addr < top) {
@@ -1967,7 +1967,7 @@ ppc64_in_emergency_stack(int cpu, ulong addr, bool verbose)
 		}
 	}
 
-	if (ms->mc_emergency_sp) {
+	if (ms->mc_emergency_sp && IS_KVADDR(ms->mc_emergency_sp[cpu])) {
 		top = ms->mc_emergency_sp[cpu];
 		base =  top - STACKSIZE();
 		if (addr >= base && addr < top) {