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/*
* Kernel Debugger Architecture Independent Stack Traceback
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved.
* Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
*/
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/kdb.h>
#include <linux/nmi.h>
#include "kdb_private.h"
static void kdb_show_stack(struct task_struct *p, void *addr)
{
kdb_trap_printk++;
if (!addr && kdb_task_has_cpu(p)) {
int old_lvl = console_loglevel;
console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
kdb_dump_stack_on_cpu(kdb_process_cpu(p));
console_loglevel = old_lvl;
} else {
show_stack(p, addr, KERN_EMERG);
}
kdb_trap_printk--;
}
/*
* kdb_bt
*
* This function implements the 'bt' command. Print a stack
* traceback.
*
* bt [<address-expression>] (addr-exp is for alternate stacks)
* btp <pid> Kernel stack for <pid>
* btt <address-expression> Kernel stack for task structure at
* <address-expression>
* bta [state_chars>|A] All useful processes, optionally
* filtered by state
* btc [<cpu>] The current process on one cpu,
* default is all cpus
*
* bt <address-expression> refers to a address on the stack, that location
* is assumed to contain a return address.
*
* btt <address-expression> refers to the address of a struct task.
*
* Inputs:
* argc argument count
* argv argument vector
* Outputs:
* None.
* Returns:
* zero for success, a kdb diagnostic if error
* Locking:
* none.
* Remarks:
* Backtrack works best when the code uses frame pointers. But even
* without frame pointers we should get a reasonable trace.
*
* mds comes in handy when examining the stack to do a manual traceback or
* to get a starting point for bt <address-expression>.
*/
static int
kdb_bt1(struct task_struct *p, const char *mask, bool btaprompt)
{
char ch;
if (kdb_getarea(ch, (unsigned long)p) ||
kdb_getarea(ch, (unsigned long)(p+1)-1))
return KDB_BADADDR;
if (!kdb_task_state(p, mask))
return 0;
kdb_printf("Stack traceback for pid %d\n", p->pid);
kdb_ps1(p);
kdb_show_stack(p, NULL);
if (btaprompt) {
kdb_printf("Enter <q> to end, <cr> or <space> to continue:");
do {
ch = kdb_getchar();
} while (!strchr("\r\n q", ch));
kdb_printf("\n");
/* reset the pager */
kdb_nextline = 1;
if (ch == 'q')
return 1;
}
touch_nmi_watchdog();
return 0;
}
static void
kdb_bt_cpu(unsigned long cpu)
{
struct task_struct *kdb_tsk;
if (cpu >= num_possible_cpus() || !cpu_online(cpu)) {
kdb_printf("WARNING: no process for cpu %ld\n", cpu);
return;
}
/* If a CPU failed to round up we could be here */
kdb_tsk = KDB_TSK(cpu);
if (!kdb_tsk) {
kdb_printf("WARNING: no task for cpu %ld\n", cpu);
return;
}
kdb_bt1(kdb_tsk, "A", false);
}
int
kdb_bt(int argc, const char **argv)
{
int diag;
int btaprompt = 1;
int nextarg;
unsigned long addr;
long offset;
/* Prompt after each proc in bta */
kdbgetintenv("BTAPROMPT", &btaprompt);
if (strcmp(argv[0], "bta") == 0) {
struct task_struct *g, *p;
unsigned long cpu;
const char *mask = argc ? argv[1] : kdbgetenv("PS");
if (argc == 0)
kdb_ps_suppressed();
/* Run the active tasks first */
for_each_online_cpu(cpu) {
p = kdb_curr_task(cpu);
if (kdb_bt1(p, mask, btaprompt))
return 0;
}
/* Now the inactive tasks */
for_each_process_thread(g, p) {
if (KDB_FLAG(CMD_INTERRUPT))
return 0;
if (task_curr(p))
continue;
if (kdb_bt1(p, mask, btaprompt))
return 0;
}
} else if (strcmp(argv[0], "btp") == 0) {
struct task_struct *p;
unsigned long pid;
if (argc != 1)
return KDB_ARGCOUNT;
diag = kdbgetularg((char *)argv[1], &pid);
if (diag)
return diag;
p = find_task_by_pid_ns(pid, &init_pid_ns);
if (p)
return kdb_bt1(p, "A", false);
kdb_printf("No process with pid == %ld found\n", pid);
return 0;
} else if (strcmp(argv[0], "btt") == 0) {
if (argc != 1)
return KDB_ARGCOUNT;
diag = kdbgetularg((char *)argv[1], &addr);
if (diag)
return diag;
return kdb_bt1((struct task_struct *)addr, "A", false);
} else if (strcmp(argv[0], "btc") == 0) {
unsigned long cpu = ~0;
if (argc > 1)
return KDB_ARGCOUNT;
if (argc == 1) {
diag = kdbgetularg((char *)argv[1], &cpu);
if (diag)
return diag;
}
if (cpu != ~0) {
kdb_bt_cpu(cpu);
} else {
/*
* Recursive use of kdb_parse, do not use argv after
* this point.
*/
argv = NULL;
kdb_printf("btc: cpu status: ");
kdb_parse("cpu\n");
for_each_online_cpu(cpu) {
kdb_bt_cpu(cpu);
touch_nmi_watchdog();
}
}
return 0;
} else {
if (argc) {
nextarg = 1;
diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
&offset, NULL);
if (diag)
return diag;
kdb_show_stack(kdb_current_task, (void *)addr);
return 0;
} else {
return kdb_bt1(kdb_current_task, "A", false);
}
}
/* NOTREACHED */
return 0;
}
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