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![Douglas Anderson](/assets/img/avatar_default.png)
[ Upstream commit 162bc7f5af
]
If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL. Let's add a check.
It's wise to also set the task to NULL when leaving the debugger so
that if we fail to round up on a later entry into the debugger we
won't backtrace a stale task.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
220 lines
5.4 KiB
C
220 lines
5.4 KiB
C
/*
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* Kernel Debugger Architecture Independent Stack Traceback
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved.
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* Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
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*/
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#include <linux/ctype.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/debug.h>
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#include <linux/kdb.h>
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#include <linux/nmi.h>
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#include "kdb_private.h"
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static void kdb_show_stack(struct task_struct *p, void *addr)
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{
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int old_lvl = console_loglevel;
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console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
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kdb_trap_printk++;
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kdb_set_current_task(p);
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if (addr) {
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show_stack((struct task_struct *)p, addr);
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} else if (kdb_current_regs) {
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#ifdef CONFIG_X86
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show_stack(p, &kdb_current_regs->sp);
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#else
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show_stack(p, NULL);
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#endif
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} else {
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show_stack(p, NULL);
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}
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console_loglevel = old_lvl;
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kdb_trap_printk--;
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}
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/*
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* kdb_bt
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*
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* This function implements the 'bt' command. Print a stack
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* traceback.
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*
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* bt [<address-expression>] (addr-exp is for alternate stacks)
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* btp <pid> Kernel stack for <pid>
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* btt <address-expression> Kernel stack for task structure at
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* <address-expression>
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* bta [DRSTCZEUIMA] All useful processes, optionally
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* filtered by state
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* btc [<cpu>] The current process on one cpu,
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* default is all cpus
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*
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* bt <address-expression> refers to a address on the stack, that location
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* is assumed to contain a return address.
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*
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* btt <address-expression> refers to the address of a struct task.
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*
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* Inputs:
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* argc argument count
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* argv argument vector
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* Outputs:
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* None.
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* Returns:
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* zero for success, a kdb diagnostic if error
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* Locking:
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* none.
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* Remarks:
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* Backtrack works best when the code uses frame pointers. But even
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* without frame pointers we should get a reasonable trace.
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*
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* mds comes in handy when examining the stack to do a manual traceback or
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* to get a starting point for bt <address-expression>.
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*/
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static int
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kdb_bt1(struct task_struct *p, unsigned long mask,
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int argcount, int btaprompt)
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{
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char buffer[2];
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if (kdb_getarea(buffer[0], (unsigned long)p) ||
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kdb_getarea(buffer[0], (unsigned long)(p+1)-1))
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return KDB_BADADDR;
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if (!kdb_task_state(p, mask))
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return 0;
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kdb_printf("Stack traceback for pid %d\n", p->pid);
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kdb_ps1(p);
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kdb_show_stack(p, NULL);
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if (btaprompt) {
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kdb_getstr(buffer, sizeof(buffer),
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"Enter <q> to end, <cr> to continue:");
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if (buffer[0] == 'q') {
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kdb_printf("\n");
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return 1;
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}
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}
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touch_nmi_watchdog();
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return 0;
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}
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int
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kdb_bt(int argc, const char **argv)
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{
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int diag;
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int argcount = 5;
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int btaprompt = 1;
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int nextarg;
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unsigned long addr;
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long offset;
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/* Prompt after each proc in bta */
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kdbgetintenv("BTAPROMPT", &btaprompt);
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if (strcmp(argv[0], "bta") == 0) {
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struct task_struct *g, *p;
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unsigned long cpu;
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unsigned long mask = kdb_task_state_string(argc ? argv[1] :
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NULL);
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if (argc == 0)
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kdb_ps_suppressed();
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/* Run the active tasks first */
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for_each_online_cpu(cpu) {
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p = kdb_curr_task(cpu);
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if (kdb_bt1(p, mask, argcount, btaprompt))
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return 0;
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}
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/* Now the inactive tasks */
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kdb_do_each_thread(g, p) {
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if (KDB_FLAG(CMD_INTERRUPT))
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return 0;
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if (task_curr(p))
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continue;
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if (kdb_bt1(p, mask, argcount, btaprompt))
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return 0;
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} kdb_while_each_thread(g, p);
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} else if (strcmp(argv[0], "btp") == 0) {
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struct task_struct *p;
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unsigned long pid;
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if (argc != 1)
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return KDB_ARGCOUNT;
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diag = kdbgetularg((char *)argv[1], &pid);
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if (diag)
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return diag;
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p = find_task_by_pid_ns(pid, &init_pid_ns);
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if (p) {
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kdb_set_current_task(p);
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return kdb_bt1(p, ~0UL, argcount, 0);
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}
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kdb_printf("No process with pid == %ld found\n", pid);
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return 0;
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} else if (strcmp(argv[0], "btt") == 0) {
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if (argc != 1)
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return KDB_ARGCOUNT;
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diag = kdbgetularg((char *)argv[1], &addr);
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if (diag)
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return diag;
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kdb_set_current_task((struct task_struct *)addr);
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return kdb_bt1((struct task_struct *)addr, ~0UL, argcount, 0);
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} else if (strcmp(argv[0], "btc") == 0) {
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unsigned long cpu = ~0;
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struct task_struct *save_current_task = kdb_current_task;
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char buf[80];
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if (argc > 1)
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return KDB_ARGCOUNT;
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if (argc == 1) {
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diag = kdbgetularg((char *)argv[1], &cpu);
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if (diag)
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return diag;
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}
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/* Recursive use of kdb_parse, do not use argv after
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* this point */
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argv = NULL;
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if (cpu != ~0) {
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if (cpu >= num_possible_cpus() || !cpu_online(cpu)) {
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kdb_printf("no process for cpu %ld\n", cpu);
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return 0;
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}
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sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
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kdb_parse(buf);
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return 0;
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}
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kdb_printf("btc: cpu status: ");
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kdb_parse("cpu\n");
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for_each_online_cpu(cpu) {
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void *kdb_tsk = KDB_TSK(cpu);
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/* If a CPU failed to round up we could be here */
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if (!kdb_tsk) {
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kdb_printf("WARNING: no task for cpu %ld\n",
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cpu);
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continue;
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}
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sprintf(buf, "btt 0x%px\n", kdb_tsk);
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kdb_parse(buf);
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touch_nmi_watchdog();
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}
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kdb_set_current_task(save_current_task);
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return 0;
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} else {
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if (argc) {
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nextarg = 1;
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diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
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&offset, NULL);
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if (diag)
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return diag;
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kdb_show_stack(kdb_current_task, (void *)addr);
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return 0;
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} else {
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return kdb_bt1(kdb_current_task, ~0UL, argcount, 0);
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}
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}
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/* NOTREACHED */
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return 0;
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}
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