// SPDX-License-Identifier: GPL-2.0
/*
 * Kernel Debugger Architecture Independent Stack Traceback
 *
 * 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 = 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;
}