/*
   * 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 [DRSTCZEUIMA]		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, unsigned long 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
  ", 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
   q", ch));
  		kdb_printf("
  ");
  
  		/* 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
  ", 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
  ", cpu);
  		return;
  	}

  	kdb_bt1(kdb_tsk, ~0UL, 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;
  		unsigned long mask = kdb_task_state_string(argc ? argv[1] :
  							   NULL);
  		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, ~0UL, false);

  		kdb_printf("No process with pid == %ld found
  ", 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, ~0UL, 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
  ");
  			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, ~0UL, false);

  		}
  	}
  
  	/* NOTREACHED */
  	return 0;
  }