// 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 intkdb_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 voidkdb_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);} intkdb_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;}