1 /* 2 * Kernel Debugger Architecture Independent Stack Traceback 3 * 4 * This file is subject to the terms and conditions of the GNU General Public 5 * License. See the file "COPYING" in the main directory of this archive 6 * for more details. 7 * 8 * Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved. 9 * Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved. 10 */ 11 12 #include <linux/ctype.h> 13 #include <linux/string.h> 14 #include <linux/kernel.h> 15 #include <linux/sched/signal.h> 16 #include <linux/sched/debug.h> 17 #include <linux/kdb.h> 18 #include <linux/nmi.h> 19 #include "kdb_private.h" 20 21 22 static void kdb_show_stack(struct task_struct *p, void *addr) 23 { 24 int old_lvl = console_loglevel; 25 26 console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; 27 kdb_trap_printk++; 28 29 if (!addr && kdb_task_has_cpu(p)) 30 kdb_dump_stack_on_cpu(kdb_process_cpu(p)); 31 else 32 show_stack(p, addr); 33 34 console_loglevel = old_lvl; 35 kdb_trap_printk--; 36 } 37 38 /* 39 * kdb_bt 40 * 41 * This function implements the 'bt' command. Print a stack 42 * traceback. 43 * 44 * bt [<address-expression>] (addr-exp is for alternate stacks) 45 * btp <pid> Kernel stack for <pid> 46 * btt <address-expression> Kernel stack for task structure at 47 * <address-expression> 48 * bta [DRSTCZEUIMA] All useful processes, optionally 49 * filtered by state 50 * btc [<cpu>] The current process on one cpu, 51 * default is all cpus 52 * 53 * bt <address-expression> refers to a address on the stack, that location 54 * is assumed to contain a return address. 55 * 56 * btt <address-expression> refers to the address of a struct task. 57 * 58 * Inputs: 59 * argc argument count 60 * argv argument vector 61 * Outputs: 62 * None. 63 * Returns: 64 * zero for success, a kdb diagnostic if error 65 * Locking: 66 * none. 67 * Remarks: 68 * Backtrack works best when the code uses frame pointers. But even 69 * without frame pointers we should get a reasonable trace. 70 * 71 * mds comes in handy when examining the stack to do a manual traceback or 72 * to get a starting point for bt <address-expression>. 73 */ 74 75 static int 76 kdb_bt1(struct task_struct *p, unsigned long mask, bool btaprompt) 77 { 78 char buffer[2]; 79 if (kdb_getarea(buffer[0], (unsigned long)p) || 80 kdb_getarea(buffer[0], (unsigned long)(p+1)-1)) 81 return KDB_BADADDR; 82 if (!kdb_task_state(p, mask)) 83 return 0; 84 kdb_printf("Stack traceback for pid %d\n", p->pid); 85 kdb_ps1(p); 86 kdb_show_stack(p, NULL); 87 if (btaprompt) { 88 kdb_getstr(buffer, sizeof(buffer), 89 "Enter <q> to end, <cr> to continue:"); 90 if (buffer[0] == 'q') { 91 kdb_printf("\n"); 92 return 1; 93 } 94 } 95 touch_nmi_watchdog(); 96 return 0; 97 } 98 99 static void 100 kdb_bt_cpu(unsigned long cpu) 101 { 102 struct task_struct *kdb_tsk; 103 104 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 105 kdb_printf("WARNING: no process for cpu %ld\n", cpu); 106 return; 107 } 108 109 /* If a CPU failed to round up we could be here */ 110 kdb_tsk = KDB_TSK(cpu); 111 if (!kdb_tsk) { 112 kdb_printf("WARNING: no task for cpu %ld\n", cpu); 113 return; 114 } 115 116 kdb_set_current_task(kdb_tsk); 117 kdb_bt1(kdb_tsk, ~0UL, false); 118 } 119 120 int 121 kdb_bt(int argc, const char **argv) 122 { 123 int diag; 124 int btaprompt = 1; 125 int nextarg; 126 unsigned long addr; 127 long offset; 128 129 /* Prompt after each proc in bta */ 130 kdbgetintenv("BTAPROMPT", &btaprompt); 131 132 if (strcmp(argv[0], "bta") == 0) { 133 struct task_struct *g, *p; 134 unsigned long cpu; 135 unsigned long mask = kdb_task_state_string(argc ? argv[1] : 136 NULL); 137 if (argc == 0) 138 kdb_ps_suppressed(); 139 /* Run the active tasks first */ 140 for_each_online_cpu(cpu) { 141 p = kdb_curr_task(cpu); 142 if (kdb_bt1(p, mask, btaprompt)) 143 return 0; 144 } 145 /* Now the inactive tasks */ 146 kdb_do_each_thread(g, p) { 147 if (KDB_FLAG(CMD_INTERRUPT)) 148 return 0; 149 if (task_curr(p)) 150 continue; 151 if (kdb_bt1(p, mask, btaprompt)) 152 return 0; 153 } kdb_while_each_thread(g, p); 154 } else if (strcmp(argv[0], "btp") == 0) { 155 struct task_struct *p; 156 unsigned long pid; 157 if (argc != 1) 158 return KDB_ARGCOUNT; 159 diag = kdbgetularg((char *)argv[1], &pid); 160 if (diag) 161 return diag; 162 p = find_task_by_pid_ns(pid, &init_pid_ns); 163 if (p) { 164 kdb_set_current_task(p); 165 return kdb_bt1(p, ~0UL, false); 166 } 167 kdb_printf("No process with pid == %ld found\n", pid); 168 return 0; 169 } else if (strcmp(argv[0], "btt") == 0) { 170 if (argc != 1) 171 return KDB_ARGCOUNT; 172 diag = kdbgetularg((char *)argv[1], &addr); 173 if (diag) 174 return diag; 175 kdb_set_current_task((struct task_struct *)addr); 176 return kdb_bt1((struct task_struct *)addr, ~0UL, false); 177 } else if (strcmp(argv[0], "btc") == 0) { 178 unsigned long cpu = ~0; 179 struct task_struct *save_current_task = kdb_current_task; 180 if (argc > 1) 181 return KDB_ARGCOUNT; 182 if (argc == 1) { 183 diag = kdbgetularg((char *)argv[1], &cpu); 184 if (diag) 185 return diag; 186 } 187 if (cpu != ~0) { 188 kdb_bt_cpu(cpu); 189 } else { 190 /* 191 * Recursive use of kdb_parse, do not use argv after 192 * this point. 193 */ 194 argv = NULL; 195 kdb_printf("btc: cpu status: "); 196 kdb_parse("cpu\n"); 197 for_each_online_cpu(cpu) { 198 kdb_bt_cpu(cpu); 199 touch_nmi_watchdog(); 200 } 201 kdb_set_current_task(save_current_task); 202 } 203 return 0; 204 } else { 205 if (argc) { 206 nextarg = 1; 207 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 208 &offset, NULL); 209 if (diag) 210 return diag; 211 kdb_show_stack(kdb_current_task, (void *)addr); 212 return 0; 213 } else { 214 return kdb_bt1(kdb_current_task, ~0UL, false); 215 } 216 } 217 218 /* NOTREACHED */ 219 return 0; 220 } 221