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 ch; 79 80 if (kdb_getarea(ch, (unsigned long)p) || 81 kdb_getarea(ch, (unsigned long)(p+1)-1)) 82 return KDB_BADADDR; 83 if (!kdb_task_state(p, mask)) 84 return 0; 85 kdb_printf("Stack traceback for pid %d\n", p->pid); 86 kdb_ps1(p); 87 kdb_show_stack(p, NULL); 88 if (btaprompt) { 89 kdb_printf("Enter <q> to end, <cr> or <space> to continue:"); 90 do { 91 ch = kdb_getchar(); 92 } while (!strchr("\r\n q", ch)); 93 kdb_printf("\n"); 94 95 /* reset the pager */ 96 kdb_nextline = 1; 97 98 if (ch == 'q') 99 return 1; 100 } 101 touch_nmi_watchdog(); 102 return 0; 103 } 104 105 static void 106 kdb_bt_cpu(unsigned long cpu) 107 { 108 struct task_struct *kdb_tsk; 109 110 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 111 kdb_printf("WARNING: no process for cpu %ld\n", cpu); 112 return; 113 } 114 115 /* If a CPU failed to round up we could be here */ 116 kdb_tsk = KDB_TSK(cpu); 117 if (!kdb_tsk) { 118 kdb_printf("WARNING: no task for cpu %ld\n", cpu); 119 return; 120 } 121 122 kdb_set_current_task(kdb_tsk); 123 kdb_bt1(kdb_tsk, ~0UL, false); 124 } 125 126 int 127 kdb_bt(int argc, const char **argv) 128 { 129 int diag; 130 int btaprompt = 1; 131 int nextarg; 132 unsigned long addr; 133 long offset; 134 135 /* Prompt after each proc in bta */ 136 kdbgetintenv("BTAPROMPT", &btaprompt); 137 138 if (strcmp(argv[0], "bta") == 0) { 139 struct task_struct *g, *p; 140 unsigned long cpu; 141 unsigned long mask = kdb_task_state_string(argc ? argv[1] : 142 NULL); 143 if (argc == 0) 144 kdb_ps_suppressed(); 145 /* Run the active tasks first */ 146 for_each_online_cpu(cpu) { 147 p = kdb_curr_task(cpu); 148 if (kdb_bt1(p, mask, btaprompt)) 149 return 0; 150 } 151 /* Now the inactive tasks */ 152 kdb_do_each_thread(g, p) { 153 if (KDB_FLAG(CMD_INTERRUPT)) 154 return 0; 155 if (task_curr(p)) 156 continue; 157 if (kdb_bt1(p, mask, btaprompt)) 158 return 0; 159 } kdb_while_each_thread(g, p); 160 } else if (strcmp(argv[0], "btp") == 0) { 161 struct task_struct *p; 162 unsigned long pid; 163 if (argc != 1) 164 return KDB_ARGCOUNT; 165 diag = kdbgetularg((char *)argv[1], &pid); 166 if (diag) 167 return diag; 168 p = find_task_by_pid_ns(pid, &init_pid_ns); 169 if (p) { 170 kdb_set_current_task(p); 171 return kdb_bt1(p, ~0UL, false); 172 } 173 kdb_printf("No process with pid == %ld found\n", pid); 174 return 0; 175 } else if (strcmp(argv[0], "btt") == 0) { 176 if (argc != 1) 177 return KDB_ARGCOUNT; 178 diag = kdbgetularg((char *)argv[1], &addr); 179 if (diag) 180 return diag; 181 kdb_set_current_task((struct task_struct *)addr); 182 return kdb_bt1((struct task_struct *)addr, ~0UL, false); 183 } else if (strcmp(argv[0], "btc") == 0) { 184 unsigned long cpu = ~0; 185 struct task_struct *save_current_task = kdb_current_task; 186 if (argc > 1) 187 return KDB_ARGCOUNT; 188 if (argc == 1) { 189 diag = kdbgetularg((char *)argv[1], &cpu); 190 if (diag) 191 return diag; 192 } 193 if (cpu != ~0) { 194 kdb_bt_cpu(cpu); 195 } else { 196 /* 197 * Recursive use of kdb_parse, do not use argv after 198 * this point. 199 */ 200 argv = NULL; 201 kdb_printf("btc: cpu status: "); 202 kdb_parse("cpu\n"); 203 for_each_online_cpu(cpu) { 204 kdb_bt_cpu(cpu); 205 touch_nmi_watchdog(); 206 } 207 kdb_set_current_task(save_current_task); 208 } 209 return 0; 210 } else { 211 if (argc) { 212 nextarg = 1; 213 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 214 &offset, NULL); 215 if (diag) 216 return diag; 217 kdb_show_stack(kdb_current_task, (void *)addr); 218 return 0; 219 } else { 220 return kdb_bt1(kdb_current_task, ~0UL, false); 221 } 222 } 223 224 /* NOTREACHED */ 225 return 0; 226 } 227