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 kdb_trap_printk++; 25 26 if (!addr && kdb_task_has_cpu(p)) { 27 int old_lvl = console_loglevel; 28 29 console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; 30 kdb_dump_stack_on_cpu(kdb_process_cpu(p)); 31 console_loglevel = old_lvl; 32 } else { 33 show_stack(p, addr, KERN_EMERG); 34 } 35 36 kdb_trap_printk--; 37 } 38 39 /* 40 * kdb_bt 41 * 42 * This function implements the 'bt' command. Print a stack 43 * traceback. 44 * 45 * bt [<address-expression>] (addr-exp is for alternate stacks) 46 * btp <pid> Kernel stack for <pid> 47 * btt <address-expression> Kernel stack for task structure at 48 * <address-expression> 49 * bta [state_chars>|A] All useful processes, optionally 50 * filtered by state 51 * btc [<cpu>] The current process on one cpu, 52 * default is all cpus 53 * 54 * bt <address-expression> refers to a address on the stack, that location 55 * is assumed to contain a return address. 56 * 57 * btt <address-expression> refers to the address of a struct task. 58 * 59 * Inputs: 60 * argc argument count 61 * argv argument vector 62 * Outputs: 63 * None. 64 * Returns: 65 * zero for success, a kdb diagnostic if error 66 * Locking: 67 * none. 68 * Remarks: 69 * Backtrack works best when the code uses frame pointers. But even 70 * without frame pointers we should get a reasonable trace. 71 * 72 * mds comes in handy when examining the stack to do a manual traceback or 73 * to get a starting point for bt <address-expression>. 74 */ 75 76 static int 77 kdb_bt1(struct task_struct *p, const char *mask, bool btaprompt) 78 { 79 char ch; 80 81 if (kdb_getarea(ch, (unsigned long)p) || 82 kdb_getarea(ch, (unsigned long)(p+1)-1)) 83 return KDB_BADADDR; 84 if (!kdb_task_state(p, mask)) 85 return 0; 86 kdb_printf("Stack traceback for pid %d\n", p->pid); 87 kdb_ps1(p); 88 kdb_show_stack(p, NULL); 89 if (btaprompt) { 90 kdb_printf("Enter <q> to end, <cr> or <space> to continue:"); 91 do { 92 ch = kdb_getchar(); 93 } while (!strchr("\r\n q", ch)); 94 kdb_printf("\n"); 95 96 /* reset the pager */ 97 kdb_nextline = 1; 98 99 if (ch == 'q') 100 return 1; 101 } 102 touch_nmi_watchdog(); 103 return 0; 104 } 105 106 static void 107 kdb_bt_cpu(unsigned long cpu) 108 { 109 struct task_struct *kdb_tsk; 110 111 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 112 kdb_printf("WARNING: no process for cpu %ld\n", cpu); 113 return; 114 } 115 116 /* If a CPU failed to round up we could be here */ 117 kdb_tsk = KDB_TSK(cpu); 118 if (!kdb_tsk) { 119 kdb_printf("WARNING: no task for cpu %ld\n", cpu); 120 return; 121 } 122 123 kdb_bt1(kdb_tsk, "A", 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 const char *mask = argc ? argv[1] : kdbgetenv("PS"); 142 143 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 for_each_process_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 } 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 return kdb_bt1(p, "A", false); 171 kdb_printf("No process with pid == %ld found\n", pid); 172 return 0; 173 } else if (strcmp(argv[0], "btt") == 0) { 174 if (argc != 1) 175 return KDB_ARGCOUNT; 176 diag = kdbgetularg((char *)argv[1], &addr); 177 if (diag) 178 return diag; 179 return kdb_bt1((struct task_struct *)addr, "A", false); 180 } else if (strcmp(argv[0], "btc") == 0) { 181 unsigned long cpu = ~0; 182 if (argc > 1) 183 return KDB_ARGCOUNT; 184 if (argc == 1) { 185 diag = kdbgetularg((char *)argv[1], &cpu); 186 if (diag) 187 return diag; 188 } 189 if (cpu != ~0) { 190 kdb_bt_cpu(cpu); 191 } else { 192 /* 193 * Recursive use of kdb_parse, do not use argv after 194 * this point. 195 */ 196 argv = NULL; 197 kdb_printf("btc: cpu status: "); 198 kdb_parse("cpu\n"); 199 for_each_online_cpu(cpu) { 200 kdb_bt_cpu(cpu); 201 touch_nmi_watchdog(); 202 } 203 } 204 return 0; 205 } else { 206 if (argc) { 207 nextarg = 1; 208 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 209 &offset, NULL); 210 if (diag) 211 return diag; 212 kdb_show_stack(kdb_current_task, (void *)addr); 213 return 0; 214 } else { 215 return kdb_bt1(kdb_current_task, "A", false); 216 } 217 } 218 219 /* NOTREACHED */ 220 return 0; 221 } 222