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 console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; 26 kdb_trap_printk++; 27 kdb_set_current_task(p); 28 if (addr) { 29 show_stack((struct task_struct *)p, addr); 30 } else if (kdb_current_regs) { 31 #ifdef CONFIG_X86 32 show_stack(p, &kdb_current_regs->sp); 33 #else 34 show_stack(p, NULL); 35 #endif 36 } else { 37 show_stack(p, NULL); 38 } 39 console_loglevel = old_lvl; 40 kdb_trap_printk--; 41 } 42 43 /* 44 * kdb_bt 45 * 46 * This function implements the 'bt' command. Print a stack 47 * traceback. 48 * 49 * bt [<address-expression>] (addr-exp is for alternate stacks) 50 * btp <pid> Kernel stack for <pid> 51 * btt <address-expression> Kernel stack for task structure at 52 * <address-expression> 53 * bta [DRSTCZEUIMA] All useful processes, optionally 54 * filtered by state 55 * btc [<cpu>] The current process on one cpu, 56 * default is all cpus 57 * 58 * bt <address-expression> refers to a address on the stack, that location 59 * is assumed to contain a return address. 60 * 61 * btt <address-expression> refers to the address of a struct task. 62 * 63 * Inputs: 64 * argc argument count 65 * argv argument vector 66 * Outputs: 67 * None. 68 * Returns: 69 * zero for success, a kdb diagnostic if error 70 * Locking: 71 * none. 72 * Remarks: 73 * Backtrack works best when the code uses frame pointers. But even 74 * without frame pointers we should get a reasonable trace. 75 * 76 * mds comes in handy when examining the stack to do a manual traceback or 77 * to get a starting point for bt <address-expression>. 78 */ 79 80 static int 81 kdb_bt1(struct task_struct *p, unsigned long mask, bool btaprompt) 82 { 83 char buffer[2]; 84 if (kdb_getarea(buffer[0], (unsigned long)p) || 85 kdb_getarea(buffer[0], (unsigned long)(p+1)-1)) 86 return KDB_BADADDR; 87 if (!kdb_task_state(p, mask)) 88 return 0; 89 kdb_printf("Stack traceback for pid %d\n", p->pid); 90 kdb_ps1(p); 91 kdb_show_stack(p, NULL); 92 if (btaprompt) { 93 kdb_getstr(buffer, sizeof(buffer), 94 "Enter <q> to end, <cr> to continue:"); 95 if (buffer[0] == 'q') { 96 kdb_printf("\n"); 97 return 1; 98 } 99 } 100 touch_nmi_watchdog(); 101 return 0; 102 } 103 104 int 105 kdb_bt(int argc, const char **argv) 106 { 107 int diag; 108 int btaprompt = 1; 109 int nextarg; 110 unsigned long addr; 111 long offset; 112 113 /* Prompt after each proc in bta */ 114 kdbgetintenv("BTAPROMPT", &btaprompt); 115 116 if (strcmp(argv[0], "bta") == 0) { 117 struct task_struct *g, *p; 118 unsigned long cpu; 119 unsigned long mask = kdb_task_state_string(argc ? argv[1] : 120 NULL); 121 if (argc == 0) 122 kdb_ps_suppressed(); 123 /* Run the active tasks first */ 124 for_each_online_cpu(cpu) { 125 p = kdb_curr_task(cpu); 126 if (kdb_bt1(p, mask, btaprompt)) 127 return 0; 128 } 129 /* Now the inactive tasks */ 130 kdb_do_each_thread(g, p) { 131 if (KDB_FLAG(CMD_INTERRUPT)) 132 return 0; 133 if (task_curr(p)) 134 continue; 135 if (kdb_bt1(p, mask, btaprompt)) 136 return 0; 137 } kdb_while_each_thread(g, p); 138 } else if (strcmp(argv[0], "btp") == 0) { 139 struct task_struct *p; 140 unsigned long pid; 141 if (argc != 1) 142 return KDB_ARGCOUNT; 143 diag = kdbgetularg((char *)argv[1], &pid); 144 if (diag) 145 return diag; 146 p = find_task_by_pid_ns(pid, &init_pid_ns); 147 if (p) { 148 kdb_set_current_task(p); 149 return kdb_bt1(p, ~0UL, false); 150 } 151 kdb_printf("No process with pid == %ld found\n", pid); 152 return 0; 153 } else if (strcmp(argv[0], "btt") == 0) { 154 if (argc != 1) 155 return KDB_ARGCOUNT; 156 diag = kdbgetularg((char *)argv[1], &addr); 157 if (diag) 158 return diag; 159 kdb_set_current_task((struct task_struct *)addr); 160 return kdb_bt1((struct task_struct *)addr, ~0UL, false); 161 } else if (strcmp(argv[0], "btc") == 0) { 162 unsigned long cpu = ~0; 163 struct task_struct *save_current_task = kdb_current_task; 164 char buf[80]; 165 if (argc > 1) 166 return KDB_ARGCOUNT; 167 if (argc == 1) { 168 diag = kdbgetularg((char *)argv[1], &cpu); 169 if (diag) 170 return diag; 171 } 172 /* Recursive use of kdb_parse, do not use argv after 173 * this point */ 174 argv = NULL; 175 if (cpu != ~0) { 176 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 177 kdb_printf("no process for cpu %ld\n", cpu); 178 return 0; 179 } 180 sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu)); 181 kdb_parse(buf); 182 return 0; 183 } 184 kdb_printf("btc: cpu status: "); 185 kdb_parse("cpu\n"); 186 for_each_online_cpu(cpu) { 187 void *kdb_tsk = KDB_TSK(cpu); 188 189 /* If a CPU failed to round up we could be here */ 190 if (!kdb_tsk) { 191 kdb_printf("WARNING: no task for cpu %ld\n", 192 cpu); 193 continue; 194 } 195 196 sprintf(buf, "btt 0x%px\n", kdb_tsk); 197 kdb_parse(buf); 198 touch_nmi_watchdog(); 199 } 200 kdb_set_current_task(save_current_task); 201 return 0; 202 } else { 203 if (argc) { 204 nextarg = 1; 205 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 206 &offset, NULL); 207 if (diag) 208 return diag; 209 kdb_show_stack(kdb_current_task, (void *)addr); 210 return 0; 211 } else { 212 return kdb_bt1(kdb_current_task, ~0UL, false); 213 } 214 } 215 216 /* NOTREACHED */ 217 return 0; 218 } 219