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.h> 16 #include <linux/kdb.h> 17 #include <linux/nmi.h> 18 #include "kdb_private.h" 19 20 21 static void kdb_show_stack(struct task_struct *p, void *addr) 22 { 23 int old_lvl = console_loglevel; 24 console_loglevel = 15; 25 kdb_trap_printk++; 26 kdb_set_current_task(p); 27 if (addr) { 28 show_stack((struct task_struct *)p, addr); 29 } else if (kdb_current_regs) { 30 #ifdef CONFIG_X86 31 show_stack(p, &kdb_current_regs->sp); 32 #else 33 show_stack(p, NULL); 34 #endif 35 } else { 36 show_stack(p, NULL); 37 } 38 console_loglevel = old_lvl; 39 kdb_trap_printk--; 40 } 41 42 /* 43 * kdb_bt 44 * 45 * This function implements the 'bt' command. Print a stack 46 * traceback. 47 * 48 * bt [<address-expression>] (addr-exp is for alternate stacks) 49 * btp <pid> Kernel stack for <pid> 50 * btt <address-expression> Kernel stack for task structure at 51 * <address-expression> 52 * bta [DRSTCZEUIMA] All useful processes, optionally 53 * filtered by state 54 * btc [<cpu>] The current process on one cpu, 55 * default is all cpus 56 * 57 * bt <address-expression> refers to a address on the stack, that location 58 * is assumed to contain a return address. 59 * 60 * btt <address-expression> refers to the address of a struct task. 61 * 62 * Inputs: 63 * argc argument count 64 * argv argument vector 65 * Outputs: 66 * None. 67 * Returns: 68 * zero for success, a kdb diagnostic if error 69 * Locking: 70 * none. 71 * Remarks: 72 * Backtrack works best when the code uses frame pointers. But even 73 * without frame pointers we should get a reasonable trace. 74 * 75 * mds comes in handy when examining the stack to do a manual traceback or 76 * to get a starting point for bt <address-expression>. 77 */ 78 79 static int 80 kdb_bt1(struct task_struct *p, unsigned long mask, 81 int argcount, int 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 argcount = 5; 109 int btaprompt = 1; 110 int nextarg; 111 unsigned long addr; 112 long offset; 113 114 /* Prompt after each proc in bta */ 115 kdbgetintenv("BTAPROMPT", &btaprompt); 116 117 if (strcmp(argv[0], "bta") == 0) { 118 struct task_struct *g, *p; 119 unsigned long cpu; 120 unsigned long mask = kdb_task_state_string(argc ? argv[1] : 121 NULL); 122 if (argc == 0) 123 kdb_ps_suppressed(); 124 /* Run the active tasks first */ 125 for_each_online_cpu(cpu) { 126 p = kdb_curr_task(cpu); 127 if (kdb_bt1(p, mask, argcount, btaprompt)) 128 return 0; 129 } 130 /* Now the inactive tasks */ 131 kdb_do_each_thread(g, p) { 132 if (KDB_FLAG(CMD_INTERRUPT)) 133 return 0; 134 if (task_curr(p)) 135 continue; 136 if (kdb_bt1(p, mask, argcount, btaprompt)) 137 return 0; 138 } kdb_while_each_thread(g, p); 139 } else if (strcmp(argv[0], "btp") == 0) { 140 struct task_struct *p; 141 unsigned long pid; 142 if (argc != 1) 143 return KDB_ARGCOUNT; 144 diag = kdbgetularg((char *)argv[1], &pid); 145 if (diag) 146 return diag; 147 p = find_task_by_pid_ns(pid, &init_pid_ns); 148 if (p) { 149 kdb_set_current_task(p); 150 return kdb_bt1(p, ~0UL, argcount, 0); 151 } 152 kdb_printf("No process with pid == %ld found\n", pid); 153 return 0; 154 } else if (strcmp(argv[0], "btt") == 0) { 155 if (argc != 1) 156 return KDB_ARGCOUNT; 157 diag = kdbgetularg((char *)argv[1], &addr); 158 if (diag) 159 return diag; 160 kdb_set_current_task((struct task_struct *)addr); 161 return kdb_bt1((struct task_struct *)addr, ~0UL, argcount, 0); 162 } else if (strcmp(argv[0], "btc") == 0) { 163 unsigned long cpu = ~0; 164 struct task_struct *save_current_task = kdb_current_task; 165 char buf[80]; 166 if (argc > 1) 167 return KDB_ARGCOUNT; 168 if (argc == 1) { 169 diag = kdbgetularg((char *)argv[1], &cpu); 170 if (diag) 171 return diag; 172 } 173 /* Recursive use of kdb_parse, do not use argv after 174 * this point */ 175 argv = NULL; 176 if (cpu != ~0) { 177 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 178 kdb_printf("no process for cpu %ld\n", cpu); 179 return 0; 180 } 181 sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu)); 182 kdb_parse(buf); 183 return 0; 184 } 185 kdb_printf("btc: cpu status: "); 186 kdb_parse("cpu\n"); 187 for_each_online_cpu(cpu) { 188 sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu)); 189 kdb_parse(buf); 190 touch_nmi_watchdog(); 191 } 192 kdb_set_current_task(save_current_task); 193 return 0; 194 } else { 195 if (argc) { 196 nextarg = 1; 197 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 198 &offset, NULL); 199 if (diag) 200 return diag; 201 kdb_show_stack(kdb_current_task, (void *)addr); 202 return 0; 203 } else { 204 return kdb_bt1(kdb_current_task, ~0UL, argcount, 0); 205 } 206 } 207 208 /* NOTREACHED */ 209 return 0; 210 } 211