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, 82 int argcount, int btaprompt) 83 { 84 char buffer[2]; 85 if (kdb_getarea(buffer[0], (unsigned long)p) || 86 kdb_getarea(buffer[0], (unsigned long)(p+1)-1)) 87 return KDB_BADADDR; 88 if (!kdb_task_state(p, mask)) 89 return 0; 90 kdb_printf("Stack traceback for pid %d\n", p->pid); 91 kdb_ps1(p); 92 kdb_show_stack(p, NULL); 93 if (btaprompt) { 94 kdb_getstr(buffer, sizeof(buffer), 95 "Enter <q> to end, <cr> to continue:"); 96 if (buffer[0] == 'q') { 97 kdb_printf("\n"); 98 return 1; 99 } 100 } 101 touch_nmi_watchdog(); 102 return 0; 103 } 104 105 int 106 kdb_bt(int argc, const char **argv) 107 { 108 int diag; 109 int argcount = 5; 110 int btaprompt = 1; 111 int nextarg; 112 unsigned long addr; 113 long offset; 114 115 /* Prompt after each proc in bta */ 116 kdbgetintenv("BTAPROMPT", &btaprompt); 117 118 if (strcmp(argv[0], "bta") == 0) { 119 struct task_struct *g, *p; 120 unsigned long cpu; 121 unsigned long mask = kdb_task_state_string(argc ? argv[1] : 122 NULL); 123 if (argc == 0) 124 kdb_ps_suppressed(); 125 /* Run the active tasks first */ 126 for_each_online_cpu(cpu) { 127 p = kdb_curr_task(cpu); 128 if (kdb_bt1(p, mask, argcount, btaprompt)) 129 return 0; 130 } 131 /* Now the inactive tasks */ 132 kdb_do_each_thread(g, p) { 133 if (KDB_FLAG(CMD_INTERRUPT)) 134 return 0; 135 if (task_curr(p)) 136 continue; 137 if (kdb_bt1(p, mask, argcount, btaprompt)) 138 return 0; 139 } kdb_while_each_thread(g, p); 140 } else if (strcmp(argv[0], "btp") == 0) { 141 struct task_struct *p; 142 unsigned long pid; 143 if (argc != 1) 144 return KDB_ARGCOUNT; 145 diag = kdbgetularg((char *)argv[1], &pid); 146 if (diag) 147 return diag; 148 p = find_task_by_pid_ns(pid, &init_pid_ns); 149 if (p) { 150 kdb_set_current_task(p); 151 return kdb_bt1(p, ~0UL, argcount, 0); 152 } 153 kdb_printf("No process with pid == %ld found\n", pid); 154 return 0; 155 } else if (strcmp(argv[0], "btt") == 0) { 156 if (argc != 1) 157 return KDB_ARGCOUNT; 158 diag = kdbgetularg((char *)argv[1], &addr); 159 if (diag) 160 return diag; 161 kdb_set_current_task((struct task_struct *)addr); 162 return kdb_bt1((struct task_struct *)addr, ~0UL, argcount, 0); 163 } else if (strcmp(argv[0], "btc") == 0) { 164 unsigned long cpu = ~0; 165 struct task_struct *save_current_task = kdb_current_task; 166 char buf[80]; 167 if (argc > 1) 168 return KDB_ARGCOUNT; 169 if (argc == 1) { 170 diag = kdbgetularg((char *)argv[1], &cpu); 171 if (diag) 172 return diag; 173 } 174 /* Recursive use of kdb_parse, do not use argv after 175 * this point */ 176 argv = NULL; 177 if (cpu != ~0) { 178 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) { 179 kdb_printf("no process for cpu %ld\n", cpu); 180 return 0; 181 } 182 sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu)); 183 kdb_parse(buf); 184 return 0; 185 } 186 kdb_printf("btc: cpu status: "); 187 kdb_parse("cpu\n"); 188 for_each_online_cpu(cpu) { 189 sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu)); 190 kdb_parse(buf); 191 touch_nmi_watchdog(); 192 } 193 kdb_set_current_task(save_current_task); 194 return 0; 195 } else { 196 if (argc) { 197 nextarg = 1; 198 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr, 199 &offset, NULL); 200 if (diag) 201 return diag; 202 kdb_show_stack(kdb_current_task, (void *)addr); 203 return 0; 204 } else { 205 return kdb_bt1(kdb_current_task, ~0UL, argcount, 0); 206 } 207 } 208 209 /* NOTREACHED */ 210 return 0; 211 } 212