1 /* 2 * Copyright (C) 1991, 1992 Linus Torvalds 3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs 4 */ 5 #include <linux/kallsyms.h> 6 #include <linux/kprobes.h> 7 #include <linux/uaccess.h> 8 #include <linux/hardirq.h> 9 #include <linux/kdebug.h> 10 #include <linux/module.h> 11 #include <linux/ptrace.h> 12 #include <linux/kexec.h> 13 #include <linux/sysfs.h> 14 #include <linux/bug.h> 15 #include <linux/nmi.h> 16 17 #include <asm/stacktrace.h> 18 19 #include "dumpstack.h" 20 21 #define N_EXCEPTION_STACKS_END \ 22 (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2) 23 24 static char x86_stack_ids[][8] = { 25 [ DEBUG_STACK-1 ] = "#DB", 26 [ NMI_STACK-1 ] = "NMI", 27 [ DOUBLEFAULT_STACK-1 ] = "#DF", 28 [ STACKFAULT_STACK-1 ] = "#SS", 29 [ MCE_STACK-1 ] = "#MC", 30 #if DEBUG_STKSZ > EXCEPTION_STKSZ 31 [ N_EXCEPTION_STACKS ... 32 N_EXCEPTION_STACKS_END ] = "#DB[?]" 33 #endif 34 }; 35 36 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack, 37 unsigned *usedp, char **idp) 38 { 39 unsigned k; 40 41 /* 42 * Iterate over all exception stacks, and figure out whether 43 * 'stack' is in one of them: 44 */ 45 for (k = 0; k < N_EXCEPTION_STACKS; k++) { 46 unsigned long end = per_cpu(orig_ist, cpu).ist[k]; 47 /* 48 * Is 'stack' above this exception frame's end? 49 * If yes then skip to the next frame. 50 */ 51 if (stack >= end) 52 continue; 53 /* 54 * Is 'stack' above this exception frame's start address? 55 * If yes then we found the right frame. 56 */ 57 if (stack >= end - EXCEPTION_STKSZ) { 58 /* 59 * Make sure we only iterate through an exception 60 * stack once. If it comes up for the second time 61 * then there's something wrong going on - just 62 * break out and return NULL: 63 */ 64 if (*usedp & (1U << k)) 65 break; 66 *usedp |= 1U << k; 67 *idp = x86_stack_ids[k]; 68 return (unsigned long *)end; 69 } 70 /* 71 * If this is a debug stack, and if it has a larger size than 72 * the usual exception stacks, then 'stack' might still 73 * be within the lower portion of the debug stack: 74 */ 75 #if DEBUG_STKSZ > EXCEPTION_STKSZ 76 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) { 77 unsigned j = N_EXCEPTION_STACKS - 1; 78 79 /* 80 * Black magic. A large debug stack is composed of 81 * multiple exception stack entries, which we 82 * iterate through now. Dont look: 83 */ 84 do { 85 ++j; 86 end -= EXCEPTION_STKSZ; 87 x86_stack_ids[j][4] = '1' + 88 (j - N_EXCEPTION_STACKS); 89 } while (stack < end - EXCEPTION_STKSZ); 90 if (*usedp & (1U << j)) 91 break; 92 *usedp |= 1U << j; 93 *idp = x86_stack_ids[j]; 94 return (unsigned long *)end; 95 } 96 #endif 97 } 98 return NULL; 99 } 100 101 static inline int 102 in_irq_stack(unsigned long *stack, unsigned long *irq_stack, 103 unsigned long *irq_stack_end) 104 { 105 return (stack >= irq_stack && stack < irq_stack_end); 106 } 107 108 /* 109 * We are returning from the irq stack and go to the previous one. 110 * If the previous stack is also in the irq stack, then bp in the first 111 * frame of the irq stack points to the previous, interrupted one. 112 * Otherwise we have another level of indirection: We first save 113 * the bp of the previous stack, then we switch the stack to the irq one 114 * and save a new bp that links to the previous one. 115 * (See save_args()) 116 */ 117 static inline unsigned long 118 fixup_bp_irq_link(unsigned long bp, unsigned long *stack, 119 unsigned long *irq_stack, unsigned long *irq_stack_end) 120 { 121 #ifdef CONFIG_FRAME_POINTER 122 struct stack_frame *frame = (struct stack_frame *)bp; 123 unsigned long next; 124 125 if (!in_irq_stack(stack, irq_stack, irq_stack_end)) { 126 if (!probe_kernel_address(&frame->next_frame, next)) 127 return next; 128 else 129 WARN_ONCE(1, "Perf: bad frame pointer = %p in " 130 "callchain\n", &frame->next_frame); 131 } 132 #endif 133 return bp; 134 } 135 136 /* 137 * x86-64 can have up to three kernel stacks: 138 * process stack 139 * interrupt stack 140 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack 141 */ 142 143 void dump_trace(struct task_struct *task, struct pt_regs *regs, 144 unsigned long *stack, unsigned long bp, 145 const struct stacktrace_ops *ops, void *data) 146 { 147 const unsigned cpu = get_cpu(); 148 unsigned long *irq_stack_end = 149 (unsigned long *)per_cpu(irq_stack_ptr, cpu); 150 unsigned used = 0; 151 struct thread_info *tinfo; 152 int graph = 0; 153 154 if (!task) 155 task = current; 156 157 if (!stack) { 158 unsigned long dummy; 159 stack = &dummy; 160 if (task && task != current) 161 stack = (unsigned long *)task->thread.sp; 162 } 163 164 #ifdef CONFIG_FRAME_POINTER 165 if (!bp) { 166 if (task == current) { 167 /* Grab bp right from our regs */ 168 get_bp(bp); 169 } else { 170 /* bp is the last reg pushed by switch_to */ 171 bp = *(unsigned long *) task->thread.sp; 172 } 173 } 174 #endif 175 176 /* 177 * Print function call entries in all stacks, starting at the 178 * current stack address. If the stacks consist of nested 179 * exceptions 180 */ 181 tinfo = task_thread_info(task); 182 for (;;) { 183 char *id; 184 unsigned long *estack_end; 185 estack_end = in_exception_stack(cpu, (unsigned long)stack, 186 &used, &id); 187 188 if (estack_end) { 189 if (ops->stack(data, id) < 0) 190 break; 191 192 bp = ops->walk_stack(tinfo, stack, bp, ops, 193 data, estack_end, &graph); 194 ops->stack(data, "<EOE>"); 195 /* 196 * We link to the next stack via the 197 * second-to-last pointer (index -2 to end) in the 198 * exception stack: 199 */ 200 stack = (unsigned long *) estack_end[-2]; 201 continue; 202 } 203 if (irq_stack_end) { 204 unsigned long *irq_stack; 205 irq_stack = irq_stack_end - 206 (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack); 207 208 if (in_irq_stack(stack, irq_stack, irq_stack_end)) { 209 if (ops->stack(data, "IRQ") < 0) 210 break; 211 bp = ops->walk_stack(tinfo, stack, bp, 212 ops, data, irq_stack_end, &graph); 213 /* 214 * We link to the next stack (which would be 215 * the process stack normally) the last 216 * pointer (index -1 to end) in the IRQ stack: 217 */ 218 stack = (unsigned long *) (irq_stack_end[-1]); 219 bp = fixup_bp_irq_link(bp, stack, irq_stack, 220 irq_stack_end); 221 irq_stack_end = NULL; 222 ops->stack(data, "EOI"); 223 continue; 224 } 225 } 226 break; 227 } 228 229 /* 230 * This handles the process stack: 231 */ 232 bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph); 233 put_cpu(); 234 } 235 EXPORT_SYMBOL(dump_trace); 236 237 void 238 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 239 unsigned long *sp, unsigned long bp, char *log_lvl) 240 { 241 unsigned long *irq_stack_end; 242 unsigned long *irq_stack; 243 unsigned long *stack; 244 int cpu; 245 int i; 246 247 preempt_disable(); 248 cpu = smp_processor_id(); 249 250 irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu)); 251 irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE); 252 253 /* 254 * Debugging aid: "show_stack(NULL, NULL);" prints the 255 * back trace for this cpu: 256 */ 257 if (sp == NULL) { 258 if (task) 259 sp = (unsigned long *)task->thread.sp; 260 else 261 sp = (unsigned long *)&sp; 262 } 263 264 stack = sp; 265 for (i = 0; i < kstack_depth_to_print; i++) { 266 if (stack >= irq_stack && stack <= irq_stack_end) { 267 if (stack == irq_stack_end) { 268 stack = (unsigned long *) (irq_stack_end[-1]); 269 printk(" <EOI> "); 270 } 271 } else { 272 if (((long) stack & (THREAD_SIZE-1)) == 0) 273 break; 274 } 275 if (i && ((i % STACKSLOTS_PER_LINE) == 0)) 276 printk("\n%s", log_lvl); 277 printk(" %016lx", *stack++); 278 touch_nmi_watchdog(); 279 } 280 preempt_enable(); 281 282 printk("\n"); 283 show_trace_log_lvl(task, regs, sp, bp, log_lvl); 284 } 285 286 void show_registers(struct pt_regs *regs) 287 { 288 int i; 289 unsigned long sp; 290 const int cpu = smp_processor_id(); 291 struct task_struct *cur = current; 292 293 sp = regs->sp; 294 printk("CPU %d ", cpu); 295 print_modules(); 296 __show_regs(regs, 1); 297 printk("Process %s (pid: %d, threadinfo %p, task %p)\n", 298 cur->comm, cur->pid, task_thread_info(cur), cur); 299 300 /* 301 * When in-kernel, we also print out the stack and code at the 302 * time of the fault.. 303 */ 304 if (!user_mode(regs)) { 305 unsigned int code_prologue = code_bytes * 43 / 64; 306 unsigned int code_len = code_bytes; 307 unsigned char c; 308 u8 *ip; 309 310 printk(KERN_EMERG "Stack:\n"); 311 show_stack_log_lvl(NULL, regs, (unsigned long *)sp, 312 regs->bp, KERN_EMERG); 313 314 printk(KERN_EMERG "Code: "); 315 316 ip = (u8 *)regs->ip - code_prologue; 317 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) { 318 /* try starting at IP */ 319 ip = (u8 *)regs->ip; 320 code_len = code_len - code_prologue + 1; 321 } 322 for (i = 0; i < code_len; i++, ip++) { 323 if (ip < (u8 *)PAGE_OFFSET || 324 probe_kernel_address(ip, c)) { 325 printk(" Bad RIP value."); 326 break; 327 } 328 if (ip == (u8 *)regs->ip) 329 printk("<%02x> ", c); 330 else 331 printk("%02x ", c); 332 } 333 } 334 printk("\n"); 335 } 336 337 int is_valid_bugaddr(unsigned long ip) 338 { 339 unsigned short ud2; 340 341 if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2))) 342 return 0; 343 344 return ud2 == 0x0b0f; 345 } 346