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 20 #define N_EXCEPTION_STACKS_END \ 21 (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2) 22 23 static char x86_stack_ids[][8] = { 24 [ DEBUG_STACK-1 ] = "#DB", 25 [ NMI_STACK-1 ] = "NMI", 26 [ DOUBLEFAULT_STACK-1 ] = "#DF", 27 [ MCE_STACK-1 ] = "#MC", 28 #if DEBUG_STKSZ > EXCEPTION_STKSZ 29 [ N_EXCEPTION_STACKS ... 30 N_EXCEPTION_STACKS_END ] = "#DB[?]" 31 #endif 32 }; 33 34 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack, 35 unsigned *usedp, char **idp) 36 { 37 unsigned k; 38 39 /* 40 * Iterate over all exception stacks, and figure out whether 41 * 'stack' is in one of them: 42 */ 43 for (k = 0; k < N_EXCEPTION_STACKS; k++) { 44 unsigned long end = per_cpu(orig_ist, cpu).ist[k]; 45 /* 46 * Is 'stack' above this exception frame's end? 47 * If yes then skip to the next frame. 48 */ 49 if (stack >= end) 50 continue; 51 /* 52 * Is 'stack' above this exception frame's start address? 53 * If yes then we found the right frame. 54 */ 55 if (stack >= end - EXCEPTION_STKSZ) { 56 /* 57 * Make sure we only iterate through an exception 58 * stack once. If it comes up for the second time 59 * then there's something wrong going on - just 60 * break out and return NULL: 61 */ 62 if (*usedp & (1U << k)) 63 break; 64 *usedp |= 1U << k; 65 *idp = x86_stack_ids[k]; 66 return (unsigned long *)end; 67 } 68 /* 69 * If this is a debug stack, and if it has a larger size than 70 * the usual exception stacks, then 'stack' might still 71 * be within the lower portion of the debug stack: 72 */ 73 #if DEBUG_STKSZ > EXCEPTION_STKSZ 74 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) { 75 unsigned j = N_EXCEPTION_STACKS - 1; 76 77 /* 78 * Black magic. A large debug stack is composed of 79 * multiple exception stack entries, which we 80 * iterate through now. Dont look: 81 */ 82 do { 83 ++j; 84 end -= EXCEPTION_STKSZ; 85 x86_stack_ids[j][4] = '1' + 86 (j - N_EXCEPTION_STACKS); 87 } while (stack < end - EXCEPTION_STKSZ); 88 if (*usedp & (1U << j)) 89 break; 90 *usedp |= 1U << j; 91 *idp = x86_stack_ids[j]; 92 return (unsigned long *)end; 93 } 94 #endif 95 } 96 return NULL; 97 } 98 99 static inline int 100 in_irq_stack(unsigned long *stack, unsigned long *irq_stack, 101 unsigned long *irq_stack_end) 102 { 103 return (stack >= irq_stack && stack < irq_stack_end); 104 } 105 106 static const unsigned long irq_stack_size = 107 (IRQ_STACK_SIZE - 64) / sizeof(unsigned long); 108 109 enum stack_type { 110 STACK_IS_UNKNOWN, 111 STACK_IS_NORMAL, 112 STACK_IS_EXCEPTION, 113 STACK_IS_IRQ, 114 }; 115 116 static enum stack_type 117 analyze_stack(int cpu, struct task_struct *task, unsigned long *stack, 118 unsigned long **stack_end, unsigned long *irq_stack, 119 unsigned *used, char **id) 120 { 121 unsigned long addr; 122 123 addr = ((unsigned long)stack & (~(THREAD_SIZE - 1))); 124 if ((unsigned long)task_stack_page(task) == addr) 125 return STACK_IS_NORMAL; 126 127 *stack_end = in_exception_stack(cpu, (unsigned long)stack, 128 used, id); 129 if (*stack_end) 130 return STACK_IS_EXCEPTION; 131 132 if (!irq_stack) 133 return STACK_IS_NORMAL; 134 135 *stack_end = irq_stack; 136 irq_stack = irq_stack - irq_stack_size; 137 138 if (in_irq_stack(stack, irq_stack, *stack_end)) 139 return STACK_IS_IRQ; 140 141 return STACK_IS_UNKNOWN; 142 } 143 144 /* 145 * x86-64 can have up to three kernel stacks: 146 * process stack 147 * interrupt stack 148 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack 149 */ 150 151 void dump_trace(struct task_struct *task, struct pt_regs *regs, 152 unsigned long *stack, unsigned long bp, 153 const struct stacktrace_ops *ops, void *data) 154 { 155 const unsigned cpu = get_cpu(); 156 struct thread_info *tinfo; 157 unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu); 158 unsigned long dummy; 159 unsigned used = 0; 160 int graph = 0; 161 int done = 0; 162 163 if (!task) 164 task = current; 165 166 if (!stack) { 167 if (regs) 168 stack = (unsigned long *)regs->sp; 169 else if (task != current) 170 stack = (unsigned long *)task->thread.sp; 171 else 172 stack = &dummy; 173 } 174 175 if (!bp) 176 bp = stack_frame(task, regs); 177 /* 178 * Print function call entries in all stacks, starting at the 179 * current stack address. If the stacks consist of nested 180 * exceptions 181 */ 182 tinfo = task_thread_info(task); 183 while (!done) { 184 unsigned long *stack_end; 185 enum stack_type stype; 186 char *id; 187 188 stype = analyze_stack(cpu, task, stack, &stack_end, 189 irq_stack, &used, &id); 190 191 /* Default finish unless specified to continue */ 192 done = 1; 193 194 switch (stype) { 195 196 /* Break out early if we are on the thread stack */ 197 case STACK_IS_NORMAL: 198 break; 199 200 case STACK_IS_EXCEPTION: 201 202 if (ops->stack(data, id) < 0) 203 break; 204 205 bp = ops->walk_stack(tinfo, stack, bp, ops, 206 data, stack_end, &graph); 207 ops->stack(data, "<EOE>"); 208 /* 209 * We link to the next stack via the 210 * second-to-last pointer (index -2 to end) in the 211 * exception stack: 212 */ 213 stack = (unsigned long *) stack_end[-2]; 214 done = 0; 215 break; 216 217 case STACK_IS_IRQ: 218 219 if (ops->stack(data, "IRQ") < 0) 220 break; 221 bp = ops->walk_stack(tinfo, stack, bp, 222 ops, data, stack_end, &graph); 223 /* 224 * We link to the next stack (which would be 225 * the process stack normally) the last 226 * pointer (index -1 to end) in the IRQ stack: 227 */ 228 stack = (unsigned long *) (stack_end[-1]); 229 irq_stack = NULL; 230 ops->stack(data, "EOI"); 231 done = 0; 232 break; 233 234 case STACK_IS_UNKNOWN: 235 ops->stack(data, "UNK"); 236 break; 237 } 238 } 239 240 /* 241 * This handles the process stack: 242 */ 243 bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph); 244 put_cpu(); 245 } 246 EXPORT_SYMBOL(dump_trace); 247 248 void 249 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 250 unsigned long *sp, unsigned long bp, char *log_lvl) 251 { 252 unsigned long *irq_stack_end; 253 unsigned long *irq_stack; 254 unsigned long *stack; 255 int cpu; 256 int i; 257 258 preempt_disable(); 259 cpu = smp_processor_id(); 260 261 irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu)); 262 irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE); 263 264 /* 265 * Debugging aid: "show_stack(NULL, NULL);" prints the 266 * back trace for this cpu: 267 */ 268 if (sp == NULL) { 269 if (task) 270 sp = (unsigned long *)task->thread.sp; 271 else 272 sp = (unsigned long *)&sp; 273 } 274 275 stack = sp; 276 for (i = 0; i < kstack_depth_to_print; i++) { 277 if (stack >= irq_stack && stack <= irq_stack_end) { 278 if (stack == irq_stack_end) { 279 stack = (unsigned long *) (irq_stack_end[-1]); 280 pr_cont(" <EOI> "); 281 } 282 } else { 283 if (((long) stack & (THREAD_SIZE-1)) == 0) 284 break; 285 } 286 if (i && ((i % STACKSLOTS_PER_LINE) == 0)) 287 pr_cont("\n"); 288 pr_cont(" %016lx", *stack++); 289 touch_nmi_watchdog(); 290 } 291 preempt_enable(); 292 293 pr_cont("\n"); 294 show_trace_log_lvl(task, regs, sp, bp, log_lvl); 295 } 296 297 void show_regs(struct pt_regs *regs) 298 { 299 int i; 300 unsigned long sp; 301 302 sp = regs->sp; 303 show_regs_print_info(KERN_DEFAULT); 304 __show_regs(regs, 1); 305 306 /* 307 * When in-kernel, we also print out the stack and code at the 308 * time of the fault.. 309 */ 310 if (!user_mode(regs)) { 311 unsigned int code_prologue = code_bytes * 43 / 64; 312 unsigned int code_len = code_bytes; 313 unsigned char c; 314 u8 *ip; 315 316 printk(KERN_DEFAULT "Stack:\n"); 317 show_stack_log_lvl(NULL, regs, (unsigned long *)sp, 318 0, KERN_DEFAULT); 319 320 printk(KERN_DEFAULT "Code: "); 321 322 ip = (u8 *)regs->ip - code_prologue; 323 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) { 324 /* try starting at IP */ 325 ip = (u8 *)regs->ip; 326 code_len = code_len - code_prologue + 1; 327 } 328 for (i = 0; i < code_len; i++, ip++) { 329 if (ip < (u8 *)PAGE_OFFSET || 330 probe_kernel_address(ip, c)) { 331 pr_cont(" Bad RIP value."); 332 break; 333 } 334 if (ip == (u8 *)regs->ip) 335 pr_cont("<%02x> ", c); 336 else 337 pr_cont("%02x ", c); 338 } 339 } 340 pr_cont("\n"); 341 } 342 343 int is_valid_bugaddr(unsigned long ip) 344 { 345 unsigned short ud2; 346 347 if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2))) 348 return 0; 349 350 return ud2 == 0x0b0f; 351 } 352