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