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/utsname.h> 9 #include <linux/hardirq.h> 10 #include <linux/kdebug.h> 11 #include <linux/module.h> 12 #include <linux/ptrace.h> 13 #include <linux/sched/debug.h> 14 #include <linux/sched/task_stack.h> 15 #include <linux/ftrace.h> 16 #include <linux/kexec.h> 17 #include <linux/bug.h> 18 #include <linux/nmi.h> 19 #include <linux/sysfs.h> 20 21 #include <asm/cpu_entry_area.h> 22 #include <asm/stacktrace.h> 23 #include <asm/unwind.h> 24 25 int panic_on_unrecovered_nmi; 26 int panic_on_io_nmi; 27 unsigned int code_bytes = 64; 28 static int die_counter; 29 30 bool in_task_stack(unsigned long *stack, struct task_struct *task, 31 struct stack_info *info) 32 { 33 unsigned long *begin = task_stack_page(task); 34 unsigned long *end = task_stack_page(task) + THREAD_SIZE; 35 36 if (stack < begin || stack >= end) 37 return false; 38 39 info->type = STACK_TYPE_TASK; 40 info->begin = begin; 41 info->end = end; 42 info->next_sp = NULL; 43 44 return true; 45 } 46 47 bool in_entry_stack(unsigned long *stack, struct stack_info *info) 48 { 49 struct entry_stack *ss = cpu_entry_stack(smp_processor_id()); 50 51 void *begin = ss; 52 void *end = ss + 1; 53 54 if ((void *)stack < begin || (void *)stack >= end) 55 return false; 56 57 info->type = STACK_TYPE_ENTRY; 58 info->begin = begin; 59 info->end = end; 60 info->next_sp = NULL; 61 62 return true; 63 } 64 65 static void printk_stack_address(unsigned long address, int reliable, 66 char *log_lvl) 67 { 68 touch_nmi_watchdog(); 69 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address); 70 } 71 72 void show_iret_regs(struct pt_regs *regs) 73 { 74 printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip); 75 printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss, 76 regs->sp, regs->flags); 77 } 78 79 static void show_regs_safe(struct stack_info *info, struct pt_regs *regs) 80 { 81 if (on_stack(info, regs, sizeof(*regs))) 82 __show_regs(regs, 0); 83 else if (on_stack(info, (void *)regs + IRET_FRAME_OFFSET, 84 IRET_FRAME_SIZE)) { 85 /* 86 * When an interrupt or exception occurs in entry code, the 87 * full pt_regs might not have been saved yet. In that case 88 * just print the iret frame. 89 */ 90 show_iret_regs(regs); 91 } 92 } 93 94 void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, 95 unsigned long *stack, char *log_lvl) 96 { 97 struct unwind_state state; 98 struct stack_info stack_info = {0}; 99 unsigned long visit_mask = 0; 100 int graph_idx = 0; 101 102 printk("%sCall Trace:\n", log_lvl); 103 104 unwind_start(&state, task, regs, stack); 105 stack = stack ? : get_stack_pointer(task, regs); 106 107 /* 108 * Iterate through the stacks, starting with the current stack pointer. 109 * Each stack has a pointer to the next one. 110 * 111 * x86-64 can have several stacks: 112 * - task stack 113 * - interrupt stack 114 * - HW exception stacks (double fault, nmi, debug, mce) 115 * - entry stack 116 * 117 * x86-32 can have up to four stacks: 118 * - task stack 119 * - softirq stack 120 * - hardirq stack 121 * - entry stack 122 */ 123 for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { 124 const char *stack_name; 125 126 if (get_stack_info(stack, task, &stack_info, &visit_mask)) { 127 /* 128 * We weren't on a valid stack. It's possible that 129 * we overflowed a valid stack into a guard page. 130 * See if the next page up is valid so that we can 131 * generate some kind of backtrace if this happens. 132 */ 133 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack); 134 if (get_stack_info(stack, task, &stack_info, &visit_mask)) 135 break; 136 } 137 138 stack_name = stack_type_name(stack_info.type); 139 if (stack_name) 140 printk("%s <%s>\n", log_lvl, stack_name); 141 142 if (regs) 143 show_regs_safe(&stack_info, regs); 144 145 /* 146 * Scan the stack, printing any text addresses we find. At the 147 * same time, follow proper stack frames with the unwinder. 148 * 149 * Addresses found during the scan which are not reported by 150 * the unwinder are considered to be additional clues which are 151 * sometimes useful for debugging and are prefixed with '?'. 152 * This also serves as a failsafe option in case the unwinder 153 * goes off in the weeds. 154 */ 155 for (; stack < stack_info.end; stack++) { 156 unsigned long real_addr; 157 int reliable = 0; 158 unsigned long addr = READ_ONCE_NOCHECK(*stack); 159 unsigned long *ret_addr_p = 160 unwind_get_return_address_ptr(&state); 161 162 if (!__kernel_text_address(addr)) 163 continue; 164 165 /* 166 * Don't print regs->ip again if it was already printed 167 * by show_regs_safe() below. 168 */ 169 if (regs && stack == ®s->ip) 170 goto next; 171 172 if (stack == ret_addr_p) 173 reliable = 1; 174 175 /* 176 * When function graph tracing is enabled for a 177 * function, its return address on the stack is 178 * replaced with the address of an ftrace handler 179 * (return_to_handler). In that case, before printing 180 * the "real" address, we want to print the handler 181 * address as an "unreliable" hint that function graph 182 * tracing was involved. 183 */ 184 real_addr = ftrace_graph_ret_addr(task, &graph_idx, 185 addr, stack); 186 if (real_addr != addr) 187 printk_stack_address(addr, 0, log_lvl); 188 printk_stack_address(real_addr, reliable, log_lvl); 189 190 if (!reliable) 191 continue; 192 193 next: 194 /* 195 * Get the next frame from the unwinder. No need to 196 * check for an error: if anything goes wrong, the rest 197 * of the addresses will just be printed as unreliable. 198 */ 199 unwind_next_frame(&state); 200 201 /* if the frame has entry regs, print them */ 202 regs = unwind_get_entry_regs(&state); 203 if (regs) 204 show_regs_safe(&stack_info, regs); 205 } 206 207 if (stack_name) 208 printk("%s </%s>\n", log_lvl, stack_name); 209 } 210 } 211 212 void show_stack(struct task_struct *task, unsigned long *sp) 213 { 214 task = task ? : current; 215 216 /* 217 * Stack frames below this one aren't interesting. Don't show them 218 * if we're printing for %current. 219 */ 220 if (!sp && task == current) 221 sp = get_stack_pointer(current, NULL); 222 223 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT); 224 } 225 226 void show_stack_regs(struct pt_regs *regs) 227 { 228 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT); 229 } 230 231 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED; 232 static int die_owner = -1; 233 static unsigned int die_nest_count; 234 235 unsigned long oops_begin(void) 236 { 237 int cpu; 238 unsigned long flags; 239 240 oops_enter(); 241 242 /* racy, but better than risking deadlock. */ 243 raw_local_irq_save(flags); 244 cpu = smp_processor_id(); 245 if (!arch_spin_trylock(&die_lock)) { 246 if (cpu == die_owner) 247 /* nested oops. should stop eventually */; 248 else 249 arch_spin_lock(&die_lock); 250 } 251 die_nest_count++; 252 die_owner = cpu; 253 console_verbose(); 254 bust_spinlocks(1); 255 return flags; 256 } 257 EXPORT_SYMBOL_GPL(oops_begin); 258 NOKPROBE_SYMBOL(oops_begin); 259 260 void __noreturn rewind_stack_do_exit(int signr); 261 262 void oops_end(unsigned long flags, struct pt_regs *regs, int signr) 263 { 264 if (regs && kexec_should_crash(current)) 265 crash_kexec(regs); 266 267 bust_spinlocks(0); 268 die_owner = -1; 269 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 270 die_nest_count--; 271 if (!die_nest_count) 272 /* Nest count reaches zero, release the lock. */ 273 arch_spin_unlock(&die_lock); 274 raw_local_irq_restore(flags); 275 oops_exit(); 276 277 if (!signr) 278 return; 279 if (in_interrupt()) 280 panic("Fatal exception in interrupt"); 281 if (panic_on_oops) 282 panic("Fatal exception"); 283 284 /* 285 * We're not going to return, but we might be on an IST stack or 286 * have very little stack space left. Rewind the stack and kill 287 * the task. 288 */ 289 rewind_stack_do_exit(signr); 290 } 291 NOKPROBE_SYMBOL(oops_end); 292 293 int __die(const char *str, struct pt_regs *regs, long err) 294 { 295 #ifdef CONFIG_X86_32 296 unsigned short ss; 297 unsigned long sp; 298 #endif 299 printk(KERN_DEFAULT 300 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter, 301 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "", 302 IS_ENABLED(CONFIG_SMP) ? " SMP" : "", 303 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "", 304 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "", 305 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ? 306 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : ""); 307 308 if (notify_die(DIE_OOPS, str, regs, err, 309 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP) 310 return 1; 311 312 print_modules(); 313 show_regs(regs); 314 #ifdef CONFIG_X86_32 315 if (user_mode(regs)) { 316 sp = regs->sp; 317 ss = regs->ss; 318 } else { 319 sp = kernel_stack_pointer(regs); 320 savesegment(ss, ss); 321 } 322 printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n", 323 (void *)regs->ip, ss, sp); 324 #else 325 /* Executive summary in case the oops scrolled away */ 326 printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp); 327 #endif 328 return 0; 329 } 330 NOKPROBE_SYMBOL(__die); 331 332 /* 333 * This is gone through when something in the kernel has done something bad 334 * and is about to be terminated: 335 */ 336 void die(const char *str, struct pt_regs *regs, long err) 337 { 338 unsigned long flags = oops_begin(); 339 int sig = SIGSEGV; 340 341 if (__die(str, regs, err)) 342 sig = 0; 343 oops_end(flags, regs, sig); 344 } 345 346 static int __init code_bytes_setup(char *s) 347 { 348 ssize_t ret; 349 unsigned long val; 350 351 if (!s) 352 return -EINVAL; 353 354 ret = kstrtoul(s, 0, &val); 355 if (ret) 356 return ret; 357 358 code_bytes = val; 359 if (code_bytes > 8192) 360 code_bytes = 8192; 361 362 return 1; 363 } 364 __setup("code_bytes=", code_bytes_setup); 365