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