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