/* *  Copyright (C) 1991, 1992  Linus Torvalds *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs */#include <linux/kallsyms.h>#include <linux/kprobes.h>#include <linux/uaccess.h>#include <linux/utsname.h>#include <linux/hardirq.h>#include <linux/kdebug.h>#include <linux/module.h>#include <linux/ptrace.h>#include <linux/sched/debug.h>#include <linux/sched/task_stack.h>#include <linux/ftrace.h>#include <linux/kexec.h>#include <linux/bug.h>#include <linux/nmi.h>#include <linux/sysfs.h>#include <linux/kasan.h> #include <asm/cpu_entry_area.h>#include <asm/stacktrace.h>#include <asm/unwind.h> int panic_on_unrecovered_nmi;int panic_on_io_nmi;static int die_counter; static struct pt_regs exec_summary_regs; bool noinstr in_task_stack(unsigned long *stack, struct task_struct *task,			   struct stack_info *info){	unsigned long *begin = task_stack_page(task);	unsigned long *end   = task_stack_page(task) + THREAD_SIZE; 	if (stack < begin || stack >= end)		return false; 	info->type	= STACK_TYPE_TASK;	info->begin	= begin;	info->end	= end;	info->next_sp	= NULL; 	return true;} /* Called from get_stack_info_noinstr - so must be noinstr too */bool noinstr in_entry_stack(unsigned long *stack, struct stack_info *info){	struct entry_stack *ss = cpu_entry_stack(smp_processor_id()); 	void *begin = ss;	void *end = ss + 1; 	if ((void *)stack < begin || (void *)stack >= end)		return false; 	info->type	= STACK_TYPE_ENTRY;	info->begin	= begin;	info->end	= end;	info->next_sp	= NULL; 	return true;} static void printk_stack_address(unsigned long address, int reliable,				 const char *log_lvl){	touch_nmi_watchdog();	printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);} static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src,		     unsigned int nbytes){	if (!user_mode(regs))		return copy_from_kernel_nofault(buf, (u8 *)src, nbytes); 	/* The user space code from other tasks cannot be accessed. */	if (regs != task_pt_regs(current))		return -EPERM;	/*	 * Make sure userspace isn't trying to trick us into dumping kernel	 * memory by pointing the userspace instruction pointer at it.	 */	if (__chk_range_not_ok(src, nbytes, TASK_SIZE_MAX))		return -EINVAL; 	/*	 * Even if named copy_from_user_nmi() this can be invoked from	 * other contexts and will not try to resolve a pagefault, which is	 * the correct thing to do here as this code can be called from any	 * context.	 */	return copy_from_user_nmi(buf, (void __user *)src, nbytes);} /* * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus: * * In case where we don't have the exact kernel image (which, if we did, we can * simply disassemble and navigate to the RIP), the purpose of the bigger * prologue is to have more context and to be able to correlate the code from * the different toolchains better. * * In addition, it helps in recreating the register allocation of the failing * kernel and thus make sense of the register dump. * * What is more, the additional complication of a variable length insn arch like * x86 warrants having longer byte sequence before rIP so that the disassembler * can "sync" up properly and find instruction boundaries when decoding the * opcode bytes. * * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random * guesstimate in attempt to achieve all of the above. */void show_opcodes(struct pt_regs *regs, const char *loglvl){#define PROLOGUE_SIZE 42#define EPILOGUE_SIZE 21#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)	u8 opcodes[OPCODE_BUFSIZE];	unsigned long prologue = regs->ip - PROLOGUE_SIZE; 	switch (copy_code(regs, opcodes, prologue, sizeof(opcodes))) {	case 0:		printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"		       __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,		       opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);		break;	case -EPERM:		/* No access to the user space stack of other tasks. Ignore. */		break;	default:		printk("%sCode: Unable to access opcode bytes at RIP 0x%lx.\n",		       loglvl, prologue);		break;	}} void show_ip(struct pt_regs *regs, const char *loglvl){#ifdef CONFIG_X86_32	printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);#else	printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);#endif	show_opcodes(regs, loglvl);} void show_iret_regs(struct pt_regs *regs, const char *log_lvl){	show_ip(regs, log_lvl);	printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss,		regs->sp, regs->flags);} static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,				  bool partial, const char *log_lvl){	/*	 * These on_stack() checks aren't strictly necessary: the unwind code	 * has already validated the 'regs' pointer.  The checks are done for	 * ordering reasons: if the registers are on the next stack, we don't	 * want to print them out yet.  Otherwise they'll be shown as part of	 * the wrong stack.  Later, when show_trace_log_lvl() switches to the	 * next stack, this function will be called again with the same regs so	 * they can be printed in the right context.	 */	if (!partial && on_stack(info, regs, sizeof(*regs))) {		__show_regs(regs, SHOW_REGS_SHORT, log_lvl); 	} else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,				       IRET_FRAME_SIZE)) {		/*		 * When an interrupt or exception occurs in entry code, the		 * full pt_regs might not have been saved yet.  In that case		 * just print the iret frame.		 */		show_iret_regs(regs, log_lvl);	}} static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,			unsigned long *stack, const char *log_lvl){	struct unwind_state state;	struct stack_info stack_info = {0};	unsigned long visit_mask = 0;	int graph_idx = 0;	bool partial = false; 	printk("%sCall Trace:\n", log_lvl); 	unwind_start(&state, task, regs, stack);	stack = stack ? : get_stack_pointer(task, regs);	regs = unwind_get_entry_regs(&state, &partial); 	/*	 * Iterate through the stacks, starting with the current stack pointer.	 * Each stack has a pointer to the next one.	 *	 * x86-64 can have several stacks:	 * - task stack	 * - interrupt stack	 * - HW exception stacks (double fault, nmi, debug, mce)	 * - entry stack	 *	 * x86-32 can have up to four stacks:	 * - task stack	 * - softirq stack	 * - hardirq stack	 * - entry stack	 */	for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {		const char *stack_name; 		if (get_stack_info(stack, task, &stack_info, &visit_mask)) {			/*			 * We weren't on a valid stack.  It's possible that			 * we overflowed a valid stack into a guard page.			 * See if the next page up is valid so that we can			 * generate some kind of backtrace if this happens.			 */			stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);			if (get_stack_info(stack, task, &stack_info, &visit_mask))				break;		} 		stack_name = stack_type_name(stack_info.type);		if (stack_name)			printk("%s <%s>\n", log_lvl, stack_name); 		if (regs)			show_regs_if_on_stack(&stack_info, regs, partial, log_lvl); 		/*		 * Scan the stack, printing any text addresses we find.  At the		 * same time, follow proper stack frames with the unwinder.		 *		 * Addresses found during the scan which are not reported by		 * the unwinder are considered to be additional clues which are		 * sometimes useful for debugging and are prefixed with '?'.		 * This also serves as a failsafe option in case the unwinder		 * goes off in the weeds.		 */		for (; stack < stack_info.end; stack++) {			unsigned long real_addr;			int reliable = 0;			unsigned long addr = READ_ONCE_NOCHECK(*stack);			unsigned long *ret_addr_p =				unwind_get_return_address_ptr(&state); 			if (!__kernel_text_address(addr))				continue; 			/*			 * Don't print regs->ip again if it was already printed			 * by show_regs_if_on_stack().			 */			if (regs && stack == &regs->ip)				goto next; 			if (stack == ret_addr_p)				reliable = 1; 			/*			 * When function graph tracing is enabled for a			 * function, its return address on the stack is			 * replaced with the address of an ftrace handler			 * (return_to_handler).  In that case, before printing			 * the "real" address, we want to print the handler			 * address as an "unreliable" hint that function graph			 * tracing was involved.			 */			real_addr = ftrace_graph_ret_addr(task, &graph_idx,							  addr, stack);			if (real_addr != addr)				printk_stack_address(addr, 0, log_lvl);			printk_stack_address(real_addr, reliable, log_lvl); 			if (!reliable)				continue; next:			/*			 * Get the next frame from the unwinder.  No need to			 * check for an error: if anything goes wrong, the rest			 * of the addresses will just be printed as unreliable.			 */			unwind_next_frame(&state); 			/* if the frame has entry regs, print them */			regs = unwind_get_entry_regs(&state, &partial);			if (regs)				show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);		} 		if (stack_name)			printk("%s </%s>\n", log_lvl, stack_name);	}} void show_stack(struct task_struct *task, unsigned long *sp,		       const char *loglvl){	task = task ? : current; 	/*	 * Stack frames below this one aren't interesting.  Don't show them	 * if we're printing for %current.	 */	if (!sp && task == current)		sp = get_stack_pointer(current, NULL); 	show_trace_log_lvl(task, NULL, sp, loglvl);} void show_stack_regs(struct pt_regs *regs){	show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);} static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;static int die_owner = -1;static unsigned int die_nest_count; unsigned long oops_begin(void){	int cpu;	unsigned long flags; 	oops_enter(); 	/* racy, but better than risking deadlock. */	raw_local_irq_save(flags);	cpu = smp_processor_id();	if (!arch_spin_trylock(&die_lock)) {		if (cpu == die_owner)			/* nested oops. should stop eventually */;		else			arch_spin_lock(&die_lock);	}	die_nest_count++;	die_owner = cpu;	console_verbose();	bust_spinlocks(1);	return flags;}NOKPROBE_SYMBOL(oops_begin); void __noreturn rewind_stack_do_exit(int signr); void oops_end(unsigned long flags, struct pt_regs *regs, int signr){	if (regs && kexec_should_crash(current))		crash_kexec(regs); 	bust_spinlocks(0);	die_owner = -1;	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);	die_nest_count--;	if (!die_nest_count)		/* Nest count reaches zero, release the lock. */		arch_spin_unlock(&die_lock);	raw_local_irq_restore(flags);	oops_exit(); 	/* Executive summary in case the oops scrolled away */	__show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT); 	if (!signr)		return;	if (in_interrupt())		panic("Fatal exception in interrupt");	if (panic_on_oops)		panic("Fatal exception"); 	/*	 * We're not going to return, but we might be on an IST stack or	 * have very little stack space left.  Rewind the stack and kill	 * the task.	 * Before we rewind the stack, we have to tell KASAN that we're going to	 * reuse the task stack and that existing poisons are invalid.	 */	kasan_unpoison_task_stack(current);	rewind_stack_do_exit(signr);}NOKPROBE_SYMBOL(oops_end); static void __die_header(const char *str, struct pt_regs *regs, long err){	const char *pr = ""; 	/* Save the regs of the first oops for the executive summary later. */	if (!die_counter)		exec_summary_regs = *regs; 	if (IS_ENABLED(CONFIG_PREEMPTION))		pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT"; 	printk(KERN_DEFAULT	       "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,	       pr,	       IS_ENABLED(CONFIG_SMP)     ? " SMP"             : "",	       debug_pagealloc_enabled()  ? " DEBUG_PAGEALLOC" : "",	       IS_ENABLED(CONFIG_KASAN)   ? " KASAN"           : "",	       IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?	       (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");}NOKPROBE_SYMBOL(__die_header); static int __die_body(const char *str, struct pt_regs *regs, long err){	show_regs(regs);	print_modules(); 	if (notify_die(DIE_OOPS, str, regs, err,			current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)		return 1; 	return 0;}NOKPROBE_SYMBOL(__die_body); int __die(const char *str, struct pt_regs *regs, long err){	__die_header(str, regs, err);	return __die_body(str, regs, err);}NOKPROBE_SYMBOL(__die); /* * This is gone through when something in the kernel has done something bad * and is about to be terminated: */void die(const char *str, struct pt_regs *regs, long err){	unsigned long flags = oops_begin();	int sig = SIGSEGV; 	if (__die(str, regs, err))		sig = 0;	oops_end(flags, regs, sig);} void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr){	unsigned long flags = oops_begin();	int sig = SIGSEGV; 	__die_header(str, regs, err);	if (gp_addr)		kasan_non_canonical_hook(gp_addr);	if (__die_body(str, regs, err))		sig = 0;	oops_end(flags, regs, sig);} void show_regs(struct pt_regs *regs){	enum show_regs_mode print_kernel_regs; 	show_regs_print_info(KERN_DEFAULT); 	print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL;	__show_regs(regs, print_kernel_regs, KERN_DEFAULT); 	/*	 * When in-kernel, we also print out the stack at the time of the fault..	 */	if (!user_mode(regs))		show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);}