/*
   *  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/hardirq.h>
  #include <linux/kdebug.h>
  #include <linux/module.h>
  #include <linux/ptrace.h>
  #include <linux/kexec.h>

  #include <linux/sysfs.h>

  #include <linux/bug.h>
  #include <linux/nmi.h>
  
  #include <asm/stacktrace.h>

  #define N_EXCEPTION_STACKS_END \
  		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)

  
  static char x86_stack_ids[][8] = {

  		[ DEBUG_STACK-1			]	= "#DB",
  		[ NMI_STACK-1			]	= "NMI",
  		[ DOUBLEFAULT_STACK-1		]	= "#DF",
  		[ STACKFAULT_STACK-1		]	= "#SS",
  		[ MCE_STACK-1			]	= "#MC",

  #if DEBUG_STKSZ > EXCEPTION_STKSZ

  		[ N_EXCEPTION_STACKS ...
  		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"

  #endif

  };

  static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,

  					 unsigned *usedp, char **idp)

  {

  	unsigned k;
  
  	/*
  	 * Iterate over all exception stacks, and figure out whether
  	 * 'stack' is in one of them:
  	 */
  	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
  		unsigned long end = per_cpu(orig_ist, cpu).ist[k];
  		/*
  		 * Is 'stack' above this exception frame's end?
  		 * If yes then skip to the next frame.
  		 */
  		if (stack >= end)
  			continue;
  		/*
  		 * Is 'stack' above this exception frame's start address?
  		 * If yes then we found the right frame.
  		 */
  		if (stack >= end - EXCEPTION_STKSZ) {
  			/*
  			 * Make sure we only iterate through an exception
  			 * stack once. If it comes up for the second time
  			 * then there's something wrong going on - just
  			 * break out and return NULL:
  			 */
  			if (*usedp & (1U << k))
  				break;
  			*usedp |= 1U << k;

  			*idp = x86_stack_ids[k];

  			return (unsigned long *)end;
  		}
  		/*
  		 * If this is a debug stack, and if it has a larger size than
  		 * the usual exception stacks, then 'stack' might still
  		 * be within the lower portion of the debug stack:
  		 */
  #if DEBUG_STKSZ > EXCEPTION_STKSZ
  		if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
  			unsigned j = N_EXCEPTION_STACKS - 1;
  
  			/*
  			 * Black magic. A large debug stack is composed of
  			 * multiple exception stack entries, which we
  			 * iterate through now. Dont look:
  			 */
  			do {
  				++j;
  				end -= EXCEPTION_STKSZ;

  				x86_stack_ids[j][4] = '1' +
  						(j - N_EXCEPTION_STACKS);

  			} while (stack < end - EXCEPTION_STKSZ);
  			if (*usedp & (1U << j))
  				break;
  			*usedp |= 1U << j;

  			*idp = x86_stack_ids[j];

  			return (unsigned long *)end;
  		}
  #endif
  	}
  	return NULL;
  }

  static inline int
  in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
  	     unsigned long *irq_stack_end)
  {
  	return (stack >= irq_stack && stack < irq_stack_end);
  }
  
  /*

   * x86-64 can have up to three kernel stacks:
   * process stack
   * interrupt stack
   * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
   */

  void dump_trace(struct task_struct *task, struct pt_regs *regs,
  		unsigned long *stack, unsigned long bp,

  		const struct stacktrace_ops *ops, void *data)
  {
  	const unsigned cpu = get_cpu();

  	unsigned long *irq_stack_end =
  		(unsigned long *)per_cpu(irq_stack_ptr, cpu);

  	unsigned used = 0;
  	struct thread_info *tinfo;

  	int graph = 0;

  	unsigned long dummy;

  
  	if (!task)
  		task = current;
  
  	if (!stack) {

  		if (regs)
  			stack = (unsigned long *)regs->sp;
  		else if (task && task != current)

  			stack = (unsigned long *)task->thread.sp;

  		else
  			stack = &dummy;

  	}

  	if (!bp)
  		bp = stack_frame(task, regs);

  	/*
  	 * Print function call entries in all stacks, starting at the
  	 * current stack address. If the stacks consist of nested
  	 * exceptions
  	 */
  	tinfo = task_thread_info(task);
  	for (;;) {
  		char *id;
  		unsigned long *estack_end;
  		estack_end = in_exception_stack(cpu, (unsigned long)stack,
  						&used, &id);
  
  		if (estack_end) {
  			if (ops->stack(data, id) < 0)
  				break;

  			bp = ops->walk_stack(tinfo, stack, bp, ops,
  					     data, estack_end, &graph);

  			ops->stack(data, "<EOE>");
  			/*
  			 * We link to the next stack via the
  			 * second-to-last pointer (index -2 to end) in the
  			 * exception stack:
  			 */
  			stack = (unsigned long *) estack_end[-2];
  			continue;
  		}

  		if (irq_stack_end) {
  			unsigned long *irq_stack;
  			irq_stack = irq_stack_end -
  				(IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);

  			if (in_irq_stack(stack, irq_stack, irq_stack_end)) {

  				if (ops->stack(data, "IRQ") < 0)
  					break;

  				bp = ops->walk_stack(tinfo, stack, bp,

  					ops, data, irq_stack_end, &graph);

  				/*
  				 * We link to the next stack (which would be
  				 * the process stack normally) the last
  				 * pointer (index -1 to end) in the IRQ stack:
  				 */

  				stack = (unsigned long *) (irq_stack_end[-1]);
  				irq_stack_end = NULL;

  				ops->stack(data, "EOI");
  				continue;
  			}
  		}
  		break;
  	}
  
  	/*
  	 * This handles the process stack:
  	 */

  	bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);

  	put_cpu();
  }
  EXPORT_SYMBOL(dump_trace);

  void

  show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,

  		   unsigned long *sp, unsigned long bp, char *log_lvl)

  {

  	unsigned long *irq_stack_end;
  	unsigned long *irq_stack;

  	unsigned long *stack;

  	int cpu;

  	int i;

  
  	preempt_disable();
  	cpu = smp_processor_id();
  
  	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
  	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);

  
  	/*

  	 * Debugging aid: "show_stack(NULL, NULL);" prints the
  	 * back trace for this cpu:

  	 */

  	if (sp == NULL) {
  		if (task)
  			sp = (unsigned long *)task->thread.sp;
  		else
  			sp = (unsigned long *)&sp;
  	}
  
  	stack = sp;
  	for (i = 0; i < kstack_depth_to_print; i++) {

  		if (stack >= irq_stack && stack <= irq_stack_end) {
  			if (stack == irq_stack_end) {
  				stack = (unsigned long *) (irq_stack_end[-1]);

  				printk(KERN_CONT " <EOI> ");

  			}
  		} else {
  		if (((long) stack & (THREAD_SIZE-1)) == 0)
  			break;
  		}

  		if (i && ((i % STACKSLOTS_PER_LINE) == 0))

  			printk(KERN_CONT "
  ");
  		printk(KERN_CONT " %016lx", *stack++);

  		touch_nmi_watchdog();
  	}

  	preempt_enable();

  	printk(KERN_CONT "
  ");

  	show_trace_log_lvl(task, regs, sp, bp, log_lvl);

  }

  void show_registers(struct pt_regs *regs)
  {
  	int i;
  	unsigned long sp;
  	const int cpu = smp_processor_id();

  	struct task_struct *cur = current;

  
  	sp = regs->sp;
  	printk("CPU %d ", cpu);

  	print_modules();

  	__show_regs(regs, 1);
  	printk("Process %s (pid: %d, threadinfo %p, task %p)
  ",
  		cur->comm, cur->pid, task_thread_info(cur), cur);
  
  	/*
  	 * When in-kernel, we also print out the stack and code at the
  	 * time of the fault..
  	 */
  	if (!user_mode(regs)) {
  		unsigned int code_prologue = code_bytes * 43 / 64;
  		unsigned int code_len = code_bytes;
  		unsigned char c;
  		u8 *ip;

  		printk(KERN_EMERG "Stack:
  ");

  		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,

  				   0, KERN_EMERG);

  
  		printk(KERN_EMERG "Code: ");
  
  		ip = (u8 *)regs->ip - code_prologue;
  		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {

  			/* try starting at IP */

  			ip = (u8 *)regs->ip;
  			code_len = code_len - code_prologue + 1;
  		}
  		for (i = 0; i < code_len; i++, ip++) {
  			if (ip < (u8 *)PAGE_OFFSET ||
  					probe_kernel_address(ip, c)) {

  				printk(KERN_CONT " Bad RIP value.");

  				break;
  			}
  			if (ip == (u8 *)regs->ip)

  				printk(KERN_CONT "<%02x> ", c);

  			else

  				printk(KERN_CONT "%02x ", c);

  		}
  	}

  	printk(KERN_CONT "
  ");

  }
  
  int is_valid_bugaddr(unsigned long ip)
  {
  	unsigned short ud2;
  
  	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
  		return 0;
  
  	return ud2 == 0x0b0f;
  }