// SPDX-License-Identifier: GPL-2.0-only

  /*
   * kernel/stacktrace.c
   *
   * Stack trace management functions
   *
   *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   */

  #include <linux/sched/task_stack.h>
  #include <linux/sched/debug.h>

  #include <linux/sched.h>

  #include <linux/kernel.h>

  #include <linux/export.h>

  #include <linux/kallsyms.h>
  #include <linux/stacktrace.h>

  /**
   * stack_trace_print - Print the entries in the stack trace
   * @entries:	Pointer to storage array
   * @nr_entries:	Number of entries in the storage array
   * @spaces:	Number of leading spaces to print
   */

  void stack_trace_print(const unsigned long *entries, unsigned int nr_entries,

  		       int spaces)

  {

  	unsigned int i;

  	if (WARN_ON(!entries))

  		return;

  	for (i = 0; i < nr_entries; i++)
  		printk("%*c%pS
  ", 1 + spaces, ' ', (void *)entries[i]);
  }
  EXPORT_SYMBOL_GPL(stack_trace_print);

  /**
   * stack_trace_snprint - Print the entries in the stack trace into a buffer
   * @buf:	Pointer to the print buffer
   * @size:	Size of the print buffer
   * @entries:	Pointer to storage array
   * @nr_entries:	Number of entries in the storage array
   * @spaces:	Number of leading spaces to print
   *
   * Return: Number of bytes printed.
   */

  int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,

  			unsigned int nr_entries, int spaces)

  {

  	unsigned int generated, i, total = 0;

  	if (WARN_ON(!entries))

  		return 0;

  	for (i = 0; i < nr_entries && size; i++) {

  		generated = snprintf(buf, size, "%*c%pS
  ", 1 + spaces, ' ',

  				     (void *)entries[i]);

  
  		total += generated;

  		if (generated >= size) {
  			buf += size;
  			size = 0;
  		} else {
  			buf += generated;
  			size -= generated;
  		}
  	}
  
  	return total;
  }

  EXPORT_SYMBOL_GPL(stack_trace_snprint);

  #ifdef CONFIG_ARCH_STACKWALK
  
  struct stacktrace_cookie {
  	unsigned long	*store;
  	unsigned int	size;
  	unsigned int	skip;
  	unsigned int	len;
  };

  static bool stack_trace_consume_entry(void *cookie, unsigned long addr)

  {
  	struct stacktrace_cookie *c = cookie;
  
  	if (c->len >= c->size)
  		return false;
  
  	if (c->skip > 0) {
  		c->skip--;
  		return true;
  	}
  	c->store[c->len++] = addr;
  	return c->len < c->size;
  }

  static bool stack_trace_consume_entry_nosched(void *cookie, unsigned long addr)

  {
  	if (in_sched_functions(addr))
  		return true;

  	return stack_trace_consume_entry(cookie, addr);

  }
  
  /**
   * stack_trace_save - Save a stack trace into a storage array
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored.
   */
  unsigned int stack_trace_save(unsigned long *store, unsigned int size,
  			      unsigned int skipnr)
  {
  	stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
  	struct stacktrace_cookie c = {
  		.store	= store,
  		.size	= size,
  		.skip	= skipnr + 1,
  	};
  
  	arch_stack_walk(consume_entry, &c, current, NULL);
  	return c.len;
  }
  EXPORT_SYMBOL_GPL(stack_trace_save);
  
  /**
   * stack_trace_save_tsk - Save a task stack trace into a storage array
   * @task:	The task to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored.
   */
  unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store,
  				  unsigned int size, unsigned int skipnr)
  {
  	stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched;
  	struct stacktrace_cookie c = {
  		.store	= store,
  		.size	= size,

  		/* skip this function if they are tracing us */

  		.skip	= skipnr + (current == tsk),

  	};
  
  	if (!try_get_task_stack(tsk))
  		return 0;
  
  	arch_stack_walk(consume_entry, &c, tsk, NULL);
  	put_task_stack(tsk);
  	return c.len;
  }
  
  /**
   * stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
   * @regs:	Pointer to pt_regs to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored.
   */
  unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
  				   unsigned int size, unsigned int skipnr)
  {
  	stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
  	struct stacktrace_cookie c = {
  		.store	= store,
  		.size	= size,
  		.skip	= skipnr,
  	};
  
  	arch_stack_walk(consume_entry, &c, current, regs);
  	return c.len;
  }
  
  #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
  /**
   * stack_trace_save_tsk_reliable - Save task stack with verification
   * @tsk:	Pointer to the task to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   *
   * Return:	An error if it detects any unreliable features of the
   *		stack. Otherwise it guarantees that the stack trace is
   *		reliable and returns the number of entries stored.
   *
   * If the task is not 'current', the caller *must* ensure the task is inactive.
   */
  int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
  				  unsigned int size)
  {
  	stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
  	struct stacktrace_cookie c = {
  		.store	= store,
  		.size	= size,
  	};
  	int ret;
  
  	/*
  	 * If the task doesn't have a stack (e.g., a zombie), the stack is
  	 * "reliably" empty.
  	 */
  	if (!try_get_task_stack(tsk))
  		return 0;
  
  	ret = arch_stack_walk_reliable(consume_entry, &c, tsk);
  	put_task_stack(tsk);

  	return ret ? ret : c.len;

  }
  #endif
  
  #ifdef CONFIG_USER_STACKTRACE_SUPPORT
  /**
   * stack_trace_save_user - Save a user space stack trace into a storage array
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   *
   * Return: Number of trace entries stored.
   */
  unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
  {
  	stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
  	struct stacktrace_cookie c = {
  		.store	= store,
  		.size	= size,
  	};

  	mm_segment_t fs;

  
  	/* Trace user stack if not a kernel thread */

  	if (current->flags & PF_KTHREAD)

  		return 0;

  	fs = force_uaccess_begin();

  	arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));

  	force_uaccess_end(fs);

  	return c.len;
  }
  #endif
  
  #else /* CONFIG_ARCH_STACKWALK */

  /*

   * Architectures that do not implement save_stack_trace_*()
   * get these weak aliases and once-per-bootup warnings

   * (whenever this facility is utilized - for example by procfs):

   */
  __weak void
  save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  {
  	WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.
  ");
  }

  
  __weak void
  save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
  {
  	WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.
  ");
  }

  /**
   * stack_trace_save - Save a stack trace into a storage array
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored
   */
  unsigned int stack_trace_save(unsigned long *store, unsigned int size,
  			      unsigned int skipnr)
  {
  	struct stack_trace trace = {
  		.entries	= store,
  		.max_entries	= size,
  		.skip		= skipnr + 1,
  	};
  
  	save_stack_trace(&trace);
  	return trace.nr_entries;
  }
  EXPORT_SYMBOL_GPL(stack_trace_save);
  
  /**
   * stack_trace_save_tsk - Save a task stack trace into a storage array
   * @task:	The task to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored
   */
  unsigned int stack_trace_save_tsk(struct task_struct *task,
  				  unsigned long *store, unsigned int size,
  				  unsigned int skipnr)
  {
  	struct stack_trace trace = {
  		.entries	= store,
  		.max_entries	= size,

  		/* skip this function if they are tracing us */

  		.skip	= skipnr + (current == task),

  	};
  
  	save_stack_trace_tsk(task, &trace);
  	return trace.nr_entries;
  }
  
  /**
   * stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
   * @regs:	Pointer to pt_regs to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   * @skipnr:	Number of entries to skip at the start of the stack trace
   *
   * Return: Number of trace entries stored
   */
  unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
  				   unsigned int size, unsigned int skipnr)
  {
  	struct stack_trace trace = {
  		.entries	= store,
  		.max_entries	= size,
  		.skip		= skipnr,
  	};
  
  	save_stack_trace_regs(regs, &trace);
  	return trace.nr_entries;
  }
  
  #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
  /**
   * stack_trace_save_tsk_reliable - Save task stack with verification
   * @tsk:	Pointer to the task to examine
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   *
   * Return:	An error if it detects any unreliable features of the
   *		stack. Otherwise it guarantees that the stack trace is
   *		reliable and returns the number of entries stored.
   *
   * If the task is not 'current', the caller *must* ensure the task is inactive.
   */
  int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
  				  unsigned int size)
  {
  	struct stack_trace trace = {
  		.entries	= store,
  		.max_entries	= size,
  	};
  	int ret = save_stack_trace_tsk_reliable(tsk, &trace);
  
  	return ret ? ret : trace.nr_entries;
  }
  #endif
  
  #ifdef CONFIG_USER_STACKTRACE_SUPPORT
  /**
   * stack_trace_save_user - Save a user space stack trace into a storage array
   * @store:	Pointer to storage array
   * @size:	Size of the storage array
   *
   * Return: Number of trace entries stored
   */
  unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
  {
  	struct stack_trace trace = {
  		.entries	= store,
  		.max_entries	= size,
  	};
  
  	save_stack_trace_user(&trace);
  	return trace.nr_entries;
  }
  #endif /* CONFIG_USER_STACKTRACE_SUPPORT */

  
  #endif /* !CONFIG_ARCH_STACKWALK */