Quelle stacktrace.c Sprache: C

// 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>
#include <linux/interrupt.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\n", 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\n", 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
* @tsk: 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;
}
EXPORT_SYMBOL_GPL(stack_trace_save_tsk);

/**
* 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,
};

/* Trace user stack if not a kernel thread */
if (current->flags & PF_KTHREAD)
  return 0;

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

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.\n");
}

__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.\n");
}

/**
* 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;
}
EXPORT_SYMBOL_GPL(stack_trace_save_tsk);

/**
* 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 */

static inline bool in_irqentry_text(unsigned long ptr)
{
return (ptr >= (unsigned long)&__irqentry_text_start &&
  ptr < (unsigned long)&__irqentry_text_end) ||
  (ptr >= (unsigned long)&__softirqentry_text_start &&
   ptr < (unsigned long)&__softirqentry_text_end);
}

/**
* filter_irq_stacks - Find first IRQ stack entry in trace
* @entries: Pointer to stack trace array
* @nr_entries: Number of entries in the storage array
*
* Return: Number of trace entries until IRQ stack starts.
*/
unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries)
{
unsigned int i;

for (i = 0; i < nr_entries; i++) {
  if (in_irqentry_text(entries[i])) {
   /* Include the irqentry function into the stack. */
   return i + 1;
  }
}
return nr_entries;
}
EXPORT_SYMBOL_GPL(filter_irq_stacks);

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