linux/include/linux/trace_recursion.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TRACE_RECURSION_H
#define _LINUX_TRACE_RECURSION_H

#include <linux/interrupt.h>
#include <linux/sched.h>

#ifdef CONFIG_TRACING

/* Only current can touch trace_recursion */

/*
 * For function tracing recursion:
 *  The order of these bits are important.
 *
 *  When function tracing occurs, the following steps are made:
 *   If arch does not support a ftrace feature:
 *    call internal function (uses INTERNAL bits) which calls...
 *   The function callback, which can use the FTRACE bits to
 *    check for recursion.
 */
enum { … };

#define trace_recursion_set(bit) …
#define trace_recursion_clear(bit) …
#define trace_recursion_test(bit) …

#define TRACE_CONTEXT_BITS …

#define TRACE_FTRACE_START …

#define TRACE_LIST_START …

#define TRACE_CONTEXT_MASK …

/*
 * Used for setting context
 *  NMI     = 0
 *  IRQ     = 1
 *  SOFTIRQ = 2
 *  NORMAL  = 3
 */
enum { … };

static __always_inline int trace_get_context_bit(void)
{ … }

#ifdef CONFIG_FTRACE_RECORD_RECURSION
extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip);
#define do_ftrace_record_recursion(ip, pip) …
#else
#define do_ftrace_record_recursion …
#endif

#ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING
#define trace_warn_on_no_rcu(ip) …
#else
#define trace_warn_on_no_rcu …
#endif

/*
 * Preemption is promised to be disabled when return bit >= 0.
 */
static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,
							int start)
{ … }

/*
 * Preemption will be enabled (if it was previously enabled).
 */
static __always_inline void trace_clear_recursion(int bit)
{ … }

/**
 * ftrace_test_recursion_trylock - tests for recursion in same context
 *
 * Use this for ftrace callbacks. This will detect if the function
 * tracing recursed in the same context (normal vs interrupt),
 *
 * Returns: -1 if a recursion happened.
 *           >= 0 if no recursion.
 */
static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
							 unsigned long parent_ip)
{ … }

/**
 * ftrace_test_recursion_unlock - called when function callback is complete
 * @bit: The return of a successful ftrace_test_recursion_trylock()
 *
 * This is used at the end of a ftrace callback.
 */
static __always_inline void ftrace_test_recursion_unlock(int bit)
{ … }

#endif /* CONFIG_TRACING */
#endif /* _LINUX_TRACE_RECURSION_H */