kernel/trace/trace.h

// SPDX-License-Identifier: GPL-2.0

#ifndef _LINUX_KERNEL_TRACE_H
#define _LINUX_KERNEL_TRACE_H

#include <linux/fs.h>
#include <linux/atomic.h>
#include <linux/sched.h>
#include <linux/clocksource.h>
#include <linux/ring_buffer.h>
#include <linux/mmiotrace.h>
#include <linux/tracepoint.h>
#include <linux/ftrace.h>
#include <linux/trace.h>
#include <linux/hw_breakpoint.h>
#include <linux/trace_seq.h>
#include <linux/trace_events.h>
#include <linux/compiler.h>
#include <linux/glob.h>
#include <linux/irq_work.h>
#include <linux/workqueue.h>
#include <linux/ctype.h>

#ifdef CONFIG_FTRACE_SYSCALLS
#include <asm/unistd.h>		/* For NR_SYSCALLS	     */
#include <asm/syscall.h>	/* some archs define it here */
#endif

enum trace_type {
	__TRACE_FIRST_TYPE = 0,

	TRACE_FN,
	TRACE_CTX,
	TRACE_WAKE,
	TRACE_STACK,
	TRACE_PRINT,
	TRACE_BPRINT,
	TRACE_MMIO_RW,
	TRACE_MMIO_MAP,
	TRACE_BRANCH,
	TRACE_GRAPH_RET,
	TRACE_GRAPH_ENT,
	TRACE_USER_STACK,
	TRACE_BLK,
	TRACE_BPUTS,
	TRACE_HWLAT,
	TRACE_RAW_DATA,

	__TRACE_LAST_TYPE,
};


#undef __field
#define __field(type, item)		type	item;

#undef __field_fn
#define __field_fn(type, item)		type	item;

#undef __field_struct
#define __field_struct(type, item)	__field(type, item)

#undef __field_desc
#define __field_desc(type, container, item)

#undef __field_packed
#define __field_packed(type, container, item)

#undef __array
#define __array(type, item, size)	type	item[size];

#undef __array_desc
#define __array_desc(type, container, item, size)

#undef __dynamic_array
#define __dynamic_array(type, item)	type	item[];

#undef F_STRUCT
#define F_STRUCT(args...)		args

#undef FTRACE_ENTRY
#define FTRACE_ENTRY(name, struct_name, id, tstruct, print)		\
	struct struct_name {						\
		struct trace_entry	ent;				\
		tstruct							\
	}

#undef FTRACE_ENTRY_DUP
#define FTRACE_ENTRY_DUP(name, name_struct, id, tstruct, printk)

#undef FTRACE_ENTRY_REG
#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print,	regfn)	\
	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))

#undef FTRACE_ENTRY_PACKED
#define FTRACE_ENTRY_PACKED(name, struct_name, id, tstruct, print)	\
	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print)) __packed

#include "trace_entries.h"

/* Use this for memory failure errors */
#define MEM_FAIL(condition, fmt, ...) ({			\
	static bool __section(".data.once") __warned;		\
	int __ret_warn_once = !!(condition);			\
								\
	if (unlikely(__ret_warn_once && !__warned)) {		\
		__warned = true;				\
		pr_err("ERROR: " fmt, ##__VA_ARGS__);		\
	}							\
	unlikely(__ret_warn_once);				\
})

/*
 * syscalls are special, and need special handling, this is why
 * they are not included in trace_entries.h
 */
struct syscall_trace_enter {
	struct trace_entry	ent;
	int			nr;
	unsigned long		args[];
};

struct syscall_trace_exit {
	struct trace_entry	ent;
	int			nr;
	long			ret;
};

struct kprobe_trace_entry_head {
	struct trace_entry	ent;
	unsigned long		ip;
};

struct kretprobe_trace_entry_head {
	struct trace_entry	ent;
	unsigned long		func;
	unsigned long		ret_ip;
};

/*
 * trace_flag_type is an enumeration that holds different
 * states when a trace occurs. These are:
 *  IRQS_OFF		- interrupts were disabled
 *  IRQS_NOSUPPORT	- arch does not support irqs_disabled_flags
 *  NEED_RESCHED	- reschedule is requested
 *  HARDIRQ		- inside an interrupt handler
 *  SOFTIRQ		- inside a softirq handler
 */
enum trace_flag_type {
	TRACE_FLAG_IRQS_OFF		= 0x01,
	TRACE_FLAG_IRQS_NOSUPPORT	= 0x02,
	TRACE_FLAG_NEED_RESCHED		= 0x04,
	TRACE_FLAG_HARDIRQ		= 0x08,
	TRACE_FLAG_SOFTIRQ		= 0x10,
	TRACE_FLAG_PREEMPT_RESCHED	= 0x20,
	TRACE_FLAG_NMI			= 0x40,
};

#define TRACE_BUF_SIZE		1024

struct trace_array;

/*
 * The CPU trace array - it consists of thousands of trace entries
 * plus some other descriptor data: (for example which task started
 * the trace, etc.)
 */
struct trace_array_cpu {
	atomic_t		disabled;
	void			*buffer_page;	/* ring buffer spare */

	unsigned long		entries;
	unsigned long		saved_latency;
	unsigned long		critical_start;
	unsigned long		critical_end;
	unsigned long		critical_sequence;
	unsigned long		nice;
	unsigned long		policy;
	unsigned long		rt_priority;
	unsigned long		skipped_entries;
	u64			preempt_timestamp;
	pid_t			pid;
	kuid_t			uid;
	char			comm[TASK_COMM_LEN];

#ifdef CONFIG_FUNCTION_TRACER
	int			ftrace_ignore_pid;
#endif
	bool			ignore_pid;
};

struct tracer;
struct trace_option_dentry;

struct array_buffer {
	struct trace_array		*tr;
	struct trace_buffer		*buffer;
	struct trace_array_cpu __percpu	*data;
	u64				time_start;
	int				cpu;
};

#define TRACE_FLAGS_MAX_SIZE		32

struct trace_options {
	struct tracer			*tracer;
	struct trace_option_dentry	*topts;
};

struct trace_pid_list {
	int				pid_max;
	unsigned long			*pids;
};

enum {
	TRACE_PIDS		= BIT(0),
	TRACE_NO_PIDS		= BIT(1),
};

static inline bool pid_type_enabled(int type, struct trace_pid_list *pid_list,
				    struct trace_pid_list *no_pid_list)
{
	/* Return true if the pid list in type has pids */
	return ((type & TRACE_PIDS) && pid_list) ||
		((type & TRACE_NO_PIDS) && no_pid_list);
}

static inline bool still_need_pid_events(int type, struct trace_pid_list *pid_list,
					 struct trace_pid_list *no_pid_list)
{
	/*
	 * Turning off what is in @type, return true if the "other"
	 * pid list, still has pids in it.
	 */
	return (!(type & TRACE_PIDS) && pid_list) ||
		(!(type & TRACE_NO_PIDS) && no_pid_list);
}

typedef bool (*cond_update_fn_t)(struct trace_array *tr, void *cond_data);

/**
 * struct cond_snapshot - conditional snapshot data and callback
 *
 * The cond_snapshot structure encapsulates a callback function and
 * data associated with the snapshot for a given tracing instance.
 *
 * When a snapshot is taken conditionally, by invoking
 * tracing_snapshot_cond(tr, cond_data), the cond_data passed in is
 * passed in turn to the cond_snapshot.update() function.  That data
 * can be compared by the update() implementation with the cond_data
 * contained within the struct cond_snapshot instance associated with
 * the trace_array.  Because the tr->max_lock is held throughout the
 * update() call, the update() function can directly retrieve the
 * cond_snapshot and cond_data associated with the per-instance
 * snapshot associated with the trace_array.
 *
 * The cond_snapshot.update() implementation can save data to be
 * associated with the snapshot if it decides to, and returns 'true'
 * in that case, or it returns 'false' if the conditional snapshot
 * shouldn't be taken.
 *
 * The cond_snapshot instance is created and associated with the
 * user-defined cond_data by tracing_cond_snapshot_enable().
 * Likewise, the cond_snapshot instance is destroyed and is no longer
 * associated with the trace instance by
 * tracing_cond_snapshot_disable().
 *
 * The method below is required.
 *
 * @update: When a conditional snapshot is invoked, the update()
 *	callback function is invoked with the tr->max_lock held.  The
 *	update() implementation signals whether or not to actually
 *	take the snapshot, by returning 'true' if so, 'false' if no
 *	snapshot should be taken.  Because the max_lock is held for
 *	the duration of update(), the implementation is safe to
 *	directly retrieved and save any implementation data it needs
 *	to in association with the snapshot.
 */
struct cond_snapshot {
	void				*cond_data;
	cond_update_fn_t		update;
};

/*
 * The trace array - an array of per-CPU trace arrays. This is the
 * highest level data structure that individual tracers deal with.
 * They have on/off state as well:
 */
struct trace_array {
	struct list_head	list;
	char			*name;
	struct array_buffer	array_buffer;
#ifdef CONFIG_TRACER_MAX_TRACE
	/*
	 * The max_buffer is used to snapshot the trace when a maximum
	 * latency is reached, or when the user initiates a snapshot.
	 * Some tracers will use this to store a maximum trace while
	 * it continues examining live traces.
	 *
	 * The buffers for the max_buffer are set up the same as the array_buffer
	 * When a snapshot is taken, the buffer of the max_buffer is swapped
	 * with the buffer of the array_buffer and the buffers are reset for
	 * the array_buffer so the tracing can continue.
	 */
	struct array_buffer	max_buffer;
	bool			allocated_snapshot;
#endif
#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
	unsigned long		max_latency;
#ifdef CONFIG_FSNOTIFY
	struct dentry		*d_max_latency;
	struct work_struct	fsnotify_work;
	struct irq_work		fsnotify_irqwork;
#endif
#endif
	struct trace_pid_list	__rcu *filtered_pids;
	struct trace_pid_list	__rcu *filtered_no_pids;
	/*
	 * max_lock is used to protect the swapping of buffers
	 * when taking a max snapshot. The buffers themselves are
	 * protected by per_cpu spinlocks. But the action of the swap
	 * needs its own lock.
	 *
	 * This is defined as a arch_spinlock_t in order to help
	 * with performance when lockdep debugging is enabled.
	 *
	 * It is also used in other places outside the update_max_tr
	 * so it needs to be defined outside of the
	 * CONFIG_TRACER_MAX_TRACE.
	 */
	arch_spinlock_t		max_lock;
	int			buffer_disabled;
#ifdef CONFIG_FTRACE_SYSCALLS
	int			sys_refcount_enter;
	int			sys_refcount_exit;
	struct trace_event_file __rcu *enter_syscall_files[NR_syscalls];
	struct trace_event_file __rcu *exit_syscall_files[NR_syscalls];
#endif
	int			stop_count;
	int			clock_id;
	int			nr_topts;
	bool			clear_trace;
	int			buffer_percent;
	unsigned int		n_err_log_entries;
	struct tracer		*current_trace;
	unsigned int		trace_flags;
	unsigned char		trace_flags_index[TRACE_FLAGS_MAX_SIZE];
	unsigned int		flags;
	raw_spinlock_t		start_lock;
	struct list_head	err_log;
	struct dentry		*dir;
	struct dentry		*options;
	struct dentry		*percpu_dir;
	struct dentry		*event_dir;
	struct trace_options	*topts;
	struct list_head	systems;
	struct list_head	events;
	struct trace_event_file *trace_marker_file;
	cpumask_var_t		tracing_cpumask; /* only trace on set CPUs */
	int			ref;
	int			trace_ref;
#ifdef CONFIG_FUNCTION_TRACER
	struct ftrace_ops	*ops;
	struct trace_pid_list	__rcu *function_pids;
	struct trace_pid_list	__rcu *function_no_pids;
#ifdef CONFIG_DYNAMIC_FTRACE
	/* All of these are protected by the ftrace_lock */
	struct list_head	func_probes;
	struct list_head	mod_trace;
	struct list_head	mod_notrace;
#endif
	/* function tracing enabled */
	int			function_enabled;
#endif
	int			time_stamp_abs_ref;
	struct list_head	hist_vars;
#ifdef CONFIG_TRACER_SNAPSHOT
	struct cond_snapshot	*cond_snapshot;
#endif
};

enum {
	TRACE_ARRAY_FL_GLOBAL	= (1 << 0)
};

extern struct list_head ftrace_trace_arrays;

extern struct mutex trace_types_lock;

extern int trace_array_get(struct trace_array *tr);
extern int tracing_check_open_get_tr(struct trace_array *tr);
extern struct trace_array *trace_array_find(const char *instance);
extern struct trace_array *trace_array_find_get(const char *instance);

extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);

extern bool trace_clock_in_ns(struct trace_array *tr);

/*
 * The global tracer (top) should be the first trace array added,
 * but we check the flag anyway.
 */
static inline struct trace_array *top_trace_array(void)
{
	struct trace_array *tr;

	if (list_empty(&ftrace_trace_arrays))
		return NULL;

	tr = list_entry(ftrace_trace_arrays.prev,
			typeof(*tr), list);
	WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
	return tr;
}

#define FTRACE_CMP_TYPE(var, type) \
	__builtin_types_compatible_p(typeof(var), type *)

#undef IF_ASSIGN
#define IF_ASSIGN(var, entry, etype, id)			\
	if (FTRACE_CMP_TYPE(var, etype)) {			\
		var = (typeof(var))(entry);			\
		WARN_ON(id != 0 && (entry)->type != id);	\
		break;						\
	}

/* Will cause compile errors if type is not found. */
extern void __ftrace_bad_type(void);

/*
 * The trace_assign_type is a verifier that the entry type is
 * the same as the type being assigned. To add new types simply
 * add a line with the following format:
 *
 * IF_ASSIGN(var, ent, type, id);
 *
 *  Where "type" is the trace type that includes the trace_entry
 *  as the "ent" item. And "id" is the trace identifier that is
 *  used in the trace_type enum.
 *
 *  If the type can have more than one id, then use zero.
 */
#define trace_assign_type(var, ent)					\
	do {								\
		IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);	\
		IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);	\
		IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);	\
		IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
		IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);	\
		IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT);	\
		IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS);	\
		IF_ASSIGN(var, ent, struct hwlat_entry, TRACE_HWLAT);	\
		IF_ASSIGN(var, ent, struct raw_data_entry, TRACE_RAW_DATA);\
		IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,		\
			  TRACE_MMIO_RW);				\
		IF_ASSIGN(var, ent, struct trace_mmiotrace_map,		\
			  TRACE_MMIO_MAP);				\
		IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
		IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,	\
			  TRACE_GRAPH_ENT);		\
		IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,	\
			  TRACE_GRAPH_RET);		\
		__ftrace_bad_type();					\
	} while (0)

/*
 * An option specific to a tracer. This is a boolean value.
 * The bit is the bit index that sets its value on the
 * flags value in struct tracer_flags.
 */
struct tracer_opt {
	const char	*name; /* Will appear on the trace_options file */
	u32		bit; /* Mask assigned in val field in tracer_flags */
};

/*
 * The set of specific options for a tracer. Your tracer
 * have to set the initial value of the flags val.
 */
struct tracer_flags {
	u32			val;
	struct tracer_opt	*opts;
	struct tracer		*trace;
};

/* Makes more easy to define a tracer opt */
#define TRACER_OPT(s, b)	.name = #s, .bit = b


struct trace_option_dentry {
	struct tracer_opt		*opt;
	struct tracer_flags		*flags;
	struct trace_array		*tr;
	struct dentry			*entry;
};

/**
 * struct tracer - a specific tracer and its callbacks to interact with tracefs
 * @name: the name chosen to select it on the available_tracers file
 * @init: called when one switches to this tracer (echo name > current_tracer)
 * @reset: called when one switches to another tracer
 * @start: called when tracing is unpaused (echo 1 > tracing_on)
 * @stop: called when tracing is paused (echo 0 > tracing_on)
 * @update_thresh: called when tracing_thresh is updated
 * @open: called when the trace file is opened
 * @pipe_open: called when the trace_pipe file is opened
 * @close: called when the trace file is released
 * @pipe_close: called when the trace_pipe file is released
 * @read: override the default read callback on trace_pipe
 * @splice_read: override the default splice_read callback on trace_pipe
 * @selftest: selftest to run on boot (see trace_selftest.c)
 * @print_headers: override the first lines that describe your columns
 * @print_line: callback that prints a trace
 * @set_flag: signals one of your private flags changed (trace_options file)
 * @flags: your private flags
 */
struct tracer {
	const char		*name;
	int			(*init)(struct trace_array *tr);
	void			(*reset)(struct trace_array *tr);
	void			(*start)(struct trace_array *tr);
	void			(*stop)(struct trace_array *tr);
	int			(*update_thresh)(struct trace_array *tr);
	void			(*open)(struct trace_iterator *iter);
	void			(*pipe_open)(struct trace_iterator *iter);
	void			(*close)(struct trace_iterator *iter);
	void			(*pipe_close)(struct trace_iterator *iter);
	ssize_t			(*read)(struct trace_iterator *iter,
					struct file *filp, char __user *ubuf,
					size_t cnt, loff_t *ppos);
	ssize_t			(*splice_read)(struct trace_iterator *iter,
					       struct file *filp,
					       loff_t *ppos,
					       struct pipe_inode_info *pipe,
					       size_t len,
					       unsigned int flags);
#ifdef CONFIG_FTRACE_STARTUP_TEST
	int			(*selftest)(struct tracer *trace,
					    struct trace_array *tr);
#endif
	void			(*print_header)(struct seq_file *m);
	enum print_line_t	(*print_line)(struct trace_iterator *iter);
	/* If you handled the flag setting, return 0 */
	int			(*set_flag)(struct trace_array *tr,
					    u32 old_flags, u32 bit, int set);
	/* Return 0 if OK with change, else return non-zero */
	int			(*flag_changed)(struct trace_array *tr,
						u32 mask, int set);
	struct tracer		*next;
	struct tracer_flags	*flags;
	int			enabled;
	bool			print_max;
	bool			allow_instances;
#ifdef CONFIG_TRACER_MAX_TRACE
	bool			use_max_tr;
#endif
	/* True if tracer cannot be enabled in kernel param */
	bool			noboot;
};


/* 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...
 *   If callback is registered to the "global" list, the list
 *    function is called and recursion checks the GLOBAL bits.
 *    then this function calls...
 *   The function callback, which can use the FTRACE bits to
 *    check for recursion.
 */
enum {
	/* Function recursion bits */
	TRACE_FTRACE_BIT,
	TRACE_FTRACE_NMI_BIT,
	TRACE_FTRACE_IRQ_BIT,
	TRACE_FTRACE_SIRQ_BIT,
	TRACE_FTRACE_TRANSITION_BIT,

	/* Internal use recursion bits */
	TRACE_INTERNAL_BIT,
	TRACE_INTERNAL_NMI_BIT,
	TRACE_INTERNAL_IRQ_BIT,
	TRACE_INTERNAL_SIRQ_BIT,
	TRACE_INTERNAL_TRANSITION_BIT,

	TRACE_BRANCH_BIT,
/*
 * Abuse of the trace_recursion.
 * As we need a way to maintain state if we are tracing the function
 * graph in irq because we want to trace a particular function that
 * was called in irq context but we have irq tracing off. Since this
 * can only be modified by current, we can reuse trace_recursion.
 */
	TRACE_IRQ_BIT,

	/* Set if the function is in the set_graph_function file */
	TRACE_GRAPH_BIT,

	/*
	 * In the very unlikely case that an interrupt came in
	 * at a start of graph tracing, and we want to trace
	 * the function in that interrupt, the depth can be greater
	 * than zero, because of the preempted start of a previous
	 * trace. In an even more unlikely case, depth could be 2
	 * if a softirq interrupted the start of graph tracing,
	 * followed by an interrupt preempting a start of graph
	 * tracing in the softirq, and depth can even be 3
	 * if an NMI came in at the start of an interrupt function
	 * that preempted a softirq start of a function that
	 * preempted normal context!!!! Luckily, it can't be
	 * greater than 3, so the next two bits are a mask
	 * of what the depth is when we set TRACE_GRAPH_BIT
	 */

	TRACE_GRAPH_DEPTH_START_BIT,
	TRACE_GRAPH_DEPTH_END_BIT,

	/*
	 * To implement set_graph_notrace, if this bit is set, we ignore
	 * function graph tracing of called functions, until the return
	 * function is called to clear it.
	 */
	TRACE_GRAPH_NOTRACE_BIT,
};

#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (1<<(bit)); } while (0)
#define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
#define trace_recursion_test(bit)	((current)->trace_recursion & (1<<(bit)))

#define trace_recursion_depth() \
	(((current)->trace_recursion >> TRACE_GRAPH_DEPTH_START_BIT) & 3)
#define trace_recursion_set_depth(depth) \
	do {								\
		current->trace_recursion &=				\
			~(3 << TRACE_GRAPH_DEPTH_START_BIT);		\
		current->trace_recursion |=				\
			((depth) & 3) << TRACE_GRAPH_DEPTH_START_BIT;	\
	} while (0)

#define TRACE_CONTEXT_BITS	4

#define TRACE_FTRACE_START	TRACE_FTRACE_BIT

#define TRACE_LIST_START	TRACE_INTERNAL_BIT

#define TRACE_CONTEXT_MASK	((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)

enum {
	TRACE_CTX_NMI,
	TRACE_CTX_IRQ,
	TRACE_CTX_SOFTIRQ,
	TRACE_CTX_NORMAL,
	TRACE_CTX_TRANSITION,
};

static __always_inline int trace_get_context_bit(void)
{
	int bit;

	if (in_interrupt()) {
		if (in_nmi())
			bit = TRACE_CTX_NMI;

		else if (in_irq())
			bit = TRACE_CTX_IRQ;
		else
			bit = TRACE_CTX_SOFTIRQ;
	} else
		bit = TRACE_CTX_NORMAL;

	return bit;
}

static __always_inline int trace_test_and_set_recursion(int start)
{
	unsigned int val = current->trace_recursion;
	int bit;

	bit = trace_get_context_bit() + start;
	if (unlikely(val & (1 << bit))) {
		/*
		 * It could be that preempt_count has not been updated during
		 * a switch between contexts. Allow for a single recursion.
		 */
		bit = start + TRACE_CTX_TRANSITION;
		if (trace_recursion_test(bit))
			return -1;
		trace_recursion_set(bit);
		barrier();
		return bit;
	}

	val |= 1 << bit;
	current->trace_recursion = val;
	barrier();

	return bit;
}

static __always_inline void trace_clear_recursion(int bit)
{
	unsigned int val = current->trace_recursion;

	bit = 1 << bit;
	val &= ~bit;

	barrier();
	current->trace_recursion = val;
}

static inline struct ring_buffer_iter *
trace_buffer_iter(struct trace_iterator *iter, int cpu)
{
	return iter->buffer_iter ? iter->buffer_iter[cpu] : NULL;
}

int tracer_init(struct tracer *t, struct trace_array *tr);
int tracing_is_enabled(void);
void tracing_reset_online_cpus(struct array_buffer *buf);
void tracing_reset_current(int cpu);
void tracing_reset_all_online_cpus(void);
int tracing_open_generic(struct inode *inode, struct file *filp);
int tracing_open_generic_tr(struct inode *inode, struct file *filp);
bool tracing_is_disabled(void);
bool tracer_tracing_is_on(struct trace_array *tr);
void tracer_tracing_on(struct trace_array *tr);
void tracer_tracing_off(struct trace_array *tr);
struct dentry *trace_create_file(const char *name,
				 umode_t mode,
				 struct dentry *parent,
				 void *data,
				 const struct file_operations *fops);

int tracing_init_dentry(void);

struct ring_buffer_event;

struct ring_buffer_event *
trace_buffer_lock_reserve(struct trace_buffer *buffer,
			  int type,
			  unsigned long len,
			  unsigned long flags,
			  int pc);

struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
						struct trace_array_cpu *data);

struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
					  int *ent_cpu, u64 *ent_ts);

void trace_buffer_unlock_commit_nostack(struct trace_buffer *buffer,
					struct ring_buffer_event *event);

int trace_empty(struct trace_iterator *iter);

void *trace_find_next_entry_inc(struct trace_iterator *iter);

void trace_init_global_iter(struct trace_iterator *iter);

void tracing_iter_reset(struct trace_iterator *iter, int cpu);

unsigned long trace_total_entries_cpu(struct trace_array *tr, int cpu);
unsigned long trace_total_entries(struct trace_array *tr);

void trace_function(struct trace_array *tr,
		    unsigned long ip,
		    unsigned long parent_ip,
		    unsigned long flags, int pc);
void trace_graph_function(struct trace_array *tr,
		    unsigned long ip,
		    unsigned long parent_ip,
		    unsigned long flags, int pc);
void trace_latency_header(struct seq_file *m);
void trace_default_header(struct seq_file *m);
void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
int trace_empty(struct trace_iterator *iter);

void trace_graph_return(struct ftrace_graph_ret *trace);
int trace_graph_entry(struct ftrace_graph_ent *trace);
void set_graph_array(struct trace_array *tr);

void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
void tracing_start_tgid_record(void);
void tracing_stop_tgid_record(void);

int register_tracer(struct tracer *type);
int is_tracing_stopped(void);

loff_t tracing_lseek(struct file *file, loff_t offset, int whence);

extern cpumask_var_t __read_mostly tracing_buffer_mask;

#define for_each_tracing_cpu(cpu)	\
	for_each_cpu(cpu, tracing_buffer_mask)

extern unsigned long nsecs_to_usecs(unsigned long nsecs);

extern unsigned long tracing_thresh;

/* PID filtering */

extern int pid_max;

bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids,
			     pid_t search_pid);
bool trace_ignore_this_task(struct trace_pid_list *filtered_pids,
			    struct trace_pid_list *filtered_no_pids,
			    struct task_struct *task);
void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
				  struct task_struct *self,
				  struct task_struct *task);
void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos);
void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos);
int trace_pid_show(struct seq_file *m, void *v);
void trace_free_pid_list(struct trace_pid_list *pid_list);
int trace_pid_write(struct trace_pid_list *filtered_pids,
		    struct trace_pid_list **new_pid_list,
		    const char __user *ubuf, size_t cnt);

#ifdef CONFIG_TRACER_MAX_TRACE
void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
		   void *cond_data);
void update_max_tr_single(struct trace_array *tr,
			  struct task_struct *tsk, int cpu);
#endif /* CONFIG_TRACER_MAX_TRACE */

#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
	defined(CONFIG_FSNOTIFY)

void latency_fsnotify(struct trace_array *tr);

#else

static inline void latency_fsnotify(struct trace_array *tr) { }

#endif

#ifdef CONFIG_STACKTRACE
void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
		   int pc);
#else
static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
				 int skip, int pc)
{
}
#endif /* CONFIG_STACKTRACE */

extern u64 ftrace_now(int cpu);

extern void trace_find_cmdline(int pid, char comm[]);
extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);

#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_update_tot_cnt;
extern unsigned long ftrace_number_of_pages;
extern unsigned long ftrace_number_of_groups;
void ftrace_init_trace_array(struct trace_array *tr);
#else
static inline void ftrace_init_trace_array(struct trace_array *tr) { }
#endif
#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
extern int DYN_FTRACE_TEST_NAME(void);
#define DYN_FTRACE_TEST_NAME2 trace_selftest_dynamic_test_func2
extern int DYN_FTRACE_TEST_NAME2(void);

extern bool ring_buffer_expanded;
extern bool tracing_selftest_disabled;

#ifdef CONFIG_FTRACE_STARTUP_TEST
extern void __init disable_tracing_selftest(const char *reason);

extern int trace_selftest_startup_function(struct tracer *trace,
					   struct trace_array *tr);
extern int trace_selftest_startup_function_graph(struct tracer *trace,
						 struct trace_array *tr);
extern int trace_selftest_startup_irqsoff(struct tracer *trace,
					  struct trace_array *tr);
extern int trace_selftest_startup_preemptoff(struct tracer *trace,
					     struct trace_array *tr);
extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
						 struct trace_array *tr);
extern int trace_selftest_startup_wakeup(struct tracer *trace,
					 struct trace_array *tr);
extern int trace_selftest_startup_nop(struct tracer *trace,
					 struct trace_array *tr);
extern int trace_selftest_startup_branch(struct tracer *trace,
					 struct trace_array *tr);
/*
 * Tracer data references selftest functions that only occur
 * on boot up. These can be __init functions. Thus, when selftests
 * are enabled, then the tracers need to reference __init functions.
 */
#define __tracer_data		__refdata
#else
static inline void __init disable_tracing_selftest(const char *reason)
{
}
/* Tracers are seldom changed. Optimize when selftests are disabled. */
#define __tracer_data		__read_mostly
#endif /* CONFIG_FTRACE_STARTUP_TEST */

extern void *head_page(struct trace_array_cpu *data);
extern unsigned long long ns2usecs(u64 nsec);
extern int
trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
extern int
trace_vprintk(unsigned long ip, const char *fmt, va_list args);
extern int
trace_array_vprintk(struct trace_array *tr,
		    unsigned long ip, const char *fmt, va_list args);
int trace_array_printk_buf(struct trace_buffer *buffer,
			   unsigned long ip, const char *fmt, ...);
void trace_printk_seq(struct trace_seq *s);
enum print_line_t print_trace_line(struct trace_iterator *iter);

extern char trace_find_mark(unsigned long long duration);

struct ftrace_hash;

struct ftrace_mod_load {
	struct list_head	list;
	char			*func;
	char			*module;
	int			 enable;
};

enum {
	FTRACE_HASH_FL_MOD	= (1 << 0),
};

struct ftrace_hash {
	unsigned long		size_bits;
	struct hlist_head	*buckets;
	unsigned long		count;
	unsigned long		flags;
	struct rcu_head		rcu;
};

struct ftrace_func_entry *
ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip);

static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
{
	return !hash || !(hash->count || (hash->flags & FTRACE_HASH_FL_MOD));
}

/* Standard output formatting function used for function return traces */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

/* Flag options */
#define TRACE_GRAPH_PRINT_OVERRUN       0x1
#define TRACE_GRAPH_PRINT_CPU           0x2
#define TRACE_GRAPH_PRINT_OVERHEAD      0x4
#define TRACE_GRAPH_PRINT_PROC          0x8
#define TRACE_GRAPH_PRINT_DURATION      0x10
#define TRACE_GRAPH_PRINT_ABS_TIME      0x20
#define TRACE_GRAPH_PRINT_REL_TIME      0x40
#define TRACE_GRAPH_PRINT_IRQS          0x80
#define TRACE_GRAPH_PRINT_TAIL          0x100
#define TRACE_GRAPH_SLEEP_TIME          0x200
#define TRACE_GRAPH_GRAPH_TIME          0x400
#define TRACE_GRAPH_PRINT_FILL_SHIFT	28
#define TRACE_GRAPH_PRINT_FILL_MASK	(0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)

extern void ftrace_graph_sleep_time_control(bool enable);

#ifdef CONFIG_FUNCTION_PROFILER
extern void ftrace_graph_graph_time_control(bool enable);
#else
static inline void ftrace_graph_graph_time_control(bool enable) { }
#endif

extern enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags);
extern void print_graph_headers_flags(struct seq_file *s, u32 flags);
extern void
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
extern void graph_trace_open(struct trace_iterator *iter);
extern void graph_trace_close(struct trace_iterator *iter);
extern int __trace_graph_entry(struct trace_array *tr,
			       struct ftrace_graph_ent *trace,
			       unsigned long flags, int pc);
extern void __trace_graph_return(struct trace_array *tr,
				 struct ftrace_graph_ret *trace,
				 unsigned long flags, int pc);

#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;

static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
	unsigned long addr = trace->func;
	int ret = 0;
	struct ftrace_hash *hash;

	preempt_disable_notrace();

	/*
	 * Have to open code "rcu_dereference_sched()" because the
	 * function graph tracer can be called when RCU is not
	 * "watching".
	 * Protected with schedule_on_each_cpu(ftrace_sync)
	 */
	hash = rcu_dereference_protected(ftrace_graph_hash, !preemptible());

	if (ftrace_hash_empty(hash)) {
		ret = 1;
		goto out;
	}

	if (ftrace_lookup_ip(hash, addr)) {

		/*
		 * This needs to be cleared on the return functions
		 * when the depth is zero.
		 */
		trace_recursion_set(TRACE_GRAPH_BIT);
		trace_recursion_set_depth(trace->depth);

		/*
		 * If no irqs are to be traced, but a set_graph_function
		 * is set, and called by an interrupt handler, we still
		 * want to trace it.
		 */
		if (in_irq())
			trace_recursion_set(TRACE_IRQ_BIT);
		else
			trace_recursion_clear(TRACE_IRQ_BIT);
		ret = 1;
	}

out:
	preempt_enable_notrace();
	return ret;
}

static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
{
	if (trace_recursion_test(TRACE_GRAPH_BIT) &&
	    trace->depth == trace_recursion_depth())
		trace_recursion_clear(TRACE_GRAPH_BIT);
}

static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
	int ret = 0;
	struct ftrace_hash *notrace_hash;

	preempt_disable_notrace();

	/*
	 * Have to open code "rcu_dereference_sched()" because the
	 * function graph tracer can be called when RCU is not
	 * "watching".
	 * Protected with schedule_on_each_cpu(ftrace_sync)
	 */
	notrace_hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
						 !preemptible());

	if (ftrace_lookup_ip(notrace_hash, addr))
		ret = 1;

	preempt_enable_notrace();
	return ret;
}
#else
static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
	return 1;
}

static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
	return 0;
}
static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
{ }
#endif /* CONFIG_DYNAMIC_FTRACE */

extern unsigned int fgraph_max_depth;

static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
{
	/* trace it when it is-nested-in or is a function enabled. */
	return !(trace_recursion_test(TRACE_GRAPH_BIT) ||
		 ftrace_graph_addr(trace)) ||
		(trace->depth < 0) ||
		(fgraph_max_depth && trace->depth >= fgraph_max_depth);
}

#else /* CONFIG_FUNCTION_GRAPH_TRACER */
static inline enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
	return TRACE_TYPE_UNHANDLED;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

extern struct list_head ftrace_pids;

#ifdef CONFIG_FUNCTION_TRACER

#define FTRACE_PID_IGNORE	-1
#define FTRACE_PID_TRACE	-2

struct ftrace_func_command {
	struct list_head	list;
	char			*name;
	int			(*func)(struct trace_array *tr,
					struct ftrace_hash *hash,
					char *func, char *cmd,
					char *params, int enable);
};
extern bool ftrace_filter_param __initdata;
static inline int ftrace_trace_task(struct trace_array *tr)
{
	return this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid) !=
		FTRACE_PID_IGNORE;
}
extern int ftrace_is_dead(void);
int ftrace_create_function_files(struct trace_array *tr,
				 struct dentry *parent);
void ftrace_destroy_function_files(struct trace_array *tr);
int ftrace_allocate_ftrace_ops(struct trace_array *tr);
void ftrace_free_ftrace_ops(struct trace_array *tr);
void ftrace_init_global_array_ops(struct trace_array *tr);
void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func);
void ftrace_reset_array_ops(struct trace_array *tr);
void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer);
void ftrace_init_tracefs_toplevel(struct trace_array *tr,
				  struct dentry *d_tracer);
void ftrace_clear_pids(struct trace_array *tr);
int init_function_trace(void);
void ftrace_pid_follow_fork(struct trace_array *tr, bool enable);
#else
static inline int ftrace_trace_task(struct trace_array *tr)
{
	return 1;
}
static inline int ftrace_is_dead(void) { return 0; }
static inline int
ftrace_create_function_files(struct trace_array *tr,
			     struct dentry *parent)
{
	return 0;
}
static inline int ftrace_allocate_ftrace_ops(struct trace_array *tr)
{
	return 0;
}
static inline void ftrace_free_ftrace_ops(struct trace_array *tr) { }
static inline void ftrace_destroy_function_files(struct trace_array *tr) { }
static inline __init void
ftrace_init_global_array_ops(struct trace_array *tr) { }
static inline void ftrace_reset_array_ops(struct trace_array *tr) { }
static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }
static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }
static inline void ftrace_clear_pids(struct trace_array *tr) { }
static inline int init_function_trace(void) { return 0; }
static inline void ftrace_pid_follow_fork(struct trace_array *tr, bool enable) { }
/* ftace_func_t type is not defined, use macro instead of static inline */
#define ftrace_init_array_ops(tr, func) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER */

#if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_DYNAMIC_FTRACE)

struct ftrace_probe_ops {
	void			(*func)(unsigned long ip,
					unsigned long parent_ip,
					struct trace_array *tr,
					struct ftrace_probe_ops *ops,
					void *data);
	int			(*init)(struct ftrace_probe_ops *ops,
					struct trace_array *tr,
					unsigned long ip, void *init_data,
					void **data);
	void			(*free)(struct ftrace_probe_ops *ops,
					struct trace_array *tr,
					unsigned long ip, void *data);
	int			(*print)(struct seq_file *m,
					 unsigned long ip,
					 struct ftrace_probe_ops *ops,
					 void *data);
};

struct ftrace_func_mapper;
typedef int (*ftrace_mapper_func)(void *data);

struct ftrace_func_mapper *allocate_ftrace_func_mapper(void);
void **ftrace_func_mapper_find_ip(struct ftrace_func_mapper *mapper,
					   unsigned long ip);
int ftrace_func_mapper_add_ip(struct ftrace_func_mapper *mapper,
			       unsigned long ip, void *data);
void *ftrace_func_mapper_remove_ip(struct ftrace_func_mapper *mapper,
				   unsigned long ip);
void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
			     ftrace_mapper_func free_func);

extern int
register_ftrace_function_probe(char *glob, struct trace_array *tr,
			       struct ftrace_probe_ops *ops, void *data);
extern int
unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
				      struct ftrace_probe_ops *ops);
extern void clear_ftrace_function_probes(struct trace_array *tr);

int register_ftrace_command(struct ftrace_func_command *cmd);
int unregister_ftrace_command(struct ftrace_func_command *cmd);

void ftrace_create_filter_files(struct ftrace_ops *ops,
				struct dentry *parent);
void ftrace_destroy_filter_files(struct ftrace_ops *ops);

extern int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
			     int len, int reset);
extern int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
			      int len, int reset);
#else
struct ftrace_func_command;

static inline __init int register_ftrace_command(struct ftrace_func_command *cmd)
{
	return -EINVAL;
}
static inline __init int unregister_ftrace_command(char *cmd_name)
{
	return -EINVAL;
}
static inline void clear_ftrace_function_probes(struct trace_array *tr)
{
}

/*
 * The ops parameter passed in is usually undefined.
 * This must be a macro.
 */
#define ftrace_create_filter_files(ops, parent) do { } while (0)
#define ftrace_destroy_filter_files(ops) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER && CONFIG_DYNAMIC_FTRACE */

bool ftrace_event_is_function(struct trace_event_call *call);

/*
 * struct trace_parser - servers for reading the user input separated by spaces
 * @cont: set if the input is not complete - no final space char was found
 * @buffer: holds the parsed user input
 * @idx: user input length
 * @size: buffer size
 */
struct trace_parser {
	bool		cont;
	char		*buffer;
	unsigned	idx;
	unsigned	size;
};

static inline bool trace_parser_loaded(struct trace_parser *parser)
{
	return (parser->idx != 0);
}

static inline bool trace_parser_cont(struct trace_parser *parser)
{
	return parser->cont;
}

static inline void trace_parser_clear(struct trace_parser *parser)
{
	parser->cont = false;
	parser->idx = 0;
}

extern int trace_parser_get_init(struct trace_parser *parser, int size);
extern void trace_parser_put(struct trace_parser *parser);
extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
	size_t cnt, loff_t *ppos);

/*
 * Only create function graph options if function graph is configured.
 */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# define FGRAPH_FLAGS						\
		C(DISPLAY_GRAPH,	"display-graph"),
#else
# define FGRAPH_FLAGS
#endif

#ifdef CONFIG_BRANCH_TRACER
# define BRANCH_FLAGS					\
		C(BRANCH,		"branch"),
#else
# define BRANCH_FLAGS
#endif

#ifdef CONFIG_FUNCTION_TRACER
# define FUNCTION_FLAGS						\
		C(FUNCTION,		"function-trace"),	\
		C(FUNC_FORK,		"function-fork"),
# define FUNCTION_DEFAULT_FLAGS		TRACE_ITER_FUNCTION
#else
# define FUNCTION_FLAGS
# define FUNCTION_DEFAULT_FLAGS		0UL
# define TRACE_ITER_FUNC_FORK		0UL
#endif

#ifdef CONFIG_STACKTRACE
# define STACK_FLAGS				\
		C(STACKTRACE,		"stacktrace"),
#else
# define STACK_FLAGS
#endif

/*
 * trace_iterator_flags is an enumeration that defines bit
 * positions into trace_flags that controls the output.
 *
 * NOTE: These bits must match the trace_options array in
 *       trace.c (this macro guarantees it).
 */
#define TRACE_FLAGS						\
		C(PRINT_PARENT,		"print-parent"),	\
		C(SYM_OFFSET,		"sym-offset"),		\
		C(SYM_ADDR,		"sym-addr"),		\
		C(VERBOSE,		"verbose"),		\
		C(RAW,			"raw"),			\
		C(HEX,			"hex"),			\
		C(BIN,			"bin"),			\
		C(BLOCK,		"block"),		\
		C(PRINTK,		"trace_printk"),	\
		C(ANNOTATE,		"annotate"),		\
		C(USERSTACKTRACE,	"userstacktrace"),	\
		C(SYM_USEROBJ,		"sym-userobj"),		\
		C(PRINTK_MSGONLY,	"printk-msg-only"),	\
		C(CONTEXT_INFO,		"context-info"),   /* Print pid/cpu/time */ \
		C(LATENCY_FMT,		"latency-format"),	\
		C(RECORD_CMD,		"record-cmd"),		\
		C(RECORD_TGID,		"record-tgid"),		\
		C(OVERWRITE,		"overwrite"),		\
		C(STOP_ON_FREE,		"disable_on_free"),	\
		C(IRQ_INFO,		"irq-info"),		\
		C(MARKERS,		"markers"),		\
		C(EVENT_FORK,		"event-fork"),		\
		C(PAUSE_ON_TRACE,	"pause-on-trace"),	\
		FUNCTION_FLAGS					\
		FGRAPH_FLAGS					\
		STACK_FLAGS					\
		BRANCH_FLAGS

/*
 * By defining C, we can make TRACE_FLAGS a list of bit names
 * that will define the bits for the flag masks.
 */
#undef C
#define C(a, b) TRACE_ITER_##a##_BIT

enum trace_iterator_bits {
	TRACE_FLAGS
	/* Make sure we don't go more than we have bits for */
	TRACE_ITER_LAST_BIT
};

/*
 * By redefining C, we can make TRACE_FLAGS a list of masks that
 * use the bits as defined above.
 */
#undef C
#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)

enum trace_iterator_flags { TRACE_FLAGS };

/*
 * TRACE_ITER_SYM_MASK masks the options in trace_flags that
 * control the output of kernel symbols.
 */
#define TRACE_ITER_SYM_MASK \
	(TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)

extern struct tracer nop_trace;

#ifdef CONFIG_BRANCH_TRACER
extern int enable_branch_tracing(struct trace_array *tr);
extern void disable_branch_tracing(void);
static inline int trace_branch_enable(struct trace_array *tr)
{
	if (tr->trace_flags & TRACE_ITER_BRANCH)
		return enable_branch_tracing(tr);
	return 0;
}
static inline void trace_branch_disable(void)
{
	/* due to races, always disable */
	disable_branch_tracing();
}
#else
static inline int trace_branch_enable(struct trace_array *tr)
{
	return 0;
}
static inline void trace_branch_disable(void)
{
}
#endif /* CONFIG_BRANCH_TRACER */

/* set ring buffers to default size if not already done so */
int tracing_update_buffers(void);

struct ftrace_event_field {
	struct list_head	link;
	const char		*name;
	const char		*type;
	int			filter_type;
	int			offset;
	int			size;
	int			is_signed;
};

struct prog_entry;

struct event_filter {
	struct prog_entry __rcu	*prog;
	char			*filter_string;
};

struct event_subsystem {
	struct list_head	list;
	const char		*name;
	struct event_filter	*filter;
	int			ref_count;
};

struct trace_subsystem_dir {
	struct list_head		list;
	struct event_subsystem		*subsystem;
	struct trace_array		*tr;
	struct dentry			*entry;
	int				ref_count;
	int				nr_events;
};

extern int call_filter_check_discard(struct trace_event_call *call, void *rec,
				     struct trace_buffer *buffer,
				     struct ring_buffer_event *event);

void trace_buffer_unlock_commit_regs(struct trace_array *tr,
				     struct trace_buffer *buffer,
				     struct ring_buffer_event *event,
				     unsigned long flags, int pc,
				     struct pt_regs *regs);

static inline void trace_buffer_unlock_commit(struct trace_array *tr,
					      struct trace_buffer *buffer,
					      struct ring_buffer_event *event,
					      unsigned long flags, int pc)
{
	trace_buffer_unlock_commit_regs(tr, buffer, event, flags, pc, NULL);
}

DECLARE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
DECLARE_PER_CPU(int, trace_buffered_event_cnt);
void trace_buffered_event_disable(void);
void trace_buffered_event_enable(void);

static inline void
__trace_event_discard_commit(struct trace_buffer *buffer,
			     struct ring_buffer_event *event)
{
	if (this_cpu_read(trace_buffered_event) == event) {
		/* Simply release the temp buffer */
		this_cpu_dec(trace_buffered_event_cnt);
		return;
	}
	ring_buffer_discard_commit(buffer, event);
}

/*
 * Helper function for event_trigger_unlock_commit{_regs}().
 * If there are event triggers attached to this event that requires
 * filtering against its fields, then they will be called as the
 * entry already holds the field information of the current event.
 *
 * It also checks if the event should be discarded or not.
 * It is to be discarded if the event is soft disabled and the
 * event was only recorded to process triggers, or if the event
 * filter is active and this event did not match the filters.
 *
 * Returns true if the event is discarded, false otherwise.
 */
static inline bool
__event_trigger_test_discard(struct trace_event_file *file,
			     struct trace_buffer *buffer,
			     struct ring_buffer_event *event,
			     void *entry,
			     enum event_trigger_type *tt)
{
	unsigned long eflags = file->flags;

	if (eflags & EVENT_FILE_FL_TRIGGER_COND)
		*tt = event_triggers_call(file, entry, event);

	if (likely(!(file->flags & (EVENT_FILE_FL_SOFT_DISABLED |
				    EVENT_FILE_FL_FILTERED |
				    EVENT_FILE_FL_PID_FILTER))))
		return false;

	if (file->flags & EVENT_FILE_FL_SOFT_DISABLED)
		goto discard;

	if (file->flags & EVENT_FILE_FL_FILTERED &&
	    !filter_match_preds(file->filter, entry))
		goto discard;

	if ((file->flags & EVENT_FILE_FL_PID_FILTER) &&
	    trace_event_ignore_this_pid(file))
		goto discard;

	return false;
 discard:
	__trace_event_discard_commit(buffer, event);
	return true;
}

/**
 * event_trigger_unlock_commit - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 */
static inline void
event_trigger_unlock_commit(struct trace_event_file *file,
			    struct trace_buffer *buffer,
			    struct ring_buffer_event *event,
			    void *entry, unsigned long irq_flags, int pc)
{
	enum event_trigger_type tt = ETT_NONE;

	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
		trace_buffer_unlock_commit(file->tr, buffer, event, irq_flags, pc);

	if (tt)
		event_triggers_post_call(file, tt);
}

/**
 * event_trigger_unlock_commit_regs - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 *
 * Same as event_trigger_unlock_commit() but calls
 * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
 */
static inline void
event_trigger_unlock_commit_regs(struct trace_event_file *file,
				 struct trace_buffer *buffer,
				 struct ring_buffer_event *event,
				 void *entry, unsigned long irq_flags, int pc,
				 struct pt_regs *regs)
{
	enum event_trigger_type tt = ETT_NONE;

	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
		trace_buffer_unlock_commit_regs(file->tr, buffer, event,
						irq_flags, pc, regs);

	if (tt)
		event_triggers_post_call(file, tt);
}

#define FILTER_PRED_INVALID	((unsigned short)-1)
#define FILTER_PRED_IS_RIGHT	(1 << 15)
#define FILTER_PRED_FOLD	(1 << 15)

/*
 * The max preds is the size of unsigned short with
 * two flags at the MSBs. One bit is used for both the IS_RIGHT
 * and FOLD flags. The other is reserved.
 *
 * 2^14 preds is way more than enough.
 */
#define MAX_FILTER_PRED		16384

struct filter_pred;
struct regex;

typedef int (*filter_pred_fn_t) (struct filter_pred *pred, void *event);

typedef int (*regex_match_func)(char *str, struct regex *r, int len);

enum regex_type {
	MATCH_FULL = 0,
	MATCH_FRONT_ONLY,
	MATCH_MIDDLE_ONLY,
	MATCH_END_ONLY,
	MATCH_GLOB,
	MATCH_INDEX,
};

struct regex {
	char			pattern[MAX_FILTER_STR_VAL];
	int			len;
	int			field_len;
	regex_match_func	match;
};

struct filter_pred {
	filter_pred_fn_t 	fn;
	u64 			val;
	struct regex		regex;
	unsigned short		*ops;
	struct ftrace_event_field *field;
	int 			offset;
	int			not;
	int 			op;
};

static inline bool is_string_field(struct ftrace_event_field *field)
{
	return field->filter_type == FILTER_DYN_STRING ||
	       field->filter_type == FILTER_STATIC_STRING ||
	       field->filter_type == FILTER_PTR_STRING ||
	       field->filter_type == FILTER_COMM;
}

static inline bool is_function_field(struct ftrace_event_field *field)
{
	return field->filter_type == FILTER_TRACE_FN;
}

extern enum regex_type
filter_parse_regex(char *buff, int len, char **search, int *not);
extern void print_event_filter(struct trace_event_file *file,
			       struct trace_seq *s);
extern int apply_event_filter(struct trace_event_file *file,
			      char *filter_string);
extern int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
					char *filter_string);
extern void print_subsystem_event_filter(struct event_subsystem *system,
					 struct trace_seq *s);
extern int filter_assign_type(const char *type);
extern int create_event_filter(struct trace_array *tr,
			       struct trace_event_call *call,
			       char *filter_str, bool set_str,
			       struct event_filter **filterp);
extern void free_event_filter(struct event_filter *filter);

struct ftrace_event_field *
trace_find_event_field(struct trace_event_call *call, char *name);

extern void trace_event_enable_cmd_record(bool enable);
extern void trace_event_enable_tgid_record(bool enable);

extern int event_trace_init(void);
extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
extern int event_trace_del_tracer(struct trace_array *tr);
extern void __trace_early_add_events(struct trace_array *tr);

extern struct trace_event_file *__find_event_file(struct trace_array *tr,
						  const char *system,
						  const char *event);
extern struct trace_event_file *find_event_file(struct trace_array *tr,
						const char *system,
						const char *event);

static inline void *event_file_data(struct file *filp)
{
	return READ_ONCE(file_inode(filp)->i_private);
}

extern struct mutex event_mutex;
extern struct list_head ftrace_events;

extern const struct file_operations event_trigger_fops;
extern const struct file_operations event_hist_fops;
extern const struct file_operations event_hist_debug_fops;
extern const struct file_operations event_inject_fops;

#ifdef CONFIG_HIST_TRIGGERS
extern int register_trigger_hist_cmd(void);
extern int register_trigger_hist_enable_disable_cmds(void);
#else
static inline int register_trigger_hist_cmd(void) { return 0; }
static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
#endif

extern int register_trigger_cmds(void);
extern void clear_event_triggers(struct trace_array *tr);

struct event_trigger_data {
	unsigned long			count;
	int				ref;
	struct event_trigger_ops	*ops;
	struct event_command		*cmd_ops;
	struct event_filter __rcu	*filter;
	char				*filter_str;
	void				*private_data;
	bool				paused;
	bool				paused_tmp;
	struct list_head		list;
	char				*name;
	struct list_head		named_list;
	struct event_trigger_data	*named_data;
};

/* Avoid typos */
#define ENABLE_EVENT_STR	"enable_event"
#define DISABLE_EVENT_STR	"disable_event"
#define ENABLE_HIST_STR		"enable_hist"
#define DISABLE_HIST_STR	"disable_hist"

struct enable_trigger_data {
	struct trace_event_file		*file;
	bool				enable;
	bool				hist;
};

extern int event_enable_trigger_print(struct seq_file *m,
				      struct event_trigger_ops *ops,
				      struct event_trigger_data *data);
extern void event_enable_trigger_free(struct event_trigger_ops *ops,
				      struct event_trigger_data *data);
extern int event_enable_trigger_func(struct event_command *cmd_ops,
				     struct trace_event_file *file,
				     char *glob, char *cmd, char *param);
extern int event_enable_register_trigger(char *glob,
					 struct event_trigger_ops *ops,
					 struct event_trigger_data *data,
					 struct trace_event_file *file);
extern void event_enable_unregister_trigger(char *glob,
					    struct event_trigger_ops *ops,
					    struct event_trigger_data *test,
					    struct trace_event_file *file);
extern void trigger_data_free(struct event_trigger_data *data);
extern int event_trigger_init(struct event_trigger_ops *ops,
			      struct event_trigger_data *data);
extern int trace_event_trigger_enable_disable(struct trace_event_file *file,
					      int trigger_enable);
extern void update_cond_flag(struct trace_event_file *file);
extern int set_trigger_filter(char *filter_str,
			      struct event_trigger_data *trigger_data,
			      struct trace_event_file *file);
extern struct event_trigger_data *find_named_trigger(const char *name);
extern bool is_named_trigger(struct event_trigger_data *test);
extern int save_named_trigger(const char *name,
			      struct event_trigger_data *data);
extern void del_named_trigger(struct event_trigger_data *data);
extern void pause_named_trigger(struct event_trigger_data *data);
extern void unpause_named_trigger(struct event_trigger_data *data);
extern void set_named_trigger_data(struct event_trigger_data *data,
				   struct event_trigger_data *named_data);
extern struct event_trigger_data *
get_named_trigger_data(struct event_trigger_data *data);
extern int register_event_command(struct event_command *cmd);
extern int unregister_event_command(struct event_command *cmd);
extern int register_trigger_hist_enable_disable_cmds(void);

/**
 * struct event_trigger_ops - callbacks for trace event triggers
 *
 * The methods in this structure provide per-event trigger hooks for
 * various trigger operations.
 *
 * All the methods below, except for @init() and @free(), must be
 * implemented.
 *
 * @func: The trigger 'probe' function called when the triggering
 *	event occurs.  The data passed into this callback is the data
 *	that was supplied to the event_command @reg() function that
 *	registered the trigger (see struct event_command) along with
 *	the trace record, rec.
 *
 * @init: An optional initialization function called for the trigger
 *	when the trigger is registered (via the event_command reg()
 *	function).  This can be used to perform per-trigger
 *	initialization such as incrementing a per-trigger reference
 *	count, for instance.  This is usually implemented by the
 *	generic utility function @event_trigger_init() (see
 *	trace_event_triggers.c).
 *
 * @free: An optional de-initialization function called for the
 *	trigger when the trigger is unregistered (via the
 *	event_command @reg() function).  This can be used to perform
 *	per-trigger de-initialization such as decrementing a
 *	per-trigger reference count and freeing corresponding trigger
 *	data, for instance.  This is usually implemented by the
 *	generic utility function @event_trigger_free() (see
 *	trace_event_triggers.c).
 *
 * @print: The callback function invoked to have the trigger print
 *	itself.  This is usually implemented by a wrapper function
 *	that calls the generic utility function @event_trigger_print()
 *	(see trace_event_triggers.c).
 */
struct event_trigger_ops {
	void			(*func)(struct event_trigger_data *data,
					void *rec,
					struct ring_buffer_event *rbe);
	int			(*init)(struct event_trigger_ops *ops,
					struct event_trigger_data *data);
	void			(*free)(struct event_trigger_ops *ops,
					struct event_trigger_data *data);
	int			(*print)(struct seq_file *m,
					 struct event_trigger_ops *ops,
					 struct event_trigger_data *data);
};

/**
 * struct event_command - callbacks and data members for event commands
 *
 * Event commands are invoked by users by writing the command name
 * into the 'trigger' file associated with a trace event.  The
 * parameters associated with a specific invocation of an event
 * command are used to create an event trigger instance, which is
 * added to the list of trigger instances associated with that trace
 * event.  When the event is hit, the set of triggers associated with
 * that event is invoked.
 *
 * The data members in this structure provide per-event command data
 * for various event commands.
 *
 * All the data members below, except for @post_trigger, must be set
 * for each event command.
 *
 * @name: The unique name that identifies the event command.  This is
 *	the name used when setting triggers via trigger files.
 *
 * @trigger_type: A unique id that identifies the event command
 *	'type'.  This value has two purposes, the first to ensure that
 *	only one trigger of the same type can be set at a given time
 *	for a particular event e.g. it doesn't make sense to have both
 *	a traceon and traceoff trigger attached to a single event at
 *	the same time, so traceon and traceoff have the same type
 *	though they have different names.  The @trigger_type value is
 *	also used as a bit value for deferring the actual trigger
 *	action until after the current event is finished.  Some
 *	commands need to do this if they themselves log to the trace
 *	buffer (see the @post_trigger() member below).  @trigger_type
 *	values are defined by adding new values to the trigger_type
 *	enum in include/linux/trace_events.h.
 *
 * @flags: See the enum event_command_flags below.
 *
 * All the methods below, except for @set_filter() and @unreg_all(),
 * must be implemented.
 *
 * @func: The callback function responsible for parsing and
 *	registering the trigger written to the 'trigger' file by the
 *	user.  It allocates the trigger instance and registers it with
 *	the appropriate trace event.  It makes use of the other
 *	event_command callback functions to orchestrate this, and is
 *	usually implemented by the generic utility function
 *	@event_trigger_callback() (see trace_event_triggers.c).
 *
 * @reg: Adds the trigger to the list of triggers associated with the
 *	event, and enables the event trigger itself, after
 *	initializing it (via the event_trigger_ops @init() function).
 *	This is also where commands can use the @trigger_type value to
 *	make the decision as to whether or not multiple instances of
 *	the trigger should be allowed.  This is usually implemented by
 *	the generic utility function @register_trigger() (see
 *	trace_event_triggers.c).
 *
 * @unreg: Removes the trigger from the list of triggers associated
 *	with the event, and disables the event trigger itself, after
 *	initializing it (via the event_trigger_ops @free() function).
 *	This is usually implemented by the generic utility function
 *	@unregister_trigger() (see trace_event_triggers.c).
 *
 * @unreg_all: An optional function called to remove all the triggers
 *	from the list of triggers associated with the event.  Called
 *	when a trigger file is opened in truncate mode.
 *
 * @set_filter: An optional function called to parse and set a filter
 *	for the trigger.  If no @set_filter() method is set for the
 *	event command, filters set by the user for the command will be
 *	ignored.  This is usually implemented by the generic utility
 *	function @set_trigger_filter() (see trace_event_triggers.c).
 *
 * @get_trigger_ops: The callback function invoked to retrieve the
 *	event_trigger_ops implementation associated with the command.
 */
struct event_command {
	struct list_head	list;
	char			*name;
	enum event_trigger_type	trigger_type;
	int			flags;
	int			(*func)(struct event_command *cmd_ops,
					struct trace_event_file *file,
					char *glob, char *cmd, char *params);
	int			(*reg)(char *glob,
				       struct event_trigger_ops *ops,
				       struct event_trigger_data *data,
				       struct trace_event_file *file);
	void			(*unreg)(char *glob,
					 struct event_trigger_ops *ops,
					 struct event_trigger_data *data,
					 struct trace_event_file *file);
	void			(*unreg_all)(struct trace_event_file *file);
	int			(*set_filter)(char *filter_str,
					      struct event_trigger_data *data,
					      struct trace_event_file *file);
	struct event_trigger_ops *(*get_trigger_ops)(char *cmd, char *param);
};

/**
 * enum event_command_flags - flags for struct event_command
 *
 * @POST_TRIGGER: A flag that says whether or not this command needs
 *	to have its action delayed until after the current event has
 *	been closed.  Some triggers need to avoid being invoked while
 *	an event is currently in the process of being logged, since
 *	the trigger may itself log data into the trace buffer.  Thus
 *	we make sure the current event is committed before invoking
 *	those triggers.  To do that, the trigger invocation is split
 *	in two - the first part checks the filter using the current
 *	trace record; if a command has the @post_trigger flag set, it
 *	sets a bit for itself in the return value, otherwise it
 *	directly invokes the trigger.  Once all commands have been
 *	either invoked or set their return flag, the current record is
 *	either committed or discarded.  At that point, if any commands
 *	have deferred their triggers, those commands are finally
 *	invoked following the close of the current event.  In other
 *	words, if the event_trigger_ops @func() probe implementation
 *	itself logs to the trace buffer, this flag should be set,
 *	otherwise it can be left unspecified.
 *
 * @NEEDS_REC: A flag that says whether or not this command needs
 *	access to the trace record in order to perform its function,
 *	regardless of whether or not it has a filter associated with
 *	it (filters make a trigger require access to the trace record
 *	but are not always present).
 */
enum event_command_flags {
	EVENT_CMD_FL_POST_TRIGGER	= 1,
	EVENT_CMD_FL_NEEDS_REC		= 2,
};

static inline bool event_command_post_trigger(struct event_command *cmd_ops)
{
	return cmd_ops->flags & EVENT_CMD_FL_POST_TRIGGER;
}

static inline bool event_command_needs_rec(struct event_command *cmd_ops)
{
	return cmd_ops->flags & EVENT_CMD_FL_NEEDS_REC;
}

extern int trace_event_enable_disable(struct trace_event_file *file,
				      int enable, int soft_disable);
extern int tracing_alloc_snapshot(void);
extern void tracing_snapshot_cond(struct trace_array *tr, void *cond_data);
extern int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update);

extern int tracing_snapshot_cond_disable(struct trace_array *tr);
extern void *tracing_cond_snapshot_data(struct trace_array *tr);

extern const char *__start___trace_bprintk_fmt[];
extern const char *__stop___trace_bprintk_fmt[];

extern const char *__start___tracepoint_str[];
extern const char *__stop___tracepoint_str[];

void trace_printk_control(bool enabled);
void trace_printk_start_comm(void);
int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);

/* Used from boot time tracer */
extern int trace_set_options(struct trace_array *tr, char *option);
extern int tracing_set_tracer(struct trace_array *tr, const char *buf);
extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
					  unsigned long size, int cpu_id);
extern int tracing_set_cpumask(struct trace_array *tr,
				cpumask_var_t tracing_cpumask_new);


#define MAX_EVENT_NAME_LEN	64

extern int trace_run_command(const char *buf, int (*createfn)(int, char**));
extern ssize_t trace_parse_run_command(struct file *file,
		const char __user *buffer, size_t count, loff_t *ppos,
		int (*createfn)(int, char**));

extern unsigned int err_pos(char *cmd, const char *str);
extern void tracing_log_err(struct trace_array *tr,
			    const char *loc, const char *cmd,
			    const char **errs, u8 type, u8 pos);

/*
 * Normal trace_printk() and friends allocates special buffers
 * to do the manipulation, as well as saves the print formats
 * into sections to display. But the trace infrastructure wants
 * to use these without the added overhead at the price of being
 * a bit slower (used mainly for warnings, where we don't care
 * about performance). The internal_trace_puts() is for such
 * a purpose.
 */
#define internal_trace_puts(str) __trace_puts(_THIS_IP_, str, strlen(str))

#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, id, tstruct, print)	\
	extern struct trace_event_call					\
	__aligned(4) event_##call;
#undef FTRACE_ENTRY_DUP
#define FTRACE_ENTRY_DUP(call, struct_name, id, tstruct, print)	\
	FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
#undef FTRACE_ENTRY_PACKED
#define FTRACE_ENTRY_PACKED(call, struct_name, id, tstruct, print) \
	FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))

#include "trace_entries.h"

#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_FUNCTION_TRACER)
int perf_ftrace_event_register(struct trace_event_call *call,
			       enum trace_reg type, void *data);
#else
#define perf_ftrace_event_register NULL
#endif

#ifdef CONFIG_FTRACE_SYSCALLS
void init_ftrace_syscalls(void);
const char *get_syscall_name(int syscall);
#else
static inline void init_ftrace_syscalls(void) { }
static inline const char *get_syscall_name(int syscall)
{
	return NULL;
}
#endif

#ifdef CONFIG_EVENT_TRACING
void trace_event_init(void);
void trace_event_eval_update(struct trace_eval_map **map, int len);
/* Used from boot time tracer */
extern int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
extern int trigger_process_regex(struct trace_event_file *file, char *buff);
#else
static inline void __init trace_event_init(void) { }
static inline void trace_event_eval_update(struct trace_eval_map **map, int len) { }
#endif

#ifdef CONFIG_TRACER_SNAPSHOT
void tracing_snapshot_instance(struct trace_array *tr);
int tracing_alloc_snapshot_instance(struct trace_array *tr);
#else
static inline void tracing_snapshot_instance(struct trace_array *tr) { }
static inline int tracing_alloc_snapshot_instance(struct trace_array *tr)
{
	return 0;
}
#endif

#ifdef CONFIG_PREEMPT_TRACER
void tracer_preempt_on(unsigned long a0, unsigned long a1);
void tracer_preempt_off(unsigned long a0, unsigned long a1);
#else
static inline void tracer_preempt_on(unsigned long a0, unsigned long a1) { }
static inline void tracer_preempt_off(unsigned long a0, unsigned long a1) { }
#endif
#ifdef CONFIG_IRQSOFF_TRACER
void tracer_hardirqs_on(unsigned long a0, unsigned long a1);
void tracer_hardirqs_off(unsigned long a0, unsigned long a1);
#else
static inline void tracer_hardirqs_on(unsigned long a0, unsigned long a1) { }
static inline void tracer_hardirqs_off(unsigned long a0, unsigned long a1) { }
#endif

extern struct trace_iterator *tracepoint_print_iter;

/*
 * Reset the state of the trace_iterator so that it can read consumed data.
 * Normally, the trace_iterator is used for reading the data when it is not
 * consumed, and must retain state.
 */
static __always_inline void trace_iterator_reset(struct trace_iterator *iter)
{
	const size_t offset = offsetof(struct trace_iterator, seq);

	/*
	 * Keep gcc from complaining about overwriting more than just one
	 * member in the structure.
	 */
	memset((char *)iter + offset, 0, sizeof(struct trace_iterator) - offset);

	iter->pos = -1;
}

/* Check the name is good for event/group/fields */
static inline bool is_good_name(const char *name)
{
	if (!isalpha(*name) && *name != '_')
		return false;
	while (*++name != '\0') {
		if (!isalpha(*name) && !isdigit(*name) && *name != '_')
			return false;
	}
	return true;
}

#endif /* _LINUX_KERNEL_TRACE_H */