text: // SPDX-License-Identifier: GPL-2.0
  /*
   * trace_output.c
   *
   * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
   *
   */
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/ftrace.h>
  #include <linux/kprobes.h>
  #include <linux/sched/clock.h>
  #include <linux/sched/mm.h>
  
  #include "trace_output.h"
  
  /* must be a power of 2 */
  #define EVENT_HASHSIZE	128
  
  DECLARE_RWSEM(trace_event_sem);
  
  static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
  
  static int next_event_type = __TRACE_LAST_TYPE;
  
  enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry = iter->ent;
  	struct bputs_entry *field;
  
  	trace_assign_type(field, entry);
  
  	trace_seq_puts(s, field->str);
  
  	return trace_handle_return(s);
  }
  
  enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry = iter->ent;
  	struct bprint_entry *field;
  
  	trace_assign_type(field, entry);
  
  	trace_seq_bprintf(s, field->fmt, field->buf);
  
  	return trace_handle_return(s);
  }
  
  enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry = iter->ent;
  	struct print_entry *field;
  
  	trace_assign_type(field, entry);
  
  	trace_seq_puts(s, field->buf);
  
  	return trace_handle_return(s);
  }
  
  const char *
  trace_print_flags_seq(struct trace_seq *p, const char *delim,
  		      unsigned long flags,
  		      const struct trace_print_flags *flag_array)
  {
  	unsigned long mask;
  	const char *str;
  	const char *ret = trace_seq_buffer_ptr(p);
  	int i, first = 1;
  
  	for (i = 0;  flag_array[i].name && flags; i++) {
  
  		mask = flag_array[i].mask;
  		if ((flags & mask) != mask)
  			continue;
  
  		str = flag_array[i].name;
  		flags &= ~mask;
  		if (!first && delim)
  			trace_seq_puts(p, delim);
  		else
  			first = 0;
  		trace_seq_puts(p, str);
  	}
  
  	/* check for left over flags */
  	if (flags) {
  		if (!first && delim)
  			trace_seq_puts(p, delim);
  		trace_seq_printf(p, "0x%lx", flags);
  	}
  
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_flags_seq);
  
  const char *
  trace_print_symbols_seq(struct trace_seq *p, unsigned long val,
  			const struct trace_print_flags *symbol_array)
  {
  	int i;
  	const char *ret = trace_seq_buffer_ptr(p);
  
  	for (i = 0;  symbol_array[i].name; i++) {
  
  		if (val != symbol_array[i].mask)
  			continue;
  
  		trace_seq_puts(p, symbol_array[i].name);
  		break;
  	}
  
  	if (ret == (const char *)(trace_seq_buffer_ptr(p)))
  		trace_seq_printf(p, "0x%lx", val);
  
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_symbols_seq);
  
  #if BITS_PER_LONG == 32
  const char *
  trace_print_flags_seq_u64(struct trace_seq *p, const char *delim,
  		      unsigned long long flags,
  		      const struct trace_print_flags_u64 *flag_array)
  {
  	unsigned long long mask;
  	const char *str;
  	const char *ret = trace_seq_buffer_ptr(p);
  	int i, first = 1;
  
  	for (i = 0;  flag_array[i].name && flags; i++) {
  
  		mask = flag_array[i].mask;
  		if ((flags & mask) != mask)
  			continue;
  
  		str = flag_array[i].name;
  		flags &= ~mask;
  		if (!first && delim)
  			trace_seq_puts(p, delim);
  		else
  			first = 0;
  		trace_seq_puts(p, str);
  	}
  
  	/* check for left over flags */
  	if (flags) {
  		if (!first && delim)
  			trace_seq_puts(p, delim);
  		trace_seq_printf(p, "0x%llx", flags);
  	}
  
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_flags_seq_u64);
  
  const char *
  trace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
  			 const struct trace_print_flags_u64 *symbol_array)
  {
  	int i;
  	const char *ret = trace_seq_buffer_ptr(p);
  
  	for (i = 0;  symbol_array[i].name; i++) {
  
  		if (val != symbol_array[i].mask)
  			continue;
  
  		trace_seq_puts(p, symbol_array[i].name);
  		break;
  	}
  
  	if (ret == (const char *)(trace_seq_buffer_ptr(p)))
  		trace_seq_printf(p, "0x%llx", val);
  
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_symbols_seq_u64);
  #endif
  
  const char *
  trace_print_bitmask_seq(struct trace_seq *p, void *bitmask_ptr,
  			unsigned int bitmask_size)
  {
  	const char *ret = trace_seq_buffer_ptr(p);
  
  	trace_seq_bitmask(p, bitmask_ptr, bitmask_size * 8);
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(trace_print_bitmask_seq);
  
  /**
   * trace_print_hex_seq - print buffer as hex sequence
   * @p: trace seq struct to write to
   * @buf: The buffer to print
   * @buf_len: Length of @buf in bytes
   * @concatenate: Print @buf as single hex string or with spacing
   *
   * Prints the passed buffer as a hex sequence either as a whole,
   * single hex string if @concatenate is true or with spacing after
   * each byte in case @concatenate is false.
   */
  const char *
  trace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len,
  		    bool concatenate)
  {
  	int i;
  	const char *ret = trace_seq_buffer_ptr(p);
  	const char *fmt = concatenate ? "%*phN" : "%*ph";
  
  	for (i = 0; i < buf_len; i += 16)
  		trace_seq_printf(p, fmt, min(buf_len - i, 16), &buf[i]);
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_hex_seq);
  
  const char *
  trace_print_array_seq(struct trace_seq *p, const void *buf, int count,
  		      size_t el_size)
  {
  	const char *ret = trace_seq_buffer_ptr(p);
  	const char *prefix = "";
  	void *ptr = (void *)buf;
  	size_t buf_len = count * el_size;
  
  	trace_seq_putc(p, '{');
  
  	while (ptr < buf + buf_len) {
  		switch (el_size) {
  		case 1:
  			trace_seq_printf(p, "%s0x%x", prefix,
  					 *(u8 *)ptr);
  			break;
  		case 2:
  			trace_seq_printf(p, "%s0x%x", prefix,
  					 *(u16 *)ptr);
  			break;
  		case 4:
  			trace_seq_printf(p, "%s0x%x", prefix,
  					 *(u32 *)ptr);
  			break;
  		case 8:
  			trace_seq_printf(p, "%s0x%llx", prefix,
  					 *(u64 *)ptr);
  			break;
  		default:
  			trace_seq_printf(p, "BAD SIZE:%zu 0x%x", el_size,
  					 *(u8 *)ptr);
  			el_size = 1;
  		}
  		prefix = ",";
  		ptr += el_size;
  	}
  
  	trace_seq_putc(p, '}');
  	trace_seq_putc(p, 0);
  
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_array_seq);
  
  const char *
  trace_print_hex_dump_seq(struct trace_seq *p, const char *prefix_str,
  			 int prefix_type, int rowsize, int groupsize,
  			 const void *buf, size_t len, bool ascii)
  {
  	const char *ret = trace_seq_buffer_ptr(p);
  
  	trace_seq_putc(p, '\n');
  	trace_seq_hex_dump(p, prefix_str, prefix_type,
  			   rowsize, groupsize, buf, len, ascii);
  	trace_seq_putc(p, 0);
  	return ret;
  }
  EXPORT_SYMBOL(trace_print_hex_dump_seq);
  
  int trace_raw_output_prep(struct trace_iterator *iter,
  			  struct trace_event *trace_event)
  {
  	struct trace_event_call *event;
  	struct trace_seq *s = &iter->seq;
  	struct trace_seq *p = &iter->tmp_seq;
  	struct trace_entry *entry;
  
  	event = container_of(trace_event, struct trace_event_call, event);
  	entry = iter->ent;
  
  	if (entry->type != event->event.type) {
  		WARN_ON_ONCE(1);
  		return TRACE_TYPE_UNHANDLED;
  	}
  
  	trace_seq_init(p);
  	trace_seq_printf(s, "%s: ", trace_event_name(event));
  
  	return trace_handle_return(s);
  }
  EXPORT_SYMBOL(trace_raw_output_prep);
  
  void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...)
  {
  	va_list ap;
  
  	va_start(ap, fmt);
  	trace_check_vprintf(iter, trace_event_format(iter, fmt), ap);
  	va_end(ap);
  }
  EXPORT_SYMBOL(trace_event_printf);
  
  static int trace_output_raw(struct trace_iterator *iter, char *name,
  			    char *fmt, va_list ap)
  {
  	struct trace_seq *s = &iter->seq;
  
  	trace_seq_printf(s, "%s: ", name);
  	trace_seq_vprintf(s, trace_event_format(iter, fmt), ap);
  
  	return trace_handle_return(s);
  }
  
  int trace_output_call(struct trace_iterator *iter, char *name, char *fmt, ...)
  {
  	va_list ap;
  	int ret;
  
  	va_start(ap, fmt);
  	ret = trace_output_raw(iter, name, fmt, ap);
  	va_end(ap);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(trace_output_call);
  
  static inline const char *kretprobed(const char *name, unsigned long addr)
  {
  	if (is_kretprobe_trampoline(addr))
  		return "[unknown/kretprobe'd]";
  	return name;
  }
  
  void
  trace_seq_print_sym(struct trace_seq *s, unsigned long address, bool offset)
  {
  #ifdef CONFIG_KALLSYMS
  	char str[KSYM_SYMBOL_LEN];
  	const char *name;
  
  	if (offset)
  		sprint_symbol(str, address);
  	else
  		kallsyms_lookup(address, NULL, NULL, NULL, str);
  	name = kretprobed(str, address);
  
  	if (name && strlen(name)) {
  		trace_seq_puts(s, name);
  		return;
  	}
  #endif
  	trace_seq_printf(s, "0x%08lx", address);
  }
  
  #ifndef CONFIG_64BIT
  # define IP_FMT "%08lx"
  #else
  # define IP_FMT "%016lx"
  #endif
  
  static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
  			     unsigned long ip, unsigned long sym_flags)
  {
  	struct file *file = NULL;
  	unsigned long vmstart = 0;
  	int ret = 1;
  
  	if (s->full)
  		return 0;
  
  	if (mm) {
  		const struct vm_area_struct *vma;
  
  		mmap_read_lock(mm);
  		vma = find_vma(mm, ip);
  		if (vma) {
  			file = vma->vm_file;
  			vmstart = vma->vm_start;
  		}
  		if (file) {
  			ret = trace_seq_path(s, &file->f_path);
  			if (ret)
  				trace_seq_printf(s, "[+0x%lx]",
  						 ip - vmstart);
  		}
  		mmap_read_unlock(mm);
  	}
  	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))
  		trace_seq_printf(s, " <" IP_FMT ">", ip);
  	return !trace_seq_has_overflowed(s);
  }
  
  int
  seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
  {
  	if (!ip) {
  		trace_seq_putc(s, '0');
  		goto out;
  	}
  
  	trace_seq_print_sym(s, ip, sym_flags & TRACE_ITER_SYM_OFFSET);
  
  	if (sym_flags & TRACE_ITER_SYM_ADDR)
  		trace_seq_printf(s, " <" IP_FMT ">", ip);
  
   out:
  	return !trace_seq_has_overflowed(s);
  }
  
  /**
   * trace_print_lat_fmt - print the irq, preempt and lockdep fields
   * @s: trace seq struct to write to
   * @entry: The trace entry field from the ring buffer
   *
   * Prints the generic fields of irqs off, in hard or softirq, preempt
   * count.
   */
  int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
  {
  	char hardsoft_irq;
  	char need_resched;
  	char irqs_off;
  	int hardirq;
  	int softirq;
  	int nmi;
  
  	nmi = entry->flags & TRACE_FLAG_NMI;
  	hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
  	softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
  
  	irqs_off =
  		(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
  		(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' :
  		'.';
  
  	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |
  				TRACE_FLAG_PREEMPT_RESCHED)) {
  	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED:
  		need_resched = 'N';
  		break;
  	case TRACE_FLAG_NEED_RESCHED:
  		need_resched = 'n';
  		break;
  	case TRACE_FLAG_PREEMPT_RESCHED:
  		need_resched = 'p';
  		break;
  	default:
  		need_resched = '.';
  		break;
  	}
  
  	hardsoft_irq =
  		(nmi && hardirq)     ? 'Z' :
  		nmi                  ? 'z' :
  		(hardirq && softirq) ? 'H' :
  		hardirq              ? 'h' :
  		softirq              ? 's' :
  		                       '.' ;
  
  	trace_seq_printf(s, "%c%c%c",
  			 irqs_off, need_resched, hardsoft_irq);
  
  	if (entry->preempt_count & 0xf)
  		trace_seq_printf(s, "%x", entry->preempt_count & 0xf);
  	else
  		trace_seq_putc(s, '.');
  
  	if (entry->preempt_count & 0xf0)
  		trace_seq_printf(s, "%x", entry->preempt_count >> 4);
  	else
  		trace_seq_putc(s, '.');
  
  	return !trace_seq_has_overflowed(s);
  }
  
  static int
  lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
  {
  	char comm[TASK_COMM_LEN];
  
  	trace_find_cmdline(entry->pid, comm);
  
  	trace_seq_printf(s, "%8.8s-%-7d %3d",
  			 comm, entry->pid, cpu);
  
  	return trace_print_lat_fmt(s, entry);
  }
  
  #undef MARK
  #define MARK(v, s) {.val = v, .sym = s}
  /* trace overhead mark */
  static const struct trace_mark {
  	unsigned long long	val; /* unit: nsec */
  	char			sym;
  } mark[] = {
  	MARK(1000000000ULL	, '$'), /* 1 sec */
  	MARK(100000000ULL	, '@'), /* 100 msec */
  	MARK(10000000ULL	, '*'), /* 10 msec */
  	MARK(1000000ULL		, '#'), /* 1000 usecs */
  	MARK(100000ULL		, '!'), /* 100 usecs */
  	MARK(10000ULL		, '+'), /* 10 usecs */
  };
  #undef MARK
  
  char trace_find_mark(unsigned long long d)
  {
  	int i;
  	int size = ARRAY_SIZE(mark);
  
  	for (i = 0; i < size; i++) {
  		if (d > mark[i].val)
  			break;
  	}
  
  	return (i == size) ? ' ' : mark[i].sym;
  }
  
  static int
  lat_print_timestamp(struct trace_iterator *iter, u64 next_ts)
  {
  	struct trace_array *tr = iter->tr;
  	unsigned long verbose = tr->trace_flags & TRACE_ITER_VERBOSE;
  	unsigned long in_ns = iter->iter_flags & TRACE_FILE_TIME_IN_NS;
  	unsigned long long abs_ts = iter->ts - iter->array_buffer->time_start;
  	unsigned long long rel_ts = next_ts - iter->ts;
  	struct trace_seq *s = &iter->seq;
  
  	if (in_ns) {
  		abs_ts = ns2usecs(abs_ts);
  		rel_ts = ns2usecs(rel_ts);
  	}
  
  	if (verbose && in_ns) {
  		unsigned long abs_usec = do_div(abs_ts, USEC_PER_MSEC);
  		unsigned long abs_msec = (unsigned long)abs_ts;
  		unsigned long rel_usec = do_div(rel_ts, USEC_PER_MSEC);
  		unsigned long rel_msec = (unsigned long)rel_ts;
  
  		trace_seq_printf(
  			s, "[%08llx] %ld.%03ldms (+%ld.%03ldms): ",
  			ns2usecs(iter->ts),
  			abs_msec, abs_usec,
  			rel_msec, rel_usec);
  
  	} else if (verbose && !in_ns) {
  		trace_seq_printf(
  			s, "[%016llx] %lld (+%lld): ",
  			iter->ts, abs_ts, rel_ts);
  
  	} else if (!verbose && in_ns) {
  		trace_seq_printf(
  			s, " %4lldus%c: ",
  			abs_ts,
  			trace_find_mark(rel_ts * NSEC_PER_USEC));
  
  	} else { /* !verbose && !in_ns */
  		trace_seq_printf(s, " %4lld: ", abs_ts);
  	}
  
  	return !trace_seq_has_overflowed(s);
  }
  
  static void trace_print_time(struct trace_seq *s, struct trace_iterator *iter,
  			     unsigned long long ts)
  {
  	unsigned long secs, usec_rem;
  	unsigned long long t;
  
  	if (iter->iter_flags & TRACE_FILE_TIME_IN_NS) {
  		t = ns2usecs(ts);
  		usec_rem = do_div(t, USEC_PER_SEC);
  		secs = (unsigned long)t;
  		trace_seq_printf(s, " %5lu.%06lu", secs, usec_rem);
  	} else
  		trace_seq_printf(s, " %12llu", ts);
  }
  
  int trace_print_context(struct trace_iterator *iter)
  {
  	struct trace_array *tr = iter->tr;
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *entry = iter->ent;
  	char comm[TASK_COMM_LEN];
  
  	trace_find_cmdline(entry->pid, comm);
  
  	trace_seq_printf(s, "%16s-%-7d ", comm, entry->pid);
  
  	if (tr->trace_flags & TRACE_ITER_RECORD_TGID) {
  		unsigned int tgid = trace_find_tgid(entry->pid);
  
  		if (!tgid)
  			trace_seq_printf(s, "(-------) ");
  		else
  			trace_seq_printf(s, "(%7d) ", tgid);
  	}
  
  	trace_seq_printf(s, "[%03d] ", iter->cpu);
  
  	if (tr->trace_flags & TRACE_ITER_IRQ_INFO)
  		trace_print_lat_fmt(s, entry);
  
  	trace_print_time(s, iter, iter->ts);
  	trace_seq_puts(s, ": ");
  
  	return !trace_seq_has_overflowed(s);
  }
  
  int trace_print_lat_context(struct trace_iterator *iter)
  {
  	struct trace_entry *entry, *next_entry;
  	struct trace_array *tr = iter->tr;
  	struct trace_seq *s = &iter->seq;
  	unsigned long verbose = (tr->trace_flags & TRACE_ITER_VERBOSE);
  	u64 next_ts;
  
  	next_entry = trace_find_next_entry(iter, NULL, &next_ts);
  	if (!next_entry)
  		next_ts = iter->ts;
  
  	/* trace_find_next_entry() may change iter->ent */
  	entry = iter->ent;
  
  	if (verbose) {
  		char comm[TASK_COMM_LEN];
  
  		trace_find_cmdline(entry->pid, comm);
  
  		trace_seq_printf(
  			s, "%16s %7d %3d %d %08x %08lx ",
  			comm, entry->pid, iter->cpu, entry->flags,
  			entry->preempt_count & 0xf, iter->idx);
  	} else {
  		lat_print_generic(s, entry, iter->cpu);
  	}
  
  	lat_print_timestamp(iter, next_ts);
  
  	return !trace_seq_has_overflowed(s);
  }
  
  /**
   * ftrace_find_event - find a registered event
   * @type: the type of event to look for
   *
   * Returns an event of type @type otherwise NULL
   * Called with trace_event_read_lock() held.
   */
  struct trace_event *ftrace_find_event(int type)
  {
  	struct trace_event *event;
  	unsigned key;
  
  	key = type & (EVENT_HASHSIZE - 1);
  
  	hlist_for_each_entry(event, &event_hash[key], node) {
  		if (event->type == type)
  			return event;
  	}
  
  	return NULL;
  }
  
  static LIST_HEAD(ftrace_event_list);
  
  static int trace_search_list(struct list_head **list)
  {
  	struct trace_event *e;
  	int next = __TRACE_LAST_TYPE;
  
  	if (list_empty(&ftrace_event_list)) {
  		*list = &ftrace_event_list;
  		return next;
  	}
  
  	/*
  	 * We used up all possible max events,
  	 * lets see if somebody freed one.
  	 */
  	list_for_each_entry(e, &ftrace_event_list, list) {
  		if (e->type != next)
  			break;
  		next++;
  	}
  
  	/* Did we used up all 65 thousand events??? */
  	if (next > TRACE_EVENT_TYPE_MAX)
  		return 0;
  
  	*list = &e->list;
  	return next;
  }
  
  void trace_event_read_lock(void)
  {
  	down_read(&trace_event_sem);
  }
  
  void trace_event_read_unlock(void)
  {
  	up_read(&trace_event_sem);
  }
  
  /**
   * register_trace_event - register output for an event type
   * @event: the event type to register
   *
   * Event types are stored in a hash and this hash is used to
   * find a way to print an event. If the @event->type is set
   * then it will use that type, otherwise it will assign a
   * type to use.
   *
   * If you assign your own type, please make sure it is added
   * to the trace_type enum in trace.h, to avoid collisions
   * with the dynamic types.
   *
   * Returns the event type number or zero on error.
   */
  int register_trace_event(struct trace_event *event)
  {
  	unsigned key;
  	int ret = 0;
  
  	down_write(&trace_event_sem);
  
  	if (WARN_ON(!event))
  		goto out;
  
  	if (WARN_ON(!event->funcs))
  		goto out;
  
  	INIT_LIST_HEAD(&event->list);
  
  	if (!event->type) {
  		struct list_head *list = NULL;
  
  		if (next_event_type > TRACE_EVENT_TYPE_MAX) {
  
  			event->type = trace_search_list(&list);
  			if (!event->type)
  				goto out;
  
  		} else {
  
  			event->type = next_event_type++;
  			list = &ftrace_event_list;
  		}
  
  		if (WARN_ON(ftrace_find_event(event->type)))
  			goto out;
  
  		list_add_tail(&event->list, list);
  
  	} else if (event->type > __TRACE_LAST_TYPE) {
  		printk(KERN_WARNING "Need to add type to trace.h\n");
  		WARN_ON(1);
  		goto out;
  	} else {
  		/* Is this event already used */
  		if (ftrace_find_event(event->type))
  			goto out;
  	}
  
  	if (event->funcs->trace == NULL)
  		event->funcs->trace = trace_nop_print;
  	if (event->funcs->raw == NULL)
  		event->funcs->raw = trace_nop_print;
  	if (event->funcs->hex == NULL)
  		event->funcs->hex = trace_nop_print;
  	if (event->funcs->binary == NULL)
  		event->funcs->binary = trace_nop_print;
  
  	key = event->type & (EVENT_HASHSIZE - 1);
  
  	hlist_add_head(&event->node, &event_hash[key]);
  
  	ret = event->type;
   out:
  	up_write(&trace_event_sem);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(register_trace_event);
  
  /*
   * Used by module code with the trace_event_sem held for write.
   */
  int __unregister_trace_event(struct trace_event *event)
  {
  	hlist_del(&event->node);
  	list_del(&event->list);
  	return 0;
  }
  
  /**
   * unregister_trace_event - remove a no longer used event
   * @event: the event to remove
   */
  int unregister_trace_event(struct trace_event *event)
  {
  	down_write(&trace_event_sem);
  	__unregister_trace_event(event);
  	up_write(&trace_event_sem);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(unregister_trace_event);
  
  /*
   * Standard events
   */
  
  enum print_line_t trace_nop_print(struct trace_iterator *iter, int flags,
  				  struct trace_event *event)
  {
  	trace_seq_printf(&iter->seq, "type: %d\n", iter->ent->type);
  
  	return trace_handle_return(&iter->seq);
  }
  
  static void print_fn_trace(struct trace_seq *s, unsigned long ip,
  			   unsigned long parent_ip, int flags)
  {
  	seq_print_ip_sym(s, ip, flags);
  
  	if ((flags & TRACE_ITER_PRINT_PARENT) && parent_ip) {
  		trace_seq_puts(s, " <-");
  		seq_print_ip_sym(s, parent_ip, flags);
  	}
  }
  
  /* TRACE_FN */
  static enum print_line_t trace_fn_trace(struct trace_iterator *iter, int flags,
  					struct trace_event *event)
  {
  	struct ftrace_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	print_fn_trace(s, field->ip, field->parent_ip, flags);
  	trace_seq_putc(s, '\n');
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t trace_fn_raw(struct trace_iterator *iter, int flags,
  				      struct trace_event *event)
  {
  	struct ftrace_entry *field;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(&iter->seq, "%lx %lx\n",
  			 field->ip,
  			 field->parent_ip);
  
  	return trace_handle_return(&iter->seq);
  }
  
  static enum print_line_t trace_fn_hex(struct trace_iterator *iter, int flags,
  				      struct trace_event *event)
  {
  	struct ftrace_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	SEQ_PUT_HEX_FIELD(s, field->ip);
  	SEQ_PUT_HEX_FIELD(s, field->parent_ip);
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t trace_fn_bin(struct trace_iterator *iter, int flags,
  				      struct trace_event *event)
  {
  	struct ftrace_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	SEQ_PUT_FIELD(s, field->ip);
  	SEQ_PUT_FIELD(s, field->parent_ip);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_fn_funcs = {
  	.trace		= trace_fn_trace,
  	.raw		= trace_fn_raw,
  	.hex		= trace_fn_hex,
  	.binary		= trace_fn_bin,
  };
  
  static struct trace_event trace_fn_event = {
  	.type		= TRACE_FN,
  	.funcs		= &trace_fn_funcs,
  };
  
  /* TRACE_CTX an TRACE_WAKE */
  static enum print_line_t trace_ctxwake_print(struct trace_iterator *iter,
  					     char *delim)
  {
  	struct ctx_switch_entry *field;
  	char comm[TASK_COMM_LEN];
  	int S, T;
  
  
  	trace_assign_type(field, iter->ent);
  
  	T = task_index_to_char(field->next_state);
  	S = task_index_to_char(field->prev_state);
  	trace_find_cmdline(field->next_pid, comm);
  	trace_seq_printf(&iter->seq,
  			 " %7d:%3d:%c %s [%03d] %7d:%3d:%c %s\n",
  			 field->prev_pid,
  			 field->prev_prio,
  			 S, delim,
  			 field->next_cpu,
  			 field->next_pid,
  			 field->next_prio,
  			 T, comm);
  
  	return trace_handle_return(&iter->seq);
  }
  
  static enum print_line_t trace_ctx_print(struct trace_iterator *iter, int flags,
  					 struct trace_event *event)
  {
  	return trace_ctxwake_print(iter, "==>");
  }
  
  static enum print_line_t trace_wake_print(struct trace_iterator *iter,
  					  int flags, struct trace_event *event)
  {
  	return trace_ctxwake_print(iter, "  +");
  }
  
  static int trace_ctxwake_raw(struct trace_iterator *iter, char S)
  {
  	struct ctx_switch_entry *field;
  	int T;
  
  	trace_assign_type(field, iter->ent);
  
  	if (!S)
  		S = task_index_to_char(field->prev_state);
  	T = task_index_to_char(field->next_state);
  	trace_seq_printf(&iter->seq, "%d %d %c %d %d %d %c\n",
  			 field->prev_pid,
  			 field->prev_prio,
  			 S,
  			 field->next_cpu,
  			 field->next_pid,
  			 field->next_prio,
  			 T);
  
  	return trace_handle_return(&iter->seq);
  }
  
  static enum print_line_t trace_ctx_raw(struct trace_iterator *iter, int flags,
  				       struct trace_event *event)
  {
  	return trace_ctxwake_raw(iter, 0);
  }
  
  static enum print_line_t trace_wake_raw(struct trace_iterator *iter, int flags,
  					struct trace_event *event)
  {
  	return trace_ctxwake_raw(iter, '+');
  }
  
  
  static int trace_ctxwake_hex(struct trace_iterator *iter, char S)
  {
  	struct ctx_switch_entry *field;
  	struct trace_seq *s = &iter->seq;
  	int T;
  
  	trace_assign_type(field, iter->ent);
  
  	if (!S)
  		S = task_index_to_char(field->prev_state);
  	T = task_index_to_char(field->next_state);
  
  	SEQ_PUT_HEX_FIELD(s, field->prev_pid);
  	SEQ_PUT_HEX_FIELD(s, field->prev_prio);
  	SEQ_PUT_HEX_FIELD(s, S);
  	SEQ_PUT_HEX_FIELD(s, field->next_cpu);
  	SEQ_PUT_HEX_FIELD(s, field->next_pid);
  	SEQ_PUT_HEX_FIELD(s, field->next_prio);
  	SEQ_PUT_HEX_FIELD(s, T);
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t trace_ctx_hex(struct trace_iterator *iter, int flags,
  				       struct trace_event *event)
  {
  	return trace_ctxwake_hex(iter, 0);
  }
  
  static enum print_line_t trace_wake_hex(struct trace_iterator *iter, int flags,
  					struct trace_event *event)
  {
  	return trace_ctxwake_hex(iter, '+');
  }
  
  static enum print_line_t trace_ctxwake_bin(struct trace_iterator *iter,
  					   int flags, struct trace_event *event)
  {
  	struct ctx_switch_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	SEQ_PUT_FIELD(s, field->prev_pid);
  	SEQ_PUT_FIELD(s, field->prev_prio);
  	SEQ_PUT_FIELD(s, field->prev_state);
  	SEQ_PUT_FIELD(s, field->next_cpu);
  	SEQ_PUT_FIELD(s, field->next_pid);
  	SEQ_PUT_FIELD(s, field->next_prio);
  	SEQ_PUT_FIELD(s, field->next_state);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_ctx_funcs = {
  	.trace		= trace_ctx_print,
  	.raw		= trace_ctx_raw,
  	.hex		= trace_ctx_hex,
  	.binary		= trace_ctxwake_bin,
  };
  
  static struct trace_event trace_ctx_event = {
  	.type		= TRACE_CTX,
  	.funcs		= &trace_ctx_funcs,
  };
  
  static struct trace_event_functions trace_wake_funcs = {
  	.trace		= trace_wake_print,
  	.raw		= trace_wake_raw,
  	.hex		= trace_wake_hex,
  	.binary		= trace_ctxwake_bin,
  };
  
  static struct trace_event trace_wake_event = {
  	.type		= TRACE_WAKE,
  	.funcs		= &trace_wake_funcs,
  };
  
  /* TRACE_STACK */
  
  static enum print_line_t trace_stack_print(struct trace_iterator *iter,
  					   int flags, struct trace_event *event)
  {
  	struct stack_entry *field;
  	struct trace_seq *s = &iter->seq;
  	unsigned long *p;
  	unsigned long *end;
  
  	trace_assign_type(field, iter->ent);
  	end = (unsigned long *)((long)iter->ent + iter->ent_size);
  
  	trace_seq_puts(s, "<stack trace>\n");
  
  	for (p = field->caller; p && p < end && *p != ULONG_MAX; p++) {
  
  		if (trace_seq_has_overflowed(s))
  			break;
  
  		trace_seq_puts(s, " => ");
  		seq_print_ip_sym(s, *p, flags);
  		trace_seq_putc(s, '\n');
  	}
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_stack_funcs = {
  	.trace		= trace_stack_print,
  };
  
  static struct trace_event trace_stack_event = {
  	.type		= TRACE_STACK,
  	.funcs		= &trace_stack_funcs,
  };
  
  /* TRACE_USER_STACK */
  static enum print_line_t trace_user_stack_print(struct trace_iterator *iter,
  						int flags, struct trace_event *event)
  {
  	struct trace_array *tr = iter->tr;
  	struct userstack_entry *field;
  	struct trace_seq *s = &iter->seq;
  	struct mm_struct *mm = NULL;
  	unsigned int i;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_puts(s, "<user stack trace>\n");
  
  	if (tr->trace_flags & TRACE_ITER_SYM_USEROBJ) {
  		struct task_struct *task;
  		/*
  		 * we do the lookup on the thread group leader,
  		 * since individual threads might have already quit!
  		 */
  		rcu_read_lock();
  		task = find_task_by_vpid(field->tgid);
  		if (task)
  			mm = get_task_mm(task);
  		rcu_read_unlock();
  	}
  
  	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
  		unsigned long ip = field->caller[i];
  
  		if (!ip || trace_seq_has_overflowed(s))
  			break;
  
  		trace_seq_puts(s, " => ");
  		seq_print_user_ip(s, mm, ip, flags);
  		trace_seq_putc(s, '\n');
  	}
  
  	if (mm)
  		mmput(mm);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_user_stack_funcs = {
  	.trace		= trace_user_stack_print,
  };
  
  static struct trace_event trace_user_stack_event = {
  	.type		= TRACE_USER_STACK,
  	.funcs		= &trace_user_stack_funcs,
  };
  
  /* TRACE_HWLAT */
  static enum print_line_t
  trace_hwlat_print(struct trace_iterator *iter, int flags,
  		  struct trace_event *event)
  {
  	struct trace_entry *entry = iter->ent;
  	struct trace_seq *s = &iter->seq;
  	struct hwlat_entry *field;
  
  	trace_assign_type(field, entry);
  
  	trace_seq_printf(s, "#%-5u inner/outer(us): %4llu/%-5llu ts:%lld.%09ld count:%d",
  			 field->seqnum,
  			 field->duration,
  			 field->outer_duration,
  			 (long long)field->timestamp.tv_sec,
  			 field->timestamp.tv_nsec, field->count);
  
  	if (field->nmi_count) {
  		/*
  		 * The generic sched_clock() is not NMI safe, thus
  		 * we only record the count and not the time.
  		 */
  		if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK))
  			trace_seq_printf(s, " nmi-total:%llu",
  					 field->nmi_total_ts);
  		trace_seq_printf(s, " nmi-count:%u",
  				 field->nmi_count);
  	}
  
  	trace_seq_putc(s, '\n');
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t
  trace_hwlat_raw(struct trace_iterator *iter, int flags,
  		struct trace_event *event)
  {
  	struct hwlat_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, "%llu %lld %lld %09ld %u\n",
  			 field->duration,
  			 field->outer_duration,
  			 (long long)field->timestamp.tv_sec,
  			 field->timestamp.tv_nsec,
  			 field->seqnum);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_hwlat_funcs = {
  	.trace		= trace_hwlat_print,
  	.raw		= trace_hwlat_raw,
  };
  
  static struct trace_event trace_hwlat_event = {
  	.type		= TRACE_HWLAT,
  	.funcs		= &trace_hwlat_funcs,
  };
  
  /* TRACE_OSNOISE */
  static enum print_line_t
  trace_osnoise_print(struct trace_iterator *iter, int flags,
  		    struct trace_event *event)
  {
  	struct trace_entry *entry = iter->ent;
  	struct trace_seq *s = &iter->seq;
  	struct osnoise_entry *field;
  	u64 ratio, ratio_dec;
  	u64 net_runtime;
  
  	trace_assign_type(field, entry);
  
  	/*
  	 * compute the available % of cpu time.
  	 */
  	net_runtime = field->runtime - field->noise;
  	ratio = net_runtime * 10000000;
  	do_div(ratio, field->runtime);
  	ratio_dec = do_div(ratio, 100000);
  
  	trace_seq_printf(s, "%llu %10llu %3llu.%05llu %7llu",
  			 field->runtime,
  			 field->noise,
  			 ratio, ratio_dec,
  			 field->max_sample);
  
  	trace_seq_printf(s, " %6u", field->hw_count);
  	trace_seq_printf(s, " %6u", field->nmi_count);
  	trace_seq_printf(s, " %6u", field->irq_count);
  	trace_seq_printf(s, " %6u", field->softirq_count);
  	trace_seq_printf(s, " %6u", field->thread_count);
  
  	trace_seq_putc(s, '\n');
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t
  trace_osnoise_raw(struct trace_iterator *iter, int flags,
  		  struct trace_event *event)
  {
  	struct osnoise_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, "%lld %llu %llu %u %u %u %u %u\n",
  			 field->runtime,
  			 field->noise,
  			 field->max_sample,
  			 field->hw_count,
  			 field->nmi_count,
  			 field->irq_count,
  			 field->softirq_count,
  			 field->thread_count);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_osnoise_funcs = {
  	.trace		= trace_osnoise_print,
  	.raw		= trace_osnoise_raw,
  };
  
  static struct trace_event trace_osnoise_event = {
  	.type		= TRACE_OSNOISE,
  	.funcs		= &trace_osnoise_funcs,
  };
  
  /* TRACE_TIMERLAT */
  static enum print_line_t
  trace_timerlat_print(struct trace_iterator *iter, int flags,
  		     struct trace_event *event)
  {
  	struct trace_entry *entry = iter->ent;
  	struct trace_seq *s = &iter->seq;
  	struct timerlat_entry *field;
  
  	trace_assign_type(field, entry);
  
  	trace_seq_printf(s, "#%-5u context %6s timer_latency %9llu ns\n",
  			 field->seqnum,
  			 field->context ? "thread" : "irq",
  			 field->timer_latency);
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t
  trace_timerlat_raw(struct trace_iterator *iter, int flags,
  		   struct trace_event *event)
  {
  	struct timerlat_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, "%u %d %llu\n",
  			 field->seqnum,
  			 field->context,
  			 field->timer_latency);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_timerlat_funcs = {
  	.trace		= trace_timerlat_print,
  	.raw		= trace_timerlat_raw,
  };
  
  static struct trace_event trace_timerlat_event = {
  	.type		= TRACE_TIMERLAT,
  	.funcs		= &trace_timerlat_funcs,
  };
  
  /* TRACE_BPUTS */
  static enum print_line_t
  trace_bputs_print(struct trace_iterator *iter, int flags,
  		   struct trace_event *event)
  {
  	struct trace_entry *entry = iter->ent;
  	struct trace_seq *s = &iter->seq;
  	struct bputs_entry *field;
  
  	trace_assign_type(field, entry);
  
  	seq_print_ip_sym(s, field->ip, flags);
  	trace_seq_puts(s, ": ");
  	trace_seq_puts(s, field->str);
  
  	return trace_handle_return(s);
  }
  
  
  static enum print_line_t
  trace_bputs_raw(struct trace_iterator *iter, int flags,
  		struct trace_event *event)
  {
  	struct bputs_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, ": %lx : ", field->ip);
  	trace_seq_puts(s, field->str);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_bputs_funcs = {
  	.trace		= trace_bputs_print,
  	.raw		= trace_bputs_raw,
  };
  
  static struct trace_event trace_bputs_event = {
  	.type		= TRACE_BPUTS,
  	.funcs		= &trace_bputs_funcs,
  };
  
  /* TRACE_BPRINT */
  static enum print_line_t
  trace_bprint_print(struct trace_iterator *iter, int flags,
  		   struct trace_event *event)
  {
  	struct trace_entry *entry = iter->ent;
  	struct trace_seq *s = &iter->seq;
  	struct bprint_entry *field;
  
  	trace_assign_type(field, entry);
  
  	seq_print_ip_sym(s, field->ip, flags);
  	trace_seq_puts(s, ": ");
  	trace_seq_bprintf(s, field->fmt, field->buf);
  
  	return trace_handle_return(s);
  }
  
  
  static enum print_line_t
  trace_bprint_raw(struct trace_iterator *iter, int flags,
  		 struct trace_event *event)
  {
  	struct bprint_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, ": %lx : ", field->ip);
  	trace_seq_bprintf(s, field->fmt, field->buf);
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_bprint_funcs = {
  	.trace		= trace_bprint_print,
  	.raw		= trace_bprint_raw,
  };
  
  static struct trace_event trace_bprint_event = {
  	.type		= TRACE_BPRINT,
  	.funcs		= &trace_bprint_funcs,
  };
  
  /* TRACE_PRINT */
  static enum print_line_t trace_print_print(struct trace_iterator *iter,
  					   int flags, struct trace_event *event)
  {
  	struct print_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	seq_print_ip_sym(s, field->ip, flags);
  	trace_seq_printf(s, ": %s", field->buf);
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
  					 struct trace_event *event)
  {
  	struct print_entry *field;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf);
  
  	return trace_handle_return(&iter->seq);
  }
  
  static struct trace_event_functions trace_print_funcs = {
  	.trace		= trace_print_print,
  	.raw		= trace_print_raw,
  };
  
  static struct trace_event trace_print_event = {
  	.type	 	= TRACE_PRINT,
  	.funcs		= &trace_print_funcs,
  };
  
  static enum print_line_t trace_raw_data(struct trace_iterator *iter, int flags,
  					 struct trace_event *event)
  {
  	struct raw_data_entry *field;
  	int i;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(&iter->seq, "# %x buf:", field->id);
  
  	for (i = 0; i < iter->ent_size - offsetof(struct raw_data_entry, buf); i++)
  		trace_seq_printf(&iter->seq, " %02x",
  				 (unsigned char)field->buf[i]);
  
  	trace_seq_putc(&iter->seq, '\n');
  
  	return trace_handle_return(&iter->seq);
  }
  
  static struct trace_event_functions trace_raw_data_funcs = {
  	.trace		= trace_raw_data,
  	.raw		= trace_raw_data,
  };
  
  static struct trace_event trace_raw_data_event = {
  	.type	 	= TRACE_RAW_DATA,
  	.funcs		= &trace_raw_data_funcs,
  };
  
  static enum print_line_t
  trace_func_repeats_raw(struct trace_iterator *iter, int flags,
  			 struct trace_event *event)
  {
  	struct func_repeats_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	trace_seq_printf(s, "%lu %lu %u %llu\n",
  			 field->ip,
  			 field->parent_ip,
  			 field->count,
  			 FUNC_REPEATS_GET_DELTA_TS(field));
  
  	return trace_handle_return(s);
  }
  
  static enum print_line_t
  trace_func_repeats_print(struct trace_iterator *iter, int flags,
  			 struct trace_event *event)
  {
  	struct func_repeats_entry *field;
  	struct trace_seq *s = &iter->seq;
  
  	trace_assign_type(field, iter->ent);
  
  	print_fn_trace(s, field->ip, field->parent_ip, flags);
  	trace_seq_printf(s, " (repeats: %u, last_ts:", field->count);
  	trace_print_time(s, iter,
  			 iter->ts - FUNC_REPEATS_GET_DELTA_TS(field));
  	trace_seq_puts(s, ")\n");
  
  	return trace_handle_return(s);
  }
  
  static struct trace_event_functions trace_func_repeats_funcs = {
  	.trace		= trace_func_repeats_print,
  	.raw		= trace_func_repeats_raw,
  };
  
  static struct trace_event trace_func_repeats_event = {
  	.type	 	= TRACE_FUNC_REPEATS,
  	.funcs		= &trace_func_repeats_funcs,
  };
  
  static struct trace_event *events[] __initdata = {
  	&trace_fn_event,
  	&trace_ctx_event,
  	&trace_wake_event,
  	&trace_stack_event,
  	&trace_user_stack_event,
  	&trace_bputs_event,
  	&trace_bprint_event,
  	&trace_print_event,
  	&trace_hwlat_event,
  	&trace_osnoise_event,
  	&trace_timerlat_event,
  	&trace_raw_data_event,
  	&trace_func_repeats_event,
  	NULL
  };
  
  __init static int init_events(void)
  {
  	struct trace_event *event;
  	int i, ret;
  
  	for (i = 0; events[i]; i++) {
  		event = events[i];
  
  		ret = register_trace_event(event);
  		if (!ret) {
  			printk(KERN_WARNING "event %d failed to register\n",
  			       event->type);
  			WARN_ON_ONCE(1);
  		}
  	}
  
  	return 0;
  }
  early_initcall(init_events);
  