// SPDX-License-Identifier: GPL-2.0

  /*
   * unlikely profiler
   *
   * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
   */
  #include <linux/kallsyms.h>
  #include <linux/seq_file.h>
  #include <linux/spinlock.h>

  #include <linux/irqflags.h>

  #include <linux/uaccess.h>
  #include <linux/module.h>
  #include <linux/ftrace.h>
  #include <linux/hash.h>
  #include <linux/fs.h>
  #include <asm/local.h>

  #include "trace.h"

  #include "trace_stat.h"

  #include "trace_output.h"

  #ifdef CONFIG_BRANCH_TRACER

  static struct tracer branch_trace;

  static int branch_tracing_enabled __read_mostly;
  static DEFINE_MUTEX(branch_tracing_mutex);

  static struct trace_array *branch_tracer;

  
  static void

  probe_likely_condition(struct ftrace_likely_data *f, int val, int expect)

  {

  	struct trace_event_call *call = &event_branch;

  	struct trace_array *tr = branch_tracer;

  	struct trace_buffer *buffer;

  	struct trace_array_cpu *data;

  	struct ring_buffer_event *event;

  	struct trace_branch *entry;

  	unsigned long flags;

  	int pc;

  	const char *p;

  	if (current->trace_recursion & TRACE_BRANCH_BIT)
  		return;

  	/*
  	 * I would love to save just the ftrace_likely_data pointer, but
  	 * this code can also be used by modules. Ugly things can happen
  	 * if the module is unloaded, and then we go and read the
  	 * pointer.  This is slower, but much safer.
  	 */
  
  	if (unlikely(!tr))
  		return;

  	raw_local_irq_save(flags);
  	current->trace_recursion |= TRACE_BRANCH_BIT;

  	data = this_cpu_ptr(tr->array_buffer.data);

  	if (atomic_read(&data->disabled))

  		goto out;

  	pc = preempt_count();

  	buffer = tr->array_buffer.buffer;

  	event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,

  					  sizeof(*entry), flags, pc);

  	if (!event)
  		goto out;

  	entry	= ring_buffer_event_data(event);

  
  	/* Strip off the path, only save the file */

  	p = f->data.file + strlen(f->data.file);
  	while (p >= f->data.file && *p != '/')

  		p--;
  	p++;

  	strncpy(entry->func, f->data.func, TRACE_FUNC_SIZE);

  	strncpy(entry->file, p, TRACE_FILE_SIZE);
  	entry->func[TRACE_FUNC_SIZE] = 0;
  	entry->file[TRACE_FILE_SIZE] = 0;

  	entry->constant = f->constant;
  	entry->line = f->data.line;

  	entry->correct = val == expect;

  	if (!call_filter_check_discard(call, entry, buffer, event))

  		trace_buffer_unlock_commit_nostack(buffer, event);

  
   out:

  	current->trace_recursion &= ~TRACE_BRANCH_BIT;
  	raw_local_irq_restore(flags);

  }
  
  static inline

  void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)

  {

  	if (!branch_tracing_enabled)

  		return;
  
  	probe_likely_condition(f, val, expect);
  }

  int enable_branch_tracing(struct trace_array *tr)

  {

  	mutex_lock(&branch_tracing_mutex);
  	branch_tracer = tr;

  	/*
  	 * Must be seen before enabling. The reader is a condition
  	 * where we do not need a matching rmb()
  	 */
  	smp_wmb();

  	branch_tracing_enabled++;
  	mutex_unlock(&branch_tracing_mutex);

  	return 0;

  }

  void disable_branch_tracing(void)

  {

  	mutex_lock(&branch_tracing_mutex);

  	if (!branch_tracing_enabled)

  		goto out_unlock;

  	branch_tracing_enabled--;

  
   out_unlock:

  	mutex_unlock(&branch_tracing_mutex);

  }

  static int branch_trace_init(struct trace_array *tr)

  {

  	return enable_branch_tracing(tr);

  }
  
  static void branch_trace_reset(struct trace_array *tr)
  {

  	disable_branch_tracing();

  }

  static enum print_line_t trace_branch_print(struct trace_iterator *iter,

  					    int flags, struct trace_event *event)

  {
  	struct trace_branch *field;

  	trace_assign_type(field, iter->ent);

  	trace_seq_printf(&iter->seq, "[%s] %s:%s:%d
  ",
  			 field->correct ? "  ok  " : " MISS ",
  			 field->func,
  			 field->file,
  			 field->line);
  
  	return trace_handle_return(&iter->seq);

  }

  static void branch_print_header(struct seq_file *s)
  {
  	seq_puts(s, "#           TASK-PID    CPU#    TIMESTAMP  CORRECT"

  		    "  FUNC:FILE:LINE
  "
  		    "#              | |       |          |         |   "
  		    "    |
  ");

  }

  static struct trace_event_functions trace_branch_funcs = {
  	.trace		= trace_branch_print,
  };

  static struct trace_event trace_branch_event = {

  	.type		= TRACE_BRANCH,

  	.funcs		= &trace_branch_funcs,

  };

  static struct tracer branch_trace __read_mostly =
  {
  	.name		= "branch",
  	.init		= branch_trace_init,
  	.reset		= branch_trace_reset,
  #ifdef CONFIG_FTRACE_SELFTEST
  	.selftest	= trace_selftest_startup_branch,
  #endif /* CONFIG_FTRACE_SELFTEST */

  	.print_header	= branch_print_header,

  };
  
  __init static int init_branch_tracer(void)
  {
  	int ret;

  	ret = register_trace_event(&trace_branch_event);

  	if (!ret) {
  		printk(KERN_WARNING "Warning: could not register "
  				    "branch events
  ");
  		return 1;
  	}
  	return register_tracer(&branch_trace);
  }

  core_initcall(init_branch_tracer);

  #else
  static inline

  void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)

  {
  }

  #endif /* CONFIG_BRANCH_TRACER */

  void ftrace_likely_update(struct ftrace_likely_data *f, int val,

  			  int expect, int is_constant)

  {

  	unsigned long flags = user_access_save();

  	/* A constant is always correct */

  	if (is_constant) {
  		f->constant++;

  		val = expect;

  	}

  	/*
  	 * I would love to have a trace point here instead, but the
  	 * trace point code is so inundated with unlikely and likely
  	 * conditions that the recursive nightmare that exists is too
  	 * much to try to get working. At least for now.
  	 */

  	trace_likely_condition(f, val, expect);

  	/* FIXME: Make this atomic! */
  	if (val == expect)

  		f->data.correct++;

  	else

  		f->data.incorrect++;

  
  	user_access_restore(flags);

  }
  EXPORT_SYMBOL(ftrace_likely_update);

  extern unsigned long __start_annotated_branch_profile[];
  extern unsigned long __stop_annotated_branch_profile[];

  static int annotated_branch_stat_headers(struct seq_file *m)

  {

  	seq_puts(m, " correct incorrect  % "
  		    "       Function                "

  		    "  File              Line
  "
  		    " ------- ---------  - "
  		    "       --------                "
  		    "  ----              ----
  ");

  	return 0;

  }

  static inline long get_incorrect_percent(const struct ftrace_branch_data *p)

  {

  	long percent;

  	if (p->correct) {
  		percent = p->incorrect * 100;
  		percent /= p->correct + p->incorrect;
  	} else
  		percent = p->incorrect ? 100 : -1;

  	return percent;

  }

  static const char *branch_stat_process_file(struct ftrace_branch_data *p)

  {

  	const char *f;

  	/* Only print the file, not the path */
  	f = p->file + strlen(p->file);
  	while (f >= p->file && *f != '/')
  		f--;

  	return ++f;
  }
  
  static void branch_stat_show(struct seq_file *m,
  			     struct ftrace_branch_data *p, const char *f)
  {
  	long percent;

  	/*
  	 * The miss is overlayed on correct, and hit on incorrect.
  	 */

  	percent = get_incorrect_percent(p);

  	if (percent < 0)

  		seq_puts(m, "  X ");

  	else
  		seq_printf(m, "%3ld ", percent);

  	seq_printf(m, "%-30.30s %-20.20s %d
  ", p->func, f, p->line);

  }
  
  static int branch_stat_show_normal(struct seq_file *m,
  				   struct ftrace_branch_data *p, const char *f)
  {
  	seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
  	branch_stat_show(m, p, f);
  	return 0;
  }
  
  static int annotate_branch_stat_show(struct seq_file *m, void *v)
  {
  	struct ftrace_likely_data *p = v;
  	const char *f;
  	int l;
  
  	f = branch_stat_process_file(&p->data);
  
  	if (!p->constant)
  		return branch_stat_show_normal(m, &p->data, f);
  
  	l = snprintf(NULL, 0, "/%lu", p->constant);
  	l = l > 8 ? 0 : 8 - l;
  
  	seq_printf(m, "%8lu/%lu %*lu ",
  		   p->data.correct, p->constant, l, p->data.incorrect);
  	branch_stat_show(m, &p->data, f);

  	return 0;
  }

  static void *annotated_branch_stat_start(struct tracer_stat *trace)

  {
  	return __start_annotated_branch_profile;
  }

  static void *
  annotated_branch_stat_next(void *v, int idx)

  {

  	struct ftrace_likely_data *p = v;

  	++p;

  	if ((void *)p >= (void *)__stop_annotated_branch_profile)
  		return NULL;
  
  	return p;

  }

  static int annotated_branch_stat_cmp(const void *p1, const void *p2)

  {

  	const struct ftrace_branch_data *a = p1;
  	const struct ftrace_branch_data *b = p2;

  
  	long percent_a, percent_b;
  
  	percent_a = get_incorrect_percent(a);
  	percent_b = get_incorrect_percent(b);
  
  	if (percent_a < percent_b)
  		return -1;
  	if (percent_a > percent_b)
  		return 1;

  
  	if (a->incorrect < b->incorrect)
  		return -1;
  	if (a->incorrect > b->incorrect)
  		return 1;
  
  	/*
  	 * Since the above shows worse (incorrect) cases
  	 * first, we continue that by showing best (correct)
  	 * cases last.
  	 */
  	if (a->correct > b->correct)
  		return -1;
  	if (a->correct < b->correct)
  		return 1;
  
  	return 0;

  }

  static struct tracer_stat annotated_branch_stats = {
  	.name = "branch_annotated",
  	.stat_start = annotated_branch_stat_start,
  	.stat_next = annotated_branch_stat_next,
  	.stat_cmp = annotated_branch_stat_cmp,
  	.stat_headers = annotated_branch_stat_headers,

  	.stat_show = annotate_branch_stat_show

  };
  
  __init static int init_annotated_branch_stats(void)
  {
  	int ret;
  
  	ret = register_stat_tracer(&annotated_branch_stats);
  	if (!ret) {
  		printk(KERN_WARNING "Warning: could not register "
  				    "annotated branches stats
  ");
  		return 1;
  	}
  	return 0;
  }
  fs_initcall(init_annotated_branch_stats);

  #ifdef CONFIG_PROFILE_ALL_BRANCHES

  extern unsigned long __start_branch_profile[];
  extern unsigned long __stop_branch_profile[];

  static int all_branch_stat_headers(struct seq_file *m)
  {

  	seq_puts(m, "   miss      hit    % "
  		    "       Function                "

  		    "  File              Line
  "
  		    " ------- ---------  - "
  		    "       --------                "
  		    "  ----              ----
  ");

  	return 0;
  }

  static void *all_branch_stat_start(struct tracer_stat *trace)

  {

  	return __start_branch_profile;
  }
  
  static void *
  all_branch_stat_next(void *v, int idx)
  {
  	struct ftrace_branch_data *p = v;

  	++p;

  	if ((void *)p >= (void *)__stop_branch_profile)
  		return NULL;

  	return p;
  }

  static int all_branch_stat_show(struct seq_file *m, void *v)
  {
  	struct ftrace_branch_data *p = v;
  	const char *f;
  
  	f = branch_stat_process_file(p);
  	return branch_stat_show_normal(m, p, f);
  }

  static struct tracer_stat all_branch_stats = {
  	.name = "branch_all",

  	.stat_start = all_branch_stat_start,
  	.stat_next = all_branch_stat_next,
  	.stat_headers = all_branch_stat_headers,

  	.stat_show = all_branch_stat_show

  };

  __init static int all_annotated_branch_stats(void)

  {

  	int ret;

  
  	ret = register_stat_tracer(&all_branch_stats);

  	if (!ret) {

  		printk(KERN_WARNING "Warning: could not register "
  				    "all branches stats
  ");

  		return 1;
  	}

  	return 0;

  }

  fs_initcall(all_annotated_branch_stats);
  #endif /* CONFIG_PROFILE_ALL_BRANCHES */