1 files changed, 320 insertions, 0 deletions
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
new file mode 100644
index 00000000000..85265553918
--- /dev/null
+++ b/kernel/trace/trace_branch.c
@@ -0,0 +1,320 @@
+/*
+ * 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/debugfs.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"
+
+#ifdef CONFIG_BRANCH_TRACER
+
+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_branch_data *f, int val, int expect)
+{
+	struct trace_array *tr = branch_tracer;
+	struct ring_buffer_event *event;
+	struct trace_branch *entry;
+	unsigned long flags, irq_flags;
+	int cpu, pc;
+	const char *p;
+
+	/*
+	 * 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;
+
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
+		goto out;
+
+	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
+					 &irq_flags);
+	if (!event)
+		goto out;
+
+	pc = preempt_count();
+	entry	= ring_buffer_event_data(event);
+	tracing_generic_entry_update(&entry->ent, flags, pc);
+	entry->ent.type		= TRACE_BRANCH;
+
+	/* Strip off the path, only save the file */
+	p = f->file + strlen(f->file);
+	while (p >= f->file && *p != '/')
+		p--;
+	p++;
+
+	strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
+	strncpy(entry->file, p, TRACE_FILE_SIZE);
+	entry->func[TRACE_FUNC_SIZE] = 0;
+	entry->file[TRACE_FILE_SIZE] = 0;
+	entry->line = f->line;
+	entry->correct = val == expect;
+
+	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
+
+ out:
+	atomic_dec(&tr->data[cpu]->disabled);
+	local_irq_restore(flags);
+}
+
+static inline
+void trace_likely_condition(struct ftrace_branch_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)
+{
+	int ret = 0;
+
+	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 ret;
+}
+
+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 void start_branch_trace(struct trace_array *tr)
+{
+	enable_branch_tracing(tr);
+}
+
+static void stop_branch_trace(struct trace_array *tr)
+{
+	disable_branch_tracing();
+}
+
+static void branch_trace_init(struct trace_array *tr)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		tracing_reset(tr, cpu);
+
+	start_branch_trace(tr);
+}
+
+static void branch_trace_reset(struct trace_array *tr)
+{
+	stop_branch_trace(tr);
+}
+
+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
+};
+
+__init static int init_branch_trace(void)
+{
+	return register_tracer(&branch_trace);
+}
+
+device_initcall(init_branch_trace);
+#else
+static inline
+void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
+{
+}
+#endif /* CONFIG_BRANCH_TRACER */
+
+void ftrace_likely_update(struct ftrace_branch_data *f, int val, int 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->correct++;
+	else
+		f->incorrect++;
+}
+EXPORT_SYMBOL(ftrace_likely_update);
+
+struct ftrace_pointer {
+	void		*start;
+	void		*stop;
+};
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct ftrace_pointer *f = m->private;
+	struct ftrace_branch_data *p = v;
+
+	(*pos)++;
+
+	if (v == (void *)1)
+		return f->start;
+
+	++p;
+
+	if ((void *)p >= (void *)f->stop)
+		return NULL;
+
+	return p;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	void *t = (void *)1;
+	loff_t l = 0;
+
+	for (; t && l < *pos; t = t_next(m, t, &l))
+		;
+
+	return t;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	struct ftrace_branch_data *p = v;
+	const char *f;
+	unsigned long percent;
+
+	if (v == (void *)1) {
+		seq_printf(m, " correct incorrect  %% "
+			      "       Function                "
+			      "  File              Line\n"
+			      " ------- ---------  - "
+			      "       --------                "
+			      "  ----              ----\n");
+		return 0;
+	}
+
+	/* Only print the file, not the path */
+	f = p->file + strlen(p->file);
+	while (f >= p->file && *f != '/')
+		f--;
+	f++;
+
+	if (p->correct) {
+		percent = p->incorrect * 100;
+		percent /= p->correct + p->incorrect;
+	} else
+		percent = p->incorrect ? 100 : 0;
+
+	seq_printf(m, "%8lu %8lu %3lu ", p->correct, p->incorrect, percent);
+	seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
+	return 0;
+}
+
+static struct seq_operations tracing_likely_seq_ops = {
+	.start		= t_start,
+	.next		= t_next,
+	.stop		= t_stop,
+	.show		= t_show,
+};
+
+static int tracing_likely_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = seq_open(file, &tracing_likely_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+		m->private = (void *)inode->i_private;
+	}
+
+	return ret;
+}
+
+static struct file_operations tracing_likely_fops = {
+	.open		= tracing_likely_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+};
+
+extern unsigned long __start_likely_profile[];
+extern unsigned long __stop_likely_profile[];
+extern unsigned long __start_unlikely_profile[];
+extern unsigned long __stop_unlikely_profile[];
+
+static struct ftrace_pointer ftrace_likely_pos = {
+	.start			= __start_likely_profile,
+	.stop			= __stop_likely_profile,
+};
+
+static struct ftrace_pointer ftrace_unlikely_pos = {
+	.start			= __start_unlikely_profile,
+	.stop			= __stop_unlikely_profile,
+};
+
+static __init int ftrace_branch_init(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+
+	entry = debugfs_create_file("profile_likely", 0444, d_tracer,
+				    &ftrace_likely_pos,
+				    &tracing_likely_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'profile_likely' entry\n");
+
+	entry = debugfs_create_file("profile_unlikely", 0444, d_tracer,
+				    &ftrace_unlikely_pos,
+				    &tracing_likely_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs"
+			   " 'profile_unlikely' entry\n");
+
+	return 0;
+}
+
+device_initcall(ftrace_branch_init);