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 000000000000..85265553918f
--- /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);