// 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;
|
unsigned int trace_ctx;
|
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;
|
|
trace_ctx = tracing_gen_ctx_flags(flags);
|
buffer = tr->array_buffer.buffer;
|
event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
|
sizeof(*entry), trace_ctx);
|
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\n",
|
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\n"
|
"# | | | | | "
|
" |\n");
|
}
|
|
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\n");
|
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\n"
|
" ------- --------- - "
|
" -------- "
|
" ---- ----\n");
|
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\n", 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\n");
|
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\n"
|
" ------- --------- - "
|
" -------- "
|
" ---- ----\n");
|
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\n");
|
return 1;
|
}
|
return 0;
|
}
|
fs_initcall(all_annotated_branch_stats);
|
#endif /* CONFIG_PROFILE_ALL_BRANCHES */
|
