// SPDX-License-Identifier: GPL-2.0
|
/*
|
* ring buffer based function tracer
|
*
|
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
|
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
|
*
|
* Based on code from the latency_tracer, that is:
|
*
|
* Copyright (C) 2004-2006 Ingo Molnar
|
* Copyright (C) 2004 Nadia Yvette Chambers
|
*/
|
#include <linux/ring_buffer.h>
|
#include <linux/debugfs.h>
|
#include <linux/uaccess.h>
|
#include <linux/ftrace.h>
|
#include <linux/slab.h>
|
#include <linux/fs.h>
|
|
#include "trace.h"
|
|
static void tracing_start_function_trace(struct trace_array *tr);
|
static void tracing_stop_function_trace(struct trace_array *tr);
|
static void
|
function_trace_call(unsigned long ip, unsigned long parent_ip,
|
struct ftrace_ops *op, struct pt_regs *pt_regs);
|
static void
|
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
|
struct ftrace_ops *op, struct pt_regs *pt_regs);
|
static struct tracer_flags func_flags;
|
|
/* Our option */
|
enum {
|
TRACE_FUNC_OPT_STACK = 0x1,
|
};
|
|
int ftrace_allocate_ftrace_ops(struct trace_array *tr)
|
{
|
struct ftrace_ops *ops;
|
|
/* The top level array uses the "global_ops" */
|
if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
|
return 0;
|
|
ops = kzalloc(sizeof(*ops), GFP_KERNEL);
|
if (!ops)
|
return -ENOMEM;
|
|
/* Currently only the non stack version is supported */
|
ops->func = function_trace_call;
|
ops->flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_PID;
|
|
tr->ops = ops;
|
ops->private = tr;
|
|
return 0;
|
}
|
|
void ftrace_free_ftrace_ops(struct trace_array *tr)
|
{
|
kfree(tr->ops);
|
tr->ops = NULL;
|
}
|
|
int ftrace_create_function_files(struct trace_array *tr,
|
struct dentry *parent)
|
{
|
/*
|
* The top level array uses the "global_ops", and the files are
|
* created on boot up.
|
*/
|
if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
|
return 0;
|
|
if (!tr->ops)
|
return -EINVAL;
|
|
ftrace_create_filter_files(tr->ops, parent);
|
|
return 0;
|
}
|
|
void ftrace_destroy_function_files(struct trace_array *tr)
|
{
|
ftrace_destroy_filter_files(tr->ops);
|
ftrace_free_ftrace_ops(tr);
|
}
|
|
static int function_trace_init(struct trace_array *tr)
|
{
|
ftrace_func_t func;
|
|
/*
|
* Instance trace_arrays get their ops allocated
|
* at instance creation. Unless it failed
|
* the allocation.
|
*/
|
if (!tr->ops)
|
return -ENOMEM;
|
|
/* Currently only the global instance can do stack tracing */
|
if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
|
func_flags.val & TRACE_FUNC_OPT_STACK)
|
func = function_stack_trace_call;
|
else
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func = function_trace_call;
|
|
ftrace_init_array_ops(tr, func);
|
|
tr->array_buffer.cpu = get_cpu();
|
put_cpu();
|
|
tracing_start_cmdline_record();
|
tracing_start_function_trace(tr);
|
return 0;
|
}
|
|
static void function_trace_reset(struct trace_array *tr)
|
{
|
tracing_stop_function_trace(tr);
|
tracing_stop_cmdline_record();
|
ftrace_reset_array_ops(tr);
|
}
|
|
static void function_trace_start(struct trace_array *tr)
|
{
|
tracing_reset_online_cpus(&tr->array_buffer);
|
}
|
|
static void
|
function_trace_call(unsigned long ip, unsigned long parent_ip,
|
struct ftrace_ops *op, struct pt_regs *pt_regs)
|
{
|
struct trace_array *tr = op->private;
|
struct trace_array_cpu *data;
|
unsigned int trace_ctx;
|
int bit;
|
int cpu;
|
|
if (unlikely(!tr->function_enabled))
|
return;
|
|
trace_ctx = tracing_gen_ctx();
|
preempt_disable_notrace();
|
|
bit = trace_test_and_set_recursion(TRACE_FTRACE_START);
|
if (bit < 0)
|
goto out;
|
|
cpu = smp_processor_id();
|
data = per_cpu_ptr(tr->array_buffer.data, cpu);
|
if (!atomic_read(&data->disabled))
|
trace_function(tr, ip, parent_ip, trace_ctx);
|
|
trace_clear_recursion(bit);
|
|
out:
|
preempt_enable_notrace();
|
}
|
|
#ifdef CONFIG_UNWINDER_ORC
|
/*
|
* Skip 2:
|
*
|
* function_stack_trace_call()
|
* ftrace_call()
|
*/
|
#define STACK_SKIP 2
|
#else
|
/*
|
* Skip 3:
|
* __trace_stack()
|
* function_stack_trace_call()
|
* ftrace_call()
|
*/
|
#define STACK_SKIP 3
|
#endif
|
|
static void
|
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
|
struct ftrace_ops *op, struct pt_regs *pt_regs)
|
{
|
struct trace_array *tr = op->private;
|
struct trace_array_cpu *data;
|
unsigned long flags;
|
long disabled;
|
int cpu;
|
unsigned int trace_ctx;
|
|
if (unlikely(!tr->function_enabled))
|
return;
|
|
/*
|
* Need to use raw, since this must be called before the
|
* recursive protection is performed.
|
*/
|
local_irq_save(flags);
|
cpu = raw_smp_processor_id();
|
data = per_cpu_ptr(tr->array_buffer.data, cpu);
|
disabled = atomic_inc_return(&data->disabled);
|
|
if (likely(disabled == 1)) {
|
trace_ctx = tracing_gen_ctx_flags(flags);
|
trace_function(tr, ip, parent_ip, trace_ctx);
|
__trace_stack(tr, trace_ctx, STACK_SKIP);
|
}
|
|
atomic_dec(&data->disabled);
|
local_irq_restore(flags);
|
}
|
|
static struct tracer_opt func_opts[] = {
|
#ifdef CONFIG_STACKTRACE
|
{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
|
#endif
|
{ } /* Always set a last empty entry */
|
};
|
|
static struct tracer_flags func_flags = {
|
.val = 0, /* By default: all flags disabled */
|
.opts = func_opts
|
};
|
|
static void tracing_start_function_trace(struct trace_array *tr)
|
{
|
tr->function_enabled = 0;
|
register_ftrace_function(tr->ops);
|
tr->function_enabled = 1;
|
}
|
|
static void tracing_stop_function_trace(struct trace_array *tr)
|
{
|
tr->function_enabled = 0;
|
unregister_ftrace_function(tr->ops);
|
}
|
|
static struct tracer function_trace;
|
|
static int
|
func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
|
{
|
switch (bit) {
|
case TRACE_FUNC_OPT_STACK:
|
/* do nothing if already set */
|
if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
|
break;
|
|
/* We can change this flag when not running. */
|
if (tr->current_trace != &function_trace)
|
break;
|
|
unregister_ftrace_function(tr->ops);
|
|
if (set) {
|
tr->ops->func = function_stack_trace_call;
|
register_ftrace_function(tr->ops);
|
} else {
|
tr->ops->func = function_trace_call;
|
register_ftrace_function(tr->ops);
|
}
|
|
break;
|
default:
|
return -EINVAL;
|
}
|
|
return 0;
|
}
|
|
static struct tracer function_trace __tracer_data =
|
{
|
.name = "function",
|
.init = function_trace_init,
|
.reset = function_trace_reset,
|
.start = function_trace_start,
|
.flags = &func_flags,
|
.set_flag = func_set_flag,
|
.allow_instances = true,
|
#ifdef CONFIG_FTRACE_SELFTEST
|
.selftest = trace_selftest_startup_function,
|
#endif
|
};
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
static void update_traceon_count(struct ftrace_probe_ops *ops,
|
unsigned long ip,
|
struct trace_array *tr, bool on,
|
void *data)
|
{
|
struct ftrace_func_mapper *mapper = data;
|
long *count;
|
long old_count;
|
|
/*
|
* Tracing gets disabled (or enabled) once per count.
|
* This function can be called at the same time on multiple CPUs.
|
* It is fine if both disable (or enable) tracing, as disabling
|
* (or enabling) the second time doesn't do anything as the
|
* state of the tracer is already disabled (or enabled).
|
* What needs to be synchronized in this case is that the count
|
* only gets decremented once, even if the tracer is disabled
|
* (or enabled) twice, as the second one is really a nop.
|
*
|
* The memory barriers guarantee that we only decrement the
|
* counter once. First the count is read to a local variable
|
* and a read barrier is used to make sure that it is loaded
|
* before checking if the tracer is in the state we want.
|
* If the tracer is not in the state we want, then the count
|
* is guaranteed to be the old count.
|
*
|
* Next the tracer is set to the state we want (disabled or enabled)
|
* then a write memory barrier is used to make sure that
|
* the new state is visible before changing the counter by
|
* one minus the old counter. This guarantees that another CPU
|
* executing this code will see the new state before seeing
|
* the new counter value, and would not do anything if the new
|
* counter is seen.
|
*
|
* Note, there is no synchronization between this and a user
|
* setting the tracing_on file. But we currently don't care
|
* about that.
|
*/
|
count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
|
old_count = *count;
|
|
if (old_count <= 0)
|
return;
|
|
/* Make sure we see count before checking tracing state */
|
smp_rmb();
|
|
if (on == !!tracer_tracing_is_on(tr))
|
return;
|
|
if (on)
|
tracer_tracing_on(tr);
|
else
|
tracer_tracing_off(tr);
|
|
/* Make sure tracing state is visible before updating count */
|
smp_wmb();
|
|
*count = old_count - 1;
|
}
|
|
static void
|
ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
update_traceon_count(ops, ip, tr, 1, data);
|
}
|
|
static void
|
ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
update_traceon_count(ops, ip, tr, 0, data);
|
}
|
|
static void
|
ftrace_traceon(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
if (tracer_tracing_is_on(tr))
|
return;
|
|
tracer_tracing_on(tr);
|
}
|
|
static void
|
ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
if (!tracer_tracing_is_on(tr))
|
return;
|
|
tracer_tracing_off(tr);
|
}
|
|
#ifdef CONFIG_UNWINDER_ORC
|
/*
|
* Skip 3:
|
*
|
* function_trace_probe_call()
|
* ftrace_ops_assist_func()
|
* ftrace_call()
|
*/
|
#define FTRACE_STACK_SKIP 3
|
#else
|
/*
|
* Skip 5:
|
*
|
* __trace_stack()
|
* ftrace_stacktrace()
|
* function_trace_probe_call()
|
* ftrace_ops_assist_func()
|
* ftrace_call()
|
*/
|
#define FTRACE_STACK_SKIP 5
|
#endif
|
|
static __always_inline void trace_stack(struct trace_array *tr)
|
{
|
unsigned int trace_ctx;
|
|
trace_ctx = tracing_gen_ctx();
|
|
__trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
|
}
|
|
static void
|
ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
trace_stack(tr);
|
}
|
|
static void
|
ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
struct ftrace_func_mapper *mapper = data;
|
long *count;
|
long old_count;
|
long new_count;
|
|
if (!tracing_is_on())
|
return;
|
|
/* unlimited? */
|
if (!mapper) {
|
trace_stack(tr);
|
return;
|
}
|
|
count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
|
|
/*
|
* Stack traces should only execute the number of times the
|
* user specified in the counter.
|
*/
|
do {
|
old_count = *count;
|
|
if (!old_count)
|
return;
|
|
new_count = old_count - 1;
|
new_count = cmpxchg(count, old_count, new_count);
|
if (new_count == old_count)
|
trace_stack(tr);
|
|
if (!tracing_is_on())
|
return;
|
|
} while (new_count != old_count);
|
}
|
|
static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
|
void *data)
|
{
|
struct ftrace_func_mapper *mapper = data;
|
long *count = NULL;
|
|
if (mapper)
|
count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
|
|
if (count) {
|
if (*count <= 0)
|
return 0;
|
(*count)--;
|
}
|
|
return 1;
|
}
|
|
static void
|
ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
if (update_count(ops, ip, data))
|
ftrace_dump(DUMP_ALL);
|
}
|
|
/* Only dump the current CPU buffer. */
|
static void
|
ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
|
struct trace_array *tr, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
if (update_count(ops, ip, data))
|
ftrace_dump(DUMP_ORIG);
|
}
|
|
static int
|
ftrace_probe_print(const char *name, struct seq_file *m,
|
unsigned long ip, struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
struct ftrace_func_mapper *mapper = data;
|
long *count = NULL;
|
|
seq_printf(m, "%ps:%s", (void *)ip, name);
|
|
if (mapper)
|
count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
|
|
if (count)
|
seq_printf(m, ":count=%ld\n", *count);
|
else
|
seq_puts(m, ":unlimited\n");
|
|
return 0;
|
}
|
|
static int
|
ftrace_traceon_print(struct seq_file *m, unsigned long ip,
|
struct ftrace_probe_ops *ops,
|
void *data)
|
{
|
return ftrace_probe_print("traceon", m, ip, ops, data);
|
}
|
|
static int
|
ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
|
struct ftrace_probe_ops *ops, void *data)
|
{
|
return ftrace_probe_print("traceoff", m, ip, ops, data);
|
}
|
|
static int
|
ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
|
struct ftrace_probe_ops *ops, void *data)
|
{
|
return ftrace_probe_print("stacktrace", m, ip, ops, data);
|
}
|
|
static int
|
ftrace_dump_print(struct seq_file *m, unsigned long ip,
|
struct ftrace_probe_ops *ops, void *data)
|
{
|
return ftrace_probe_print("dump", m, ip, ops, data);
|
}
|
|
static int
|
ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
|
struct ftrace_probe_ops *ops, void *data)
|
{
|
return ftrace_probe_print("cpudump", m, ip, ops, data);
|
}
|
|
|
static int
|
ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
|
unsigned long ip, void *init_data, void **data)
|
{
|
struct ftrace_func_mapper *mapper = *data;
|
|
if (!mapper) {
|
mapper = allocate_ftrace_func_mapper();
|
if (!mapper)
|
return -ENOMEM;
|
*data = mapper;
|
}
|
|
return ftrace_func_mapper_add_ip(mapper, ip, init_data);
|
}
|
|
static void
|
ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
|
unsigned long ip, void *data)
|
{
|
struct ftrace_func_mapper *mapper = data;
|
|
if (!ip) {
|
free_ftrace_func_mapper(mapper, NULL);
|
return;
|
}
|
|
ftrace_func_mapper_remove_ip(mapper, ip);
|
}
|
|
static struct ftrace_probe_ops traceon_count_probe_ops = {
|
.func = ftrace_traceon_count,
|
.print = ftrace_traceon_print,
|
.init = ftrace_count_init,
|
.free = ftrace_count_free,
|
};
|
|
static struct ftrace_probe_ops traceoff_count_probe_ops = {
|
.func = ftrace_traceoff_count,
|
.print = ftrace_traceoff_print,
|
.init = ftrace_count_init,
|
.free = ftrace_count_free,
|
};
|
|
static struct ftrace_probe_ops stacktrace_count_probe_ops = {
|
.func = ftrace_stacktrace_count,
|
.print = ftrace_stacktrace_print,
|
.init = ftrace_count_init,
|
.free = ftrace_count_free,
|
};
|
|
static struct ftrace_probe_ops dump_probe_ops = {
|
.func = ftrace_dump_probe,
|
.print = ftrace_dump_print,
|
.init = ftrace_count_init,
|
.free = ftrace_count_free,
|
};
|
|
static struct ftrace_probe_ops cpudump_probe_ops = {
|
.func = ftrace_cpudump_probe,
|
.print = ftrace_cpudump_print,
|
};
|
|
static struct ftrace_probe_ops traceon_probe_ops = {
|
.func = ftrace_traceon,
|
.print = ftrace_traceon_print,
|
};
|
|
static struct ftrace_probe_ops traceoff_probe_ops = {
|
.func = ftrace_traceoff,
|
.print = ftrace_traceoff_print,
|
};
|
|
static struct ftrace_probe_ops stacktrace_probe_ops = {
|
.func = ftrace_stacktrace,
|
.print = ftrace_stacktrace_print,
|
};
|
|
static int
|
ftrace_trace_probe_callback(struct trace_array *tr,
|
struct ftrace_probe_ops *ops,
|
struct ftrace_hash *hash, char *glob,
|
char *cmd, char *param, int enable)
|
{
|
void *count = (void *)-1;
|
char *number;
|
int ret;
|
|
/* hash funcs only work with set_ftrace_filter */
|
if (!enable)
|
return -EINVAL;
|
|
if (glob[0] == '!')
|
return unregister_ftrace_function_probe_func(glob+1, tr, ops);
|
|
if (!param)
|
goto out_reg;
|
|
number = strsep(¶m, ":");
|
|
if (!strlen(number))
|
goto out_reg;
|
|
/*
|
* We use the callback data field (which is a pointer)
|
* as our counter.
|
*/
|
ret = kstrtoul(number, 0, (unsigned long *)&count);
|
if (ret)
|
return ret;
|
|
out_reg:
|
ret = register_ftrace_function_probe(glob, tr, ops, count);
|
|
return ret < 0 ? ret : 0;
|
}
|
|
static int
|
ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
|
char *glob, char *cmd, char *param, int enable)
|
{
|
struct ftrace_probe_ops *ops;
|
|
if (!tr)
|
return -ENODEV;
|
|
/* we register both traceon and traceoff to this callback */
|
if (strcmp(cmd, "traceon") == 0)
|
ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
|
else
|
ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
|
|
return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
|
param, enable);
|
}
|
|
static int
|
ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
|
char *glob, char *cmd, char *param, int enable)
|
{
|
struct ftrace_probe_ops *ops;
|
|
if (!tr)
|
return -ENODEV;
|
|
ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
|
|
return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
|
param, enable);
|
}
|
|
static int
|
ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
|
char *glob, char *cmd, char *param, int enable)
|
{
|
struct ftrace_probe_ops *ops;
|
|
if (!tr)
|
return -ENODEV;
|
|
ops = &dump_probe_ops;
|
|
/* Only dump once. */
|
return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
|
"1", enable);
|
}
|
|
static int
|
ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
|
char *glob, char *cmd, char *param, int enable)
|
{
|
struct ftrace_probe_ops *ops;
|
|
if (!tr)
|
return -ENODEV;
|
|
ops = &cpudump_probe_ops;
|
|
/* Only dump once. */
|
return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
|
"1", enable);
|
}
|
|
static struct ftrace_func_command ftrace_traceon_cmd = {
|
.name = "traceon",
|
.func = ftrace_trace_onoff_callback,
|
};
|
|
static struct ftrace_func_command ftrace_traceoff_cmd = {
|
.name = "traceoff",
|
.func = ftrace_trace_onoff_callback,
|
};
|
|
static struct ftrace_func_command ftrace_stacktrace_cmd = {
|
.name = "stacktrace",
|
.func = ftrace_stacktrace_callback,
|
};
|
|
static struct ftrace_func_command ftrace_dump_cmd = {
|
.name = "dump",
|
.func = ftrace_dump_callback,
|
};
|
|
static struct ftrace_func_command ftrace_cpudump_cmd = {
|
.name = "cpudump",
|
.func = ftrace_cpudump_callback,
|
};
|
|
static int __init init_func_cmd_traceon(void)
|
{
|
int ret;
|
|
ret = register_ftrace_command(&ftrace_traceoff_cmd);
|
if (ret)
|
return ret;
|
|
ret = register_ftrace_command(&ftrace_traceon_cmd);
|
if (ret)
|
goto out_free_traceoff;
|
|
ret = register_ftrace_command(&ftrace_stacktrace_cmd);
|
if (ret)
|
goto out_free_traceon;
|
|
ret = register_ftrace_command(&ftrace_dump_cmd);
|
if (ret)
|
goto out_free_stacktrace;
|
|
ret = register_ftrace_command(&ftrace_cpudump_cmd);
|
if (ret)
|
goto out_free_dump;
|
|
return 0;
|
|
out_free_dump:
|
unregister_ftrace_command(&ftrace_dump_cmd);
|
out_free_stacktrace:
|
unregister_ftrace_command(&ftrace_stacktrace_cmd);
|
out_free_traceon:
|
unregister_ftrace_command(&ftrace_traceon_cmd);
|
out_free_traceoff:
|
unregister_ftrace_command(&ftrace_traceoff_cmd);
|
|
return ret;
|
}
|
#else
|
static inline int init_func_cmd_traceon(void)
|
{
|
return 0;
|
}
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
__init int init_function_trace(void)
|
{
|
init_func_cmd_traceon();
|
return register_tracer(&function_trace);
|
}
|
