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trace_functions.c
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814 lines (669 loc) · 18 KB
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// SPDX-License-Identifier: GPL-2.0
/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
* Copyright (C) 2008 Ingo Molnar <[email protected]>
*
* 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,
};
static int allocate_ftrace_ops(struct trace_array *tr)
{
struct ftrace_ops *ops;
ops = kzalloc(sizeof(*ops), GFP_KERNEL);
if (!ops)
return -ENOMEM;
/* Currently only the non stack verision 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;
}
int ftrace_create_function_files(struct trace_array *tr,
struct dentry *parent)
{
int ret;
/*
* 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;
ret = allocate_ftrace_ops(tr);
if (ret)
return ret;
ftrace_create_filter_files(tr->ops, parent);
return 0;
}
void ftrace_destroy_function_files(struct trace_array *tr)
{
ftrace_destroy_filter_files(tr->ops);
kfree(tr->ops);
tr->ops = NULL;
}
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
func = function_trace_call;
ftrace_init_array_ops(tr, func);
tr->trace_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->trace_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 long flags;
int bit;
int cpu;
int pc;
if (unlikely(!tr->function_enabled))
return;
pc = preempt_count();
preempt_disable_notrace();
bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
if (bit < 0)
goto out;
cpu = smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
if (!atomic_read(&data->disabled)) {
local_save_flags(flags);
trace_function(tr, ip, parent_ip, flags, pc);
}
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;
int pc;
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->trace_buffer.data, cpu);
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
trace_function(tr, ip, parent_ip, flags, pc);
__trace_stack(tr, flags, STACK_SKIP, pc);
}
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 long flags;
int pc;
local_save_flags(flags);
pc = preempt_count();
__trace_stack(tr, flags, FTRACE_STACK_SKIP, pc);
}
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);
}