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linux/kernel/trace/ftrace.c
Steven Rostedt b1cff0ad10 ftrace: Add internal recursive checks 
Witold reported a reboot caused by the selftests of the dynamic function
tracer. He sent me a config and I used ktest to do a config_bisect on it
(as my config did not cause the crash). It pointed out that the problem
config was CONFIG_PROVE_RCU.

What happened was that if multiple callbacks are attached to the
function tracer, we iterate a list of callbacks. Because the list is
managed by synchronize_sched() and preempt_disable, the access to the
pointers uses rcu_dereference_raw().

When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
debugging functions, which happen to be traced. The tracing of the debug
function would then call rcu_dereference_raw() which would then call the
debug function and then... well you get the idea.

I first wrote two different patches to solve this bug.

1) add a __rcu_dereference_raw() that would not do any checks.
2) add notrace to the offending debug functions.

Both of these patches worked.

Talking with Paul McKenney on IRC, he suggested to add recursion
detection instead. This seemed to be a better solution, so I decided to
implement it. As the task_struct already has a trace_recursion to detect
recursion in the ring buffer, and that has a very small number it
allows, I decided to use that same variable to add flags that can detect
the recursion inside the infrastructure of the function tracer.

I plan to change it so that the task struct bit can be checked in
mcount, but as that requires changes to all archs, I will hold that off
to the next merge window.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com
Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-25 22:13:49 -04:00

4168 lines
88 KiB
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/*
* Infrastructure for profiling code inserted by 'gcc -pg'.
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
*
* Originally ported from the -rt patch by:
* Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
*
* Based on code in the latency_tracer, that is:
*
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/stop_machine.h>
#include <linux/clocksource.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/suspend.h>
#include <linux/debugfs.h>
#include <linux/hardirq.h>
#include <linux/kthread.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/rcupdate.h>
#include <trace/events/sched.h>
#include <asm/ftrace.h>
#include <asm/setup.h>
#include "trace_output.h"
#include "trace_stat.h"
#define FTRACE_WARN_ON(cond) \
({ \
int ___r = cond; \
if (WARN_ON(___r)) \
ftrace_kill(); \
___r; \
})
#define FTRACE_WARN_ON_ONCE(cond) \
({ \
int ___r = cond; \
if (WARN_ON_ONCE(___r)) \
ftrace_kill(); \
___r; \
})
/* hash bits for specific function selection */
#define FTRACE_HASH_BITS 7
#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)
#define FTRACE_HASH_DEFAULT_BITS 10
#define FTRACE_HASH_MAX_BITS 12
/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
static int last_ftrace_enabled;
/* Quick disabling of function tracer. */
int function_trace_stop;
/* List for set_ftrace_pid's pids. */
LIST_HEAD(ftrace_pids);
struct ftrace_pid {
struct list_head list;
struct pid *pid;
};
/*
* ftrace_disabled is set when an anomaly is discovered.
* ftrace_disabled is much stronger than ftrace_enabled.
*/
static int ftrace_disabled __read_mostly;
static DEFINE_MUTEX(ftrace_lock);
static struct ftrace_ops ftrace_list_end __read_mostly =
{
.func = ftrace_stub,
};
static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
static struct ftrace_ops global_ops;
static void
ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
/*
* Traverse the ftrace_global_list, invoking all entries. The reason that we
* can use rcu_dereference_raw() is that elements removed from this list
* are simply leaked, so there is no need to interact with a grace-period
* mechanism. The rcu_dereference_raw() calls are needed to handle
* concurrent insertions into the ftrace_global_list.
*
* Silly Alpha and silly pointer-speculation compiler optimizations!
*/
static void ftrace_global_list_func(unsigned long ip,
unsigned long parent_ip)
{
struct ftrace_ops *op;
if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
return;
trace_recursion_set(TRACE_GLOBAL_BIT);
op = rcu_dereference_raw(ftrace_global_list); /*see above*/
while (op != &ftrace_list_end) {
op->func(ip, parent_ip);
op = rcu_dereference_raw(op->next); /*see above*/
};
trace_recursion_clear(TRACE_GLOBAL_BIT);
}
static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
{
if (!test_tsk_trace_trace(current))
return;
ftrace_pid_function(ip, parent_ip);
}
static void set_ftrace_pid_function(ftrace_func_t func)
{
/* do not set ftrace_pid_function to itself! */
if (func != ftrace_pid_func)
ftrace_pid_function = func;
}
/**
* clear_ftrace_function - reset the ftrace function
*
* This NULLs the ftrace function and in essence stops
* tracing. There may be lag
*/
void clear_ftrace_function(void)
{
ftrace_trace_function = ftrace_stub;
__ftrace_trace_function = ftrace_stub;
ftrace_pid_function = ftrace_stub;
}
#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
/*
* For those archs that do not test ftrace_trace_stop in their
* mcount call site, we need to do it from C.
*/
static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
{
if (function_trace_stop)
return;
__ftrace_trace_function(ip, parent_ip);
}
#endif
static void update_global_ops(void)
{
ftrace_func_t func;
/*
* If there's only one function registered, then call that
* function directly. Otherwise, we need to iterate over the
* registered callers.
*/
if (ftrace_global_list == &ftrace_list_end ||
ftrace_global_list->next == &ftrace_list_end)
func = ftrace_global_list->func;
else
func = ftrace_global_list_func;
/* If we filter on pids, update to use the pid function */
if (!list_empty(&ftrace_pids)) {
set_ftrace_pid_function(func);
func = ftrace_pid_func;
}
global_ops.func = func;
}
static void update_ftrace_function(void)
{
ftrace_func_t func;
update_global_ops();
/*
* If we are at the end of the list and this ops is
* not dynamic, then have the mcount trampoline call
* the function directly
*/
if (ftrace_ops_list == &ftrace_list_end ||
(ftrace_ops_list->next == &ftrace_list_end &&
!(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC)))
func = ftrace_ops_list->func;
else
func = ftrace_ops_list_func;
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
ftrace_trace_function = func;
#else
__ftrace_trace_function = func;
ftrace_trace_function = ftrace_test_stop_func;
#endif
}
static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
ops->next = *list;
/*
* We are entering ops into the list but another
* CPU might be walking that list. We need to make sure
* the ops->next pointer is valid before another CPU sees
* the ops pointer included into the list.
*/
rcu_assign_pointer(*list, ops);
}
static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
struct ftrace_ops **p;
/*
* If we are removing the last function, then simply point
* to the ftrace_stub.
*/
if (*list == ops && ops->next == &ftrace_list_end) {
*list = &ftrace_list_end;
return 0;
}
for (p = list; *p != &ftrace_list_end; p = &(*p)->next)
if (*p == ops)
break;
if (*p != ops)
return -1;
*p = (*p)->next;
return 0;
}
static int __register_ftrace_function(struct ftrace_ops *ops)
{
if (ftrace_disabled)
return -ENODEV;
if (FTRACE_WARN_ON(ops == &global_ops))
return -EINVAL;
if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EBUSY;
if (!core_kernel_data((unsigned long)ops))
ops->flags |= FTRACE_OPS_FL_DYNAMIC;
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
int first = ftrace_global_list == &ftrace_list_end;
add_ftrace_ops(&ftrace_global_list, ops);
ops->flags |= FTRACE_OPS_FL_ENABLED;
if (first)
add_ftrace_ops(&ftrace_ops_list, &global_ops);
} else
add_ftrace_ops(&ftrace_ops_list, ops);
if (ftrace_enabled)
update_ftrace_function();
return 0;
}
static int __unregister_ftrace_function(struct ftrace_ops *ops)
{
int ret;
if (ftrace_disabled)
return -ENODEV;
if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
return -EBUSY;
if (FTRACE_WARN_ON(ops == &global_ops))
return -EINVAL;
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
ret = remove_ftrace_ops(&ftrace_global_list, ops);
if (!ret && ftrace_global_list == &ftrace_list_end)
ret = remove_ftrace_ops(&ftrace_ops_list, &global_ops);
if (!ret)
ops->flags &= ~FTRACE_OPS_FL_ENABLED;
} else
ret = remove_ftrace_ops(&ftrace_ops_list, ops);
if (ret < 0)
return ret;
if (ftrace_enabled)
update_ftrace_function();
/*
* Dynamic ops may be freed, we must make sure that all
* callers are done before leaving this function.
*/
if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
synchronize_sched();
return 0;
}
static void ftrace_update_pid_func(void)
{
/* Only do something if we are tracing something */
if (ftrace_trace_function == ftrace_stub)
return;
update_ftrace_function();
}
#ifdef CONFIG_FUNCTION_PROFILER
struct ftrace_profile {
struct hlist_node node;
unsigned long ip;
unsigned long counter;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
unsigned long long time;
unsigned long long time_squared;
#endif
};
struct ftrace_profile_page {
struct ftrace_profile_page *next;
unsigned long index;
struct ftrace_profile records[];
};
struct ftrace_profile_stat {
atomic_t disabled;
struct hlist_head *hash;
struct ftrace_profile_page *pages;
struct ftrace_profile_page *start;
struct tracer_stat stat;
};
#define PROFILE_RECORDS_SIZE \
(PAGE_SIZE - offsetof(struct ftrace_profile_page, records))
#define PROFILES_PER_PAGE \
(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
static int ftrace_profile_bits __read_mostly;
static int ftrace_profile_enabled __read_mostly;
/* ftrace_profile_lock - synchronize the enable and disable of the profiler */
static DEFINE_MUTEX(ftrace_profile_lock);
static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
static void *
function_stat_next(void *v, int idx)
{
struct ftrace_profile *rec = v;
struct ftrace_profile_page *pg;
pg = (struct ftrace_profile_page *)((unsigned long)rec & PAGE_MASK);
again:
if (idx != 0)
rec++;
if ((void *)rec >= (void *)&pg->records[pg->index]) {
pg = pg->next;
if (!pg)
return NULL;
rec = &pg->records[0];
if (!rec->counter)
goto again;
}
return rec;
}
static void *function_stat_start(struct tracer_stat *trace)
{
struct ftrace_profile_stat *stat =
container_of(trace, struct ftrace_profile_stat, stat);
if (!stat || !stat->start)
return NULL;
return function_stat_next(&stat->start->records[0], 0);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* function graph compares on total time */
static int function_stat_cmp(void *p1, void *p2)
{
struct ftrace_profile *a = p1;
struct ftrace_profile *b = p2;
if (a->time < b->time)
return -1;
if (a->time > b->time)
return 1;
else
return 0;
}
#else
/* not function graph compares against hits */
static int function_stat_cmp(void *p1, void *p2)
{
struct ftrace_profile *a = p1;
struct ftrace_profile *b = p2;
if (a->counter < b->counter)
return -1;
if (a->counter > b->counter)
return 1;
else
return 0;
}
#endif
static int function_stat_headers(struct seq_file *m)
{
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
seq_printf(m, " Function "
"Hit Time Avg s^2\n"
" -------- "
"--- ---- --- ---\n");
#else
seq_printf(m, " Function Hit\n"
" -------- ---\n");
#endif
return 0;
}
static int function_stat_show(struct seq_file *m, void *v)
{
struct ftrace_profile *rec = v;
char str[KSYM_SYMBOL_LEN];
int ret = 0;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static struct trace_seq s;
unsigned long long avg;
unsigned long long stddev;
#endif
mutex_lock(&ftrace_profile_lock);
/* we raced with function_profile_reset() */
if (unlikely(rec->counter == 0)) {
ret = -EBUSY;
goto out;
}
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
seq_printf(m, " %-30.30s %10lu", str, rec->counter);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
seq_printf(m, " ");
avg = rec->time;
do_div(avg, rec->counter);
/* Sample standard deviation (s^2) */
if (rec->counter <= 1)
stddev = 0;
else {
stddev = rec->time_squared - rec->counter * avg * avg;
/*
* Divide only 1000 for ns^2 -> us^2 conversion.
* trace_print_graph_duration will divide 1000 again.
*/
do_div(stddev, (rec->counter - 1) * 1000);
}
trace_seq_init(&s);
trace_print_graph_duration(rec->time, &s);
trace_seq_puts(&s, " ");
trace_print_graph_duration(avg, &s);
trace_seq_puts(&s, " ");
trace_print_graph_duration(stddev, &s);
trace_print_seq(m, &s);
#endif
seq_putc(m, '\n');
out:
mutex_unlock(&ftrace_profile_lock);
return ret;
}
static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
{
struct ftrace_profile_page *pg;
pg = stat->pages = stat->start;
while (pg) {
memset(pg->records, 0, PROFILE_RECORDS_SIZE);
pg->index = 0;
pg = pg->next;
}
memset(stat->hash, 0,
FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
}
int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
{
struct ftrace_profile_page *pg;
int functions;
int pages;
int i;
/* If we already allocated, do nothing */
if (stat->pages)
return 0;
stat->pages = (void *)get_zeroed_page(GFP_KERNEL);
if (!stat->pages)
return -ENOMEM;
#ifdef CONFIG_DYNAMIC_FTRACE
functions = ftrace_update_tot_cnt;
#else
/*
* We do not know the number of functions that exist because
* dynamic tracing is what counts them. With past experience
* we have around 20K functions. That should be more than enough.
* It is highly unlikely we will execute every function in
* the kernel.
*/
functions = 20000;
#endif
pg = stat->start = stat->pages;
pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
for (i = 0; i < pages; i++) {
pg->next = (void *)get_zeroed_page(GFP_KERNEL);
if (!pg->next)
goto out_free;
pg = pg->next;
}
return 0;
out_free:
pg = stat->start;
while (pg) {
unsigned long tmp = (unsigned long)pg;
pg = pg->next;
free_page(tmp);
}
free_page((unsigned long)stat->pages);
stat->pages = NULL;
stat->start = NULL;
return -ENOMEM;
}
static int ftrace_profile_init_cpu(int cpu)
{
struct ftrace_profile_stat *stat;
int size;
stat = &per_cpu(ftrace_profile_stats, cpu);
if (stat->hash) {
/* If the profile is already created, simply reset it */
ftrace_profile_reset(stat);
return 0;
}
/*
* We are profiling all functions, but usually only a few thousand
* functions are hit. We'll make a hash of 1024 items.
*/
size = FTRACE_PROFILE_HASH_SIZE;
stat->hash = kzalloc(sizeof(struct hlist_head) * size, GFP_KERNEL);
if (!stat->hash)
return -ENOMEM;
if (!ftrace_profile_bits) {
size--;
for (; size; size >>= 1)
ftrace_profile_bits++;
}
/* Preallocate the function profiling pages */
if (ftrace_profile_pages_init(stat) < 0) {
kfree(stat->hash);
stat->hash = NULL;
return -ENOMEM;
}
return 0;
}
static int ftrace_profile_init(void)
{
int cpu;
int ret = 0;
for_each_online_cpu(cpu) {
ret = ftrace_profile_init_cpu(cpu);
if (ret)
break;
}
return ret;
}
/* interrupts must be disabled */
static struct ftrace_profile *
ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
{
struct ftrace_profile *rec;
struct hlist_head *hhd;
struct hlist_node *n;
unsigned long key;
key = hash_long(ip, ftrace_profile_bits);
hhd = &stat->hash[key];
if (hlist_empty(hhd))
return NULL;
hlist_for_each_entry_rcu(rec, n, hhd, node) {
if (rec->ip == ip)
return rec;
}
return NULL;
}
static void ftrace_add_profile(struct ftrace_profile_stat *stat,
struct ftrace_profile *rec)
{
unsigned long key;
key = hash_long(rec->ip, ftrace_profile_bits);
hlist_add_head_rcu(&rec->node, &stat->hash[key]);
}
/*
* The memory is already allocated, this simply finds a new record to use.
*/
static struct ftrace_profile *
ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
{
struct ftrace_profile *rec = NULL;
/* prevent recursion (from NMIs) */
if (atomic_inc_return(&stat->disabled) != 1)
goto out;
/*
* Try to find the function again since an NMI
* could have added it
*/
rec = ftrace_find_profiled_func(stat, ip);
if (rec)
goto out;
if (stat->pages->index == PROFILES_PER_PAGE) {
if (!stat->pages->next)
goto out;
stat->pages = stat->pages->next;
}
rec = &stat->pages->records[stat->pages->index++];
rec->ip = ip;
ftrace_add_profile(stat, rec);
out:
atomic_dec(&stat->disabled);
return rec;
}
static void
function_profile_call(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_profile_stat *stat;
struct ftrace_profile *rec;
unsigned long flags;
if (!ftrace_profile_enabled)
return;
local_irq_save(flags);
stat = &__get_cpu_var(ftrace_profile_stats);
if (!stat->hash || !ftrace_profile_enabled)
goto out;
rec = ftrace_find_profiled_func(stat, ip);
if (!rec) {
rec = ftrace_profile_alloc(stat, ip);
if (!rec)
goto out;
}
rec->counter++;
out:
local_irq_restore(flags);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int profile_graph_entry(struct ftrace_graph_ent *trace)
{
function_profile_call(trace->func, 0);
return 1;
}
static void profile_graph_return(struct ftrace_graph_ret *trace)
{
struct ftrace_profile_stat *stat;
unsigned long long calltime;
struct ftrace_profile *rec;
unsigned long flags;
local_irq_save(flags);
stat = &__get_cpu_var(ftrace_profile_stats);
if (!stat->hash || !ftrace_profile_enabled)
goto out;
/* If the calltime was zero'd ignore it */
if (!trace->calltime)
goto out;
calltime = trace->rettime - trace->calltime;
if (!(trace_flags & TRACE_ITER_GRAPH_TIME)) {
int index;
index = trace->depth;
/* Append this call time to the parent time to subtract */
if (index)
current->ret_stack[index - 1].subtime += calltime;
if (current->ret_stack[index].subtime < calltime)
calltime -= current->ret_stack[index].subtime;
else
calltime = 0;
}
rec = ftrace_find_profiled_func(stat, trace->func);
if (rec) {
rec->time += calltime;
rec->time_squared += calltime * calltime;
}
out:
local_irq_restore(flags);
}
static int register_ftrace_profiler(void)
{
return register_ftrace_graph(&profile_graph_return,
&profile_graph_entry);
}
static void unregister_ftrace_profiler(void)
{
unregister_ftrace_graph();
}
#else
static struct ftrace_ops ftrace_profile_ops __read_mostly =
{
.func = function_profile_call,
};
static int register_ftrace_profiler(void)
{
return register_ftrace_function(&ftrace_profile_ops);
}
static void unregister_ftrace_profiler(void)
{
unregister_ftrace_function(&ftrace_profile_ops);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
static ssize_t
ftrace_profile_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long val;
char buf[64]; /* big enough to hold a number */
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
val = !!val;
mutex_lock(&ftrace_profile_lock);
if (ftrace_profile_enabled ^ val) {
if (val) {
ret = ftrace_profile_init();
if (ret < 0) {
cnt = ret;
goto out;
}
ret = register_ftrace_profiler();
if (ret < 0) {
cnt = ret;
goto out;
}
ftrace_profile_enabled = 1;
} else {
ftrace_profile_enabled = 0;
/*
* unregister_ftrace_profiler calls stop_machine
* so this acts like an synchronize_sched.
*/
unregister_ftrace_profiler();
}
}
out:
mutex_unlock(&ftrace_profile_lock);
*ppos += cnt;
return cnt;
}
static ssize_t
ftrace_profile_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64]; /* big enough to hold a number */
int r;
r = sprintf(buf, "%u\n", ftrace_profile_enabled);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static const struct file_operations ftrace_profile_fops = {
.open = tracing_open_generic,
.read = ftrace_profile_read,
.write = ftrace_profile_write,
.llseek = default_llseek,
};
/* used to initialize the real stat files */
static struct tracer_stat function_stats __initdata = {
.name = "functions",
.stat_start = function_stat_start,
.stat_next = function_stat_next,
.stat_cmp = function_stat_cmp,
.stat_headers = function_stat_headers,
.stat_show = function_stat_show
};
static __init void ftrace_profile_debugfs(struct dentry *d_tracer)
{
struct ftrace_profile_stat *stat;
struct dentry *entry;
char *name;
int ret;
int cpu;
for_each_possible_cpu(cpu) {
stat = &per_cpu(ftrace_profile_stats, cpu);
/* allocate enough for function name + cpu number */
name = kmalloc(32, GFP_KERNEL);
if (!name) {
/*
* The files created are permanent, if something happens
* we still do not free memory.
*/
WARN(1,
"Could not allocate stat file for cpu %d\n",
cpu);
return;
}
stat->stat = function_stats;
snprintf(name, 32, "function%d", cpu);
stat->stat.name = name;
ret = register_stat_tracer(&stat->stat);
if (ret) {
WARN(1,
"Could not register function stat for cpu %d\n",
cpu);
kfree(name);
return;
}
}
entry = debugfs_create_file("function_profile_enabled", 0644,
d_tracer, NULL, &ftrace_profile_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'function_profile_enabled' entry\n");
}
#else /* CONFIG_FUNCTION_PROFILER */
static __init void ftrace_profile_debugfs(struct dentry *d_tracer)
{
}
#endif /* CONFIG_FUNCTION_PROFILER */
static struct pid * const ftrace_swapper_pid = &init_struct_pid;
#ifdef CONFIG_DYNAMIC_FTRACE
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
# error Dynamic ftrace depends on MCOUNT_RECORD
#endif
static struct hlist_head ftrace_func_hash[FTRACE_FUNC_HASHSIZE] __read_mostly;
struct ftrace_func_probe {
struct hlist_node node;
struct ftrace_probe_ops *ops;
unsigned long flags;
unsigned long ip;
void *data;
struct rcu_head rcu;
};
enum {
FTRACE_ENABLE_CALLS = (1 << 0),
FTRACE_DISABLE_CALLS = (1 << 1),
FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
FTRACE_START_FUNC_RET = (1 << 3),
FTRACE_STOP_FUNC_RET = (1 << 4),
};
struct ftrace_func_entry {
struct hlist_node hlist;
unsigned long ip;
};
struct ftrace_hash {
unsigned long size_bits;
struct hlist_head *buckets;
unsigned long count;
struct rcu_head rcu;
};
/*
* We make these constant because no one should touch them,
* but they are used as the default "empty hash", to avoid allocating
* it all the time. These are in a read only section such that if
* anyone does try to modify it, it will cause an exception.
*/
static const struct hlist_head empty_buckets[1];
static const struct ftrace_hash empty_hash = {
.buckets = (struct hlist_head *)empty_buckets,
};
#define EMPTY_HASH ((struct ftrace_hash *)&empty_hash)
static struct ftrace_ops global_ops = {
.func = ftrace_stub,
.notrace_hash = EMPTY_HASH,
.filter_hash = EMPTY_HASH,
};
static struct dyn_ftrace *ftrace_new_addrs;
static DEFINE_MUTEX(ftrace_regex_lock);
struct ftrace_page {
struct ftrace_page *next;
int index;
struct dyn_ftrace records[];
};
#define ENTRIES_PER_PAGE \
((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
/* estimate from running different kernels */
#define NR_TO_INIT 10000
static struct ftrace_page *ftrace_pages_start;
static struct ftrace_page *ftrace_pages;
static struct dyn_ftrace *ftrace_free_records;
static struct ftrace_func_entry *
ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
{
unsigned long key;
struct ftrace_func_entry *entry;
struct hlist_head *hhd;
struct hlist_node *n;
if (!hash->count)
return NULL;
if (hash->size_bits > 0)
key = hash_long(ip, hash->size_bits);
else
key = 0;
hhd = &hash->buckets[key];
hlist_for_each_entry_rcu(entry, n, hhd, hlist) {
if (entry->ip == ip)
return entry;
}
return NULL;
}
static void __add_hash_entry(struct ftrace_hash *hash,
struct ftrace_func_entry *entry)
{
struct hlist_head *hhd;
unsigned long key;
if (hash->size_bits)
key = hash_long(entry->ip, hash->size_bits);
else
key = 0;
hhd = &hash->buckets[key];
hlist_add_head(&entry->hlist, hhd);
hash->count++;
}
static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
{
struct ftrace_func_entry *entry;
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
return -ENOMEM;
entry->ip = ip;
__add_hash_entry(hash, entry);
return 0;
}
static void
free_hash_entry(struct ftrace_hash *hash,
struct ftrace_func_entry *entry)
{
hlist_del(&entry->hlist);
kfree(entry);
hash->count--;
}
static void
remove_hash_entry(struct ftrace_hash *hash,
struct ftrace_func_entry *entry)
{
hlist_del(&entry->hlist);
hash->count--;
}
static void ftrace_hash_clear(struct ftrace_hash *hash)
{
struct hlist_head *hhd;
struct hlist_node *tp, *tn;
struct ftrace_func_entry *entry;
int size = 1 << hash->size_bits;
int i;
if (!hash->count)
return;
for (i = 0; i < size; i++) {
hhd = &hash->buckets[i];
hlist_for_each_entry_safe(entry, tp, tn, hhd, hlist)
free_hash_entry(hash, entry);
}
FTRACE_WARN_ON(hash->count);
}
static void free_ftrace_hash(struct ftrace_hash *hash)
{
if (!hash || hash == EMPTY_HASH)
return;
ftrace_hash_clear(hash);
kfree(hash->buckets);
kfree(hash);
}
static void __free_ftrace_hash_rcu(struct rcu_head *rcu)
{
struct ftrace_hash *hash;
hash = container_of(rcu, struct ftrace_hash, rcu);
free_ftrace_hash(hash);
}
static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
{
if (!hash || hash == EMPTY_HASH)
return;
call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
}
static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
{
struct ftrace_hash *hash;
int size;
hash = kzalloc(sizeof(*hash), GFP_KERNEL);
if (!hash)
return NULL;
size = 1 << size_bits;
hash->buckets = kzalloc(sizeof(*hash->buckets) * size, GFP_KERNEL);
if (!hash->buckets) {
kfree(hash);
return NULL;
}
hash->size_bits = size_bits;
return hash;
}
static struct ftrace_hash *
alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
{
struct ftrace_func_entry *entry;
struct ftrace_hash *new_hash;
struct hlist_node *tp;
int size;
int ret;
int i;
new_hash = alloc_ftrace_hash(size_bits);
if (!new_hash)
return NULL;
/* Empty hash? */
if (!hash || !hash->count)
return new_hash;
size = 1 << hash->size_bits;
for (i = 0; i < size; i++) {
hlist_for_each_entry(entry, tp, &hash->buckets[i], hlist) {
ret = add_hash_entry(new_hash, entry->ip);
if (ret < 0)
goto free_hash;
}
}
FTRACE_WARN_ON(new_hash->count != hash->count);
return new_hash;
free_hash:
free_ftrace_hash(new_hash);
return NULL;
}
static int
ftrace_hash_move(struct ftrace_hash **dst, struct ftrace_hash *src)
{
struct ftrace_func_entry *entry;
struct hlist_node *tp, *tn;
struct hlist_head *hhd;
struct ftrace_hash *old_hash;
struct ftrace_hash *new_hash;
unsigned long key;
int size = src->count;
int bits = 0;
int i;
/*
* If the new source is empty, just free dst and assign it
* the empty_hash.
*/
if (!src->count) {
free_ftrace_hash_rcu(*dst);
rcu_assign_pointer(*dst, EMPTY_HASH);
return 0;
}
/*
* Make the hash size about 1/2 the # found
*/
for (size /= 2; size; size >>= 1)
bits++;
/* Don't allocate too much */
if (bits > FTRACE_HASH_MAX_BITS)
bits = FTRACE_HASH_MAX_BITS;
new_hash = alloc_ftrace_hash(bits);
if (!new_hash)
return -ENOMEM;
size = 1 << src->size_bits;
for (i = 0; i < size; i++) {
hhd = &src->buckets[i];
hlist_for_each_entry_safe(entry, tp, tn, hhd, hlist) {
if (bits > 0)
key = hash_long(entry->ip, bits);
else
key = 0;
remove_hash_entry(src, entry);
__add_hash_entry(new_hash, entry);
}
}
old_hash = *dst;
rcu_assign_pointer(*dst, new_hash);
free_ftrace_hash_rcu(old_hash);
return 0;
}
/*
* Test the hashes for this ops to see if we want to call
* the ops->func or not.
*
* It's a match if the ip is in the ops->filter_hash or
* the filter_hash does not exist or is empty,
* AND
* the ip is not in the ops->notrace_hash.
*
* This needs to be called with preemption disabled as
* the hashes are freed with call_rcu_sched().
*/
static int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
{
struct ftrace_hash *filter_hash;
struct ftrace_hash *notrace_hash;
int ret;
filter_hash = rcu_dereference_raw(ops->filter_hash);
notrace_hash = rcu_dereference_raw(ops->notrace_hash);
if ((!filter_hash || !filter_hash->count ||
ftrace_lookup_ip(filter_hash, ip)) &&
(!notrace_hash || !notrace_hash->count ||
!ftrace_lookup_ip(notrace_hash, ip)))
ret = 1;
else
ret = 0;
return ret;
}
/*
* This is a double for. Do not use 'break' to break out of the loop,
* you must use a goto.
*/
#define do_for_each_ftrace_rec(pg, rec) \
for (pg = ftrace_pages_start; pg; pg = pg->next) { \
int _____i; \
for (_____i = 0; _____i < pg->index; _____i++) { \
rec = &pg->records[_____i];
#define while_for_each_ftrace_rec() \
} \
}
static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
int filter_hash,
bool inc)
{
struct ftrace_hash *hash;
struct ftrace_hash *other_hash;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
int count = 0;
int all = 0;
/* Only update if the ops has been registered */
if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
return;
/*
* In the filter_hash case:
* If the count is zero, we update all records.
* Otherwise we just update the items in the hash.
*
* In the notrace_hash case:
* We enable the update in the hash.
* As disabling notrace means enabling the tracing,
* and enabling notrace means disabling, the inc variable
* gets inversed.
*/
if (filter_hash) {
hash = ops->filter_hash;
other_hash = ops->notrace_hash;
if (!hash || !hash->count)
all = 1;
} else {
inc = !inc;
hash = ops->notrace_hash;
other_hash = ops->filter_hash;
/*
* If the notrace hash has no items,
* then there's nothing to do.
*/
if (hash && !hash->count)
return;
}
do_for_each_ftrace_rec(pg, rec) {
int in_other_hash = 0;
int in_hash = 0;
int match = 0;
if (all) {
/*
* Only the filter_hash affects all records.
* Update if the record is not in the notrace hash.
*/
if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip))
match = 1;
} else {
in_hash = hash && !!ftrace_lookup_ip(hash, rec->ip);
in_other_hash = other_hash && !!ftrace_lookup_ip(other_hash, rec->ip);
/*
*
*/
if (filter_hash && in_hash && !in_other_hash)
match = 1;
else if (!filter_hash && in_hash &&
(in_other_hash || !other_hash->count))
match = 1;
}
if (!match)
continue;
if (inc) {
rec->flags++;
if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
return;
} else {
if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
return;
rec->flags--;
}
count++;
/* Shortcut, if we handled all records, we are done. */
if (!all && count == hash->count)
return;
} while_for_each_ftrace_rec();
}
static void ftrace_hash_rec_disable(struct ftrace_ops *ops,
int filter_hash)
{
__ftrace_hash_rec_update(ops, filter_hash, 0);
}
static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
int filter_hash)
{
__ftrace_hash_rec_update(ops, filter_hash, 1);
}
static void ftrace_free_rec(struct dyn_ftrace *rec)
{
rec->freelist = ftrace_free_records;
ftrace_free_records = rec;
rec->flags |= FTRACE_FL_FREE;
}
static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
{
struct dyn_ftrace *rec;
/* First check for freed records */
if (ftrace_free_records) {
rec = ftrace_free_records;
if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
FTRACE_WARN_ON_ONCE(1);
ftrace_free_records = NULL;
return NULL;
}
ftrace_free_records = rec->freelist;
memset(rec, 0, sizeof(*rec));
return rec;
}
if (ftrace_pages->index == ENTRIES_PER_PAGE) {
if (!ftrace_pages->next) {
/* allocate another page */
ftrace_pages->next =
(void *)get_zeroed_page(GFP_KERNEL);
if (!ftrace_pages->next)
return NULL;
}
ftrace_pages = ftrace_pages->next;
}
return &ftrace_pages->records[ftrace_pages->index++];
}
static struct dyn_ftrace *
ftrace_record_ip(unsigned long ip)
{
struct dyn_ftrace *rec;
if (ftrace_disabled)
return NULL;
rec = ftrace_alloc_dyn_node(ip);
if (!rec)
return NULL;
rec->ip = ip;
rec->newlist = ftrace_new_addrs;
ftrace_new_addrs = rec;
return rec;
}
static void print_ip_ins(const char *fmt, unsigned char *p)
{
int i;
printk(KERN_CONT "%s", fmt);
for (i = 0; i < MCOUNT_INSN_SIZE; i++)
printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
}
static void ftrace_bug(int failed, unsigned long ip)
{
switch (failed) {
case -EFAULT:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on modifying ");
print_ip_sym(ip);
break;
case -EINVAL:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace failed to modify ");
print_ip_sym(ip);
print_ip_ins(" actual: ", (unsigned char *)ip);
printk(KERN_CONT "\n");
break;
case -EPERM:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on writing ");
print_ip_sym(ip);
break;
default:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on unknown error ");
print_ip_sym(ip);
}
}
/* Return 1 if the address range is reserved for ftrace */
int ftrace_text_reserved(void *start, void *end)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
do_for_each_ftrace_rec(pg, rec) {
if (rec->ip <= (unsigned long)end &&
rec->ip + MCOUNT_INSN_SIZE > (unsigned long)start)
return 1;
} while_for_each_ftrace_rec();
return 0;
}
static int
__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
unsigned long ftrace_addr;
unsigned long flag = 0UL;
ftrace_addr = (unsigned long)FTRACE_ADDR;
/*
* If we are enabling tracing:
*
* If the record has a ref count, then we need to enable it
* because someone is using it.
*
* Otherwise we make sure its disabled.
*
* If we are disabling tracing, then disable all records that
* are enabled.
*/
if (enable && (rec->flags & ~FTRACE_FL_MASK))
flag = FTRACE_FL_ENABLED;
/* If the state of this record hasn't changed, then do nothing */
if ((rec->flags & FTRACE_FL_ENABLED) == flag)
return 0;
if (flag) {
rec->flags |= FTRACE_FL_ENABLED;
return ftrace_make_call(rec, ftrace_addr);
}
rec->flags &= ~FTRACE_FL_ENABLED;
return ftrace_make_nop(NULL, rec, ftrace_addr);
}
static void ftrace_replace_code(int enable)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
int failed;
if (unlikely(ftrace_disabled))
return;
do_for_each_ftrace_rec(pg, rec) {
/* Skip over free records */
if (rec->flags & FTRACE_FL_FREE)
continue;
failed = __ftrace_replace_code(rec, enable);
if (failed) {
ftrace_bug(failed, rec->ip);
/* Stop processing */
return;
}
} while_for_each_ftrace_rec();
}
static int
ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
{
unsigned long ip;
int ret;
ip = rec->ip;
if (unlikely(ftrace_disabled))
return 0;
ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
if (ret) {
ftrace_bug(ret, ip);
return 0;
}
return 1;
}
/*
* archs can override this function if they must do something
* before the modifying code is performed.
*/
int __weak ftrace_arch_code_modify_prepare(void)
{
return 0;
}
/*
* archs can override this function if they must do something
* after the modifying code is performed.
*/
int __weak ftrace_arch_code_modify_post_process(void)
{
return 0;
}
static int __ftrace_modify_code(void *data)
{
int *command = data;
if (*command & FTRACE_ENABLE_CALLS)
ftrace_replace_code(1);
else if (*command & FTRACE_DISABLE_CALLS)
ftrace_replace_code(0);
if (*command & FTRACE_UPDATE_TRACE_FUNC)
ftrace_update_ftrace_func(ftrace_trace_function);
if (*command & FTRACE_START_FUNC_RET)
ftrace_enable_ftrace_graph_caller();
else if (*command & FTRACE_STOP_FUNC_RET)
ftrace_disable_ftrace_graph_caller();
return 0;
}
static void ftrace_run_update_code(int command)
{
int ret;
ret = ftrace_arch_code_modify_prepare();
FTRACE_WARN_ON(ret);
if (ret)
return;
stop_machine(__ftrace_modify_code, &command, NULL);
ret = ftrace_arch_code_modify_post_process();
FTRACE_WARN_ON(ret);
}
static ftrace_func_t saved_ftrace_func;
static int ftrace_start_up;
static int global_start_up;
static void ftrace_startup_enable(int command)
{
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
command |= FTRACE_UPDATE_TRACE_FUNC;
}
if (!command || !ftrace_enabled)
return;
ftrace_run_update_code(command);
}
static int ftrace_startup(struct ftrace_ops *ops, int command)
{
bool hash_enable = true;
if (unlikely(ftrace_disabled))
return -ENODEV;
ftrace_start_up++;
command |= FTRACE_ENABLE_CALLS;
/* ops marked global share the filter hashes */
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
ops = &global_ops;
/* Don't update hash if global is already set */
if (global_start_up)
hash_enable = false;
global_start_up++;
}
ops->flags |= FTRACE_OPS_FL_ENABLED;
if (hash_enable)
ftrace_hash_rec_enable(ops, 1);
ftrace_startup_enable(command);
return 0;
}
static void ftrace_shutdown(struct ftrace_ops *ops, int command)
{
bool hash_disable = true;
if (unlikely(ftrace_disabled))
return;
ftrace_start_up--;
/*
* Just warn in case of unbalance, no need to kill ftrace, it's not
* critical but the ftrace_call callers may be never nopped again after
* further ftrace uses.
*/
WARN_ON_ONCE(ftrace_start_up < 0);
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
ops = &global_ops;
global_start_up--;
WARN_ON_ONCE(global_start_up < 0);
/* Don't update hash if global still has users */
if (global_start_up) {
WARN_ON_ONCE(!ftrace_start_up);
hash_disable = false;
}
}
if (hash_disable)
ftrace_hash_rec_disable(ops, 1);
if (ops != &global_ops || !global_start_up)
ops->flags &= ~FTRACE_OPS_FL_ENABLED;
if (!ftrace_start_up)
command |= FTRACE_DISABLE_CALLS;
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
command |= FTRACE_UPDATE_TRACE_FUNC;
}
if (!command || !ftrace_enabled)
return;
ftrace_run_update_code(command);
}
static void ftrace_startup_sysctl(void)
{
if (unlikely(ftrace_disabled))
return;
/* Force update next time */
saved_ftrace_func = NULL;
/* ftrace_start_up is true if we want ftrace running */
if (ftrace_start_up)
ftrace_run_update_code(FTRACE_ENABLE_CALLS);
}
static void ftrace_shutdown_sysctl(void)
{
if (unlikely(ftrace_disabled))
return;
/* ftrace_start_up is true if ftrace is running */
if (ftrace_start_up)
ftrace_run_update_code(FTRACE_DISABLE_CALLS);
}
static cycle_t ftrace_update_time;
static unsigned long ftrace_update_cnt;
unsigned long ftrace_update_tot_cnt;
static int ftrace_update_code(struct module *mod)
{
struct dyn_ftrace *p;
cycle_t start, stop;
start = ftrace_now(raw_smp_processor_id());
ftrace_update_cnt = 0;
while (ftrace_new_addrs) {
/* If something went wrong, bail without enabling anything */
if (unlikely(ftrace_disabled))
return -1;
p = ftrace_new_addrs;
ftrace_new_addrs = p->newlist;
p->flags = 0L;
/*
* Do the initial record conversion from mcount jump
* to the NOP instructions.
*/
if (!ftrace_code_disable(mod, p)) {
ftrace_free_rec(p);
/* Game over */
break;
}
ftrace_update_cnt++;
/*
* If the tracing is enabled, go ahead and enable the record.
*
* The reason not to enable the record immediatelly is the
* inherent check of ftrace_make_nop/ftrace_make_call for
* correct previous instructions. Making first the NOP
* conversion puts the module to the correct state, thus
* passing the ftrace_make_call check.
*/
if (ftrace_start_up) {
int failed = __ftrace_replace_code(p, 1);
if (failed) {
ftrace_bug(failed, p->ip);
ftrace_free_rec(p);
}
}
}
stop = ftrace_now(raw_smp_processor_id());
ftrace_update_time = stop - start;
ftrace_update_tot_cnt += ftrace_update_cnt;
return 0;
}
static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
{
struct ftrace_page *pg;
int cnt;
int i;
/* allocate a few pages */
ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
if (!ftrace_pages_start)
return -1;
/*
* Allocate a few more pages.
*
* TODO: have some parser search vmlinux before
* final linking to find all calls to ftrace.
* Then we can:
* a) know how many pages to allocate.
* and/or
* b) set up the table then.
*
* The dynamic code is still necessary for
* modules.
*/
pg = ftrace_pages = ftrace_pages_start;
cnt = num_to_init / ENTRIES_PER_PAGE;
pr_info("ftrace: allocating %ld entries in %d pages\n",
num_to_init, cnt + 1);
for (i = 0; i < cnt; i++) {
pg->next = (void *)get_zeroed_page(GFP_KERNEL);
/* If we fail, we'll try later anyway */
if (!pg->next)
break;
pg = pg->next;
}
return 0;
}
enum {
FTRACE_ITER_FILTER = (1 << 0),
FTRACE_ITER_NOTRACE = (1 << 1),
FTRACE_ITER_PRINTALL = (1 << 2),
FTRACE_ITER_HASH = (1 << 3),
FTRACE_ITER_ENABLED = (1 << 4),
};
#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
struct ftrace_iterator {
loff_t pos;
loff_t func_pos;
struct ftrace_page *pg;
struct dyn_ftrace *func;
struct ftrace_func_probe *probe;
struct trace_parser parser;
struct ftrace_hash *hash;
struct ftrace_ops *ops;
int hidx;
int idx;
unsigned flags;
};
static void *
t_hash_next(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
struct hlist_node *hnd = NULL;
struct hlist_head *hhd;
(*pos)++;
iter->pos = *pos;
if (iter->probe)
hnd = &iter->probe->node;
retry:
if (iter->hidx >= FTRACE_FUNC_HASHSIZE)
return NULL;
hhd = &ftrace_func_hash[iter->hidx];
if (hlist_empty(hhd)) {
iter->hidx++;
hnd = NULL;
goto retry;
}
if (!hnd)
hnd = hhd->first;
else {
hnd = hnd->next;
if (!hnd) {
iter->hidx++;
goto retry;
}
}
if (WARN_ON_ONCE(!hnd))
return NULL;
iter->probe = hlist_entry(hnd, struct ftrace_func_probe, node);
return iter;
}
static void *t_hash_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
loff_t l;
if (iter->func_pos > *pos)
return NULL;
iter->hidx = 0;
for (l = 0; l <= (*pos - iter->func_pos); ) {
p = t_hash_next(m, &l);
if (!p)
break;
}
if (!p)
return NULL;
/* Only set this if we have an item */
iter->flags |= FTRACE_ITER_HASH;
return iter;
}
static int
t_hash_show(struct seq_file *m, struct ftrace_iterator *iter)
{
struct ftrace_func_probe *rec;
rec = iter->probe;
if (WARN_ON_ONCE(!rec))
return -EIO;
if (rec->ops->print)
return rec->ops->print(m, rec->ip, rec->ops, rec->data);
seq_printf(m, "%ps:%ps", (void *)rec->ip, (void *)rec->ops->func);
if (rec->data)
seq_printf(m, ":%p", rec->data);
seq_putc(m, '\n');
return 0;
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
struct ftrace_ops *ops = &global_ops;
struct dyn_ftrace *rec = NULL;
if (unlikely(ftrace_disabled))
return NULL;
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_next(m, pos);
(*pos)++;
iter->pos = iter->func_pos = *pos;
if (iter->flags & FTRACE_ITER_PRINTALL)
return t_hash_start(m, pos);
retry:
if (iter->idx >= iter->pg->index) {
if (iter->pg->next) {
iter->pg = iter->pg->next;
iter->idx = 0;
goto retry;
}
} else {
rec = &iter->pg->records[iter->idx++];
if ((rec->flags & FTRACE_FL_FREE) ||
((iter->flags & FTRACE_ITER_FILTER) &&
!(ftrace_lookup_ip(ops->filter_hash, rec->ip))) ||
((iter->flags & FTRACE_ITER_NOTRACE) &&
!ftrace_lookup_ip(ops->notrace_hash, rec->ip)) ||
((iter->flags & FTRACE_ITER_ENABLED) &&
!(rec->flags & ~FTRACE_FL_MASK))) {
rec = NULL;
goto retry;
}
}
if (!rec)
return t_hash_start(m, pos);
iter->func = rec;
return iter;
}
static void reset_iter_read(struct ftrace_iterator *iter)
{
iter->pos = 0;
iter->func_pos = 0;
iter->flags &= ~(FTRACE_ITER_PRINTALL & FTRACE_ITER_HASH);
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
struct ftrace_ops *ops = &global_ops;
void *p = NULL;
loff_t l;
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled))
return NULL;
/*
* If an lseek was done, then reset and start from beginning.
*/
if (*pos < iter->pos)
reset_iter_read(iter);
/*
* For set_ftrace_filter reading, if we have the filter
* off, we can short cut and just print out that all
* functions are enabled.
*/
if (iter->flags & FTRACE_ITER_FILTER && !ops->filter_hash->count) {
if (*pos > 0)
return t_hash_start(m, pos);
iter->flags |= FTRACE_ITER_PRINTALL;
/* reset in case of seek/pread */
iter->flags &= ~FTRACE_ITER_HASH;
return iter;
}
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_start(m, pos);
/*
* Unfortunately, we need to restart at ftrace_pages_start
* every time we let go of the ftrace_mutex. This is because
* those pointers can change without the lock.
*/
iter->pg = ftrace_pages_start;
iter->idx = 0;
for (l = 0; l <= *pos; ) {
p = t_next(m, p, &l);
if (!p)
break;
}
if (!p) {
if (iter->flags & FTRACE_ITER_FILTER)
return t_hash_start(m, pos);
return NULL;
}
return iter;
}
static void t_stop(struct seq_file *m, void *p)
{
mutex_unlock(&ftrace_lock);
}
static int t_show(struct seq_file *m, void *v)
{
struct ftrace_iterator *iter = m->private;
struct dyn_ftrace *rec;
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_show(m, iter);
if (iter->flags & FTRACE_ITER_PRINTALL) {
seq_printf(m, "#### all functions enabled ####\n");
return 0;
}
rec = iter->func;
if (!rec)
return 0;
seq_printf(m, "%ps", (void *)rec->ip);
if (iter->flags & FTRACE_ITER_ENABLED)
seq_printf(m, " (%ld)",
rec->flags & ~FTRACE_FL_MASK);
seq_printf(m, "\n");
return 0;
}
static const struct seq_operations show_ftrace_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int
ftrace_avail_open(struct inode *inode, struct file *file)
{
struct ftrace_iterator *iter;
int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
iter->pg = ftrace_pages_start;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = iter;
} else {
kfree(iter);
}
return ret;
}
static int
ftrace_enabled_open(struct inode *inode, struct file *file)
{
struct ftrace_iterator *iter;
int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
iter->pg = ftrace_pages_start;
iter->flags = FTRACE_ITER_ENABLED;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = iter;
} else {
kfree(iter);
}
return ret;
}
static void ftrace_filter_reset(struct ftrace_hash *hash)
{
mutex_lock(&ftrace_lock);
ftrace_hash_clear(hash);
mutex_unlock(&ftrace_lock);
}
static int
ftrace_regex_open(struct ftrace_ops *ops, int flag,
struct inode *inode, struct file *file)
{
struct ftrace_iterator *iter;
struct ftrace_hash *hash;
int ret = 0;
if (unlikely(ftrace_disabled))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX)) {
kfree(iter);
return -ENOMEM;
}
if (flag & FTRACE_ITER_NOTRACE)
hash = ops->notrace_hash;
else
hash = ops->filter_hash;
iter->ops = ops;
iter->flags = flag;
if (file->f_mode & FMODE_WRITE) {
mutex_lock(&ftrace_lock);
iter->hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, hash);
mutex_unlock(&ftrace_lock);
if (!iter->hash) {
trace_parser_put(&iter->parser);
kfree(iter);
return -ENOMEM;
}
}
mutex_lock(&ftrace_regex_lock);
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
ftrace_filter_reset(iter->hash);
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = iter;
} else {
/* Failed */
free_ftrace_hash(iter->hash);
trace_parser_put(&iter->parser);
kfree(iter);
}
} else
file->private_data = iter;
mutex_unlock(&ftrace_regex_lock);
return ret;
}
static int
ftrace_filter_open(struct inode *inode, struct file *file)
{
return ftrace_regex_open(&global_ops, FTRACE_ITER_FILTER,
inode, file);
}
static int
ftrace_notrace_open(struct inode *inode, struct file *file)
{
return ftrace_regex_open(&global_ops, FTRACE_ITER_NOTRACE,
inode, file);
}
static loff_t
ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
{
loff_t ret;
if (file->f_mode & FMODE_READ)
ret = seq_lseek(file, offset, origin);
else
file->f_pos = ret = 1;
return ret;
}
static int ftrace_match(char *str, char *regex, int len, int type)
{
int matched = 0;
int slen;
switch (type) {
case MATCH_FULL:
if (strcmp(str, regex) == 0)
matched = 1;
break;
case MATCH_FRONT_ONLY:
if (strncmp(str, regex, len) == 0)
matched = 1;
break;
case MATCH_MIDDLE_ONLY:
if (strstr(str, regex))
matched = 1;
break;
case MATCH_END_ONLY:
slen = strlen(str);
if (slen >= len && memcmp(str + slen - len, regex, len) == 0)
matched = 1;
break;
}
return matched;
}
static int
enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int not)
{
struct ftrace_func_entry *entry;
int ret = 0;
entry = ftrace_lookup_ip(hash, rec->ip);
if (not) {
/* Do nothing if it doesn't exist */
if (!entry)
return 0;
free_hash_entry(hash, entry);
} else {
/* Do nothing if it exists */
if (entry)
return 0;
ret = add_hash_entry(hash, rec->ip);
}
return ret;
}
static int
ftrace_match_record(struct dyn_ftrace *rec, char *mod,
char *regex, int len, int type)
{
char str[KSYM_SYMBOL_LEN];
char *modname;
kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
if (mod) {
/* module lookup requires matching the module */
if (!modname || strcmp(modname, mod))
return 0;
/* blank search means to match all funcs in the mod */
if (!len)
return 1;
}
return ftrace_match(str, regex, len, type);
}
static int
match_records(struct ftrace_hash *hash, char *buff,
int len, char *mod, int not)
{
unsigned search_len = 0;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
int type = MATCH_FULL;
char *search = buff;
int found = 0;
int ret;
if (len) {
type = filter_parse_regex(buff, len, &search, &not);
search_len = strlen(search);
}
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled))
goto out_unlock;
do_for_each_ftrace_rec(pg, rec) {
if (ftrace_match_record(rec, mod, search, search_len, type)) {
ret = enter_record(hash, rec, not);
if (ret < 0) {
found = ret;
goto out_unlock;
}
found = 1;
}
} while_for_each_ftrace_rec();
out_unlock:
mutex_unlock(&ftrace_lock);
return found;
}
static int
ftrace_match_records(struct ftrace_hash *hash, char *buff, int len)
{
return match_records(hash, buff, len, NULL, 0);
}
static int
ftrace_match_module_records(struct ftrace_hash *hash, char *buff, char *mod)
{
int not = 0;
/* blank or '*' mean the same */
if (strcmp(buff, "*") == 0)
buff[0] = 0;
/* handle the case of 'dont filter this module' */
if (strcmp(buff, "!") == 0 || strcmp(buff, "!*") == 0) {
buff[0] = 0;
not = 1;
}
return match_records(hash, buff, strlen(buff), mod, not);
}
/*
* We register the module command as a template to show others how
* to register the a command as well.
*/
static int
ftrace_mod_callback(char *func, char *cmd, char *param, int enable)
{
struct ftrace_ops *ops = &global_ops;
struct ftrace_hash *hash;
char *mod;
int ret = -EINVAL;
/*
* cmd == 'mod' because we only registered this func
* for the 'mod' ftrace_func_command.
* But if you register one func with multiple commands,
* you can tell which command was used by the cmd
* parameter.
*/
/* we must have a module name */
if (!param)
return ret;
mod = strsep(&param, ":");
if (!strlen(mod))
return ret;
if (enable)
hash = ops->filter_hash;
else
hash = ops->notrace_hash;
ret = ftrace_match_module_records(hash, func, mod);
if (!ret)
ret = -EINVAL;
if (ret < 0)
return ret;
return 0;
}
static struct ftrace_func_command ftrace_mod_cmd = {
.name = "mod",
.func = ftrace_mod_callback,
};
static int __init ftrace_mod_cmd_init(void)
{
return register_ftrace_command(&ftrace_mod_cmd);
}
device_initcall(ftrace_mod_cmd_init);
static void
function_trace_probe_call(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_func_probe *entry;
struct hlist_head *hhd;
struct hlist_node *n;
unsigned long key;
key = hash_long(ip, FTRACE_HASH_BITS);
hhd = &ftrace_func_hash[key];
if (hlist_empty(hhd))
return;
/*
* Disable preemption for these calls to prevent a RCU grace
* period. This syncs the hash iteration and freeing of items
* on the hash. rcu_read_lock is too dangerous here.
*/
preempt_disable_notrace();
hlist_for_each_entry_rcu(entry, n, hhd, node) {
if (entry->ip == ip)
entry->ops->func(ip, parent_ip, &entry->data);
}
preempt_enable_notrace();
}
static struct ftrace_ops trace_probe_ops __read_mostly =
{
.func = function_trace_probe_call,
};
static int ftrace_probe_registered;
static void __enable_ftrace_function_probe(void)
{
int ret;
int i;
if (ftrace_probe_registered)
return;
for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
struct hlist_head *hhd = &ftrace_func_hash[i];
if (hhd->first)
break;
}
/* Nothing registered? */
if (i == FTRACE_FUNC_HASHSIZE)
return;
ret = __register_ftrace_function(&trace_probe_ops);
if (!ret)
ret = ftrace_startup(&trace_probe_ops, 0);
ftrace_probe_registered = 1;
}
static void __disable_ftrace_function_probe(void)
{
int ret;
int i;
if (!ftrace_probe_registered)
return;
for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
struct hlist_head *hhd = &ftrace_func_hash[i];
if (hhd->first)
return;
}
/* no more funcs left */
ret = __unregister_ftrace_function(&trace_probe_ops);
if (!ret)
ftrace_shutdown(&trace_probe_ops, 0);
ftrace_probe_registered = 0;
}
static void ftrace_free_entry_rcu(struct rcu_head *rhp)
{
struct ftrace_func_probe *entry =
container_of(rhp, struct ftrace_func_probe, rcu);
if (entry->ops->free)
entry->ops->free(&entry->data);
kfree(entry);
}
int
register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
void *data)
{
struct ftrace_func_probe *entry;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
int type, len, not;
unsigned long key;
int count = 0;
char *search;
type = filter_parse_regex(glob, strlen(glob), &search, &not);
len = strlen(search);
/* we do not support '!' for function probes */
if (WARN_ON(not))
return -EINVAL;
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled))
goto out_unlock;
do_for_each_ftrace_rec(pg, rec) {
if (!ftrace_match_record(rec, NULL, search, len, type))
continue;
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry) {
/* If we did not process any, then return error */
if (!count)
count = -ENOMEM;
goto out_unlock;
}
count++;
entry->data = data;
/*
* The caller might want to do something special
* for each function we find. We call the callback
* to give the caller an opportunity to do so.
*/
if (ops->callback) {
if (ops->callback(rec->ip, &entry->data) < 0) {
/* caller does not like this func */
kfree(entry);
continue;
}
}
entry->ops = ops;
entry->ip = rec->ip;
key = hash_long(entry->ip, FTRACE_HASH_BITS);
hlist_add_head_rcu(&entry->node, &ftrace_func_hash[key]);
} while_for_each_ftrace_rec();
__enable_ftrace_function_probe();
out_unlock:
mutex_unlock(&ftrace_lock);
return count;
}
enum {
PROBE_TEST_FUNC = 1,
PROBE_TEST_DATA = 2
};
static void
__unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
void *data, int flags)
{
struct ftrace_func_probe *entry;
struct hlist_node *n, *tmp;
char str[KSYM_SYMBOL_LEN];
int type = MATCH_FULL;
int i, len = 0;
char *search;
if (glob && (strcmp(glob, "*") == 0 || !strlen(glob)))
glob = NULL;
else if (glob) {
int not;
type = filter_parse_regex(glob, strlen(glob), &search, &not);
len = strlen(search);
/* we do not support '!' for function probes */
if (WARN_ON(not))
return;
}
mutex_lock(&ftrace_lock);
for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
struct hlist_head *hhd = &ftrace_func_hash[i];
hlist_for_each_entry_safe(entry, n, tmp, hhd, node) {
/* break up if statements for readability */
if ((flags & PROBE_TEST_FUNC) && entry->ops != ops)
continue;
if ((flags & PROBE_TEST_DATA) && entry->data != data)
continue;
/* do this last, since it is the most expensive */
if (glob) {
kallsyms_lookup(entry->ip, NULL, NULL,
NULL, str);
if (!ftrace_match(str, glob, len, type))
continue;
}
hlist_del(&entry->node);
call_rcu(&entry->rcu, ftrace_free_entry_rcu);
}
}
__disable_ftrace_function_probe();
mutex_unlock(&ftrace_lock);
}
void
unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
void *data)
{
__unregister_ftrace_function_probe(glob, ops, data,
PROBE_TEST_FUNC | PROBE_TEST_DATA);
}
void
unregister_ftrace_function_probe_func(char *glob, struct ftrace_probe_ops *ops)
{
__unregister_ftrace_function_probe(glob, ops, NULL, PROBE_TEST_FUNC);
}
void unregister_ftrace_function_probe_all(char *glob)
{
__unregister_ftrace_function_probe(glob, NULL, NULL, 0);
}
static LIST_HEAD(ftrace_commands);
static DEFINE_MUTEX(ftrace_cmd_mutex);
int register_ftrace_command(struct ftrace_func_command *cmd)
{
struct ftrace_func_command *p;
int ret = 0;
mutex_lock(&ftrace_cmd_mutex);
list_for_each_entry(p, &ftrace_commands, list) {
if (strcmp(cmd->name, p->name) == 0) {
ret = -EBUSY;
goto out_unlock;
}
}
list_add(&cmd->list, &ftrace_commands);
out_unlock:
mutex_unlock(&ftrace_cmd_mutex);
return ret;
}
int unregister_ftrace_command(struct ftrace_func_command *cmd)
{
struct ftrace_func_command *p, *n;
int ret = -ENODEV;
mutex_lock(&ftrace_cmd_mutex);
list_for_each_entry_safe(p, n, &ftrace_commands, list) {
if (strcmp(cmd->name, p->name) == 0) {
ret = 0;
list_del_init(&p->list);
goto out_unlock;
}
}
out_unlock:
mutex_unlock(&ftrace_cmd_mutex);
return ret;
}
static int ftrace_process_regex(struct ftrace_hash *hash,
char *buff, int len, int enable)
{
char *func, *command, *next = buff;
struct ftrace_func_command *p;
int ret;
func = strsep(&next, ":");
if (!next) {
ret = ftrace_match_records(hash, func, len);
if (!ret)
ret = -EINVAL;
if (ret < 0)
return ret;
return 0;
}
/* command found */
command = strsep(&next, ":");
mutex_lock(&ftrace_cmd_mutex);
list_for_each_entry(p, &ftrace_commands, list) {
if (strcmp(p->name, command) == 0) {
ret = p->func(func, command, next, enable);
goto out_unlock;
}
}
out_unlock:
mutex_unlock(&ftrace_cmd_mutex);
return ret;
}
static ssize_t
ftrace_regex_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos, int enable)
{
struct ftrace_iterator *iter;
struct trace_parser *parser;
ssize_t ret, read;
if (!cnt)
return 0;
mutex_lock(&ftrace_regex_lock);
ret = -ENODEV;
if (unlikely(ftrace_disabled))
goto out_unlock;
if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;
iter = m->private;
} else
iter = file->private_data;
parser = &iter->parser;
read = trace_get_user(parser, ubuf, cnt, ppos);
if (read >= 0 && trace_parser_loaded(parser) &&
!trace_parser_cont(parser)) {
ret = ftrace_process_regex(iter->hash, parser->buffer,
parser->idx, enable);
trace_parser_clear(parser);
if (ret)
goto out_unlock;
}
ret = read;
out_unlock:
mutex_unlock(&ftrace_regex_lock);
return ret;
}
static ssize_t
ftrace_filter_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
}
static ssize_t
ftrace_notrace_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
}
static int
ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
int reset, int enable)
{
struct ftrace_hash **orig_hash;
struct ftrace_hash *hash;
int ret;
/* All global ops uses the global ops filters */
if (ops->flags & FTRACE_OPS_FL_GLOBAL)
ops = &global_ops;
if (unlikely(ftrace_disabled))
return -ENODEV;
if (enable)
orig_hash = &ops->filter_hash;
else
orig_hash = &ops->notrace_hash;
hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
if (!hash)
return -ENOMEM;
mutex_lock(&ftrace_regex_lock);
if (reset)
ftrace_filter_reset(hash);
if (buf)
ftrace_match_records(hash, buf, len);
mutex_lock(&ftrace_lock);
ret = ftrace_hash_move(orig_hash, hash);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ftrace_regex_lock);
free_ftrace_hash(hash);
return ret;
}
/**
* ftrace_set_filter - set a function to filter on in ftrace
* @ops - the ops to set the filter with
* @buf - the string that holds the function filter text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Filters denote which functions should be enabled when tracing is enabled.
* If @buf is NULL and reset is set, all functions will be enabled for tracing.
*/
void ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
int len, int reset)
{
ftrace_set_regex(ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter);
/**
* ftrace_set_notrace - set a function to not trace in ftrace
* @ops - the ops to set the notrace filter with
* @buf - the string that holds the function notrace text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Notrace Filters denote which functions should not be enabled when tracing
* is enabled. If @buf is NULL and reset is set, all functions will be enabled
* for tracing.
*/
void ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
int len, int reset)
{
ftrace_set_regex(ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_notrace);
/**
* ftrace_set_filter - set a function to filter on in ftrace
* @ops - the ops to set the filter with
* @buf - the string that holds the function filter text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Filters denote which functions should be enabled when tracing is enabled.
* If @buf is NULL and reset is set, all functions will be enabled for tracing.
*/
void ftrace_set_global_filter(unsigned char *buf, int len, int reset)
{
ftrace_set_regex(&global_ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_filter);
/**
* ftrace_set_notrace - set a function to not trace in ftrace
* @ops - the ops to set the notrace filter with
* @buf - the string that holds the function notrace text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Notrace Filters denote which functions should not be enabled when tracing
* is enabled. If @buf is NULL and reset is set, all functions will be enabled
* for tracing.
*/
void ftrace_set_global_notrace(unsigned char *buf, int len, int reset)
{
ftrace_set_regex(&global_ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_notrace);
/*
* command line interface to allow users to set filters on boot up.
*/
#define FTRACE_FILTER_SIZE COMMAND_LINE_SIZE
static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;
static int __init set_ftrace_notrace(char *str)
{
strncpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
return 1;
}
__setup("ftrace_notrace=", set_ftrace_notrace);
static int __init set_ftrace_filter(char *str)
{
strncpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
return 1;
}
__setup("ftrace_filter=", set_ftrace_filter);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
static int ftrace_set_func(unsigned long *array, int *idx, char *buffer);
static int __init set_graph_function(char *str)
{
strlcpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
return 1;
}
__setup("ftrace_graph_filter=", set_graph_function);
static void __init set_ftrace_early_graph(char *buf)
{
int ret;
char *func;
while (buf) {
func = strsep(&buf, ",");
/* we allow only one expression at a time */
ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
func);
if (ret)
printk(KERN_DEBUG "ftrace: function %s not "
"traceable\n", func);
}
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
static void __init
set_ftrace_early_filter(struct ftrace_ops *ops, char *buf, int enable)
{
char *func;
while (buf) {
func = strsep(&buf, ",");
ftrace_set_regex(ops, func, strlen(func), 0, enable);
}
}
static void __init set_ftrace_early_filters(void)
{
if (ftrace_filter_buf[0])
set_ftrace_early_filter(&global_ops, ftrace_filter_buf, 1);
if (ftrace_notrace_buf[0])
set_ftrace_early_filter(&global_ops, ftrace_notrace_buf, 0);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (ftrace_graph_buf[0])
set_ftrace_early_graph(ftrace_graph_buf);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
}
static int
ftrace_regex_release(struct inode *inode, struct file *file)
{
struct seq_file *m = (struct seq_file *)file->private_data;
struct ftrace_iterator *iter;
struct ftrace_hash **orig_hash;
struct trace_parser *parser;
int filter_hash;
int ret;
mutex_lock(&ftrace_regex_lock);
if (file->f_mode & FMODE_READ) {
iter = m->private;
seq_release(inode, file);
} else
iter = file->private_data;
parser = &iter->parser;
if (trace_parser_loaded(parser)) {
parser->buffer[parser->idx] = 0;
ftrace_match_records(iter->hash, parser->buffer, parser->idx);
}
trace_parser_put(parser);
if (file->f_mode & FMODE_WRITE) {
filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);
if (filter_hash)
orig_hash = &iter->ops->filter_hash;
else
orig_hash = &iter->ops->notrace_hash;
mutex_lock(&ftrace_lock);
/*
* Remove the current set, update the hash and add
* them back.
*/
ftrace_hash_rec_disable(iter->ops, filter_hash);
ret = ftrace_hash_move(orig_hash, iter->hash);
if (!ret) {
ftrace_hash_rec_enable(iter->ops, filter_hash);
if (iter->ops->flags & FTRACE_OPS_FL_ENABLED
&& ftrace_enabled)
ftrace_run_update_code(FTRACE_ENABLE_CALLS);
}
mutex_unlock(&ftrace_lock);
}
free_ftrace_hash(iter->hash);
kfree(iter);
mutex_unlock(&ftrace_regex_lock);
return 0;
}
static const struct file_operations ftrace_avail_fops = {
.open = ftrace_avail_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_private,
};
static const struct file_operations ftrace_enabled_fops = {
.open = ftrace_enabled_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_private,
};
static const struct file_operations ftrace_filter_fops = {
.open = ftrace_filter_open,
.read = seq_read,
.write = ftrace_filter_write,
.llseek = ftrace_regex_lseek,
.release = ftrace_regex_release,
};
static const struct file_operations ftrace_notrace_fops = {
.open = ftrace_notrace_open,
.read = seq_read,
.write = ftrace_notrace_write,
.llseek = ftrace_regex_lseek,
.release = ftrace_regex_release,
};
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static DEFINE_MUTEX(graph_lock);
int ftrace_graph_count;
int ftrace_graph_filter_enabled;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
static void *
__g_next(struct seq_file *m, loff_t *pos)
{
if (*pos >= ftrace_graph_count)
return NULL;
return &ftrace_graph_funcs[*pos];
}
static void *
g_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return __g_next(m, pos);
}
static void *g_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&graph_lock);
/* Nothing, tell g_show to print all functions are enabled */
if (!ftrace_graph_filter_enabled && !*pos)
return (void *)1;
return __g_next(m, pos);
}
static void g_stop(struct seq_file *m, void *p)
{
mutex_unlock(&graph_lock);
}
static int g_show(struct seq_file *m, void *v)
{
unsigned long *ptr = v;
if (!ptr)
return 0;
if (ptr == (unsigned long *)1) {
seq_printf(m, "#### all functions enabled ####\n");
return 0;
}
seq_printf(m, "%ps\n", (void *)*ptr);
return 0;
}
static const struct seq_operations ftrace_graph_seq_ops = {
.start = g_start,
.next = g_next,
.stop = g_stop,
.show = g_show,
};
static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
int ret = 0;
if (unlikely(ftrace_disabled))
return -ENODEV;
mutex_lock(&graph_lock);
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC)) {
ftrace_graph_filter_enabled = 0;
ftrace_graph_count = 0;
memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
}
mutex_unlock(&graph_lock);
if (file->f_mode & FMODE_READ)
ret = seq_open(file, &ftrace_graph_seq_ops);
return ret;
}
static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
if (file->f_mode & FMODE_READ)
seq_release(inode, file);
return 0;
}
static int
ftrace_set_func(unsigned long *array, int *idx, char *buffer)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
int search_len;
int fail = 1;
int type, not;
char *search;
bool exists;
int i;
/* decode regex */
type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
if (!not && *idx >= FTRACE_GRAPH_MAX_FUNCS)
return -EBUSY;
search_len = strlen(search);
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled)) {
mutex_unlock(&ftrace_lock);
return -ENODEV;
}
do_for_each_ftrace_rec(pg, rec) {
if (rec->flags & FTRACE_FL_FREE)
continue;
if (ftrace_match_record(rec, NULL, search, search_len, type)) {
/* if it is in the array */
exists = false;
for (i = 0; i < *idx; i++) {
if (array[i] == rec->ip) {
exists = true;
break;
}
}
if (!not) {
fail = 0;
if (!exists) {
array[(*idx)++] = rec->ip;
if (*idx >= FTRACE_GRAPH_MAX_FUNCS)
goto out;
}
} else {
if (exists) {
array[i] = array[--(*idx)];
array[*idx] = 0;
fail = 0;
}
}
}
} while_for_each_ftrace_rec();
out:
mutex_unlock(&ftrace_lock);
if (fail)
return -EINVAL;
ftrace_graph_filter_enabled = 1;
return 0;
}
static ssize_t
ftrace_graph_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_parser parser;
ssize_t read, ret;
if (!cnt)
return 0;
mutex_lock(&graph_lock);
if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
ret = -ENOMEM;
goto out_unlock;
}
read = trace_get_user(&parser, ubuf, cnt, ppos);
if (read >= 0 && trace_parser_loaded((&parser))) {
parser.buffer[parser.idx] = 0;
/* we allow only one expression at a time */
ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
parser.buffer);
if (ret)
goto out_free;
}
ret = read;
out_free:
trace_parser_put(&parser);
out_unlock:
mutex_unlock(&graph_lock);
return ret;
}
static const struct file_operations ftrace_graph_fops = {
.open = ftrace_graph_open,
.read = seq_read,
.write = ftrace_graph_write,
.release = ftrace_graph_release,
.llseek = seq_lseek,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
{
trace_create_file("available_filter_functions", 0444,
d_tracer, NULL, &ftrace_avail_fops);
trace_create_file("enabled_functions", 0444,
d_tracer, NULL, &ftrace_enabled_fops);
trace_create_file("set_ftrace_filter", 0644, d_tracer,
NULL, &ftrace_filter_fops);
trace_create_file("set_ftrace_notrace", 0644, d_tracer,
NULL, &ftrace_notrace_fops);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
trace_create_file("set_graph_function", 0444, d_tracer,
NULL,
&ftrace_graph_fops);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
return 0;
}
static int ftrace_process_locs(struct module *mod,
unsigned long *start,
unsigned long *end)
{
unsigned long *p;
unsigned long addr;
mutex_lock(&ftrace_lock);
p = start;
while (p < end) {
addr = ftrace_call_adjust(*p++);
/*
* Some architecture linkers will pad between
* the different mcount_loc sections of different
* object files to satisfy alignments.
* Skip any NULL pointers.
*/
if (!addr)
continue;
ftrace_record_ip(addr);
}
ftrace_update_code(mod);
mutex_unlock(&ftrace_lock);
return 0;
}
#ifdef CONFIG_MODULES
void ftrace_release_mod(struct module *mod)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
mutex_lock(&ftrace_lock);
if (ftrace_disabled)
goto out_unlock;
do_for_each_ftrace_rec(pg, rec) {
if (within_module_core(rec->ip, mod)) {
/*
* rec->ip is changed in ftrace_free_rec()
* It should not between s and e if record was freed.
*/
FTRACE_WARN_ON(rec->flags & FTRACE_FL_FREE);
ftrace_free_rec(rec);
}
} while_for_each_ftrace_rec();
out_unlock:
mutex_unlock(&ftrace_lock);
}
static void ftrace_init_module(struct module *mod,
unsigned long *start, unsigned long *end)
{
if (ftrace_disabled || start == end)
return;
ftrace_process_locs(mod, start, end);
}
static int ftrace_module_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct module *mod = data;
switch (val) {
case MODULE_STATE_COMING:
ftrace_init_module(mod, mod->ftrace_callsites,
mod->ftrace_callsites +
mod->num_ftrace_callsites);
break;
case MODULE_STATE_GOING:
ftrace_release_mod(mod);
break;
}
return 0;
}
#else
static int ftrace_module_notify(struct notifier_block *self,
unsigned long val, void *data)
{
return 0;
}
#endif /* CONFIG_MODULES */
struct notifier_block ftrace_module_nb = {
.notifier_call = ftrace_module_notify,
.priority = 0,
};
extern unsigned long __start_mcount_loc[];
extern unsigned long __stop_mcount_loc[];
void __init ftrace_init(void)
{
unsigned long count, addr, flags;
int ret;
/* Keep the ftrace pointer to the stub */
addr = (unsigned long)ftrace_stub;
local_irq_save(flags);
ftrace_dyn_arch_init(&addr);
local_irq_restore(flags);
/* ftrace_dyn_arch_init places the return code in addr */
if (addr)
goto failed;
count = __stop_mcount_loc - __start_mcount_loc;
ret = ftrace_dyn_table_alloc(count);
if (ret)
goto failed;
last_ftrace_enabled = ftrace_enabled = 1;
ret = ftrace_process_locs(NULL,
__start_mcount_loc,
__stop_mcount_loc);
ret = register_module_notifier(&ftrace_module_nb);
if (ret)
pr_warning("Failed to register trace ftrace module notifier\n");
set_ftrace_early_filters();
return;
failed:
ftrace_disabled = 1;
}
#else
static struct ftrace_ops global_ops = {
.func = ftrace_stub,
};
static int __init ftrace_nodyn_init(void)
{
ftrace_enabled = 1;
return 0;
}
device_initcall(ftrace_nodyn_init);
static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_enable(int command) { }
/* Keep as macros so we do not need to define the commands */
# define ftrace_startup(ops, command) \
({ \
(ops)->flags |= FTRACE_OPS_FL_ENABLED; \
0; \
})
# define ftrace_shutdown(ops, command) do { } while (0)
# define ftrace_startup_sysctl() do { } while (0)
# define ftrace_shutdown_sysctl() do { } while (0)
static inline int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
{
return 1;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
static void
ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_ops *op;
if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT)))
return;
trace_recursion_set(TRACE_INTERNAL_BIT);
/*
* Some of the ops may be dynamically allocated,
* they must be freed after a synchronize_sched().
*/
preempt_disable_notrace();
op = rcu_dereference_raw(ftrace_ops_list);
while (op != &ftrace_list_end) {
if (ftrace_ops_test(op, ip))
op->func(ip, parent_ip);
op = rcu_dereference_raw(op->next);
};
preempt_enable_notrace();
trace_recursion_clear(TRACE_INTERNAL_BIT);
}
static void clear_ftrace_swapper(void)
{
struct task_struct *p;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu) {
p = idle_task(cpu);
clear_tsk_trace_trace(p);
}
put_online_cpus();
}
static void set_ftrace_swapper(void)
{
struct task_struct *p;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu) {
p = idle_task(cpu);
set_tsk_trace_trace(p);
}
put_online_cpus();
}
static void clear_ftrace_pid(struct pid *pid)
{
struct task_struct *p;
rcu_read_lock();
do_each_pid_task(pid, PIDTYPE_PID, p) {
clear_tsk_trace_trace(p);
} while_each_pid_task(pid, PIDTYPE_PID, p);
rcu_read_unlock();
put_pid(pid);
}
static void set_ftrace_pid(struct pid *pid)
{
struct task_struct *p;
rcu_read_lock();
do_each_pid_task(pid, PIDTYPE_PID, p) {
set_tsk_trace_trace(p);
} while_each_pid_task(pid, PIDTYPE_PID, p);
rcu_read_unlock();
}
static void clear_ftrace_pid_task(struct pid *pid)
{
if (pid == ftrace_swapper_pid)
clear_ftrace_swapper();
else
clear_ftrace_pid(pid);
}
static void set_ftrace_pid_task(struct pid *pid)
{
if (pid == ftrace_swapper_pid)
set_ftrace_swapper();
else
set_ftrace_pid(pid);
}
static int ftrace_pid_add(int p)
{
struct pid *pid;
struct ftrace_pid *fpid;
int ret = -EINVAL;
mutex_lock(&ftrace_lock);
if (!p)
pid = ftrace_swapper_pid;
else
pid = find_get_pid(p);
if (!pid)
goto out;
ret = 0;
list_for_each_entry(fpid, &ftrace_pids, list)
if (fpid->pid == pid)
goto out_put;
ret = -ENOMEM;
fpid = kmalloc(sizeof(*fpid), GFP_KERNEL);
if (!fpid)
goto out_put;
list_add(&fpid->list, &ftrace_pids);
fpid->pid = pid;
set_ftrace_pid_task(pid);
ftrace_update_pid_func();
ftrace_startup_enable(0);
mutex_unlock(&ftrace_lock);
return 0;
out_put:
if (pid != ftrace_swapper_pid)
put_pid(pid);
out:
mutex_unlock(&ftrace_lock);
return ret;
}
static void ftrace_pid_reset(void)
{
struct ftrace_pid *fpid, *safe;
mutex_lock(&ftrace_lock);
list_for_each_entry_safe(fpid, safe, &ftrace_pids, list) {
struct pid *pid = fpid->pid;
clear_ftrace_pid_task(pid);
list_del(&fpid->list);
kfree(fpid);
}
ftrace_update_pid_func();
ftrace_startup_enable(0);
mutex_unlock(&ftrace_lock);
}
static void *fpid_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&ftrace_lock);
if (list_empty(&ftrace_pids) && (!*pos))
return (void *) 1;
return seq_list_start(&ftrace_pids, *pos);
}
static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)
{
if (v == (void *)1)
return NULL;
return seq_list_next(v, &ftrace_pids, pos);
}
static void fpid_stop(struct seq_file *m, void *p)
{
mutex_unlock(&ftrace_lock);
}
static int fpid_show(struct seq_file *m, void *v)
{
const struct ftrace_pid *fpid = list_entry(v, struct ftrace_pid, list);
if (v == (void *)1) {
seq_printf(m, "no pid\n");
return 0;
}
if (fpid->pid == ftrace_swapper_pid)
seq_printf(m, "swapper tasks\n");
else
seq_printf(m, "%u\n", pid_vnr(fpid->pid));
return 0;
}
static const struct seq_operations ftrace_pid_sops = {
.start = fpid_start,
.next = fpid_next,
.stop = fpid_stop,
.show = fpid_show,
};
static int
ftrace_pid_open(struct inode *inode, struct file *file)
{
int ret = 0;
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
ftrace_pid_reset();
if (file->f_mode & FMODE_READ)
ret = seq_open(file, &ftrace_pid_sops);
return ret;
}
static ssize_t
ftrace_pid_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64], *tmp;
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
/*
* Allow "echo > set_ftrace_pid" or "echo -n '' > set_ftrace_pid"
* to clean the filter quietly.
*/
tmp = strstrip(buf);
if (strlen(tmp) == 0)
return 1;
ret = strict_strtol(tmp, 10, &val);
if (ret < 0)
return ret;
ret = ftrace_pid_add(val);
return ret ? ret : cnt;
}
static int
ftrace_pid_release(struct inode *inode, struct file *file)
{
if (file->f_mode & FMODE_READ)
seq_release(inode, file);
return 0;
}
static const struct file_operations ftrace_pid_fops = {
.open = ftrace_pid_open,
.write = ftrace_pid_write,
.read = seq_read,
.llseek = seq_lseek,
.release = ftrace_pid_release,
};
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return 0;
ftrace_init_dyn_debugfs(d_tracer);
trace_create_file("set_ftrace_pid", 0644, d_tracer,
NULL, &ftrace_pid_fops);
ftrace_profile_debugfs(d_tracer);
return 0;
}
fs_initcall(ftrace_init_debugfs);
/**
* ftrace_kill - kill ftrace
*
* This function should be used by panic code. It stops ftrace
* but in a not so nice way. If you need to simply kill ftrace
* from a non-atomic section, use ftrace_kill.
*/
void ftrace_kill(void)
{
ftrace_disabled = 1;
ftrace_enabled = 0;
clear_ftrace_function();
}
/**
* register_ftrace_function - register a function for profiling
* @ops - ops structure that holds the function for profiling.
*
* Register a function to be called by all functions in the
* kernel.
*
* Note: @ops->func and all the functions it calls must be labeled
* with "notrace", otherwise it will go into a
* recursive loop.
*/
int register_ftrace_function(struct ftrace_ops *ops)
{
int ret = -1;
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled))
goto out_unlock;
ret = __register_ftrace_function(ops);
if (!ret)
ret = ftrace_startup(ops, 0);
out_unlock:
mutex_unlock(&ftrace_lock);
return ret;
}
EXPORT_SYMBOL_GPL(register_ftrace_function);
/**
* unregister_ftrace_function - unregister a function for profiling.
* @ops - ops structure that holds the function to unregister
*
* Unregister a function that was added to be called by ftrace profiling.
*/
int unregister_ftrace_function(struct ftrace_ops *ops)
{
int ret;
mutex_lock(&ftrace_lock);
ret = __unregister_ftrace_function(ops);
if (!ret)
ftrace_shutdown(ops, 0);
mutex_unlock(&ftrace_lock);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_function);
int
ftrace_enable_sysctl(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int ret = -ENODEV;
mutex_lock(&ftrace_lock);
if (unlikely(ftrace_disabled))
goto out;
ret = proc_dointvec(table, write, buffer, lenp, ppos);
if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
goto out;
last_ftrace_enabled = !!ftrace_enabled;
if (ftrace_enabled) {
ftrace_startup_sysctl();
/* we are starting ftrace again */
if (ftrace_ops_list != &ftrace_list_end) {
if (ftrace_ops_list->next == &ftrace_list_end)
ftrace_trace_function = ftrace_ops_list->func;
else
ftrace_trace_function = ftrace_ops_list_func;
}
} else {
/* stopping ftrace calls (just send to ftrace_stub) */
ftrace_trace_function = ftrace_stub;
ftrace_shutdown_sysctl();
}
out:
mutex_unlock(&ftrace_lock);
return ret;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int ftrace_graph_active;
static struct notifier_block ftrace_suspend_notifier;
int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
{
return 0;
}
/* The callbacks that hook a function */
trace_func_graph_ret_t ftrace_graph_return =
(trace_func_graph_ret_t)ftrace_stub;
trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
{
int i;
int ret = 0;
unsigned long flags;
int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
struct task_struct *g, *t;
for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
ret_stack_list[i] = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
if (!ret_stack_list[i]) {
start = 0;
end = i;
ret = -ENOMEM;
goto free;
}
}
read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, t) {
if (start == end) {
ret = -EAGAIN;
goto unlock;
}
if (t->ret_stack == NULL) {
atomic_set(&t->tracing_graph_pause, 0);
atomic_set(&t->trace_overrun, 0);
t->curr_ret_stack = -1;
/* Make sure the tasks see the -1 first: */
smp_wmb();
t->ret_stack = ret_stack_list[start++];
}
} while_each_thread(g, t);
unlock:
read_unlock_irqrestore(&tasklist_lock, flags);
free:
for (i = start; i < end; i++)
kfree(ret_stack_list[i]);
return ret;
}
static void
ftrace_graph_probe_sched_switch(void *ignore,
struct task_struct *prev, struct task_struct *next)
{
unsigned long long timestamp;
int index;
/*
* Does the user want to count the time a function was asleep.
* If so, do not update the time stamps.
*/
if (trace_flags & TRACE_ITER_SLEEP_TIME)
return;
timestamp = trace_clock_local();
prev->ftrace_timestamp = timestamp;
/* only process tasks that we timestamped */
if (!next->ftrace_timestamp)
return;
/*
* Update all the counters in next to make up for the
* time next was sleeping.
*/
timestamp -= next->ftrace_timestamp;
for (index = next->curr_ret_stack; index >= 0; index--)
next->ret_stack[index].calltime += timestamp;
}
/* Allocate a return stack for each task */
static int start_graph_tracing(void)
{
struct ftrace_ret_stack **ret_stack_list;
int ret, cpu;
ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE *
sizeof(struct ftrace_ret_stack *),
GFP_KERNEL);
if (!ret_stack_list)
return -ENOMEM;
/* The cpu_boot init_task->ret_stack will never be freed */
for_each_online_cpu(cpu) {
if (!idle_task(cpu)->ret_stack)
ftrace_graph_init_idle_task(idle_task(cpu), cpu);
}
do {
ret = alloc_retstack_tasklist(ret_stack_list);
} while (ret == -EAGAIN);
if (!ret) {
ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
if (ret)
pr_info("ftrace_graph: Couldn't activate tracepoint"
" probe to kernel_sched_switch\n");
}
kfree(ret_stack_list);
return ret;
}
/*
* Hibernation protection.
* The state of the current task is too much unstable during
* suspend/restore to disk. We want to protect against that.
*/
static int
ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
void *unused)
{
switch (state) {
case PM_HIBERNATION_PREPARE:
pause_graph_tracing();
break;
case PM_POST_HIBERNATION:
unpause_graph_tracing();
break;
}
return NOTIFY_DONE;
}
int register_ftrace_graph(trace_func_graph_ret_t retfunc,
trace_func_graph_ent_t entryfunc)
{
int ret = 0;
mutex_lock(&ftrace_lock);
/* we currently allow only one tracer registered at a time */
if (ftrace_graph_active) {
ret = -EBUSY;
goto out;
}
ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
register_pm_notifier(&ftrace_suspend_notifier);
ftrace_graph_active++;
ret = start_graph_tracing();
if (ret) {
ftrace_graph_active--;
goto out;
}
ftrace_graph_return = retfunc;
ftrace_graph_entry = entryfunc;
ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
out:
mutex_unlock(&ftrace_lock);
return ret;
}
void unregister_ftrace_graph(void)
{
mutex_lock(&ftrace_lock);
if (unlikely(!ftrace_graph_active))
goto out;
ftrace_graph_active--;
ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
ftrace_graph_entry = ftrace_graph_entry_stub;
ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET);
unregister_pm_notifier(&ftrace_suspend_notifier);
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
out:
mutex_unlock(&ftrace_lock);
}
static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
static void
graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
{
atomic_set(&t->tracing_graph_pause, 0);
atomic_set(&t->trace_overrun, 0);
t->ftrace_timestamp = 0;
/* make curr_ret_stack visible before we add the ret_stack */
smp_wmb();
t->ret_stack = ret_stack;
}
/*
* Allocate a return stack for the idle task. May be the first
* time through, or it may be done by CPU hotplug online.
*/
void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
{
t->curr_ret_stack = -1;
/*
* The idle task has no parent, it either has its own
* stack or no stack at all.
*/
if (t->ret_stack)
WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
if (ftrace_graph_active) {
struct ftrace_ret_stack *ret_stack;
ret_stack = per_cpu(idle_ret_stack, cpu);
if (!ret_stack) {
ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
if (!ret_stack)
return;
per_cpu(idle_ret_stack, cpu) = ret_stack;
}
graph_init_task(t, ret_stack);
}
}
/* Allocate a return stack for newly created task */
void ftrace_graph_init_task(struct task_struct *t)
{
/* Make sure we do not use the parent ret_stack */
t->ret_stack = NULL;
t->curr_ret_stack = -1;
if (ftrace_graph_active) {
struct ftrace_ret_stack *ret_stack;
ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
if (!ret_stack)
return;
graph_init_task(t, ret_stack);
}
}
void ftrace_graph_exit_task(struct task_struct *t)
{
struct ftrace_ret_stack *ret_stack = t->ret_stack;
t->ret_stack = NULL;
/* NULL must become visible to IRQs before we free it: */
barrier();
kfree(ret_stack);
}
void ftrace_graph_stop(void)
{
ftrace_stop();
}
#endif
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