linux/lib/dynamic_printk.c

421 lines
9.6 KiB
C

/*
* lib/dynamic_printk.c
*
* make pr_debug()/dev_dbg() calls runtime configurable based upon their
* their source module.
*
* Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
extern struct mod_debug __start___verbose[];
extern struct mod_debug __stop___verbose[];
struct debug_name {
struct hlist_node hlist;
struct hlist_node hlist2;
int hash1;
int hash2;
char *name;
int enable;
int type;
};
static int nr_entries;
static int num_enabled;
int dynamic_enabled = DYNAMIC_ENABLED_NONE;
static struct hlist_head module_table[DEBUG_HASH_TABLE_SIZE] =
{ [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
static struct hlist_head module_table2[DEBUG_HASH_TABLE_SIZE] =
{ [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
static DECLARE_MUTEX(debug_list_mutex);
/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
* use independent hash functions, to reduce the chance of false positives.
*/
long long dynamic_printk_enabled;
EXPORT_SYMBOL_GPL(dynamic_printk_enabled);
long long dynamic_printk_enabled2;
EXPORT_SYMBOL_GPL(dynamic_printk_enabled2);
/* returns the debug module pointer. */
static struct debug_name *find_debug_module(char *module_name)
{
int i;
struct hlist_head *head;
struct hlist_node *node;
struct debug_name *element;
element = NULL;
for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
head = &module_table[i];
hlist_for_each_entry_rcu(element, node, head, hlist)
if (!strcmp(element->name, module_name))
return element;
}
return NULL;
}
/* returns the debug module pointer. */
static struct debug_name *find_debug_module_hash(char *module_name, int hash)
{
struct hlist_head *head;
struct hlist_node *node;
struct debug_name *element;
element = NULL;
head = &module_table[hash];
hlist_for_each_entry_rcu(element, node, head, hlist)
if (!strcmp(element->name, module_name))
return element;
return NULL;
}
/* caller must hold mutex*/
static int __add_debug_module(char *mod_name, int hash, int hash2)
{
struct debug_name *new;
char *module_name;
int ret = 0;
if (find_debug_module(mod_name)) {
ret = -EINVAL;
goto out;
}
module_name = kmalloc(strlen(mod_name) + 1, GFP_KERNEL);
if (!module_name) {
ret = -ENOMEM;
goto out;
}
module_name = strcpy(module_name, mod_name);
module_name[strlen(mod_name)] = '\0';
new = kzalloc(sizeof(struct debug_name), GFP_KERNEL);
if (!new) {
kfree(module_name);
ret = -ENOMEM;
goto out;
}
INIT_HLIST_NODE(&new->hlist);
INIT_HLIST_NODE(&new->hlist2);
new->name = module_name;
new->hash1 = hash;
new->hash2 = hash2;
hlist_add_head_rcu(&new->hlist, &module_table[hash]);
hlist_add_head_rcu(&new->hlist2, &module_table2[hash2]);
nr_entries++;
out:
return ret;
}
int unregister_dynamic_debug_module(char *mod_name)
{
struct debug_name *element;
int ret = 0;
down(&debug_list_mutex);
element = find_debug_module(mod_name);
if (!element) {
ret = -EINVAL;
goto out;
}
hlist_del_rcu(&element->hlist);
hlist_del_rcu(&element->hlist2);
synchronize_rcu();
kfree(element->name);
if (element->enable)
num_enabled--;
kfree(element);
nr_entries--;
out:
up(&debug_list_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(unregister_dynamic_debug_module);
int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
char *flags, int hash, int hash2)
{
struct debug_name *elem;
int ret = 0;
down(&debug_list_mutex);
elem = find_debug_module(mod_name);
if (!elem) {
if (__add_debug_module(mod_name, hash, hash2))
goto out;
elem = find_debug_module(mod_name);
if (dynamic_enabled == DYNAMIC_ENABLED_ALL &&
!strcmp(mod_name, share_name)) {
elem->enable = true;
num_enabled++;
}
}
elem->type |= type;
out:
up(&debug_list_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(register_dynamic_debug_module);
int __dynamic_dbg_enabled_helper(char *mod_name, int type, int value, int hash)
{
struct debug_name *elem;
int ret = 0;
if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
return 1;
rcu_read_lock();
elem = find_debug_module_hash(mod_name, hash);
if (elem && elem->enable)
ret = 1;
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(__dynamic_dbg_enabled_helper);
static void set_all(bool enable)
{
struct debug_name *e;
struct hlist_node *node;
int i;
long long enable_mask;
for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
if (module_table[i].first != NULL) {
hlist_for_each_entry(e, node, &module_table[i], hlist) {
e->enable = enable;
}
}
}
if (enable)
enable_mask = ULLONG_MAX;
else
enable_mask = 0;
dynamic_printk_enabled = enable_mask;
dynamic_printk_enabled2 = enable_mask;
}
static int disabled_hash(int i, bool first_table)
{
struct debug_name *e;
struct hlist_node *node;
if (first_table) {
hlist_for_each_entry(e, node, &module_table[i], hlist) {
if (e->enable)
return 0;
}
} else {
hlist_for_each_entry(e, node, &module_table2[i], hlist2) {
if (e->enable)
return 0;
}
}
return 1;
}
static ssize_t pr_debug_write(struct file *file, const char __user *buf,
size_t length, loff_t *ppos)
{
char *buffer, *s, *value_str, *setting_str;
int err, value;
struct debug_name *elem = NULL;
int all = 0;
if (length > PAGE_SIZE || length < 0)
return -EINVAL;
buffer = (char *)__get_free_page(GFP_KERNEL);
if (!buffer)
return -ENOMEM;
err = -EFAULT;
if (copy_from_user(buffer, buf, length))
goto out;
err = -EINVAL;
if (length < PAGE_SIZE)
buffer[length] = '\0';
else if (buffer[PAGE_SIZE-1])
goto out;
err = -EINVAL;
down(&debug_list_mutex);
if (strncmp("set", buffer, 3))
goto out_up;
s = buffer + 3;
setting_str = strsep(&s, "=");
if (s == NULL)
goto out_up;
setting_str = strstrip(setting_str);
value_str = strsep(&s, " ");
if (s == NULL)
goto out_up;
s = strstrip(s);
if (!strncmp(s, "all", 3))
all = 1;
else
elem = find_debug_module(s);
if (!strncmp(setting_str, "enable", 6)) {
value = !!simple_strtol(value_str, NULL, 10);
if (all) {
if (value) {
set_all(true);
num_enabled = nr_entries;
dynamic_enabled = DYNAMIC_ENABLED_ALL;
} else {
set_all(false);
num_enabled = 0;
dynamic_enabled = DYNAMIC_ENABLED_NONE;
}
err = 0;
} else {
if (elem) {
if (value && (elem->enable == 0)) {
dynamic_printk_enabled |=
(1LL << elem->hash1);
dynamic_printk_enabled2 |=
(1LL << elem->hash2);
elem->enable = 1;
num_enabled++;
dynamic_enabled = DYNAMIC_ENABLED_SOME;
err = 0;
printk(KERN_DEBUG
"debugging enabled for module %s",
elem->name);
} else if (!value && (elem->enable == 1)) {
elem->enable = 0;
num_enabled--;
if (disabled_hash(elem->hash1, true))
dynamic_printk_enabled &=
~(1LL << elem->hash1);
if (disabled_hash(elem->hash2, false))
dynamic_printk_enabled2 &=
~(1LL << elem->hash2);
if (num_enabled)
dynamic_enabled =
DYNAMIC_ENABLED_SOME;
else
dynamic_enabled =
DYNAMIC_ENABLED_NONE;
err = 0;
printk(KERN_DEBUG
"debugging disabled for module "
"%s", elem->name);
}
}
}
}
if (!err)
err = length;
out_up:
up(&debug_list_mutex);
out:
free_page((unsigned long)buffer);
return err;
}
static void *pr_debug_seq_start(struct seq_file *f, loff_t *pos)
{
return (*pos < DEBUG_HASH_TABLE_SIZE) ? pos : NULL;
}
static void *pr_debug_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
(*pos)++;
if (*pos >= DEBUG_HASH_TABLE_SIZE)
return NULL;
return pos;
}
static void pr_debug_seq_stop(struct seq_file *s, void *v)
{
/* Nothing to do */
}
static int pr_debug_seq_show(struct seq_file *s, void *v)
{
struct hlist_head *head;
struct hlist_node *node;
struct debug_name *elem;
unsigned int i = *(loff_t *) v;
rcu_read_lock();
head = &module_table[i];
hlist_for_each_entry_rcu(elem, node, head, hlist) {
seq_printf(s, "%s enabled=%d", elem->name, elem->enable);
seq_printf(s, "\n");
}
rcu_read_unlock();
return 0;
}
static struct seq_operations pr_debug_seq_ops = {
.start = pr_debug_seq_start,
.next = pr_debug_seq_next,
.stop = pr_debug_seq_stop,
.show = pr_debug_seq_show
};
static int pr_debug_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &pr_debug_seq_ops);
}
static const struct file_operations pr_debug_operations = {
.open = pr_debug_open,
.read = seq_read,
.write = pr_debug_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init dynamic_printk_init(void)
{
struct dentry *dir, *file;
struct mod_debug *iter;
unsigned long value;
dir = debugfs_create_dir("dynamic_printk", NULL);
if (!dir)
return -ENOMEM;
file = debugfs_create_file("modules", 0644, dir, NULL,
&pr_debug_operations);
if (!file) {
debugfs_remove(dir);
return -ENOMEM;
}
for (value = (unsigned long)__start___verbose;
value < (unsigned long)__stop___verbose;
value += sizeof(struct mod_debug)) {
iter = (struct mod_debug *)value;
register_dynamic_debug_module(iter->modname,
iter->type,
iter->logical_modname,
iter->flag_names, iter->hash, iter->hash2);
}
if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
set_all(true);
return 0;
}
module_init(dynamic_printk_init);
/* may want to move this earlier so we can get traces as early as possible */
static int __init dynamic_printk_setup(char *str)
{
if (str)
return -ENOENT;
dynamic_enabled = DYNAMIC_ENABLED_ALL;
return 0;
}
/* Use early_param(), so we can get debug output as early as possible */
early_param("dynamic_printk", dynamic_printk_setup);