diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 55 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/dynamic_printk.c | 418 |
3 files changed, 475 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index aa81d284844..31d784dd80d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -807,6 +807,61 @@ menuconfig BUILD_DOCSRC Say N if you are unsure. +config DYNAMIC_PRINTK_DEBUG + bool "Enable dynamic printk() call support" + default n + depends on PRINTK + select PRINTK_DEBUG + help + + Compiles debug level messages into the kernel, which would not + otherwise be available at runtime. These messages can then be + enabled/disabled on a per module basis. This mechanism implicitly + enables all pr_debug() and dev_dbg() calls. The impact of this + compile option is a larger kernel text size of about 2%. + + Usage: + + Dynamic debugging is controlled by the debugfs file, + dynamic_printk/modules. This file contains a list of the modules that + can be enabled. The format of the file is the module name, followed + by a set of flags that can be enabled. The first flag is always the + 'enabled' flag. For example: + + <module_name> <enabled=0/1> + . + . + . + + <module_name> : Name of the module in which the debug call resides + <enabled=0/1> : whether the messages are enabled or not + + From a live system: + + snd_hda_intel enabled=0 + fixup enabled=0 + driver enabled=0 + + Enable a module: + + $echo "set enabled=1 <module_name>" > dynamic_printk/modules + + Disable a module: + + $echo "set enabled=0 <module_name>" > dynamic_printk/modules + + Enable all modules: + + $echo "set enabled=1 all" > dynamic_printk/modules + + Disable all modules: + + $echo "set enabled=0 all" > dynamic_printk/modules + + Finally, passing "dynamic_printk" at the command line enables + debugging for all modules. This mode can be turned off via the above + disable command. + source "samples/Kconfig" source "lib/Kconfig.kgdb" diff --git a/lib/Makefile b/lib/Makefile index 44001af76a7..16feaab057b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -81,6 +81,8 @@ obj-$(CONFIG_HAVE_LMB) += lmb.o obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o +obj-$(CONFIG_DYNAMIC_PRINTK_DEBUG) += dynamic_printk.o + hostprogs-y := gen_crc32table clean-files := crc32table.h diff --git a/lib/dynamic_printk.c b/lib/dynamic_printk.c new file mode 100644 index 00000000000..d640f87bdc9 --- /dev/null +++ b/lib/dynamic_printk.c @@ -0,0 +1,418 @@ +/* + * 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); + } + 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; + set_all(true); + return 0; +} +/* Use early_param(), so we can get debug output as early as possible */ +early_param("dynamic_printk", dynamic_printk_setup); |