[linux.git] / lib / dynamic_debug.c

/*
 * lib/dynamic_debug.c
 *
 * make pr_debug()/dev_dbg() calls runtime configurable based upon their
 * source module.
 *
 * Copyright (C) 2008 Jason Baron <[email protected]>
 * By Greg Banks <[email protected]>
 * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/sysctl.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/dynamic_debug.h>
#include <linux/debugfs.h>
#include <linux/slab.h>

extern struct _ddebug __start___verbose[];
extern struct _ddebug __stop___verbose[];

/* dynamic_debug_enabled, and dynamic_debug_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_debug_enabled;
EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
long long dynamic_debug_enabled2;
EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);

struct ddebug_table {
	struct list_head link;
	char *mod_name;
	unsigned int num_ddebugs;
	unsigned int num_enabled;
	struct _ddebug *ddebugs;
};

struct ddebug_query {
	const char *filename;
	const char *module;
	const char *function;
	const char *format;
	unsigned int first_lineno, last_lineno;
};

struct ddebug_iter {
	struct ddebug_table *table;
	unsigned int idx;
};

static DEFINE_MUTEX(ddebug_lock);
static LIST_HEAD(ddebug_tables);
static int verbose = 0;

/* Return the last part of a pathname */
static inline const char *basename(const char *path)
{
	const char *tail = strrchr(path, '/');
	return tail ? tail+1 : path;
}

/* format a string into buf[] which describes the _ddebug's flags */
static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
				    size_t maxlen)
{
	char *p = buf;

	BUG_ON(maxlen < 4);
	if (dp->flags & _DPRINTK_FLAGS_PRINT)
		*p++ = 'p';
	if (p == buf)
		*p++ = '-';
	*p = '\0';

	return buf;
}

/*
 * must be called with ddebug_lock held
 */

static int disabled_hash(char hash, bool first_table)
{
	struct ddebug_table *dt;
	char table_hash_value;

	list_for_each_entry(dt, &ddebug_tables, link) {
		if (first_table)
			table_hash_value = dt->ddebugs->primary_hash;
		else
			table_hash_value = dt->ddebugs->secondary_hash;
		if (dt->num_enabled && (hash == table_hash_value))
			return 0;
	}
	return 1;
}

/*
 * Search the tables for _ddebug's which match the given
 * `query' and apply the `flags' and `mask' to them.  Tells
 * the user which ddebug's were changed, or whether none
 * were matched.
 */
static void ddebug_change(const struct ddebug_query *query,
			   unsigned int flags, unsigned int mask)
{
	int i;
	struct ddebug_table *dt;
	unsigned int newflags;
	unsigned int nfound = 0;
	char flagbuf[8];

	/* search for matching ddebugs */
	mutex_lock(&ddebug_lock);
	list_for_each_entry(dt, &ddebug_tables, link) {

		/* match against the module name */
		if (query->module != NULL &&
		    strcmp(query->module, dt->mod_name))
			continue;

		for (i = 0 ; i < dt->num_ddebugs ; i++) {
			struct _ddebug *dp = &dt->ddebugs[i];

			/* match against the source filename */
			if (query->filename != NULL &&
			    strcmp(query->filename, dp->filename) &&
			    strcmp(query->filename, basename(dp->filename)))
				continue;

			/* match against the function */
			if (query->function != NULL &&
			    strcmp(query->function, dp->function))
				continue;

			/* match against the format */
			if (query->format != NULL &&
			    strstr(dp->format, query->format) == NULL)
				continue;

			/* match against the line number range */
			if (query->first_lineno &&
			    dp->lineno < query->first_lineno)
				continue;
			if (query->last_lineno &&
			    dp->lineno > query->last_lineno)
				continue;

			nfound++;

			newflags = (dp->flags & mask) | flags;
			if (newflags == dp->flags)
				continue;

			if (!newflags)
				dt->num_enabled--;
			else if (!dp->flags)
				dt->num_enabled++;
			dp->flags = newflags;
			if (newflags) {
				dynamic_debug_enabled |=
						(1LL << dp->primary_hash);
				dynamic_debug_enabled2 |=
						(1LL << dp->secondary_hash);
			} else {
				if (disabled_hash(dp->primary_hash, true))
					dynamic_debug_enabled &=
						~(1LL << dp->primary_hash);
				if (disabled_hash(dp->secondary_hash, false))
					dynamic_debug_enabled2 &=
						~(1LL << dp->secondary_hash);
			}
			if (verbose)
				printk(KERN_INFO
					"ddebug: changed %s:%d [%s]%s %s\n",
					dp->filename, dp->lineno,
					dt->mod_name, dp->function,
					ddebug_describe_flags(dp, flagbuf,
							sizeof(flagbuf)));
		}
	}
	mutex_unlock(&ddebug_lock);

	if (!nfound && verbose)
		printk(KERN_INFO "ddebug: no matches for query\n");
}

/*
 * Split the buffer `buf' into space-separated words.
 * Handles simple " and ' quoting, i.e. without nested,
 * embedded or escaped \".  Return the number of words
 * or <0 on error.
 */
static int ddebug_tokenize(char *buf, char *words[], int maxwords)
{
	int nwords = 0;

	while (*buf) {
		char *end;

		/* Skip leading whitespace */
		buf = skip_spaces(buf);
		if (!*buf)
			break;	/* oh, it was trailing whitespace */

		/* Run `end' over a word, either whitespace separated or quoted */
		if (*buf == '"' || *buf == '\'') {
			int quote = *buf++;
			for (end = buf ; *end && *end != quote ; end++)
				;
			if (!*end)
				return -EINVAL;	/* unclosed quote */
		} else {
			for (end = buf ; *end && !isspace(*end) ; end++)
				;
			BUG_ON(end == buf);
		}
		/* Here `buf' is the start of the word, `end' is one past the end */

		if (nwords == maxwords)
			return -EINVAL;	/* ran out of words[] before bytes */
		if (*end)
			*end++ = '\0';	/* terminate the word */
		words[nwords++] = buf;
		buf = end;
	}

	if (verbose) {
		int i;
		printk(KERN_INFO "%s: split into words:", __func__);
		for (i = 0 ; i < nwords ; i++)
			printk(" \"%s\"", words[i]);
		printk("\n");
	}

	return nwords;
}

/*
 * Parse a single line number.  Note that the empty string ""
 * is treated as a special case and converted to zero, which
 * is later treated as a "don't care" value.
 */
static inline int parse_lineno(const char *str, unsigned int *val)
{
	char *end = NULL;
	BUG_ON(str == NULL);
	if (*str == '\0') {
		*val = 0;
		return 0;
	}
	*val = simple_strtoul(str, &end, 10);
	return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
}

/*
 * Undo octal escaping in a string, inplace.  This is useful to
 * allow the user to express a query which matches a format
 * containing embedded spaces.
 */
#define isodigit(c)		((c) >= '0' && (c) <= '7')
static char *unescape(char *str)
{
	char *in = str;
	char *out = str;

	while (*in) {
		if (*in == '\\') {
			if (in[1] == '\\') {
				*out++ = '\\';
				in += 2;
				continue;
			} else if (in[1] == 't') {
				*out++ = '\t';
				in += 2;
				continue;
			} else if (in[1] == 'n') {
				*out++ = '\n';
				in += 2;
				continue;
			} else if (isodigit(in[1]) &&
			         isodigit(in[2]) &&
			         isodigit(in[3])) {
				*out++ = ((in[1] - '0')<<6) |
				          ((in[2] - '0')<<3) |
				          (in[3] - '0');
				in += 4;
				continue;
			}
		}
		*out++ = *in++;
	}
	*out = '\0';

	return str;
}

/*
 * Parse words[] as a ddebug query specification, which is a series
 * of (keyword, value) pairs chosen from these possibilities:
 *
 * func <function-name>
 * file <full-pathname>
 * file <base-filename>
 * module <module-name>
 * format <escaped-string-to-find-in-format>
 * line <lineno>
 * line <first-lineno>-<last-lineno> // where either may be empty
 */
static int ddebug_parse_query(char *words[], int nwords,
			       struct ddebug_query *query)
{
	unsigned int i;

	/* check we have an even number of words */
	if (nwords % 2 != 0)
		return -EINVAL;
	memset(query, 0, sizeof(*query));

	for (i = 0 ; i < nwords ; i += 2) {
		if (!strcmp(words[i], "func"))
			query->function = words[i+1];
		else if (!strcmp(words[i], "file"))
			query->filename = words[i+1];
		else if (!strcmp(words[i], "module"))
			query->module = words[i+1];
		else if (!strcmp(words[i], "format"))
			query->format = unescape(words[i+1]);
		else if (!strcmp(words[i], "line")) {
			char *first = words[i+1];
			char *last = strchr(first, '-');
			if (last)
				*last++ = '\0';
			if (parse_lineno(first, &query->first_lineno) < 0)
				return -EINVAL;
			if (last != NULL) {
				/* range <first>-<last> */
				if (parse_lineno(last, &query->last_lineno) < 0)
					return -EINVAL;
			} else {
				query->last_lineno = query->first_lineno;
			}
		} else {
			if (verbose)
				printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
					__func__, words[i]);
			return -EINVAL;
		}
	}

	if (verbose)
		printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
		       "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
			__func__, query->function, query->filename,
			query->module, query->format, query->first_lineno,
			query->last_lineno);

	return 0;
}

/*
 * Parse `str' as a flags specification, format [-+=][p]+.
 * Sets up *maskp and *flagsp to be used when changing the
 * flags fields of matched _ddebug's.  Returns 0 on success
 * or <0 on error.
 */
static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
			       unsigned int *maskp)
{
	unsigned flags = 0;
	int op = '=';

	switch (*str) {
	case '+':
	case '-':
	case '=':
		op = *str++;
		break;
	default:
		return -EINVAL;
	}
	if (verbose)
		printk(KERN_INFO "%s: op='%c'\n", __func__, op);

	for ( ; *str ; ++str) {
		switch (*str) {
		case 'p':
			flags |= _DPRINTK_FLAGS_PRINT;
			break;
		default:
			return -EINVAL;
		}
	}
	if (flags == 0)
		return -EINVAL;
	if (verbose)
		printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);

	/* calculate final *flagsp, *maskp according to mask and op */
	switch (op) {
	case '=':
		*maskp = 0;
		*flagsp = flags;
		break;
	case '+':
		*maskp = ~0U;
		*flagsp = flags;
		break;
	case '-':
		*maskp = ~flags;
		*flagsp = 0;
		break;
	}
	if (verbose)
		printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
			__func__, *flagsp, *maskp);
	return 0;
}

/*
 * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
 * command text from userspace, parses and executes it.
 */
static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
				  size_t len, loff_t *offp)
{
	unsigned int flags = 0, mask = 0;
	struct ddebug_query query;
#define MAXWORDS 9
	int nwords;
	char *words[MAXWORDS];
	char tmpbuf[256];

	if (len == 0)
		return 0;
	/* we don't check *offp -- multiple writes() are allowed */
	if (len > sizeof(tmpbuf)-1)
		return -E2BIG;
	if (copy_from_user(tmpbuf, ubuf, len))
		return -EFAULT;
	tmpbuf[len] = '\0';
	if (verbose)
		printk(KERN_INFO "%s: read %d bytes from userspace\n",
			__func__, (int)len);

	nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
	if (nwords <= 0)
		return -EINVAL;
	if (ddebug_parse_query(words, nwords-1, &query))
		return -EINVAL;
	if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
		return -EINVAL;

	/* actually go and implement the change */
	ddebug_change(&query, flags, mask);

	*offp += len;
	return len;
}

/*
 * Set the iterator to point to the first _ddebug object
 * and return a pointer to that first object.  Returns
 * NULL if there are no _ddebugs at all.
 */
static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
{
	if (list_empty(&ddebug_tables)) {
		iter->table = NULL;
		iter->idx = 0;
		return NULL;
	}
	iter->table = list_entry(ddebug_tables.next,
				 struct ddebug_table, link);
	iter->idx = 0;
	return &iter->table->ddebugs[iter->idx];
}

/*
 * Advance the iterator to point to the next _ddebug
 * object from the one the iterator currently points at,
 * and returns a pointer to the new _ddebug.  Returns
 * NULL if the iterator has seen all the _ddebugs.
 */
static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
{
	if (iter->table == NULL)
		return NULL;
	if (++iter->idx == iter->table->num_ddebugs) {
		/* iterate to next table */
		iter->idx = 0;
		if (list_is_last(&iter->table->link, &ddebug_tables)) {
			iter->table = NULL;
			return NULL;
		}
		iter->table = list_entry(iter->table->link.next,
					 struct ddebug_table, link);
	}
	return &iter->table->ddebugs[iter->idx];
}

/*
 * Seq_ops start method.  Called at the start of every
 * read() call from userspace.  Takes the ddebug_lock and
 * seeks the seq_file's iterator to the given position.
 */
static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp;
	int n = *pos;

	if (verbose)
		printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
			__func__, m, (unsigned long long)*pos);

	mutex_lock(&ddebug_lock);

	if (!n)
		return SEQ_START_TOKEN;
	if (n < 0)
		return NULL;
	dp = ddebug_iter_first(iter);
	while (dp != NULL && --n > 0)
		dp = ddebug_iter_next(iter);
	return dp;
}

/*
 * Seq_ops next method.  Called several times within a read()
 * call from userspace, with ddebug_lock held.  Walks to the
 * next _ddebug object with a special case for the header line.
 */
static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp;

	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
			__func__, m, p, (unsigned long long)*pos);

	if (p == SEQ_START_TOKEN)
		dp = ddebug_iter_first(iter);
	else
		dp = ddebug_iter_next(iter);
	++*pos;
	return dp;
}

/*
 * Seq_ops show method.  Called several times within a read()
 * call from userspace, with ddebug_lock held.  Formats the
 * current _ddebug as a single human-readable line, with a
 * special case for the header line.
 */
static int ddebug_proc_show(struct seq_file *m, void *p)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp = p;
	char flagsbuf[8];

	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p\n",
			__func__, m, p);

	if (p == SEQ_START_TOKEN) {
		seq_puts(m,
			"# filename:lineno [module]function flags format\n");
		return 0;
	}

	seq_printf(m, "%s:%u [%s]%s %s \"",
		   dp->filename, dp->lineno,
		   iter->table->mod_name, dp->function,
		   ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
	seq_escape(m, dp->format, "\t\r\n\"");
	seq_puts(m, "\"\n");

	return 0;
}

/*
 * Seq_ops stop method.  Called at the end of each read()
 * call from userspace.  Drops ddebug_lock.
 */
static void ddebug_proc_stop(struct seq_file *m, void *p)
{
	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p\n",
			__func__, m, p);
	mutex_unlock(&ddebug_lock);
}

static const struct seq_operations ddebug_proc_seqops = {
	.start = ddebug_proc_start,
	.next = ddebug_proc_next,
	.show = ddebug_proc_show,
	.stop = ddebug_proc_stop
};

/*
 * File_ops->open method for <debugfs>/dynamic_debug/control.  Does the seq_file
 * setup dance, and also creates an iterator to walk the _ddebugs.
 * Note that we create a seq_file always, even for O_WRONLY files
 * where it's not needed, as doing so simplifies the ->release method.
 */
static int ddebug_proc_open(struct inode *inode, struct file *file)
{
	struct ddebug_iter *iter;
	int err;

	if (verbose)
		printk(KERN_INFO "%s: called\n", __func__);

	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
	if (iter == NULL)
		return -ENOMEM;

	err = seq_open(file, &ddebug_proc_seqops);
	if (err) {
		kfree(iter);
		return err;
	}
	((struct seq_file *) file->private_data)->private = iter;
	return 0;
}

static const struct file_operations ddebug_proc_fops = {
	.owner = THIS_MODULE,
	.open = ddebug_proc_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = seq_release_private,
	.write = ddebug_proc_write
};

/*
 * Allocate a new ddebug_table for the given module
 * and add it to the global list.
 */
int ddebug_add_module(struct _ddebug *tab, unsigned int n,
			     const char *name)
{
	struct ddebug_table *dt;
	char *new_name;

	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
	if (dt == NULL)
		return -ENOMEM;
	new_name = kstrdup(name, GFP_KERNEL);
	if (new_name == NULL) {
		kfree(dt);
		return -ENOMEM;
	}
	dt->mod_name = new_name;
	dt->num_ddebugs = n;
	dt->num_enabled = 0;
	dt->ddebugs = tab;

	mutex_lock(&ddebug_lock);
	list_add_tail(&dt->link, &ddebug_tables);
	mutex_unlock(&ddebug_lock);

	if (verbose)
		printk(KERN_INFO "%u debug prints in module %s\n",
				 n, dt->mod_name);
	return 0;
}
EXPORT_SYMBOL_GPL(ddebug_add_module);

static void ddebug_table_free(struct ddebug_table *dt)
{
	list_del_init(&dt->link);
	kfree(dt->mod_name);
	kfree(dt);
}

/*
 * Called in response to a module being unloaded.  Removes
 * any ddebug_table's which point at the module.
 */
int ddebug_remove_module(const char *mod_name)
{
	struct ddebug_table *dt, *nextdt;
	int ret = -ENOENT;

	if (verbose)
		printk(KERN_INFO "%s: removing module \"%s\"\n",
				__func__, mod_name);

	mutex_lock(&ddebug_lock);
	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
		if (!strcmp(dt->mod_name, mod_name)) {
			ddebug_table_free(dt);
			ret = 0;
		}
	}
	mutex_unlock(&ddebug_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(ddebug_remove_module);

static void ddebug_remove_all_tables(void)
{
	mutex_lock(&ddebug_lock);
	while (!list_empty(&ddebug_tables)) {
		struct ddebug_table *dt = list_entry(ddebug_tables.next,
						      struct ddebug_table,
						      link);
		ddebug_table_free(dt);
	}
	mutex_unlock(&ddebug_lock);
}

static int __init dynamic_debug_init(void)
{
	struct dentry *dir, *file;
	struct _ddebug *iter, *iter_start;
	const char *modname = NULL;
	int ret = 0;
	int n = 0;

	dir = debugfs_create_dir("dynamic_debug", NULL);
	if (!dir)
		return -ENOMEM;
	file = debugfs_create_file("control", 0644, dir, NULL,
					&ddebug_proc_fops);
	if (!file) {
		debugfs_remove(dir);
		return -ENOMEM;
	}
	if (__start___verbose != __stop___verbose) {
		iter = __start___verbose;
		modname = iter->modname;
		iter_start = iter;
		for (; iter < __stop___verbose; iter++) {
			if (strcmp(modname, iter->modname)) {
				ret = ddebug_add_module(iter_start, n, modname);
				if (ret)
					goto out_free;
				n = 0;
				modname = iter->modname;
				iter_start = iter;
			}
			n++;
		}
		ret = ddebug_add_module(iter_start, n, modname);
	}
out_free:
	if (ret) {
		ddebug_remove_all_tables();
		debugfs_remove(dir);
		debugfs_remove(file);
	}
	return 0;
}
module_init(dynamic_debug_init);
Commit	Line	Data
e9d376f0 JB	1	/*
	2	* lib/dynamic_debug.c
	3	*
	4	* make pr_debug()/dev_dbg() calls runtime configurable based upon their
	5	* source module.
	6	*
	7	* Copyright (C) 2008 Jason Baron <[email protected]>
	8	* By Greg Banks <[email protected]>
	9	* Copyright (c) 2008 Silicon Graphics Inc. All Rights Reserved.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/module.h>
	14	#include <linux/moduleparam.h>
	15	#include <linux/kallsyms.h>
	16	#include <linux/version.h>
	17	#include <linux/types.h>
	18	#include <linux/mutex.h>
	19	#include <linux/proc_fs.h>
	20	#include <linux/seq_file.h>
	21	#include <linux/list.h>
	22	#include <linux/sysctl.h>
	23	#include <linux/ctype.h>
e7d2860b	24	#include <linux/string.h>
e9d376f0 JB	25	#include <linux/uaccess.h>
	26	#include <linux/dynamic_debug.h>
	27	#include <linux/debugfs.h>
5a0e3ad6	28	#include <linux/slab.h>
e9d376f0 JB	29
	30	extern struct _ddebug __start___verbose[];
	31	extern struct _ddebug __stop___verbose[];
	32
	33	/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which
	34	* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
	35	* use independent hash functions, to reduce the chance of false positives.
	36	*/
	37	long long dynamic_debug_enabled;
	38	EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
	39	long long dynamic_debug_enabled2;
	40	EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);
	41
	42	struct ddebug_table {
	43	struct list_head link;
	44	char *mod_name;
	45	unsigned int num_ddebugs;
	46	unsigned int num_enabled;
	47	struct _ddebug *ddebugs;
	48	};
	49
	50	struct ddebug_query {
	51	const char *filename;
	52	const char *module;
	53	const char *function;
	54	const char *format;
	55	unsigned int first_lineno, last_lineno;
	56	};
	57
	58	struct ddebug_iter {
	59	struct ddebug_table *table;
	60	unsigned int idx;
	61	};
	62
	63	static DEFINE_MUTEX(ddebug_lock);
	64	static LIST_HEAD(ddebug_tables);
	65	static int verbose = 0;
	66
	67	/* Return the last part of a pathname */
	68	static inline const char basename(const char path)
	69	{
	70	const char *tail = strrchr(path, '/');
	71	return tail ? tail+1 : path;
	72	}
	73
	74	/* format a string into buf[] which describes the _ddebug's flags */
	75	static char ddebug_describe_flags(struct _ddebug dp, char *buf,
	76	size_t maxlen)
	77	{
	78	char *p = buf;
	79
	80	BUG_ON(maxlen < 4);
	81	if (dp->flags & _DPRINTK_FLAGS_PRINT)
	82	*p++ = 'p';
	83	if (p == buf)
	84	*p++ = '-';
	85	*p = '\0';
	86
	87	return buf;
	88	}
	89
	90	/*
	91	* must be called with ddebug_lock held
	92	*/
93
94	static int disabled_hash(char hash, bool first_table)
95	{
96	struct ddebug_table *dt;
97	char table_hash_value;
98
99	list_for_each_entry(dt, &ddebug_tables, link) {
100	if (first_table)
101	table_hash_value = dt->ddebugs->primary_hash;
102	else
103	table_hash_value = dt->ddebugs->secondary_hash;
104	if (dt->num_enabled && (hash == table_hash_value))
105	return 0;
106	}
107	return 1;
108	}
109
110	/*
111	* Search the tables for _ddebug's which match the given
112	* `query' and apply the `flags' and `mask' to them. Tells
113	* the user which ddebug's were changed, or whether none
114	* were matched.
115	*/
116	static void ddebug_change(const struct ddebug_query *query,
117	unsigned int flags, unsigned int mask)
118	{
119	int i;
120	struct ddebug_table *dt;
121	unsigned int newflags;
122	unsigned int nfound = 0;
123	char flagbuf[8];
124
125	/* search for matching ddebugs */
126	mutex_lock(&ddebug_lock);
127	list_for_each_entry(dt, &ddebug_tables, link) {
128
129	/* match against the module name */
130	if (query->module != NULL &&
131	strcmp(query->module, dt->mod_name))
132	continue;
133
134	for (i = 0 ; i < dt->num_ddebugs ; i++) {
135	struct _ddebug *dp = &dt->ddebugs[i];
136
137	/* match against the source filename */
138	if (query->filename != NULL &&
139	strcmp(query->filename, dp->filename) &&
140	strcmp(query->filename, basename(dp->filename)))
141	continue;
142
143	/* match against the function */
144	if (query->function != NULL &&
145	strcmp(query->function, dp->function))
146	continue;
147
148	/* match against the format */
149	if (query->format != NULL &&
150	strstr(dp->format, query->format) == NULL)
151	continue;
152
153	/* match against the line number range */
154	if (query->first_lineno &&
155	dp->lineno < query->first_lineno)
156	continue;
157	if (query->last_lineno &&
158	dp->lineno > query->last_lineno)
159	continue;
160
161	nfound++;
162
163	newflags = (dp->flags & mask) \| flags;
164	if (newflags == dp->flags)
165	continue;
166
167	if (!newflags)
168	dt->num_enabled--;
4df7b3e0	169	else if (!dp->flags)
e9d376f0 JB	170	dt->num_enabled++;
	171	dp->flags = newflags;
	172	if (newflags) {
	173	dynamic_debug_enabled \|=
	174	(1LL << dp->primary_hash);
	175	dynamic_debug_enabled2 \|=
	176	(1LL << dp->secondary_hash);
	177	} else {
	178	if (disabled_hash(dp->primary_hash, true))
	179	dynamic_debug_enabled &=
	180	~(1LL << dp->primary_hash);
	181	if (disabled_hash(dp->secondary_hash, false))
	182	dynamic_debug_enabled2 &=
	183	~(1LL << dp->secondary_hash);
	184	}
	185	if (verbose)
	186	printk(KERN_INFO
	187	"ddebug: changed %s:%d [%s]%s %s\n",
	188	dp->filename, dp->lineno,
	189	dt->mod_name, dp->function,
	190	ddebug_describe_flags(dp, flagbuf,
	191	sizeof(flagbuf)));
	192	}
	193	}
	194	mutex_unlock(&ddebug_lock);
	195
	196	if (!nfound && verbose)
	197	printk(KERN_INFO "ddebug: no matches for query\n");
	198	}
	199
e9d376f0 JB	200	/*
e9d376f0 JB	201	* Split the buffer `buf' into space-separated words.
9898abb3 GB	202	* Handles simple " and ' quoting, i.e. without nested,
	203	* embedded or escaped \". Return the number of words
	204	* or <0 on error.
e9d376f0 JB	205	*/
	206	static int ddebug_tokenize(char buf, char words[], int maxwords)
	207	{
	208	int nwords = 0;
	209
9898abb3 GB	210	while (*buf) {
	211	char *end;
	212
	213	/* Skip leading whitespace */
e7d2860b	214	buf = skip_spaces(buf);
9898abb3 GB	215	if (!*buf)
	216	break; /* oh, it was trailing whitespace */
	217
	218	/* Run `end' over a word, either whitespace separated or quoted */
	219	if (buf == '"' \|\| buf == '\'') {
	220	int quote = *buf++;
	221	for (end = buf ; end && end != quote ; end++)
	222	;
	223	if (!*end)
	224	return -EINVAL; /* unclosed quote */
	225	} else {
	226	for (end = buf ; end && !isspace(end) ; end++)
	227	;
	228	BUG_ON(end == buf);
	229	}
	230	/* Here `buf' is the start of the word, `end' is one past the end */
	231
	232	if (nwords == maxwords)
	233	return -EINVAL; /* ran out of words[] before bytes */
	234	if (*end)
	235	end++ = '\0'; / terminate the word */
	236	words[nwords++] = buf;
	237	buf = end;
	238	}
e9d376f0 JB	239
	240	if (verbose) {
	241	int i;
	242	printk(KERN_INFO "%s: split into words:", __func__);
	243	for (i = 0 ; i < nwords ; i++)
	244	printk(" \"%s\"", words[i]);
	245	printk("\n");
	246	}
	247
	248	return nwords;
	249	}
	250
	251	/*
	252	* Parse a single line number. Note that the empty string ""
	253	* is treated as a special case and converted to zero, which
	254	* is later treated as a "don't care" value.
	255	*/
	256	static inline int parse_lineno(const char str, unsigned int val)
	257	{
	258	char *end = NULL;
	259	BUG_ON(str == NULL);
	260	if (*str == '\0') {
	261	*val = 0;
	262	return 0;
	263	}
	264	*val = simple_strtoul(str, &end, 10);
	265	return end == NULL \|\| end == str \|\| *end != '\0' ? -EINVAL : 0;
	266	}
	267
	268	/*
	269	* Undo octal escaping in a string, inplace. This is useful to
	270	* allow the user to express a query which matches a format
	271	* containing embedded spaces.
	272	*/
	273	#define isodigit(c) ((c) >= '0' && (c) <= '7')
	274	static char unescape(char str)
	275	{
	276	char *in = str;
	277	char *out = str;
	278
	279	while (*in) {
	280	if (*in == '\\') {
	281	if (in[1] == '\\') {
	282	*out++ = '\\';
	283	in += 2;
	284	continue;
	285	} else if (in[1] == 't') {
	286	*out++ = '\t';
	287	in += 2;
	288	continue;
	289	} else if (in[1] == 'n') {
	290	*out++ = '\n';
	291	in += 2;
	292	continue;
	293	} else if (isodigit(in[1]) &&
	294	isodigit(in[2]) &&
	295	isodigit(in[3])) {
	296	*out++ = ((in[1] - '0')<<6) \|
	297	((in[2] - '0')<<3) \|
	298	(in[3] - '0');
	299	in += 4;
	300	continue;
	301	}
	302	}
303	out++ = in++;
304	}
305	*out = '\0';
306
307	return str;
308	}
309
310	/*
311	* Parse words[] as a ddebug query specification, which is a series
312	* of (keyword, value) pairs chosen from these possibilities:
313	*
314	* func <function-name>
315	* file <full-pathname>
316	* file <base-filename>
317	* module <module-name>
318	* format <escaped-string-to-find-in-format>
319	* line <lineno>
320	* line <first-lineno>-<last-lineno> // where either may be empty
321	*/
322	static int ddebug_parse_query(char *words[], int nwords,
323	struct ddebug_query *query)
324	{
325	unsigned int i;
326
327	/* check we have an even number of words */
328	if (nwords % 2 != 0)
329	return -EINVAL;
330	memset(query, 0, sizeof(*query));
331
332	for (i = 0 ; i < nwords ; i += 2) {
333	if (!strcmp(words[i], "func"))
334	query->function = words[i+1];
335	else if (!strcmp(words[i], "file"))
336	query->filename = words[i+1];
337	else if (!strcmp(words[i], "module"))
338	query->module = words[i+1];
339	else if (!strcmp(words[i], "format"))
340	query->format = unescape(words[i+1]);
341	else if (!strcmp(words[i], "line")) {
342	char *first = words[i+1];
343	char *last = strchr(first, '-');
344	if (last)
345	*last++ = '\0';
346	if (parse_lineno(first, &query->first_lineno) < 0)
347	return -EINVAL;
348	if (last != NULL) {
349	/* range <first>-<last> */
350	if (parse_lineno(last, &query->last_lineno) < 0)
351	return -EINVAL;
352	} else {
353	query->last_lineno = query->first_lineno;
354	}
355	} else {
356	if (verbose)
357	printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
358	__func__, words[i]);
359	return -EINVAL;
360	}
361	}
362
363	if (verbose)
364	printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
365	"q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
366	__func__, query->function, query->filename,
367	query->module, query->format, query->first_lineno,
368	query->last_lineno);
369
370	return 0;
371	}
372
373	/*
374	* Parse `str' as a flags specification, format [-+=][p]+.
375	* Sets up maskp and flagsp to be used when changing the
376	* flags fields of matched _ddebug's. Returns 0 on success
377	* or <0 on error.
378	*/
379	static int ddebug_parse_flags(const char str, unsigned int flagsp,
380	unsigned int *maskp)
381	{
382	unsigned flags = 0;
383	int op = '=';
384
385	switch (*str) {
386	case '+':
387	case '-':
388	case '=':
389	op = *str++;
390	break;
391	default:
392	return -EINVAL;
393	}
394	if (verbose)
395	printk(KERN_INFO "%s: op='%c'\n", __func__, op);
396
397	for ( ; *str ; ++str) {
398	switch (*str) {
399	case 'p':
400	flags \|= _DPRINTK_FLAGS_PRINT;
401	break;
402	default:
403	return -EINVAL;
404	}
405	}
406	if (flags == 0)
407	return -EINVAL;
408	if (verbose)
409	printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);
410
411	/* calculate final flagsp, maskp according to mask and op */
412	switch (op) {
413	case '=':
414	*maskp = 0;
415	*flagsp = flags;
416	break;
417	case '+':
418	*maskp = ~0U;
419	*flagsp = flags;
420	break;
421	case '-':
422	*maskp = ~flags;
423	*flagsp = 0;
424	break;
425	}
426	if (verbose)
427	printk(KERN_INFO "%s: flagsp=0x%x maskp=0x%x\n",
428	__func__, flagsp, maskp);
429	return 0;
430	}
431
432	/*
433	* File_ops->write method for <debugfs>/dynamic_debug/conrol. Gathers the
434	* command text from userspace, parses and executes it.
435	*/
436	static ssize_t ddebug_proc_write(struct file file, const char __user ubuf,
437	size_t len, loff_t *offp)
438	{
439	unsigned int flags = 0, mask = 0;
440	struct ddebug_query query;
441	#define MAXWORDS 9
442	int nwords;
443	char *words[MAXWORDS];
444	char tmpbuf[256];
445
446	if (len == 0)
447	return 0;
448	/* we don't check offp -- multiple writes() are allowed /
449	if (len > sizeof(tmpbuf)-1)
450	return -E2BIG;
451	if (copy_from_user(tmpbuf, ubuf, len))
452	return -EFAULT;
453	tmpbuf[len] = '\0';
454	if (verbose)
455	printk(KERN_INFO "%s: read %d bytes from userspace\n",
456	__func__, (int)len);
457
458	nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
ea46c8f7	459	if (nwords <= 0)
e9d376f0 JB	460	return -EINVAL;
	461	if (ddebug_parse_query(words, nwords-1, &query))
	462	return -EINVAL;
	463	if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
	464	return -EINVAL;
	465
	466	/* actually go and implement the change */
	467	ddebug_change(&query, flags, mask);
	468
	469	*offp += len;
	470	return len;
	471	}
	472
	473	/*
	474	* Set the iterator to point to the first _ddebug object
	475	* and return a pointer to that first object. Returns
	476	* NULL if there are no _ddebugs at all.
	477	*/
	478	static struct _ddebug ddebug_iter_first(struct ddebug_iter iter)
	479	{
	480	if (list_empty(&ddebug_tables)) {
	481	iter->table = NULL;
	482	iter->idx = 0;
	483	return NULL;
	484	}
	485	iter->table = list_entry(ddebug_tables.next,
	486	struct ddebug_table, link);
	487	iter->idx = 0;
	488	return &iter->table->ddebugs[iter->idx];
	489	}
	490
	491	/*
	492	* Advance the iterator to point to the next _ddebug
	493	* object from the one the iterator currently points at,
	494	* and returns a pointer to the new _ddebug. Returns
	495	* NULL if the iterator has seen all the _ddebugs.
	496	*/
	497	static struct _ddebug ddebug_iter_next(struct ddebug_iter iter)
	498	{
	499	if (iter->table == NULL)
	500	return NULL;
	501	if (++iter->idx == iter->table->num_ddebugs) {
	502	/* iterate to next table */
	503	iter->idx = 0;
	504	if (list_is_last(&iter->table->link, &ddebug_tables)) {
	505	iter->table = NULL;
	506	return NULL;
	507	}
	508	iter->table = list_entry(iter->table->link.next,
	509	struct ddebug_table, link);
	510	}
	511	return &iter->table->ddebugs[iter->idx];
	512	}
	513
	514	/*
	515	* Seq_ops start method. Called at the start of every
	516	* read() call from userspace. Takes the ddebug_lock and
	517	* seeks the seq_file's iterator to the given position.
	518	*/
	519	static void ddebug_proc_start(struct seq_file m, loff_t *pos)
	520	{
	521	struct ddebug_iter *iter = m->private;
	522	struct _ddebug *dp;
	523	int n = *pos;
524
525	if (verbose)
526	printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
527	__func__, m, (unsigned long long)*pos);
528
529	mutex_lock(&ddebug_lock);
530
531	if (!n)
532	return SEQ_START_TOKEN;
533	if (n < 0)
534	return NULL;
535	dp = ddebug_iter_first(iter);
536	while (dp != NULL && --n > 0)
537	dp = ddebug_iter_next(iter);
538	return dp;
539	}
540
541	/*
542	* Seq_ops next method. Called several times within a read()
543	* call from userspace, with ddebug_lock held. Walks to the
544	* next _ddebug object with a special case for the header line.
545	*/
546	static void ddebug_proc_next(struct seq_file m, void p, loff_t pos)
547	{
548	struct ddebug_iter *iter = m->private;
549	struct _ddebug *dp;
550
551	if (verbose)
552	printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
553	__func__, m, p, (unsigned long long)*pos);
554
555	if (p == SEQ_START_TOKEN)
556	dp = ddebug_iter_first(iter);
557	else
558	dp = ddebug_iter_next(iter);
559	++*pos;
560	return dp;
561	}
562
563	/*
564	* Seq_ops show method. Called several times within a read()
565	* call from userspace, with ddebug_lock held. Formats the
566	* current _ddebug as a single human-readable line, with a
567	* special case for the header line.
568	*/
569	static int ddebug_proc_show(struct seq_file m, void p)
570	{
571	struct ddebug_iter *iter = m->private;
572	struct _ddebug *dp = p;
573	char flagsbuf[8];
574
575	if (verbose)
576	printk(KERN_INFO "%s: called m=%p p=%p\n",
577	__func__, m, p);
578
579	if (p == SEQ_START_TOKEN) {
580	seq_puts(m,
581	"# filename:lineno [module]function flags format\n");
582	return 0;
583	}
584
585	seq_printf(m, "%s:%u [%s]%s %s \"",
586	dp->filename, dp->lineno,
587	iter->table->mod_name, dp->function,
588	ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
589	seq_escape(m, dp->format, "\t\r\n\"");
590	seq_puts(m, "\"\n");
591
592	return 0;
593	}
594
595	/*
596	* Seq_ops stop method. Called at the end of each read()
597	* call from userspace. Drops ddebug_lock.
598	*/
599	static void ddebug_proc_stop(struct seq_file m, void p)
600	{
601	if (verbose)
602	printk(KERN_INFO "%s: called m=%p p=%p\n",
603	__func__, m, p);
604	mutex_unlock(&ddebug_lock);
605	}
606
607	static const struct seq_operations ddebug_proc_seqops = {
608	.start = ddebug_proc_start,
609	.next = ddebug_proc_next,
610	.show = ddebug_proc_show,
611	.stop = ddebug_proc_stop
612	};
613
614	/*
615	* File_ops->open method for <debugfs>/dynamic_debug/control. Does the seq_file
616	* setup dance, and also creates an iterator to walk the _ddebugs.
617	* Note that we create a seq_file always, even for O_WRONLY files
618	* where it's not needed, as doing so simplifies the ->release method.
619	*/
620	static int ddebug_proc_open(struct inode inode, struct file file)
621	{
622	struct ddebug_iter *iter;
623	int err;
624
625	if (verbose)
626	printk(KERN_INFO "%s: called\n", __func__);
627
628	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
629	if (iter == NULL)
630	return -ENOMEM;
631
632	err = seq_open(file, &ddebug_proc_seqops);
633	if (err) {
634	kfree(iter);
635	return err;
636	}
637	((struct seq_file *) file->private_data)->private = iter;
638	return 0;
639	}
640
641	static const struct file_operations ddebug_proc_fops = {
642	.owner = THIS_MODULE,
643	.open = ddebug_proc_open,
644	.read = seq_read,
645	.llseek = seq_lseek,
646	.release = seq_release_private,
647	.write = ddebug_proc_write
648	};
649
650	/*
651	* Allocate a new ddebug_table for the given module
652	* and add it to the global list.
653	*/
654	int ddebug_add_module(struct _ddebug *tab, unsigned int n,
655	const char *name)
656	{
657	struct ddebug_table *dt;
658	char *new_name;
659
660	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
661	if (dt == NULL)
662	return -ENOMEM;
663	new_name = kstrdup(name, GFP_KERNEL);
664	if (new_name == NULL) {
665	kfree(dt);
666	return -ENOMEM;
667	}
668	dt->mod_name = new_name;
669	dt->num_ddebugs = n;
670	dt->num_enabled = 0;
671	dt->ddebugs = tab;
672
673	mutex_lock(&ddebug_lock);
674	list_add_tail(&dt->link, &ddebug_tables);
675	mutex_unlock(&ddebug_lock);
676
677	if (verbose)
678	printk(KERN_INFO "%u debug prints in module %s\n",
679	n, dt->mod_name);
680	return 0;
681	}
682	EXPORT_SYMBOL_GPL(ddebug_add_module);
683
684	static void ddebug_table_free(struct ddebug_table *dt)
685	{
686	list_del_init(&dt->link);
687	kfree(dt->mod_name);
688	kfree(dt);
689	}
690
691	/*
692	* Called in response to a module being unloaded. Removes
693	* any ddebug_table's which point at the module.
694	*/
ff49d74a	695	int ddebug_remove_module(const char *mod_name)
e9d376f0 JB	696	{
	697	struct ddebug_table dt, nextdt;
	698	int ret = -ENOENT;
	699
	700	if (verbose)
	701	printk(KERN_INFO "%s: removing module \"%s\"\n",
	702	__func__, mod_name);
	703
	704	mutex_lock(&ddebug_lock);
	705	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
	706	if (!strcmp(dt->mod_name, mod_name)) {
	707	ddebug_table_free(dt);
	708	ret = 0;
	709	}
	710	}
	711	mutex_unlock(&ddebug_lock);
	712	return ret;
	713	}
	714	EXPORT_SYMBOL_GPL(ddebug_remove_module);
	715
	716	static void ddebug_remove_all_tables(void)
	717	{
	718	mutex_lock(&ddebug_lock);
	719	while (!list_empty(&ddebug_tables)) {
	720	struct ddebug_table *dt = list_entry(ddebug_tables.next,
	721	struct ddebug_table,
	722	link);
	723	ddebug_table_free(dt);
	724	}
	725	mutex_unlock(&ddebug_lock);
	726	}
	727
	728	static int __init dynamic_debug_init(void)
	729	{
	730	struct dentry dir, file;
	731	struct _ddebug iter, iter_start;
	732	const char *modname = NULL;
	733	int ret = 0;
	734	int n = 0;
	735
	736	dir = debugfs_create_dir("dynamic_debug", NULL);
	737	if (!dir)
	738	return -ENOMEM;
	739	file = debugfs_create_file("control", 0644, dir, NULL,
	740	&ddebug_proc_fops);
	741	if (!file) {
	742	debugfs_remove(dir);
	743	return -ENOMEM;
	744	}
	745	if (__start___verbose != __stop___verbose) {
	746	iter = __start___verbose;
	747	modname = iter->modname;
	748	iter_start = iter;
	749	for (; iter < __stop___verbose; iter++) {
	750	if (strcmp(modname, iter->modname)) {
	751	ret = ddebug_add_module(iter_start, n, modname);
	752	if (ret)
	753	goto out_free;
	754	n = 0;
	755	modname = iter->modname;
	756	iter_start = iter;
	757	}
	758	n++;
	759	}
760	ret = ddebug_add_module(iter_start, n, modname);
761	}
762	out_free:
763	if (ret) {
764	ddebug_remove_all_tables();
765	debugfs_remove(dir);
766	debugfs_remove(file);
767	}
768	return 0;
769	}
770	module_init(dynamic_debug_init);