path: root/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 <jbaron@redhat.com>
 * By Greg Banks <gnb@melbourne.sgi.com>
 * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
 * Copyright (C) 2011 Bart Van Assche.  All Rights Reserved.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.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>
#include <linux/jump_label.h>
#include <linux/hardirq.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/netdevice.h>

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

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

static struct { unsigned flag:8; char opt_char; } opt_array[] = {
	{ _DPRINTK_FLAGS_PRINT, 'p' },
	{ _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
	{ _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
	{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
	{ _DPRINTK_FLAGS_INCL_TID, 't' },
};

/* 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;
	int i;

	BUG_ON(maxlen < 4);
	for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
		if (dp->flags & opt_array[i].flag)
			*p++ = opt_array[i].opt_char;
	if (p == buf)
		*p++ = '-';
	*p = '\0';

	return buf;
}

/*
 * 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;
			dp->flags = newflags;
			if (newflags)
				dp->enabled = 1;
			else
				dp->enabled = 0;
			if (verbose)
				pr_info("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)
		pr_info("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<