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.
 * Copyright (C) 2013 Du, Changbin <changbin.du@gmail.com>
 */

#define pr_fmt(fmt) "dyndbg: " fmt

#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/parser.h>
#include <linux/string_helpers.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>

#include <rdma/ib_verbs.h>

extern struct _ddebug __start___dyndbg[];
extern struct _ddebug __stop___dyndbg[];
extern struct ddebug_class_map __start___dyndbg_classes[];
extern struct ddebug_class_map __stop___dyndbg_classes[];

struct ddebug_table {
	struct list_head link, maps;
	const 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;
	const char *class_string;
	unsigned int first_lineno, last_lineno;
};

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

struct flag_settings {
	unsigned int flags;
	unsigned int mask;
};

static DEFINE_MUTEX(ddebug_lock);
static LIST_HEAD(ddebug_tables);
static int verbose;
module_param(verbose, int, 0644);
MODULE_PARM_DESC(verbose, " dynamic_debug/control processing "
		 "( 0 = off (default), 1 = module add/rm, 2 = >control summary, 3 = parsing, 4 = per-site changes)");

/* Return the path relative to source root */
static inline const char *trim_prefix(const char *path)
{
	int skip = strlen(__FILE__) - strlen("lib/dynamic_debug.c");

	if (strncmp(path, __FILE__, skip))
		skip = 0; /* prefix mismatch, don't skip */

	return path + skip;
}

static const 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_SOURCENAME, 's' },
	{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
	{ _DPRINTK_FLAGS_INCL_TID, 't' },
	{ _DPRINTK_FLAGS_NONE, '_' },
};

struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };

/* format a string into buf[] which describes the _ddebug's flags */
static char *ddebug_describe_flags(unsigned int flags, struct flagsbuf *fb)
{
	char *p = fb->buf;
	int i;

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

	return fb->buf;
}

#define vnpr_info(lvl, fmt, ...)				\
do {								\
	if (verbose >= lvl)					\
		pr_info(fmt, ##__VA_ARGS__);			\
} while (0)

#define vpr_info(fmt, ...)	vnpr_info(1, fmt, ##__VA_ARGS__)
#define v2pr_info(fmt, ...)	vnpr_info(2, fmt, ##__VA_ARGS__)
#define v3pr_info(fmt, ...)	vnpr_info(3, fmt, ##__VA_ARGS__)
#define v4pr_info(fmt, ...)	vnpr_info(4, fmt, ##__VA_ARGS__)

static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
{
	/* trim any trailing newlines */
	int fmtlen = 0;

	if (query->format) {
		fmtlen = strlen(query->format);
		while (fmtlen && query->format[fmtlen - 1] == '\n')
			fmtlen--;
	}

	v3pr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u class=%s\n",
		  msg,
		  query->function ?: "",
		  query->filename ?: "",
		  query->module ?: "",
		  fmtlen, query->format ?: "",
		  query->first_lineno, query->last_lineno, query->class_string);
}

static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
							  const char *class_string, int *class_id)
{
	struct ddebug_class_map *map;
	int idx;

	list_for_each_entry(map, &dt->maps, link) {
		idx = match_string(map->class_names, map->length, class_string);
		if (idx >= 0) {
			*class_id = idx + map->base;
			return map;
		}
	}
	*class_id = -ENOENT;
	return NULL;
}

#define __outvar /* filled by callee */
/*
 * Search the tables for _ddebug's which match the given `query' and
 * apply the `flags' and `mask' to them.  Returns number of matching
 * callsites, normally the same as number of changes.  If verbose,
 * logs the changes.  Takes ddebug_lock.
 */
static int ddebug_change(const struct ddebug_query *query,
			 struct flag_settings *modifiers)
{
	int i;
	struct ddebug_table *dt;
	unsigned int newflags;
	unsigned int nfound = 0;
	struct flagsbuf fbuf, nbuf;
	struct ddebug_class_map *map = NULL;
	int __outvar valid_class;

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

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

		if (query->class_string) {
			map = ddebug_find_valid_class(dt, query->class_string, &valid_class);
			if (!map)
				continue;
		} else {
			/* constrain query, do not touch class'd callsites */
			valid_class = _DPRINTK_CLASS_DFLT;
		}

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

			/* match site against query-class */
			if (dp->class_id != valid_class)
				continue;

			/* match against the source filename */
			if (query->filename &&
			    !match_wildcard(query->filename, dp->filename) &&
			    !match_wildcard(query->filename,
					   kbasename(dp->filename)) &&
			    !match_wildcard(query->filename,
					   trim_prefix(dp->filename)))
				continue;

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

			/* match against the format */
			if (query->format) {
				if (*query->format == '^') {
					char *p;
					/* anchored search. match must be at beginning */
					p = strstr(dp->format, query->format+1);
					if (p != dp->format)
						continue;
				} else if (!strstr(dp->format, query->format))
					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 & modifiers->mask) | modifiers->flags;
			if (newflags == dp->flags)
				continue;
#ifdef CONFIG_JUMP_LABEL
			if (dp->flags & _DPRINTK_FLAGS_PRINT) {
				if (!(newflags & _DPRINTK_FLAGS_PRINT))
					static_branch_disable(&dp->key.dd_key_true);
			} else if (newflags & _DPRINTK_FLAGS_PRINT) {
				static_branch_enable(&dp->key.dd_key_true);
			}
#endif
			v4pr_info("changed %s:%d [%s]%s %s => %s\n",
				  trim_prefix(dp->filename), dp->lineno,
				  dt->mod_name, dp->function,
				  ddebug_describe_flags(dp->flags, &fbuf),
				  ddebug_describe_flags(newflags, &nbuf));
			dp->flags = newflags;
		}
	}
	mutex_unlock(&ddebug_lock);

	if (!nfound && verbose)
		pr_info("no matches for query\n");

	return nfound;
}

/*
 * 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 */
		if (*buf == '#')
			break;	/* token starts comment, skip rest of line */

		/* find `end' of word, whitespace separated or quoted */
		if (*buf == '"' || *buf == '\'') {
			int quote = *buf++;
			for (end = buf; *end && *end != quote; end++)
				;
			if (!*end) {
				pr_err("unclosed quote: %s\n", buf);
				return -EINVAL;	/* unclosed quote */
			}
		} else {
			for (end = buf; *e