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[];

struct ddebug_table {
	struct list_head link;
	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;
	unsigned int first_lineno, last_lineno;
};

struct ddebug_iter {
	struct ddebug_table *table;
	unsigned 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 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' },
	{ _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\n",
		 msg,
		 query->function ?: "",
		 query->filename ?: "",
		 query->module ?: "",
		 fmtlen, query->format ?: "",
		 query->first_lineno, query->last_lineno);
}

/*
 * 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 newf