Release 4.12 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) 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/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>

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


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;
};

static DEFINE_MUTEX(ddebug_lock);
static LIST_HEAD(ddebug_tables);

static int verbose;
module_param(verbose, int, 0644);

/* 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;
}

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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, '_' },
};

/* 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 < 6);
	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;
}

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#define vpr_info(fmt, ...)					\
do {                                                            \
        if (verbose)                                            \
                pr_info(fmt, ##__VA_ARGS__);                    \
} while (0)



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--;
	}

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

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/*
 * 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,
			unsigned int flags, unsigned int mask)
{
	int i;
	struct ddebug_table *dt;
	unsigned int newflags;
	unsigned int nfound = 0;
	char flagbuf[10];

	/* 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;

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

			/* 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 &&
			    !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 & mask) | flags;
			if (newflags == dp->flags)
				continue;
#ifdef HAVE_JUMP_LABEL
			if (dp->flags & _DPRINTK_FLAGS_PRINT) {
				if (!(flags & _DPRINTK_FLAGS_PRINT))
					static_branch_disable(&dp->key.dd_key_true);
			} else if (flags & _DPRINTK_FLAGS_PRINT)
				static_branch_enable(&dp->key.dd_key_true);
#endif
			dp->flags = newflags;
			vpr_info("changed %s:%d [%s]%s =%s\n",
				 trim_prefix(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");

	return nfound;
}

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Andy Shevchenko
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/*
 * 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; *end && !isspace(*end); end++)
				;
			BUG_ON(end == buf);
		}

		/* `buf' is start of word, `end' is one past its end */
		if (nwords == maxwords) {
			pr_err("too many words, legal max <=%d\n", 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;
		pr_info("split into words:");
		for (i = 0; i < nwords; i++)
			pr_cont(" \"%s\"", words[i]);
		pr_cont("\n");
	}

	return nwords;
}

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/*
 * 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)
{
	BUG_ON(str == NULL);
	if (*str == '\0') {
		*val = 0;
		return 0;
	}
	if (kstrtouint(str, 10, val) < 0) {
		pr_err("bad line-number: %s\n", str);
		return -EINVAL;
	}
	return 0;
}

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static int check_set(const char **dest, char *src, char *name)
{
	int rc = 0;

	if (*dest) {
		rc = -EINVAL;
		pr_err("match-spec:%s val:%s overridden by %s\n",
		       name, *dest, src);
	}
	*dest = src;
	return rc;
}

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/*
 * 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
 *
 * Only 1 of each type is allowed.
 * Returns 0 on success, <0 on error.
 */


static int ddebug_parse_query(char *words[], int nwords,
			struct ddebug_query *query, const char *modname)
{
	unsigned int i;
	int rc = 0;

	/* check we have an even number of words */
	if (nwords % 2 != 0) {
		pr_err("expecting pairs of match-spec <value>\n");
		return -EINVAL;
	}
	memset(query, 0, sizeof(*query));

	if (modname)
		/* support $modname.dyndbg=<multiple queries> */
		query->module = modname;

	for (i = 0; i < nwords; i += 2) {
		if (!strcmp(words[i], "func")) {
			rc = check_set(&query->function, words[i+1], "func");
		} else if (!strcmp(words[i], "file")) {
			rc = check_set(&query->filename, words[i+1], "file");
		} else if (!strcmp(words[i], "module")) {
			rc = check_set(&query->module, words[i+1], "module");
		} else if (!strcmp(words[i], "format")) {
			string_unescape_inplace(words[i+1], UNESCAPE_SPACE |
							    UNESCAPE_OCTAL |
							    UNESCAPE_SPECIAL);
			rc = check_set(&query->format, words[i+1], "format");
		} else if (!strcmp(words[i], "line")) {
			char *first = words[i+1];
			char *last = strchr(first, '-');
			if (query->first_lineno || query->last_lineno) {
				pr_err("match-spec: line used 2x\n");
				return -EINVAL;
			}
			if (last)
				*last++ = '\0';
			if (parse_lineno(first, &query->first_lineno) < 0)
				return -EINVAL;
			if (last) {
				/* range <first>-<last> */
				if (parse_lineno(last, &query->last_lineno) < 0)
					return -EINVAL;

				if (query->last_lineno < query->first_lineno) {
					pr_err("last-line:%d < 1st-line:%d\n",
						query->last_lineno,
						query->first_lineno);
					return -EINVAL;
				}
			} else {
				query->last_lineno = query->first_lineno;
			}
		} else {
			pr_err("unknown keyword \"%s\"\n", words[i]);
			return -EINVAL;
		}
		if (rc)
			return rc;
	}
	vpr_info_dq(query, "parsed");
	return 0;
}

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/*
 * 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 = '=', i;

	switch (*str) {
	case '+':
	case '-':
	case '=':
		op = *str++;
		break;
	default:
		pr_err("bad flag-op %c, at start of %s\n", *str, str);
		return -EINVAL;
	}
	vpr_info("op='%c'\n", op);

	for (; *str ; ++str) {
		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
			if (*str == opt_array[i].opt_char) {
				flags |= opt_array[i].flag;
				break;
			}
		}
		if (i < 0) {
			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
			return -EINVAL;
		}
	}
	vpr_info("flags=0x%x\n", 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;
	}
	vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
	return 0;
}

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static int ddebug_exec_query(char *query_string, const char *modname)
{
	unsigned int flags = 0, mask = 0;
	struct ddebug_query query;

#define MAXWORDS 9
	int nwords, nfound;
	char *words[MAXWORDS];

	nwords = ddebug_tokenize(query_string, words, MAXWORDS);
	if (nwords <= 0) {
		pr_err("tokenize failed\n");
		return -EINVAL;
	}
	/* check flags 1st (last arg) so query is pairs of spec,val */
	if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) {
		pr_err("flags parse failed\n");
		return -EINVAL;
	}
	if (ddebug_parse_query(words, nwords-1, &query, modname)) {
		pr_err("query parse failed\n");
		return -EINVAL;
	}
	/* actually go and implement the change */
	nfound = ddebug_change(&query, flags, mask);
	vpr_info_dq(&query, nfound ? "applied" : "no-match");

	return nfound;
}

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/* handle multiple queries in query string, continue on error, return
   last error or number of matching callsites.  Module name is either
   in param (for boot arg) or perhaps in query string.
*/


static int ddebug_exec_queries(char *query, const char *modname)
{
	char *split;
	int i, errs = 0, exitcode = 0, rc, nfound = 0;

	for (i = 0; query; query = split) {
		split = strpbrk(query, ";\n");
		if (split)
			*split++ = '\0';

		query = skip_spaces(query);
		if (!query || !*query || *query == '#')
			continue;

		vpr_info("query %d: \"%s\"\n", i, query);

		rc = ddebug_exec_query(query, modname);
		if (rc < 0) {
			errs++;
			exitcode = rc;
		} else {
			nfound += rc;
		}
		i++;
	}
	vpr_info("processed %d queries, with %d matches, %d errs\n",
		 i, nfound, errs);

	if (exitcode)
		return exitcode;
	return nfound;
}

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#define PREFIX_SIZE 64



static int remaining(int wrote)
{
	if (PREFIX_SIZE - wrote > 0)
		return PREFIX_SIZE - wrote;
	return 0;
}

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static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
{
	int pos_after_tid;
	int pos = 0;

	*buf = '\0';

	if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
		if (in_interrupt())
			pos += snprintf(buf + pos, remaining(pos), "<intr> ");
		else
			pos += snprintf(buf + pos, remaining(pos), "[%d] ",
					task_pid_vnr(current));
	}
	pos_after_tid = pos;
	if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
		pos += snprintf(buf + pos, remaining(pos), "%s:",
				desc->modname);
	if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
		pos += snprintf(buf + pos, remaining(pos), "%s:",
				desc->function);
	if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
		pos += snprintf(buf + pos, remaining(pos), "%d:",
				desc->lineno);
	if (pos - pos_after_tid)
		pos += snprintf(buf + pos, remaining(pos), " ");
	if (pos >= PREFIX_SIZE)
		buf[PREFIX_SIZE - 1] = '\0';

	return buf;
}

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void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
{
	va_list args;
	struct va_format vaf;
	char buf[PREFIX_SIZE];

	BUG_ON(!descriptor);
	BUG_ON(!fmt);

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	printk(KERN_DEBUG "%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);

	va_end(args);
}
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EXPORT_SYMBOL(__dynamic_pr_debug);



void __dynamic_dev_dbg(struct _ddebug *descriptor,
		      const struct device *dev, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	BUG_ON(!descriptor);
	BUG_ON(!fmt);

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	if (!dev) {
		printk(KERN_DEBUG "(NULL device *): %pV", &vaf);
	} else {
		char buf[PREFIX_SIZE];

		dev_printk_emit(LOGLEVEL_DEBUG, dev, "%s%s %s: %pV",
				dynamic_emit_prefix(descriptor, buf),
				dev_driver_string(dev), dev_name(dev),
				&vaf);
	}

	va_end(args);
}
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EXPORT_SYMBOL(__dynamic_dev_dbg);

#ifdef CONFIG_NET



void __dynamic_netdev_dbg(struct _ddebug *descriptor,
			  const struct net_device *dev, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	BUG_ON(!descriptor);
	BUG_ON(!fmt);

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	if (dev && dev->dev.parent) {
		char buf[PREFIX_SIZE];

		dev_printk_emit(LOGLEVEL_DEBUG, dev->dev.parent,
				"%s%s %s %s%s: %pV",
				dynamic_emit_prefix(descriptor, buf),
				dev_driver_string(dev->dev.parent),
				dev_name(dev->dev.parent),
				netdev_name(dev), netdev_reg_state(dev),