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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This code exports profiling data as debugfs files to userspace.
4 *
5 * Copyright IBM Corp. 2009
6 * Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
7 *
8 * Uses gcc-internal data definitions.
9 * Based on the gcov-kernel patch by:
10 * Hubertus Franke <frankeh@us.ibm.com>
11 * Nigel Hinds <nhinds@us.ibm.com>
12 * Rajan Ravindran <rajancr@us.ibm.com>
13 * Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
14 * Paul Larson
15 * Yi CDL Yang
16 */
17
18#define pr_fmt(fmt) "gcov: " fmt
19
20#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/debugfs.h>
23#include <linux/fs.h>
24#include <linux/list.h>
25#include <linux/string.h>
26#include <linux/slab.h>
27#include <linux/mutex.h>
28#include <linux/seq_file.h>
29#include "gcov.h"
30
31/**
32 * struct gcov_node - represents a debugfs entry
33 * @list: list head for child node list
34 * @children: child nodes
35 * @all: list head for list of all nodes
36 * @parent: parent node
37 * @loaded_info: array of pointers to profiling data sets for loaded object
38 * files.
39 * @num_loaded: number of profiling data sets for loaded object files.
40 * @unloaded_info: accumulated copy of profiling data sets for unloaded
41 * object files. Used only when gcov_persist=1.
42 * @dentry: main debugfs entry, either a directory or data file
43 * @links: associated symbolic links
44 * @name: data file basename
45 *
46 * struct gcov_node represents an entity within the gcov/ subdirectory
47 * of debugfs. There are directory and data file nodes. The latter represent
48 * the actual synthesized data file plus any associated symbolic links which
49 * are needed by the gcov tool to work correctly.
50 */
51struct gcov_node {
52 struct list_head list;
53 struct list_head children;
54 struct list_head all;
55 struct gcov_node *parent;
56 struct gcov_info **loaded_info;
57 struct gcov_info *unloaded_info;
58 struct dentry *dentry;
59 struct dentry **links;
60 int num_loaded;
61 char name[0];
62};
63
64static const char objtree[] = OBJTREE;
65static const char srctree[] = SRCTREE;
66static struct gcov_node root_node;
67static struct dentry *reset_dentry;
68static LIST_HEAD(all_head);
69static DEFINE_MUTEX(node_lock);
70
71/* If non-zero, keep copies of profiling data for unloaded modules. */
72static int gcov_persist = 1;
73
74static int __init gcov_persist_setup(char *str)
75{
76 unsigned long val;
77
78 if (kstrtoul(str, 0, &val)) {
79 pr_warn("invalid gcov_persist parameter '%s'\n", str);
80 return 0;
81 }
82 gcov_persist = val;
83 pr_info("setting gcov_persist to %d\n", gcov_persist);
84
85 return 1;
86}
87__setup("gcov_persist=", gcov_persist_setup);
88
89/*
90 * seq_file.start() implementation for gcov data files. Note that the
91 * gcov_iterator interface is designed to be more restrictive than seq_file
92 * (no start from arbitrary position, etc.), to simplify the iterator
93 * implementation.
94 */
95static void *gcov_seq_start(struct seq_file *seq, loff_t *pos)
96{
97 loff_t i;
98
99 gcov_iter_start(seq->private);
100 for (i = 0; i < *pos; i++) {
101 if (gcov_iter_next(seq->private))
102 return NULL;
103 }
104 return seq->private;
105}
106
107/* seq_file.next() implementation for gcov data files. */
108static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
109{
110 struct gcov_iterator *iter = data;
111
112 if (gcov_iter_next(iter))
113 return NULL;
114 (*pos)++;
115
116 return iter;
117}
118
119/* seq_file.show() implementation for gcov data files. */
120static int gcov_seq_show(struct seq_file *seq, void *data)
121{
122 struct gcov_iterator *iter = data;
123
124 if (gcov_iter_write(iter, seq))
125 return -EINVAL;
126 return 0;
127}
128
129static void gcov_seq_stop(struct seq_file *seq, void *data)
130{
131 /* Unused. */
132}
133
134static const struct seq_operations gcov_seq_ops = {
135 .start = gcov_seq_start,
136 .next = gcov_seq_next,
137 .show = gcov_seq_show,
138 .stop = gcov_seq_stop,
139};
140
141/*
142 * Return a profiling data set associated with the given node. This is
143 * either a data set for a loaded object file or a data set copy in case
144 * all associated object files have been unloaded.
145 */
146static struct gcov_info *get_node_info(struct gcov_node *node)
147{
148 if (node->num_loaded > 0)
149 return node->loaded_info[0];
150
151 return node->unloaded_info;
152}
153
154/*
155 * Return a newly allocated profiling data set which contains the sum of
156 * all profiling data associated with the given node.
157 */
158static struct gcov_info *get_accumulated_info(struct gcov_node *node)
159{
160 struct gcov_info *info;
161 int i = 0;
162
163 if (node->unloaded_info)
164 info = gcov_info_dup(node->unloaded_info);
165 else
166 info = gcov_info_dup(node->loaded_info[i++]);
167 if (!info)
168 return NULL;
169 for (; i < node->num_loaded; i++)
170 gcov_info_add(info, node->loaded_info[i]);
171
172 return info;
173}
174
175/*
176 * open() implementation for gcov data files. Create a copy of the profiling
177 * data set and initialize the iterator and seq_file interface.
178 */
179static int gcov_seq_open(struct inode *inode, struct file *file)
180{
181 struct gcov_node *node = inode->i_private;
182 struct gcov_iterator *iter;
183 struct seq_file *seq;
184 struct gcov_info *info;
185 int rc = -ENOMEM;
186
187 mutex_lock(&node_lock);
188 /*
189 * Read from a profiling data copy to minimize reference tracking
190 * complexity and concurrent access and to keep accumulating multiple
191 * profiling data sets associated with one node simple.
192 */
193 info = get_accumulated_info(node);
194 if (!info)
195 goto out_unlock;
196 iter = gcov_iter_new(info);
197 if (!iter)
198 goto err_free_info;
199 rc = seq_open(file, &gcov_seq_ops);
200 if (rc)
201 goto err_free_iter_info;
202 seq = file->private_data;
203 seq->private = iter;
204out_unlock:
205 mutex_unlock(&node_lock);
206 return rc;
207
208err_free_iter_info:
209 gcov_iter_free(iter);
210err_free_info:
211 gcov_info_free(info);
212 goto out_unlock;
213}
214
215/*
216 * release() implementation for gcov data files. Release resources allocated
217 * by open().
218 */
219static int gcov_seq_release(struct inode *inode, struct file *file)
220{
221 struct gcov_iterator *iter;
222 struct gcov_info *info;
223 struct seq_file *seq;
224
225 seq = file->private_data;
226 iter = seq->private;
227 info = gcov_iter_get_info(iter);
228 gcov_iter_free(iter);
229 gcov_info_free(info);
230 seq_release(inode, file);
231
232 return 0;
233}
234
235/*
236 * Find a node by the associated data file name. Needs to be called with
237 * node_lock held.
238 */
239static struct gcov_node *get_node_by_name(const char *name)
240{
241 struct gcov_node *node;
242 struct gcov_info *info;
243
244 list_for_each_entry(node, &all_head, all) {
245 info = get_node_info(node);
246 if (info && (strcmp(gcov_info_filename(info), name) == 0))
247 return node;
248 }
249
250 return NULL;
251}
252
253/*
254 * Reset all profiling data associated with the specified node.
255 */
256static void reset_node(struct gcov_node *node)
257{
258 int i;
259
260 if (node->unloaded_info)
261 gcov_info_reset(node->unloaded_info);
262 for (i = 0; i < node->num_loaded; i++)
263 gcov_info_reset(node->loaded_info[i]);
264}
265
266static void remove_node(struct gcov_node *node);
267
268/*
269 * write() implementation for gcov data files. Reset profiling data for the
270 * corresponding file. If all associated object files have been unloaded,
271 * remove the debug fs node as well.
272 */
273static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
274 size_t len, loff_t *pos)
275{
276 struct seq_file *seq;
277 struct gcov_info *info;
278 struct gcov_node *node;
279
280 seq = file->private_data;
281 info = gcov_iter_get_info(seq->private);
282 mutex_lock(&node_lock);
283 node = get_node_by_name(gcov_info_filename(info));
284 if (node) {
285 /* Reset counts or remove node for unloaded modules. */
286 if (node->num_loaded == 0)
287 remove_node(node);
288 else
289 reset_node(node);
290 }
291 /* Reset counts for open file. */
292 gcov_info_reset(info);
293 mutex_unlock(&node_lock);
294
295 return len;
296}
297
298/*
299 * Given a string <path> representing a file path of format:
300 * path/to/file.gcda
301 * construct and return a new string:
302 * <dir/>path/to/file.<ext>
303 */
304static char *link_target(const char *dir, const char *path, const char *ext)
305{
306 char *target;
307 char *old_ext;
308 char *copy;
309
310 copy = kstrdup(path, GFP_KERNEL);
311 if (!copy)
312 return NULL;
313 old_ext = strrchr(copy, '.');
314 if (old_ext)
315 *old_ext = '\0';
316 if (dir)
317 target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
318 else
319 target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
320 kfree(copy);
321
322 return target;
323}
324
325/*
326 * Construct a string representing the symbolic link target for the given
327 * gcov data file name and link type. Depending on the link type and the
328 * location of the data file, the link target can either point to a
329 * subdirectory of srctree, objtree or in an external location.
330 */
331static char *get_link_target(const char *filename, const struct gcov_link *ext)
332{
333 const char *rel;
334 char *result;
335
336 if (strncmp(filename, objtree, strlen(objtree)) == 0) {
337 rel = filename + strlen(objtree) + 1;
338 if (ext->dir == SRC_TREE)
339 result = link_target(srctree, rel, ext->ext);
340 else
341 result = link_target(objtree, rel, ext->ext);
342 } else {
343 /* External compilation. */
344 result = link_target(NULL, filename, ext->ext);
345 }
346
347 return result;
348}
349
350#define SKEW_PREFIX ".tmp_"
351
352/*
353 * For a filename .tmp_filename.ext return filename.ext. Needed to compensate
354 * for filename skewing caused by the mod-versioning mechanism.
355 */
356static const char *deskew(const char *basename)
357{
358 if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
359 return basename + sizeof(SKEW_PREFIX) - 1;
360 return basename;
361}
362
363/*
364 * Create links to additional files (usually .c and .gcno files) which the
365 * gcov tool expects to find in the same directory as the gcov data file.
366 */
367static void add_links(struct gcov_node *node, struct dentry *parent)
368{
369 const char *basename;
370 char *target;
371 int num;
372 int i;
373
374 for (num = 0; gcov_link[num].ext; num++)
375 /* Nothing. */;
376 node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
377 if (!node->links)
378 return;
379 for (i = 0; i < num; i++) {
380 target = get_link_target(
381 gcov_info_filename(get_node_info(node)),
382 &gcov_link[i]);
383 if (!target)
384 goto out_err;
385 basename = kbasename(target);
386 if (basename == target)
387 goto out_err;
388 node->links[i] = debugfs_create_symlink(deskew(basename),
389 parent, target);
390 if (!node->links[i])
391 goto out_err;
392 kfree(target);
393 }
394
395 return;
396out_err:
397 kfree(target);
398 while (i-- > 0)
399 debugfs_remove(node->links[i]);
400 kfree(node->links);
401 node->links = NULL;
402}
403
404static const struct file_operations gcov_data_fops = {
405 .open = gcov_seq_open,
406 .release = gcov_seq_release,
407 .read = seq_read,
408 .llseek = seq_lseek,
409 .write = gcov_seq_write,
410};
411
412/* Basic initialization of a new node. */
413static void init_node(struct gcov_node *node, struct gcov_info *info,
414 const char *name, struct gcov_node *parent)
415{
416 INIT_LIST_HEAD(&node->list);
417 INIT_LIST_HEAD(&node->children);
418 INIT_LIST_HEAD(&node->all);
419 if (node->loaded_info) {
420 node->loaded_info[0] = info;
421 node->num_loaded = 1;
422 }
423 node->parent = parent;
424 if (name)
425 strcpy(node->name, name);
426}
427
428/*
429 * Create a new node and associated debugfs entry. Needs to be called with
430 * node_lock held.
431 */
432static struct gcov_node *new_node(struct gcov_node *parent,
433 struct gcov_info *info, const char *name)
434{
435 struct gcov_node *node;
436
437 node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
438 if (!node)
439 goto err_nomem;
440 if (info) {
441 node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
442 GFP_KERNEL);
443 if (!node->loaded_info)
444 goto err_nomem;
445 }
446 init_node(node, info, name, parent);
447 /* Differentiate between gcov data file nodes and directory nodes. */
448 if (info) {
449 node->dentry = debugfs_create_file(deskew(node->name), 0600,
450 parent->dentry, node, &gcov_data_fops);
451 } else
452 node->dentry = debugfs_create_dir(node->name, parent->dentry);
453 if (!node->dentry) {
454 pr_warn("could not create file\n");
455 kfree(node);
456 return NULL;
457 }
458 if (info)
459 add_links(node, parent->dentry);
460 list_add(&node->list, &parent->children);
461 list_add(&node->all, &all_head);
462
463 return node;
464
465err_nomem:
466 kfree(node);
467 pr_warn("out of memory\n");
468 return NULL;
469}
470
471/* Remove symbolic links associated with node. */
472static void remove_links(struct gcov_node *node)
473{
474 int i;
475
476 if (!node->links)
477 return;
478 for (i = 0; gcov_link[i].ext; i++)
479 debugfs_remove(node->links[i]);
480 kfree(node->links);
481 node->links = NULL;
482}
483
484/*
485 * Remove node from all lists and debugfs and release associated resources.
486 * Needs to be called with node_lock held.
487 */
488static void release_node(struct gcov_node *node)
489{
490 list_del(&node->list);
491 list_del(&node->all);
492 debugfs_remove(node->dentry);
493 remove_links(node);
494 kfree(node->loaded_info);
495 if (node->unloaded_info)
496 gcov_info_free(node->unloaded_info);
497 kfree(node);
498}
499
500/* Release node and empty parents. Needs to be called with node_lock held. */
501static void remove_node(struct gcov_node *node)
502{
503 struct gcov_node *parent;
504
505 while ((node != &root_node) && list_empty(&node->children)) {
506 parent = node->parent;
507 release_node(node);
508 node = parent;
509 }
510}
511
512/*
513 * Find child node with given basename. Needs to be called with node_lock
514 * held.
515 */
516static struct gcov_node *get_child_by_name(struct gcov_node *parent,
517 const char *name)
518{
519 struct gcov_node *node;
520
521 list_for_each_entry(node, &parent->children, list) {
522 if (strcmp(node->name, name) == 0)
523 return node;
524 }
525
526 return NULL;
527}
528
529/*
530 * write() implementation for reset file. Reset all profiling data to zero
531 * and remove nodes for which all associated object files are unloaded.
532 */
533static ssize_t reset_write(struct file *file, const char __user *addr,
534 size_t len, loff_t *pos)
535{
536 struct gcov_node *node;
537
538 mutex_lock(&node_lock);
539restart:
540 list_for_each_entry(node, &all_head, all) {
541 if (node->num_loaded > 0)
542 reset_node(node);
543 else if (list_empty(&node->children)) {
544 remove_node(node);
545 /* Several nodes may have gone - restart loop. */
546 goto restart;
547 }
548 }
549 mutex_unlock(&node_lock);
550
551 return len;
552}
553
554/* read() implementation for reset file. Unused. */
555static ssize_t reset_read(struct file *file, char __user *addr, size_t len,
556 loff_t *pos)
557{
558 /* Allow read operation so that a recursive copy won't fail. */
559 return 0;
560}
561
562static const struct file_operations gcov_reset_fops = {
563 .write = reset_write,
564 .read = reset_read,
565 .llseek = noop_llseek,
566};
567
568/*
569 * Create a node for a given profiling data set and add it to all lists and
570 * debugfs. Needs to be called with node_lock held.
571 */
572static void add_node(struct gcov_info *info)
573{
574 char *filename;
575 char *curr;
576 char *next;
577 struct gcov_node *parent;
578 struct gcov_node *node;
579
580 filename = kstrdup(gcov_info_filename(info), GFP_KERNEL);
581 if (!filename)
582 return;
583 parent = &root_node;
584 /* Create directory nodes along the path. */
585 for (curr = filename; (next = strchr(curr, '/')); curr = next + 1) {
586 if (curr == next)
587 continue;
588 *next = 0;
589 if (strcmp(curr, ".") == 0)
590 continue;
591 if (strcmp(curr, "..") == 0) {
592 if (!parent->parent)
593 goto err_remove;
594 parent = parent->parent;
595 continue;
596 }
597 node = get_child_by_name(parent, curr);
598 if (!node) {
599 node = new_node(parent, NULL, curr);
600 if (!node)
601 goto err_remove;
602 }
603 parent = node;
604 }
605 /* Create file node. */
606 node = new_node(parent, info, curr);
607 if (!node)
608 goto err_remove;
609out:
610 kfree(filename);
611 return;
612
613err_remove:
614 remove_node(parent);
615 goto out;
616}
617
618/*
619 * Associate a profiling data set with an existing node. Needs to be called
620 * with node_lock held.
621 */
622static void add_info(struct gcov_node *node, struct gcov_info *info)
623{
624 struct gcov_info **loaded_info;
625 int num = node->num_loaded;
626
627 /*
628 * Prepare new array. This is done first to simplify cleanup in
629 * case the new data set is incompatible, the node only contains
630 * unloaded data sets and there's not enough memory for the array.
631 */
632 loaded_info = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
633 if (!loaded_info) {
634 pr_warn("could not add '%s' (out of memory)\n",
635 gcov_info_filename(info));
636 return;
637 }
638 memcpy(loaded_info, node->loaded_info,
639 num * sizeof(struct gcov_info *));
640 loaded_info[num] = info;
641 /* Check if the new data set is compatible. */
642 if (num == 0) {
643 /*
644 * A module was unloaded, modified and reloaded. The new
645 * data set replaces the copy of the last one.
646 */
647 if (!gcov_info_is_compatible(node->unloaded_info, info)) {
648 pr_warn("discarding saved data for %s "
649 "(incompatible version)\n",
650 gcov_info_filename(info));
651 gcov_info_free(node->unloaded_info);
652 node->unloaded_info = NULL;
653 }
654 } else {
655 /*
656 * Two different versions of the same object file are loaded.
657 * The initial one takes precedence.
658 */
659 if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
660 pr_warn("could not add '%s' (incompatible "
661 "version)\n", gcov_info_filename(info));
662 kfree(loaded_info);
663 return;
664 }
665 }
666 /* Overwrite previous array. */
667 kfree(node->loaded_info);
668 node->loaded_info = loaded_info;
669 node->num_loaded = num + 1;
670}
671
672/*
673 * Return the index of a profiling data set associated with a node.
674 */
675static int get_info_index(struct gcov_node *node, struct gcov_info *info)
676{
677 int i;
678
679 for (i = 0; i < node->num_loaded; i++) {
680 if (node->loaded_info[i] == info)
681 return i;
682 }
683 return -ENOENT;
684}
685
686/*
687 * Save the data of a profiling data set which is being unloaded.
688 */
689static void save_info(struct gcov_node *node, struct gcov_info *info)
690{
691 if (node->unloaded_info)
692 gcov_info_add(node->unloaded_info, info);
693 else {
694 node->unloaded_info = gcov_info_dup(info);
695 if (!node->unloaded_info) {
696 pr_warn("could not save data for '%s' "
697 "(out of memory)\n",
698 gcov_info_filename(info));
699 }
700 }
701}
702
703/*
704 * Disassociate a profiling data set from a node. Needs to be called with
705 * node_lock held.
706 */
707static void remove_info(struct gcov_node *node, struct gcov_info *info)
708{
709 int i;
710
711 i = get_info_index(node, info);
712 if (i < 0) {
713 pr_warn("could not remove '%s' (not found)\n",
714 gcov_info_filename(info));
715 return;
716 }
717 if (gcov_persist)
718 save_info(node, info);
719 /* Shrink array. */
720 node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
721 node->num_loaded--;
722 if (node->num_loaded > 0)
723 return;
724 /* Last loaded data set was removed. */
725 kfree(node->loaded_info);
726 node->loaded_info = NULL;
727 node->num_loaded = 0;
728 if (!node->unloaded_info)
729 remove_node(node);
730}
731
732/*
733 * Callback to create/remove profiling files when code compiled with
734 * -fprofile-arcs is loaded/unloaded.
735 */
736void gcov_event(enum gcov_action action, struct gcov_info *info)
737{
738 struct gcov_node *node;
739
740 mutex_lock(&node_lock);
741 node = get_node_by_name(gcov_info_filename(info));
742 switch (action) {
743 case GCOV_ADD:
744 if (node)
745 add_info(node, info);
746 else
747 add_node(info);
748 break;
749 case GCOV_REMOVE:
750 if (node)
751 remove_info(node, info);
752 else {
753 pr_warn("could not remove '%s' (not found)\n",
754 gcov_info_filename(info));
755 }
756 break;
757 }
758 mutex_unlock(&node_lock);
759}
760
761/* Create debugfs entries. */
762static __init int gcov_fs_init(void)
763{
764 int rc = -EIO;
765
766 init_node(&root_node, NULL, NULL, NULL);
767 /*
768 * /sys/kernel/debug/gcov will be parent for the reset control file
769 * and all profiling files.
770 */
771 root_node.dentry = debugfs_create_dir("gcov", NULL);
772 if (!root_node.dentry)
773 goto err_remove;
774 /*
775 * Create reset file which resets all profiling counts when written
776 * to.
777 */
778 reset_dentry = debugfs_create_file("reset", 0600, root_node.dentry,
779 NULL, &gcov_reset_fops);
780 if (!reset_dentry)
781 goto err_remove;
782 /* Replay previous events to get our fs hierarchy up-to-date. */
783 gcov_enable_events();
784 return 0;
785
786err_remove:
787 pr_err("init failed\n");
788 debugfs_remove(root_node.dentry);
789
790 return rc;
791}
792device_initcall(gcov_fs_init);
1/*
2 * This code exports profiling data as debugfs files to userspace.
3 *
4 * Copyright IBM Corp. 2009
5 * Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
6 *
7 * Uses gcc-internal data definitions.
8 * Based on the gcov-kernel patch by:
9 * Hubertus Franke <frankeh@us.ibm.com>
10 * Nigel Hinds <nhinds@us.ibm.com>
11 * Rajan Ravindran <rajancr@us.ibm.com>
12 * Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
13 * Paul Larson
14 * Yi CDL Yang
15 */
16
17#define pr_fmt(fmt) "gcov: " fmt
18
19#include <linux/init.h>
20#include <linux/module.h>
21#include <linux/debugfs.h>
22#include <linux/fs.h>
23#include <linux/list.h>
24#include <linux/string.h>
25#include <linux/slab.h>
26#include <linux/mutex.h>
27#include <linux/seq_file.h>
28#include "gcov.h"
29
30/**
31 * struct gcov_node - represents a debugfs entry
32 * @list: list head for child node list
33 * @children: child nodes
34 * @all: list head for list of all nodes
35 * @parent: parent node
36 * @loaded_info: array of pointers to profiling data sets for loaded object
37 * files.
38 * @num_loaded: number of profiling data sets for loaded object files.
39 * @unloaded_info: accumulated copy of profiling data sets for unloaded
40 * object files. Used only when gcov_persist=1.
41 * @dentry: main debugfs entry, either a directory or data file
42 * @links: associated symbolic links
43 * @name: data file basename
44 *
45 * struct gcov_node represents an entity within the gcov/ subdirectory
46 * of debugfs. There are directory and data file nodes. The latter represent
47 * the actual synthesized data file plus any associated symbolic links which
48 * are needed by the gcov tool to work correctly.
49 */
50struct gcov_node {
51 struct list_head list;
52 struct list_head children;
53 struct list_head all;
54 struct gcov_node *parent;
55 struct gcov_info **loaded_info;
56 struct gcov_info *unloaded_info;
57 struct dentry *dentry;
58 struct dentry **links;
59 int num_loaded;
60 char name[0];
61};
62
63static const char objtree[] = OBJTREE;
64static const char srctree[] = SRCTREE;
65static struct gcov_node root_node;
66static struct dentry *reset_dentry;
67static LIST_HEAD(all_head);
68static DEFINE_MUTEX(node_lock);
69
70/* If non-zero, keep copies of profiling data for unloaded modules. */
71static int gcov_persist = 1;
72
73static int __init gcov_persist_setup(char *str)
74{
75 unsigned long val;
76
77 if (strict_strtoul(str, 0, &val)) {
78 pr_warning("invalid gcov_persist parameter '%s'\n", str);
79 return 0;
80 }
81 gcov_persist = val;
82 pr_info("setting gcov_persist to %d\n", gcov_persist);
83
84 return 1;
85}
86__setup("gcov_persist=", gcov_persist_setup);
87
88/*
89 * seq_file.start() implementation for gcov data files. Note that the
90 * gcov_iterator interface is designed to be more restrictive than seq_file
91 * (no start from arbitrary position, etc.), to simplify the iterator
92 * implementation.
93 */
94static void *gcov_seq_start(struct seq_file *seq, loff_t *pos)
95{
96 loff_t i;
97
98 gcov_iter_start(seq->private);
99 for (i = 0; i < *pos; i++) {
100 if (gcov_iter_next(seq->private))
101 return NULL;
102 }
103 return seq->private;
104}
105
106/* seq_file.next() implementation for gcov data files. */
107static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
108{
109 struct gcov_iterator *iter = data;
110
111 if (gcov_iter_next(iter))
112 return NULL;
113 (*pos)++;
114
115 return iter;
116}
117
118/* seq_file.show() implementation for gcov data files. */
119static int gcov_seq_show(struct seq_file *seq, void *data)
120{
121 struct gcov_iterator *iter = data;
122
123 if (gcov_iter_write(iter, seq))
124 return -EINVAL;
125 return 0;
126}
127
128static void gcov_seq_stop(struct seq_file *seq, void *data)
129{
130 /* Unused. */
131}
132
133static const struct seq_operations gcov_seq_ops = {
134 .start = gcov_seq_start,
135 .next = gcov_seq_next,
136 .show = gcov_seq_show,
137 .stop = gcov_seq_stop,
138};
139
140/*
141 * Return a profiling data set associated with the given node. This is
142 * either a data set for a loaded object file or a data set copy in case
143 * all associated object files have been unloaded.
144 */
145static struct gcov_info *get_node_info(struct gcov_node *node)
146{
147 if (node->num_loaded > 0)
148 return node->loaded_info[0];
149
150 return node->unloaded_info;
151}
152
153/*
154 * Return a newly allocated profiling data set which contains the sum of
155 * all profiling data associated with the given node.
156 */
157static struct gcov_info *get_accumulated_info(struct gcov_node *node)
158{
159 struct gcov_info *info;
160 int i = 0;
161
162 if (node->unloaded_info)
163 info = gcov_info_dup(node->unloaded_info);
164 else
165 info = gcov_info_dup(node->loaded_info[i++]);
166 if (!info)
167 return NULL;
168 for (; i < node->num_loaded; i++)
169 gcov_info_add(info, node->loaded_info[i]);
170
171 return info;
172}
173
174/*
175 * open() implementation for gcov data files. Create a copy of the profiling
176 * data set and initialize the iterator and seq_file interface.
177 */
178static int gcov_seq_open(struct inode *inode, struct file *file)
179{
180 struct gcov_node *node = inode->i_private;
181 struct gcov_iterator *iter;
182 struct seq_file *seq;
183 struct gcov_info *info;
184 int rc = -ENOMEM;
185
186 mutex_lock(&node_lock);
187 /*
188 * Read from a profiling data copy to minimize reference tracking
189 * complexity and concurrent access and to keep accumulating multiple
190 * profiling data sets associated with one node simple.
191 */
192 info = get_accumulated_info(node);
193 if (!info)
194 goto out_unlock;
195 iter = gcov_iter_new(info);
196 if (!iter)
197 goto err_free_info;
198 rc = seq_open(file, &gcov_seq_ops);
199 if (rc)
200 goto err_free_iter_info;
201 seq = file->private_data;
202 seq->private = iter;
203out_unlock:
204 mutex_unlock(&node_lock);
205 return rc;
206
207err_free_iter_info:
208 gcov_iter_free(iter);
209err_free_info:
210 gcov_info_free(info);
211 goto out_unlock;
212}
213
214/*
215 * release() implementation for gcov data files. Release resources allocated
216 * by open().
217 */
218static int gcov_seq_release(struct inode *inode, struct file *file)
219{
220 struct gcov_iterator *iter;
221 struct gcov_info *info;
222 struct seq_file *seq;
223
224 seq = file->private_data;
225 iter = seq->private;
226 info = gcov_iter_get_info(iter);
227 gcov_iter_free(iter);
228 gcov_info_free(info);
229 seq_release(inode, file);
230
231 return 0;
232}
233
234/*
235 * Find a node by the associated data file name. Needs to be called with
236 * node_lock held.
237 */
238static struct gcov_node *get_node_by_name(const char *name)
239{
240 struct gcov_node *node;
241 struct gcov_info *info;
242
243 list_for_each_entry(node, &all_head, all) {
244 info = get_node_info(node);
245 if (info && (strcmp(info->filename, name) == 0))
246 return node;
247 }
248
249 return NULL;
250}
251
252/*
253 * Reset all profiling data associated with the specified node.
254 */
255static void reset_node(struct gcov_node *node)
256{
257 int i;
258
259 if (node->unloaded_info)
260 gcov_info_reset(node->unloaded_info);
261 for (i = 0; i < node->num_loaded; i++)
262 gcov_info_reset(node->loaded_info[i]);
263}
264
265static void remove_node(struct gcov_node *node);
266
267/*
268 * write() implementation for gcov data files. Reset profiling data for the
269 * corresponding file. If all associated object files have been unloaded,
270 * remove the debug fs node as well.
271 */
272static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
273 size_t len, loff_t *pos)
274{
275 struct seq_file *seq;
276 struct gcov_info *info;
277 struct gcov_node *node;
278
279 seq = file->private_data;
280 info = gcov_iter_get_info(seq->private);
281 mutex_lock(&node_lock);
282 node = get_node_by_name(info->filename);
283 if (node) {
284 /* Reset counts or remove node for unloaded modules. */
285 if (node->num_loaded == 0)
286 remove_node(node);
287 else
288 reset_node(node);
289 }
290 /* Reset counts for open file. */
291 gcov_info_reset(info);
292 mutex_unlock(&node_lock);
293
294 return len;
295}
296
297/*
298 * Given a string <path> representing a file path of format:
299 * path/to/file.gcda
300 * construct and return a new string:
301 * <dir/>path/to/file.<ext>
302 */
303static char *link_target(const char *dir, const char *path, const char *ext)
304{
305 char *target;
306 char *old_ext;
307 char *copy;
308
309 copy = kstrdup(path, GFP_KERNEL);
310 if (!copy)
311 return NULL;
312 old_ext = strrchr(copy, '.');
313 if (old_ext)
314 *old_ext = '\0';
315 if (dir)
316 target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
317 else
318 target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
319 kfree(copy);
320
321 return target;
322}
323
324/*
325 * Construct a string representing the symbolic link target for the given
326 * gcov data file name and link type. Depending on the link type and the
327 * location of the data file, the link target can either point to a
328 * subdirectory of srctree, objtree or in an external location.
329 */
330static char *get_link_target(const char *filename, const struct gcov_link *ext)
331{
332 const char *rel;
333 char *result;
334
335 if (strncmp(filename, objtree, strlen(objtree)) == 0) {
336 rel = filename + strlen(objtree) + 1;
337 if (ext->dir == SRC_TREE)
338 result = link_target(srctree, rel, ext->ext);
339 else
340 result = link_target(objtree, rel, ext->ext);
341 } else {
342 /* External compilation. */
343 result = link_target(NULL, filename, ext->ext);
344 }
345
346 return result;
347}
348
349#define SKEW_PREFIX ".tmp_"
350
351/*
352 * For a filename .tmp_filename.ext return filename.ext. Needed to compensate
353 * for filename skewing caused by the mod-versioning mechanism.
354 */
355static const char *deskew(const char *basename)
356{
357 if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
358 return basename + sizeof(SKEW_PREFIX) - 1;
359 return basename;
360}
361
362/*
363 * Create links to additional files (usually .c and .gcno files) which the
364 * gcov tool expects to find in the same directory as the gcov data file.
365 */
366static void add_links(struct gcov_node *node, struct dentry *parent)
367{
368 char *basename;
369 char *target;
370 int num;
371 int i;
372
373 for (num = 0; gcov_link[num].ext; num++)
374 /* Nothing. */;
375 node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
376 if (!node->links)
377 return;
378 for (i = 0; i < num; i++) {
379 target = get_link_target(get_node_info(node)->filename,
380 &gcov_link[i]);
381 if (!target)
382 goto out_err;
383 basename = strrchr(target, '/');
384 if (!basename)
385 goto out_err;
386 basename++;
387 node->links[i] = debugfs_create_symlink(deskew(basename),
388 parent, target);
389 if (!node->links[i])
390 goto out_err;
391 kfree(target);
392 }
393
394 return;
395out_err:
396 kfree(target);
397 while (i-- > 0)
398 debugfs_remove(node->links[i]);
399 kfree(node->links);
400 node->links = NULL;
401}
402
403static const struct file_operations gcov_data_fops = {
404 .open = gcov_seq_open,
405 .release = gcov_seq_release,
406 .read = seq_read,
407 .llseek = seq_lseek,
408 .write = gcov_seq_write,
409};
410
411/* Basic initialization of a new node. */
412static void init_node(struct gcov_node *node, struct gcov_info *info,
413 const char *name, struct gcov_node *parent)
414{
415 INIT_LIST_HEAD(&node->list);
416 INIT_LIST_HEAD(&node->children);
417 INIT_LIST_HEAD(&node->all);
418 if (node->loaded_info) {
419 node->loaded_info[0] = info;
420 node->num_loaded = 1;
421 }
422 node->parent = parent;
423 if (name)
424 strcpy(node->name, name);
425}
426
427/*
428 * Create a new node and associated debugfs entry. Needs to be called with
429 * node_lock held.
430 */
431static struct gcov_node *new_node(struct gcov_node *parent,
432 struct gcov_info *info, const char *name)
433{
434 struct gcov_node *node;
435
436 node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
437 if (!node)
438 goto err_nomem;
439 if (info) {
440 node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
441 GFP_KERNEL);
442 if (!node->loaded_info)
443 goto err_nomem;
444 }
445 init_node(node, info, name, parent);
446 /* Differentiate between gcov data file nodes and directory nodes. */
447 if (info) {
448 node->dentry = debugfs_create_file(deskew(node->name), 0600,
449 parent->dentry, node, &gcov_data_fops);
450 } else
451 node->dentry = debugfs_create_dir(node->name, parent->dentry);
452 if (!node->dentry) {
453 pr_warning("could not create file\n");
454 kfree(node);
455 return NULL;
456 }
457 if (info)
458 add_links(node, parent->dentry);
459 list_add(&node->list, &parent->children);
460 list_add(&node->all, &all_head);
461
462 return node;
463
464err_nomem:
465 kfree(node);
466 pr_warning("out of memory\n");
467 return NULL;
468}
469
470/* Remove symbolic links associated with node. */
471static void remove_links(struct gcov_node *node)
472{
473 int i;
474
475 if (!node->links)
476 return;
477 for (i = 0; gcov_link[i].ext; i++)
478 debugfs_remove(node->links[i]);
479 kfree(node->links);
480 node->links = NULL;
481}
482
483/*
484 * Remove node from all lists and debugfs and release associated resources.
485 * Needs to be called with node_lock held.
486 */
487static void release_node(struct gcov_node *node)
488{
489 list_del(&node->list);
490 list_del(&node->all);
491 debugfs_remove(node->dentry);
492 remove_links(node);
493 kfree(node->loaded_info);
494 if (node->unloaded_info)
495 gcov_info_free(node->unloaded_info);
496 kfree(node);
497}
498
499/* Release node and empty parents. Needs to be called with node_lock held. */
500static void remove_node(struct gcov_node *node)
501{
502 struct gcov_node *parent;
503
504 while ((node != &root_node) && list_empty(&node->children)) {
505 parent = node->parent;
506 release_node(node);
507 node = parent;
508 }
509}
510
511/*
512 * Find child node with given basename. Needs to be called with node_lock
513 * held.
514 */
515static struct gcov_node *get_child_by_name(struct gcov_node *parent,
516 const char *name)
517{
518 struct gcov_node *node;
519
520 list_for_each_entry(node, &parent->children, list) {
521 if (strcmp(node->name, name) == 0)
522 return node;
523 }
524
525 return NULL;
526}
527
528/*
529 * write() implementation for reset file. Reset all profiling data to zero
530 * and remove nodes for which all associated object files are unloaded.
531 */
532static ssize_t reset_write(struct file *file, const char __user *addr,
533 size_t len, loff_t *pos)
534{
535 struct gcov_node *node;
536
537 mutex_lock(&node_lock);
538restart:
539 list_for_each_entry(node, &all_head, all) {
540 if (node->num_loaded > 0)
541 reset_node(node);
542 else if (list_empty(&node->children)) {
543 remove_node(node);
544 /* Several nodes may have gone - restart loop. */
545 goto restart;
546 }
547 }
548 mutex_unlock(&node_lock);
549
550 return len;
551}
552
553/* read() implementation for reset file. Unused. */
554static ssize_t reset_read(struct file *file, char __user *addr, size_t len,
555 loff_t *pos)
556{
557 /* Allow read operation so that a recursive copy won't fail. */
558 return 0;
559}
560
561static const struct file_operations gcov_reset_fops = {
562 .write = reset_write,
563 .read = reset_read,
564 .llseek = noop_llseek,
565};
566
567/*
568 * Create a node for a given profiling data set and add it to all lists and
569 * debugfs. Needs to be called with node_lock held.
570 */
571static void add_node(struct gcov_info *info)
572{
573 char *filename;
574 char *curr;
575 char *next;
576 struct gcov_node *parent;
577 struct gcov_node *node;
578
579 filename = kstrdup(info->filename, GFP_KERNEL);
580 if (!filename)
581 return;
582 parent = &root_node;
583 /* Create directory nodes along the path. */
584 for (curr = filename; (next = strchr(curr, '/')); curr = next + 1) {
585 if (curr == next)
586 continue;
587 *next = 0;
588 if (strcmp(curr, ".") == 0)
589 continue;
590 if (strcmp(curr, "..") == 0) {
591 if (!parent->parent)
592 goto err_remove;
593 parent = parent->parent;
594 continue;
595 }
596 node = get_child_by_name(parent, curr);
597 if (!node) {
598 node = new_node(parent, NULL, curr);
599 if (!node)
600 goto err_remove;
601 }
602 parent = node;
603 }
604 /* Create file node. */
605 node = new_node(parent, info, curr);
606 if (!node)
607 goto err_remove;
608out:
609 kfree(filename);
610 return;
611
612err_remove:
613 remove_node(parent);
614 goto out;
615}
616
617/*
618 * Associate a profiling data set with an existing node. Needs to be called
619 * with node_lock held.
620 */
621static void add_info(struct gcov_node *node, struct gcov_info *info)
622{
623 struct gcov_info **loaded_info;
624 int num = node->num_loaded;
625
626 /*
627 * Prepare new array. This is done first to simplify cleanup in
628 * case the new data set is incompatible, the node only contains
629 * unloaded data sets and there's not enough memory for the array.
630 */
631 loaded_info = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
632 if (!loaded_info) {
633 pr_warning("could not add '%s' (out of memory)\n",
634 info->filename);
635 return;
636 }
637 memcpy(loaded_info, node->loaded_info,
638 num * sizeof(struct gcov_info *));
639 loaded_info[num] = info;
640 /* Check if the new data set is compatible. */
641 if (num == 0) {
642 /*
643 * A module was unloaded, modified and reloaded. The new
644 * data set replaces the copy of the last one.
645 */
646 if (!gcov_info_is_compatible(node->unloaded_info, info)) {
647 pr_warning("discarding saved data for %s "
648 "(incompatible version)\n", info->filename);
649 gcov_info_free(node->unloaded_info);
650 node->unloaded_info = NULL;
651 }
652 } else {
653 /*
654 * Two different versions of the same object file are loaded.
655 * The initial one takes precedence.
656 */
657 if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
658 pr_warning("could not add '%s' (incompatible "
659 "version)\n", info->filename);
660 kfree(loaded_info);
661 return;
662 }
663 }
664 /* Overwrite previous array. */
665 kfree(node->loaded_info);
666 node->loaded_info = loaded_info;
667 node->num_loaded = num + 1;
668}
669
670/*
671 * Return the index of a profiling data set associated with a node.
672 */
673static int get_info_index(struct gcov_node *node, struct gcov_info *info)
674{
675 int i;
676
677 for (i = 0; i < node->num_loaded; i++) {
678 if (node->loaded_info[i] == info)
679 return i;
680 }
681 return -ENOENT;
682}
683
684/*
685 * Save the data of a profiling data set which is being unloaded.
686 */
687static void save_info(struct gcov_node *node, struct gcov_info *info)
688{
689 if (node->unloaded_info)
690 gcov_info_add(node->unloaded_info, info);
691 else {
692 node->unloaded_info = gcov_info_dup(info);
693 if (!node->unloaded_info) {
694 pr_warning("could not save data for '%s' "
695 "(out of memory)\n", info->filename);
696 }
697 }
698}
699
700/*
701 * Disassociate a profiling data set from a node. Needs to be called with
702 * node_lock held.
703 */
704static void remove_info(struct gcov_node *node, struct gcov_info *info)
705{
706 int i;
707
708 i = get_info_index(node, info);
709 if (i < 0) {
710 pr_warning("could not remove '%s' (not found)\n",
711 info->filename);
712 return;
713 }
714 if (gcov_persist)
715 save_info(node, info);
716 /* Shrink array. */
717 node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
718 node->num_loaded--;
719 if (node->num_loaded > 0)
720 return;
721 /* Last loaded data set was removed. */
722 kfree(node->loaded_info);
723 node->loaded_info = NULL;
724 node->num_loaded = 0;
725 if (!node->unloaded_info)
726 remove_node(node);
727}
728
729/*
730 * Callback to create/remove profiling files when code compiled with
731 * -fprofile-arcs is loaded/unloaded.
732 */
733void gcov_event(enum gcov_action action, struct gcov_info *info)
734{
735 struct gcov_node *node;
736
737 mutex_lock(&node_lock);
738 node = get_node_by_name(info->filename);
739 switch (action) {
740 case GCOV_ADD:
741 if (node)
742 add_info(node, info);
743 else
744 add_node(info);
745 break;
746 case GCOV_REMOVE:
747 if (node)
748 remove_info(node, info);
749 else {
750 pr_warning("could not remove '%s' (not found)\n",
751 info->filename);
752 }
753 break;
754 }
755 mutex_unlock(&node_lock);
756}
757
758/* Create debugfs entries. */
759static __init int gcov_fs_init(void)
760{
761 int rc = -EIO;
762
763 init_node(&root_node, NULL, NULL, NULL);
764 /*
765 * /sys/kernel/debug/gcov will be parent for the reset control file
766 * and all profiling files.
767 */
768 root_node.dentry = debugfs_create_dir("gcov", NULL);
769 if (!root_node.dentry)
770 goto err_remove;
771 /*
772 * Create reset file which resets all profiling counts when written
773 * to.
774 */
775 reset_dentry = debugfs_create_file("reset", 0600, root_node.dentry,
776 NULL, &gcov_reset_fops);
777 if (!reset_dentry)
778 goto err_remove;
779 /* Replay previous events to get our fs hierarchy up-to-date. */
780 gcov_enable_events();
781 return 0;
782
783err_remove:
784 pr_err("init failed\n");
785 if (root_node.dentry)
786 debugfs_remove(root_node.dentry);
787
788 return rc;
789}
790device_initcall(gcov_fs_init);