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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 <linux/mm.h>
30#include "gcov.h"
31
32/**
33 * struct gcov_node - represents a debugfs entry
34 * @list: list head for child node list
35 * @children: child nodes
36 * @all: list head for list of all nodes
37 * @parent: parent node
38 * @loaded_info: array of pointers to profiling data sets for loaded object
39 * files.
40 * @num_loaded: number of profiling data sets for loaded object files.
41 * @unloaded_info: accumulated copy of profiling data sets for unloaded
42 * object files. Used only when gcov_persist=1.
43 * @dentry: main debugfs entry, either a directory or data file
44 * @links: associated symbolic links
45 * @name: data file basename
46 *
47 * struct gcov_node represents an entity within the gcov/ subdirectory
48 * of debugfs. There are directory and data file nodes. The latter represent
49 * the actual synthesized data file plus any associated symbolic links which
50 * are needed by the gcov tool to work correctly.
51 */
52struct gcov_node {
53 struct list_head list;
54 struct list_head children;
55 struct list_head all;
56 struct gcov_node *parent;
57 struct gcov_info **loaded_info;
58 struct gcov_info *unloaded_info;
59 struct dentry *dentry;
60 struct dentry **links;
61 int num_loaded;
62 char name[];
63};
64
65static const char objtree[] = OBJTREE;
66static const char srctree[] = SRCTREE;
67static struct gcov_node root_node;
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#define ITER_STRIDE PAGE_SIZE
90
91/**
92 * struct gcov_iterator - specifies current file position in logical records
93 * @info: associated profiling data
94 * @buffer: buffer containing file data
95 * @size: size of buffer
96 * @pos: current position in file
97 */
98struct gcov_iterator {
99 struct gcov_info *info;
100 size_t size;
101 loff_t pos;
102 char buffer[] __counted_by(size);
103};
104
105/**
106 * gcov_iter_new - allocate and initialize profiling data iterator
107 * @info: profiling data set to be iterated
108 *
109 * Return file iterator on success, %NULL otherwise.
110 */
111static struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
112{
113 struct gcov_iterator *iter;
114 size_t size;
115
116 /* Dry-run to get the actual buffer size. */
117 size = convert_to_gcda(NULL, info);
118
119 iter = kvmalloc(struct_size(iter, buffer, size), GFP_KERNEL);
120 if (!iter)
121 return NULL;
122
123 iter->info = info;
124 iter->size = size;
125 convert_to_gcda(iter->buffer, info);
126
127 return iter;
128}
129
130
131/**
132 * gcov_iter_free - free iterator data
133 * @iter: file iterator
134 */
135static void gcov_iter_free(struct gcov_iterator *iter)
136{
137 kvfree(iter);
138}
139
140/**
141 * gcov_iter_get_info - return profiling data set for given file iterator
142 * @iter: file iterator
143 */
144static struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
145{
146 return iter->info;
147}
148
149/**
150 * gcov_iter_start - reset file iterator to starting position
151 * @iter: file iterator
152 */
153static void gcov_iter_start(struct gcov_iterator *iter)
154{
155 iter->pos = 0;
156}
157
158/**
159 * gcov_iter_next - advance file iterator to next logical record
160 * @iter: file iterator
161 *
162 * Return zero if new position is valid, non-zero if iterator has reached end.
163 */
164static int gcov_iter_next(struct gcov_iterator *iter)
165{
166 if (iter->pos < iter->size)
167 iter->pos += ITER_STRIDE;
168
169 if (iter->pos >= iter->size)
170 return -EINVAL;
171
172 return 0;
173}
174
175/**
176 * gcov_iter_write - write data for current pos to seq_file
177 * @iter: file iterator
178 * @seq: seq_file handle
179 *
180 * Return zero on success, non-zero otherwise.
181 */
182static int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq)
183{
184 size_t len;
185
186 if (iter->pos >= iter->size)
187 return -EINVAL;
188
189 len = ITER_STRIDE;
190 if (iter->pos + len > iter->size)
191 len = iter->size - iter->pos;
192
193 seq_write(seq, iter->buffer + iter->pos, len);
194
195 return 0;
196}
197
198/*
199 * seq_file.start() implementation for gcov data files. Note that the
200 * gcov_iterator interface is designed to be more restrictive than seq_file
201 * (no start from arbitrary position, etc.), to simplify the iterator
202 * implementation.
203 */
204static void *gcov_seq_start(struct seq_file *seq, loff_t *pos)
205{
206 loff_t i;
207
208 gcov_iter_start(seq->private);
209 for (i = 0; i < *pos; i++) {
210 if (gcov_iter_next(seq->private))
211 return NULL;
212 }
213 return seq->private;
214}
215
216/* seq_file.next() implementation for gcov data files. */
217static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
218{
219 struct gcov_iterator *iter = data;
220
221 (*pos)++;
222 if (gcov_iter_next(iter))
223 return NULL;
224
225 return iter;
226}
227
228/* seq_file.show() implementation for gcov data files. */
229static int gcov_seq_show(struct seq_file *seq, void *data)
230{
231 struct gcov_iterator *iter = data;
232
233 if (gcov_iter_write(iter, seq))
234 return -EINVAL;
235 return 0;
236}
237
238static void gcov_seq_stop(struct seq_file *seq, void *data)
239{
240 /* Unused. */
241}
242
243static const struct seq_operations gcov_seq_ops = {
244 .start = gcov_seq_start,
245 .next = gcov_seq_next,
246 .show = gcov_seq_show,
247 .stop = gcov_seq_stop,
248};
249
250/*
251 * Return a profiling data set associated with the given node. This is
252 * either a data set for a loaded object file or a data set copy in case
253 * all associated object files have been unloaded.
254 */
255static struct gcov_info *get_node_info(struct gcov_node *node)
256{
257 if (node->num_loaded > 0)
258 return node->loaded_info[0];
259
260 return node->unloaded_info;
261}
262
263/*
264 * Return a newly allocated profiling data set which contains the sum of
265 * all profiling data associated with the given node.
266 */
267static struct gcov_info *get_accumulated_info(struct gcov_node *node)
268{
269 struct gcov_info *info;
270 int i = 0;
271
272 if (node->unloaded_info)
273 info = gcov_info_dup(node->unloaded_info);
274 else
275 info = gcov_info_dup(node->loaded_info[i++]);
276 if (!info)
277 return NULL;
278 for (; i < node->num_loaded; i++)
279 gcov_info_add(info, node->loaded_info[i]);
280
281 return info;
282}
283
284/*
285 * open() implementation for gcov data files. Create a copy of the profiling
286 * data set and initialize the iterator and seq_file interface.
287 */
288static int gcov_seq_open(struct inode *inode, struct file *file)
289{
290 struct gcov_node *node = inode->i_private;
291 struct gcov_iterator *iter;
292 struct seq_file *seq;
293 struct gcov_info *info;
294 int rc = -ENOMEM;
295
296 mutex_lock(&node_lock);
297 /*
298 * Read from a profiling data copy to minimize reference tracking
299 * complexity and concurrent access and to keep accumulating multiple
300 * profiling data sets associated with one node simple.
301 */
302 info = get_accumulated_info(node);
303 if (!info)
304 goto out_unlock;
305 iter = gcov_iter_new(info);
306 if (!iter)
307 goto err_free_info;
308 rc = seq_open(file, &gcov_seq_ops);
309 if (rc)
310 goto err_free_iter_info;
311 seq = file->private_data;
312 seq->private = iter;
313out_unlock:
314 mutex_unlock(&node_lock);
315 return rc;
316
317err_free_iter_info:
318 gcov_iter_free(iter);
319err_free_info:
320 gcov_info_free(info);
321 goto out_unlock;
322}
323
324/*
325 * release() implementation for gcov data files. Release resources allocated
326 * by open().
327 */
328static int gcov_seq_release(struct inode *inode, struct file *file)
329{
330 struct gcov_iterator *iter;
331 struct gcov_info *info;
332 struct seq_file *seq;
333
334 seq = file->private_data;
335 iter = seq->private;
336 info = gcov_iter_get_info(iter);
337 gcov_iter_free(iter);
338 gcov_info_free(info);
339 seq_release(inode, file);
340
341 return 0;
342}
343
344/*
345 * Find a node by the associated data file name. Needs to be called with
346 * node_lock held.
347 */
348static struct gcov_node *get_node_by_name(const char *name)
349{
350 struct gcov_node *node;
351 struct gcov_info *info;
352
353 list_for_each_entry(node, &all_head, all) {
354 info = get_node_info(node);
355 if (info && (strcmp(gcov_info_filename(info), name) == 0))
356 return node;
357 }
358
359 return NULL;
360}
361
362/*
363 * Reset all profiling data associated with the specified node.
364 */
365static void reset_node(struct gcov_node *node)
366{
367 int i;
368
369 if (node->unloaded_info)
370 gcov_info_reset(node->unloaded_info);
371 for (i = 0; i < node->num_loaded; i++)
372 gcov_info_reset(node->loaded_info[i]);
373}
374
375static void remove_node(struct gcov_node *node);
376
377/*
378 * write() implementation for gcov data files. Reset profiling data for the
379 * corresponding file. If all associated object files have been unloaded,
380 * remove the debug fs node as well.
381 */
382static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
383 size_t len, loff_t *pos)
384{
385 struct seq_file *seq;
386 struct gcov_info *info;
387 struct gcov_node *node;
388
389 seq = file->private_data;
390 info = gcov_iter_get_info(seq->private);
391 mutex_lock(&node_lock);
392 node = get_node_by_name(gcov_info_filename(info));
393 if (node) {
394 /* Reset counts or remove node for unloaded modules. */
395 if (node->num_loaded == 0)
396 remove_node(node);
397 else
398 reset_node(node);
399 }
400 /* Reset counts for open file. */
401 gcov_info_reset(info);
402 mutex_unlock(&node_lock);
403
404 return len;
405}
406
407/*
408 * Given a string <path> representing a file path of format:
409 * path/to/file.gcda
410 * construct and return a new string:
411 * <dir/>path/to/file.<ext>
412 */
413static char *link_target(const char *dir, const char *path, const char *ext)
414{
415 char *target;
416 char *old_ext;
417 char *copy;
418
419 copy = kstrdup(path, GFP_KERNEL);
420 if (!copy)
421 return NULL;
422 old_ext = strrchr(copy, '.');
423 if (old_ext)
424 *old_ext = '\0';
425 if (dir)
426 target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
427 else
428 target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
429 kfree(copy);
430
431 return target;
432}
433
434/*
435 * Construct a string representing the symbolic link target for the given
436 * gcov data file name and link type. Depending on the link type and the
437 * location of the data file, the link target can either point to a
438 * subdirectory of srctree, objtree or in an external location.
439 */
440static char *get_link_target(const char *filename, const struct gcov_link *ext)
441{
442 const char *rel;
443 char *result;
444
445 if (strncmp(filename, objtree, strlen(objtree)) == 0) {
446 rel = filename + strlen(objtree) + 1;
447 if (ext->dir == SRC_TREE)
448 result = link_target(srctree, rel, ext->ext);
449 else
450 result = link_target(objtree, rel, ext->ext);
451 } else {
452 /* External compilation. */
453 result = link_target(NULL, filename, ext->ext);
454 }
455
456 return result;
457}
458
459#define SKEW_PREFIX ".tmp_"
460
461/*
462 * For a filename .tmp_filename.ext return filename.ext. Needed to compensate
463 * for filename skewing caused by the mod-versioning mechanism.
464 */
465static const char *deskew(const char *basename)
466{
467 if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
468 return basename + sizeof(SKEW_PREFIX) - 1;
469 return basename;
470}
471
472/*
473 * Create links to additional files (usually .c and .gcno files) which the
474 * gcov tool expects to find in the same directory as the gcov data file.
475 */
476static void add_links(struct gcov_node *node, struct dentry *parent)
477{
478 const char *basename;
479 char *target;
480 int num;
481 int i;
482
483 for (num = 0; gcov_link[num].ext; num++)
484 /* Nothing. */;
485 node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
486 if (!node->links)
487 return;
488 for (i = 0; i < num; i++) {
489 target = get_link_target(
490 gcov_info_filename(get_node_info(node)),
491 &gcov_link[i]);
492 if (!target)
493 goto out_err;
494 basename = kbasename(target);
495 if (basename == target)
496 goto out_err;
497 node->links[i] = debugfs_create_symlink(deskew(basename),
498 parent, target);
499 kfree(target);
500 }
501
502 return;
503out_err:
504 kfree(target);
505 while (i-- > 0)
506 debugfs_remove(node->links[i]);
507 kfree(node->links);
508 node->links = NULL;
509}
510
511static const struct file_operations gcov_data_fops = {
512 .open = gcov_seq_open,
513 .release = gcov_seq_release,
514 .read = seq_read,
515 .llseek = seq_lseek,
516 .write = gcov_seq_write,
517};
518
519/* Basic initialization of a new node. */
520static void init_node(struct gcov_node *node, struct gcov_info *info,
521 const char *name, struct gcov_node *parent)
522{
523 INIT_LIST_HEAD(&node->list);
524 INIT_LIST_HEAD(&node->children);
525 INIT_LIST_HEAD(&node->all);
526 if (node->loaded_info) {
527 node->loaded_info[0] = info;
528 node->num_loaded = 1;
529 }
530 node->parent = parent;
531 if (name)
532 strcpy(node->name, name);
533}
534
535/*
536 * Create a new node and associated debugfs entry. Needs to be called with
537 * node_lock held.
538 */
539static struct gcov_node *new_node(struct gcov_node *parent,
540 struct gcov_info *info, const char *name)
541{
542 struct gcov_node *node;
543
544 node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
545 if (!node)
546 goto err_nomem;
547 if (info) {
548 node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
549 GFP_KERNEL);
550 if (!node->loaded_info)
551 goto err_nomem;
552 }
553 init_node(node, info, name, parent);
554 /* Differentiate between gcov data file nodes and directory nodes. */
555 if (info) {
556 node->dentry = debugfs_create_file(deskew(node->name), 0600,
557 parent->dentry, node, &gcov_data_fops);
558 } else
559 node->dentry = debugfs_create_dir(node->name, parent->dentry);
560 if (info)
561 add_links(node, parent->dentry);
562 list_add(&node->list, &parent->children);
563 list_add(&node->all, &all_head);
564
565 return node;
566
567err_nomem:
568 kfree(node);
569 pr_warn("out of memory\n");
570 return NULL;
571}
572
573/* Remove symbolic links associated with node. */
574static void remove_links(struct gcov_node *node)
575{
576 int i;
577
578 if (!node->links)
579 return;
580 for (i = 0; gcov_link[i].ext; i++)
581 debugfs_remove(node->links[i]);
582 kfree(node->links);
583 node->links = NULL;
584}
585
586/*
587 * Remove node from all lists and debugfs and release associated resources.
588 * Needs to be called with node_lock held.
589 */
590static void release_node(struct gcov_node *node)
591{
592 list_del(&node->list);
593 list_del(&node->all);
594 debugfs_remove(node->dentry);
595 remove_links(node);
596 kfree(node->loaded_info);
597 if (node->unloaded_info)
598 gcov_info_free(node->unloaded_info);
599 kfree(node);
600}
601
602/* Release node and empty parents. Needs to be called with node_lock held. */
603static void remove_node(struct gcov_node *node)
604{
605 struct gcov_node *parent;
606
607 while ((node != &root_node) && list_empty(&node->children)) {
608 parent = node->parent;
609 release_node(node);
610 node = parent;
611 }
612}
613
614/*
615 * Find child node with given basename. Needs to be called with node_lock
616 * held.
617 */
618static struct gcov_node *get_child_by_name(struct gcov_node *parent,
619 const char *name)
620{
621 struct gcov_node *node;
622
623 list_for_each_entry(node, &parent->children, list) {
624 if (strcmp(node->name, name) == 0)
625 return node;
626 }
627
628 return NULL;
629}
630
631/*
632 * write() implementation for reset file. Reset all profiling data to zero
633 * and remove nodes for which all associated object files are unloaded.
634 */
635static ssize_t reset_write(struct file *file, const char __user *addr,
636 size_t len, loff_t *pos)
637{
638 struct gcov_node *node;
639
640 mutex_lock(&node_lock);
641restart:
642 list_for_each_entry(node, &all_head, all) {
643 if (node->num_loaded > 0)
644 reset_node(node);
645 else if (list_empty(&node->children)) {
646 remove_node(node);
647 /* Several nodes may have gone - restart loop. */
648 goto restart;
649 }
650 }
651 mutex_unlock(&node_lock);
652
653 return len;
654}
655
656/* read() implementation for reset file. Unused. */
657static ssize_t reset_read(struct file *file, char __user *addr, size_t len,
658 loff_t *pos)
659{
660 /* Allow read operation so that a recursive copy won't fail. */
661 return 0;
662}
663
664static const struct file_operations gcov_reset_fops = {
665 .write = reset_write,
666 .read = reset_read,
667 .llseek = noop_llseek,
668};
669
670/*
671 * Create a node for a given profiling data set and add it to all lists and
672 * debugfs. Needs to be called with node_lock held.
673 */
674static void add_node(struct gcov_info *info)
675{
676 char *filename;
677 char *curr;
678 char *next;
679 struct gcov_node *parent;
680 struct gcov_node *node;
681
682 filename = kstrdup(gcov_info_filename(info), GFP_KERNEL);
683 if (!filename)
684 return;
685 parent = &root_node;
686 /* Create directory nodes along the path. */
687 for (curr = filename; (next = strchr(curr, '/')); curr = next + 1) {
688 if (curr == next)
689 continue;
690 *next = 0;
691 if (strcmp(curr, ".") == 0)
692 continue;
693 if (strcmp(curr, "..") == 0) {
694 if (!parent->parent)
695 goto err_remove;
696 parent = parent->parent;
697 continue;
698 }
699 node = get_child_by_name(parent, curr);
700 if (!node) {
701 node = new_node(parent, NULL, curr);
702 if (!node)
703 goto err_remove;
704 }
705 parent = node;
706 }
707 /* Create file node. */
708 node = new_node(parent, info, curr);
709 if (!node)
710 goto err_remove;
711out:
712 kfree(filename);
713 return;
714
715err_remove:
716 remove_node(parent);
717 goto out;
718}
719
720/*
721 * Associate a profiling data set with an existing node. Needs to be called
722 * with node_lock held.
723 */
724static void add_info(struct gcov_node *node, struct gcov_info *info)
725{
726 struct gcov_info **loaded_info;
727 int num = node->num_loaded;
728
729 /*
730 * Prepare new array. This is done first to simplify cleanup in
731 * case the new data set is incompatible, the node only contains
732 * unloaded data sets and there's not enough memory for the array.
733 */
734 loaded_info = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
735 if (!loaded_info) {
736 pr_warn("could not add '%s' (out of memory)\n",
737 gcov_info_filename(info));
738 return;
739 }
740 memcpy(loaded_info, node->loaded_info,
741 num * sizeof(struct gcov_info *));
742 loaded_info[num] = info;
743 /* Check if the new data set is compatible. */
744 if (num == 0) {
745 /*
746 * A module was unloaded, modified and reloaded. The new
747 * data set replaces the copy of the last one.
748 */
749 if (!gcov_info_is_compatible(node->unloaded_info, info)) {
750 pr_warn("discarding saved data for %s "
751 "(incompatible version)\n",
752 gcov_info_filename(info));
753 gcov_info_free(node->unloaded_info);
754 node->unloaded_info = NULL;
755 }
756 } else {
757 /*
758 * Two different versions of the same object file are loaded.
759 * The initial one takes precedence.
760 */
761 if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
762 pr_warn("could not add '%s' (incompatible "
763 "version)\n", gcov_info_filename(info));
764 kfree(loaded_info);
765 return;
766 }
767 }
768 /* Overwrite previous array. */
769 kfree(node->loaded_info);
770 node->loaded_info = loaded_info;
771 node->num_loaded = num + 1;
772}
773
774/*
775 * Return the index of a profiling data set associated with a node.
776 */
777static int get_info_index(struct gcov_node *node, struct gcov_info *info)
778{
779 int i;
780
781 for (i = 0; i < node->num_loaded; i++) {
782 if (node->loaded_info[i] == info)
783 return i;
784 }
785 return -ENOENT;
786}
787
788/*
789 * Save the data of a profiling data set which is being unloaded.
790 */
791static void save_info(struct gcov_node *node, struct gcov_info *info)
792{
793 if (node->unloaded_info)
794 gcov_info_add(node->unloaded_info, info);
795 else {
796 node->unloaded_info = gcov_info_dup(info);
797 if (!node->unloaded_info) {
798 pr_warn("could not save data for '%s' "
799 "(out of memory)\n",
800 gcov_info_filename(info));
801 }
802 }
803}
804
805/*
806 * Disassociate a profiling data set from a node. Needs to be called with
807 * node_lock held.
808 */
809static void remove_info(struct gcov_node *node, struct gcov_info *info)
810{
811 int i;
812
813 i = get_info_index(node, info);
814 if (i < 0) {
815 pr_warn("could not remove '%s' (not found)\n",
816 gcov_info_filename(info));
817 return;
818 }
819 if (gcov_persist)
820 save_info(node, info);
821 /* Shrink array. */
822 node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
823 node->num_loaded--;
824 if (node->num_loaded > 0)
825 return;
826 /* Last loaded data set was removed. */
827 kfree(node->loaded_info);
828 node->loaded_info = NULL;
829 node->num_loaded = 0;
830 if (!node->unloaded_info)
831 remove_node(node);
832}
833
834/*
835 * Callback to create/remove profiling files when code compiled with
836 * -fprofile-arcs is loaded/unloaded.
837 */
838void gcov_event(enum gcov_action action, struct gcov_info *info)
839{
840 struct gcov_node *node;
841
842 mutex_lock(&node_lock);
843 node = get_node_by_name(gcov_info_filename(info));
844 switch (action) {
845 case GCOV_ADD:
846 if (node)
847 add_info(node, info);
848 else
849 add_node(info);
850 break;
851 case GCOV_REMOVE:
852 if (node)
853 remove_info(node, info);
854 else {
855 pr_warn("could not remove '%s' (not found)\n",
856 gcov_info_filename(info));
857 }
858 break;
859 }
860 mutex_unlock(&node_lock);
861}
862
863/* Create debugfs entries. */
864static __init int gcov_fs_init(void)
865{
866 init_node(&root_node, NULL, NULL, NULL);
867 /*
868 * /sys/kernel/debug/gcov will be parent for the reset control file
869 * and all profiling files.
870 */
871 root_node.dentry = debugfs_create_dir("gcov", NULL);
872 /*
873 * Create reset file which resets all profiling counts when written
874 * to.
875 */
876 debugfs_create_file("reset", 0600, root_node.dentry, NULL,
877 &gcov_reset_fops);
878 /* Replay previous events to get our fs hierarchy up-to-date. */
879 gcov_enable_events();
880 return 0;
881}
882device_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);