summaryrefslogtreecommitdiffstats
path: root/kernel/gcov/clang.c
blob: c94b820a1b62c59e76a089393761aaf2445b09b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 Google, Inc.
 * modified from kernel/gcov/gcc_4_7.c
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 *
 * LLVM uses profiling data that's deliberately similar to GCC, but has a
 * very different way of exporting that data.  LLVM calls llvm_gcov_init() once
 * per module, and provides a couple of callbacks that we can use to ask for
 * more data.
 *
 * We care about the "writeout" callback, which in turn calls back into
 * compiler-rt/this module to dump all the gathered coverage data to disk:
 *
 *    llvm_gcda_start_file()
 *      llvm_gcda_emit_function()
 *      llvm_gcda_emit_arcs()
 *      llvm_gcda_emit_function()
 *      llvm_gcda_emit_arcs()
 *      [... repeats for each function ...]
 *    llvm_gcda_summary_info()
 *    llvm_gcda_end_file()
 *
 * This design is much more stateless and unstructured than gcc's, and is
 * intended to run at process exit.  This forces us to keep some local state
 * about which module we're dealing with at the moment.  On the other hand, it
 * also means we don't depend as much on how LLVM represents profiling data
 * internally.
 *
 * See LLVM's lib/Transforms/Instrumentation/GCOVProfiling.cpp for more
 * details on how this works, particularly GCOVProfiler::emitProfileArcs(),
 * GCOVProfiler::insertCounterWriteout(), and
 * GCOVProfiler::insertFlush().
 */

#define pr_fmt(fmt)	"gcov: " fmt

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/printk.h>
#include <linux/ratelimit.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include "gcov.h"

typedef void (*llvm_gcov_callback)(void);

struct gcov_info {
	struct list_head head;

	const char *filename;
	unsigned int version;
	u32 checksum;

	struct list_head functions;
};

struct gcov_fn_info {
	struct list_head head;

	u32 ident;
	u32 checksum;
	u8 use_extra_checksum;
	u32 cfg_checksum;

	u32 num_counters;
	u64 *counters;
	const char *function_name;
};

static struct gcov_info *current_info;

static LIST_HEAD(clang_gcov_list);

void llvm_gcov_init(llvm_gcov_callback writeout, llvm_gcov_callback flush)
{
	struct gcov_info *info = kzalloc(sizeof(*info), GFP_KERNEL);

	if (!info)
		return;

	INIT_LIST_HEAD(&info->head);
	INIT_LIST_HEAD(&info->functions);

	mutex_lock(&gcov_lock);

	list_add_tail(&info->head, &clang_gcov_list);
	current_info = info;
	writeout();
	current_info = NULL;
	if (gcov_events_enabled)
		gcov_event(GCOV_ADD, info);

	mutex_unlock(&gcov_lock);
}
EXPORT_SYMBOL(llvm_gcov_init);

void llvm_gcda_start_file(const char *orig_filename, const char version[4],
		u32 checksum)
{
	current_info->filename = orig_filename;
	memcpy(&current_info->version, version, sizeof(current_info->version));
	current_info->checksum = checksum;
}
EXPORT_SYMBOL(llvm_gcda_start_file);

void llvm_gcda_emit_function(u32 ident, const char *function_name,
		u32 func_checksum, u8 use_extra_checksum, u32 cfg_checksum)
{
	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);

	if (!info)
		return;

	INIT_LIST_HEAD(&info->head);
	info->ident = ident;
	info->checksum = func_checksum;
	info->use_extra_checksum = use_extra_checksum;
	info->cfg_checksum = cfg_checksum;
	if (function_name)
		info->function_name = kstrdup(function_name, GFP_KERNEL);

	list_add_tail(&info->head, &current_info->functions);
}
EXPORT_SYMBOL(llvm_gcda_emit_function);

void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
{
	struct gcov_fn_info *info = list_last_entry(&current_info->functions,
			struct gcov_fn_info, head);

	info->num_counters = num_counters;
	info->counters = counters;
}
EXPORT_SYMBOL(llvm_gcda_emit_arcs);

void llvm_gcda_summary_info(void)
{
}
EXPORT_SYMBOL(llvm_gcda_summary_info);

void llvm_gcda_end_file(void)
{
}
EXPORT_SYMBOL(llvm_gcda_end_file);

/**
 * gcov_info_filename - return info filename
 * @info: profiling data set
 */
const char *gcov_info_filename(struct gcov_info *info)
{
	return info->filename;
}

/**
 * gcov_info_version - return info version
 * @info: profiling data set
 */
unsigned int gcov_info_version(struct gcov_info *info)
{
	return info->version;
}

/**
 * gcov_info_next - return next profiling data set
 * @info: profiling data set
 *
 * Returns next gcov_info following @info or first gcov_info in the chain if
 * @info is %NULL.
 */
struct gcov_info *gcov_info_next(struct gcov_info *info)
{
	if (!info)
		return list_first_entry_or_null(&clang_gcov_list,
				struct gcov_info, head);
	if (list_is_last(&info->head, &clang_gcov_list))
		return NULL;
	return list_next_entry(info, head);
}

/**
 * gcov_info_link - link/add profiling data set to the list
 * @info: profiling data set
 */
void gcov_info_link(struct gcov_info *info)
{
	list_add_tail(&info->head, &clang_gcov_list);
}

/**
 * gcov_info_unlink - unlink/remove profiling data set from the list
 * @prev: previous profiling data set
 * @info: profiling data set
 */
void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
{
	/* Generic code unlinks while iterating. */
	__list_del_entry(&info->head);
}

/**
 * gcov_info_within_module - check if a profiling data set belongs to a module
 * @info: profiling data set
 * @mod: module
 *
 * Returns true if profiling data belongs module, false otherwise.
 */
bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
{
	return within_module((unsigned long)info->filename, mod);
}

/* Symbolic links to be created for each profiling data file. */
const struct gcov_link gcov_link[] = {
	{ OBJ_TREE, "gcno" },	/* Link to .gcno file in $(objtree). */
	{ 0, NULL},
};

/**
 * gcov_info_reset - reset profiling data to zero
 * @info: profiling data set
 */
void gcov_info_reset(struct gcov_info *info)
{
	struct gcov_fn_info *fn;

	list_for_each_entry(fn, &info->functions, head)
		memset(fn->counters, 0,
				sizeof(fn->counters[0]) * fn->num_counters);
}

/**
 * gcov_info_is_compatible - check if profiling data can be added
 * @info1: first profiling data set
 * @info2: second profiling data set
 *
 * Returns non-zero if profiling data can be added, zero otherwise.
 */
int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
{
	struct gcov_fn_info *fn_ptr1 = list_first_entry_or_null(
			&info1->functions, struct gcov_fn_info, head);
	struct gcov_fn_info *fn_ptr2 = list_first_entry_or_null(
			&info2->functions, struct gcov_fn_info, head);

	if (info1->checksum != info2->checksum)
		return false;
	if (!fn_ptr1)
		return fn_ptr1 == fn_ptr2;
	while (!list_is_last(&fn_ptr1->head, &info1->functions) &&
		!list_is_last(&fn_ptr2->head, &info2->functions)) {
		if (fn_ptr1->checksum != fn_ptr2->checksum)
			return false;
		if (fn_ptr1->use_extra_checksum != fn_ptr2->use_extra_checksum)
			return false;
		if (fn_ptr1->use_extra_checksum &&
			fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
			return false;
		fn_ptr1 = list_next_entry(fn_ptr1, head);
		fn_ptr2 = list_next_entry(fn_ptr2, head);
	}
	return list_is_last(&fn_ptr1->head, &info1->functions) &&
		list_is_last(&fn_ptr2->head, &info2->functions);
}

/**
 * gcov_info_add - add up profiling data
 * @dest: profiling data set to which data is added
 * @source: profiling data set which is added
 *
 * Adds profiling counts of @source to @dest.
 */
void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
{
	struct gcov_fn_info *dfn_ptr;
	struct gcov_fn_info *sfn_ptr = list_first_entry_or_null(&src->functions,
			struct gcov_fn_info, head);

	list_for_each_entry(dfn_ptr, &dst->functions, head) {
		u32 i;

		for (i = 0; i < sfn_ptr->num_counters; i++)
			dfn_ptr->counters[i] += sfn_ptr->counters[i];
	}
}

static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
{
	size_t cv_size; /* counter values size */
	struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),
			GFP_KERNEL);
	if (!fn_dup)
		return NULL;
	INIT_LIST_HEAD(&fn_dup->head);

	fn_dup->function_name = kstrdup(fn->function_name, GFP_KERNEL);
	if (!fn_dup->function_name)
		goto err_name;

	cv_size = fn->num_counters * sizeof(fn->counters[0]);
	fn_dup->counters = vmalloc(cv_size);
	if (!fn_dup->counters)
		goto err_counters;
	memcpy(fn_dup->counters, fn->counters, cv_size);

	return fn_dup;

err_counters:
	kfree(fn_dup->function_name);
err_name:
	kfree(fn_dup);
	return NULL;
}

/**
 * gcov_info_dup - duplicate profiling data set
 * @info: profiling data set to duplicate
 *
 * Return newly allocated duplicate on success, %NULL on error.
 */
struct gcov_info *gcov_info_dup(struct gcov_info *info)
{
	struct gcov_info *dup;
	struct gcov_fn_info *fn;

	dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
	if (!dup)
		return NULL;
	INIT_LIST_HEAD(&dup->head);
	INIT_LIST_HEAD(&dup->functions);
	dup->filename = kstrdup(info->filename, GFP_KERNEL);
	if (!dup->filename)
		goto err;

	list_for_each_entry(fn, &info->functions, head) {
		struct gcov_fn_info *fn_dup = gcov_fn_info_dup(fn);

		if (!fn_dup)
			goto err;
		list_add_tail(&fn_dup->head, &dup->functions);
	}

	return dup;

err:
	gcov_info_free(dup);
	return NULL;
}

/**
 * gcov_info_free - release memory for profiling data set duplicate
 * @info: profiling data set duplicate to free
 */
void gcov_info_free(struct gcov_info *info)
{
	struct gcov_fn_info *fn, *tmp;

	list_for_each_entry_safe(fn, tmp, &info->functions, head) {
		kfree(fn->function_name);
		vfree(fn->counters);
		list_del(&fn->head);
		kfree(fn);
	}
	kfree(info->filename);
	kfree(info);
}

#define ITER_STRIDE	PAGE_SIZE

/**
 * struct gcov_iterator - specifies current file position in logical records
 * @info: associated profiling data
 * @buffer: buffer containing file data
 * @size: size of buffer
 * @pos: current position in file
 */
struct gcov_iterator {
	struct gcov_info *info;
	void *buffer;
	size_t size;
	loff_t pos;
};

/**
 * store_gcov_u32 - store 32 bit number in gcov format to buffer
 * @buffer: target buffer or NULL
 * @off: offset into the buffer
 * @v: value to be stored
 *
 * Number format defined by gcc: numbers are recorded in the 32 bit
 * unsigned binary form of the endianness of the machine generating the
 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
 * store anything.
 */
static size_t store_gcov_u32(void *buffer, size_t off, u32 v)
{
	u32 *data;

	if (buffer) {
		data = buffer + off;
		*data = v;
	}

	return sizeof(*data);
}

/**
 * store_gcov_u64 - store 64 bit number in gcov format to buffer
 * @buffer: target buffer or NULL
 * @off: offset into the buffer
 * @v: value to be stored
 *
 * Number format defined by gcc: numbers are recorded in the 32 bit
 * unsigned binary form of the endianness of the machine generating the
 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
 * anything.
 */
static size_t store_gcov_u64(void *buffer, size_t off, u64 v)
{
	u32 *data;

	if (buffer) {
		data = buffer + off;

		data[0] = (v & 0xffffffffUL);
		data[1] = (v >> 32);
	}

	return sizeof(*data) * 2;
}

/**
 * convert_to_gcda - convert profiling data set to gcda file format
 * @buffer: the buffer to store file data or %NULL if no data should be stored
 * @info: profiling data set to be converted
 *
 * Returns the number of bytes that were/would have been stored into the buffer.
 */
static size_t convert_to_gcda(char *buffer, struct gcov_info *info)
{
	struct gcov_fn_info *fi_ptr;
	size_t pos = 0;

	/* File header. */
	pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
	pos += store_gcov_u32(buffer, pos, info->version);
	pos += store_gcov_u32(buffer, pos, info->checksum);

	list_for_each_entry(fi_ptr, &info->functions, head) {
		u32 i;
		u32 len = 2;

		if (fi_ptr->use_extra_checksum)
			len++;

		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
		pos += store_gcov_u32(buffer, pos, len);
		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
		pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
		if (fi_ptr->use_extra_checksum)
			pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);

		pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
		pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
		for (i = 0; i < fi_ptr->num_counters; i++)
			pos += store_gcov_u64(buffer, pos, fi_ptr->counters[i]);
	}

	return pos;
}

/**
 * gcov_iter_new - allocate and initialize profiling data iterator
 * @info: profiling data set to be iterated
 *
 * Return file iterator on success, %NULL otherwise.
 */
struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
{
	struct gcov_iterator *iter;

	iter = kzalloc(sizeof(struct gcov_iterator), GFP_KERNEL);
	if (!iter)
		goto err_free;

	iter->info = info;
	/* Dry-run to get the actual buffer size. */
	iter->size = convert_to_gcda(NULL, info);
	iter->buffer = vmalloc(iter->size);
	if (!iter->buffer)
		goto err_free;

	convert_to_gcda(iter->buffer, info);

	return iter;

err_free:
	kfree(iter);
	return NULL;
}


/**
 * gcov_iter_get_info - return profiling data set for given file iterator
 * @iter: file iterator
 */
void gcov_iter_free(struct gcov_iterator *iter)
{
	vfree(iter->buffer);
	kfree(iter);
}

/**
 * gcov_iter_get_info - return profiling data set for given file iterator
 * @iter: file iterator
 */
struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
{
	return iter->info;
}

/**
 * gcov_iter_start - reset file iterator to starting position
 * @iter: file iterator
 */
void gcov_iter_start(struct gcov_iterator *iter)
{
	iter->pos = 0;
}

/**
 * gcov_iter_next - advance file iterator to next logical record
 * @iter: file iterator
 *
 * Return zero if new position is valid, non-zero if iterator has reached end.
 */
int gcov_iter_next(struct gcov_iterator *iter)
{
	if (iter->pos < iter->size)
		iter->pos += ITER_STRIDE;

	if (iter->pos >= iter->size)
		return -EINVAL;

	return 0;
}

/**
 * gcov_iter_write - write data for current pos to seq_file
 * @iter: file iterator
 * @seq: seq_file handle
 *
 * Return zero on success, non-zero otherwise.
 */
int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq)
{
	size_t len;

	if (iter->pos >= iter->size)
		return -EINVAL;

	len = ITER_STRIDE;
	if (iter->pos + len > iter->size)
		len = iter->size - iter->pos;

	seq_write(seq, iter->buffer + iter->pos, len);

	return 0;
}