1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  This code provides functions to handle gcc's profiling data format
  4 *  introduced with gcc 4.7.
  5 *
  6 *  This file is based heavily on gcc_3_4.c file.
  7 *
  8 *  For a better understanding, refer to gcc source:
  9 *  gcc/gcov-io.h
 10 *  libgcc/libgcov.c
 11 *
 12 *  Uses gcc-internal data definitions.
 13 */
 14
 15#include <linux/errno.h>
 16#include <linux/slab.h>
 17#include <linux/string.h>
 18#include <linux/seq_file.h>
 19#include <linux/vmalloc.h>
 20#include "gcov.h"
 21
 22#if (__GNUC__ >= 10)
 23#define GCOV_COUNTERS			8
 24#elif (__GNUC__ >= 7)
 25#define GCOV_COUNTERS			9
 26#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)
 27#define GCOV_COUNTERS			10
 28#elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9
 29#define GCOV_COUNTERS			9
 30#else
 31#define GCOV_COUNTERS			8
 32#endif
 33
 34#define GCOV_TAG_FUNCTION_LENGTH	3
 35
 36static struct gcov_info *gcov_info_head;
 37
 38/**
 39 * struct gcov_ctr_info - information about counters for a single function
 40 * @num: number of counter values for this type
 41 * @values: array of counter values for this type
 42 *
 43 * This data is generated by gcc during compilation and doesn't change
 44 * at run-time with the exception of the values array.
 45 */
 46struct gcov_ctr_info {
 47	unsigned int num;
 48	gcov_type *values;
 49};
 50
 51/**
 52 * struct gcov_fn_info - profiling meta data per function
 53 * @key: comdat key
 54 * @ident: unique ident of function
 55 * @lineno_checksum: function lineo_checksum
 56 * @cfg_checksum: function cfg checksum
 57 * @ctrs: instrumented counters
 58 *
 59 * This data is generated by gcc during compilation and doesn't change
 60 * at run-time.
 61 *
 62 * Information about a single function.  This uses the trailing array
 63 * idiom. The number of counters is determined from the merge pointer
 64 * array in gcov_info.  The key is used to detect which of a set of
 65 * comdat functions was selected -- it points to the gcov_info object
 66 * of the object file containing the selected comdat function.
 67 */
 68struct gcov_fn_info {
 69	const struct gcov_info *key;
 70	unsigned int ident;
 71	unsigned int lineno_checksum;
 72	unsigned int cfg_checksum;
 73	struct gcov_ctr_info ctrs[];
 74};
 75
 76/**
 77 * struct gcov_info - profiling data per object file
 78 * @version: gcov version magic indicating the gcc version used for compilation
 79 * @next: list head for a singly-linked list
 80 * @stamp: uniquifying time stamp
 81 * @filename: name of the associated gcov data file
 82 * @merge: merge functions (null for unused counter type)
 83 * @n_functions: number of instrumented functions
 84 * @functions: pointer to pointers to function information
 85 *
 86 * This data is generated by gcc during compilation and doesn't change
 87 * at run-time with the exception of the next pointer.
 88 */
 89struct gcov_info {
 90	unsigned int version;
 91	struct gcov_info *next;
 92	unsigned int stamp;
 93	const char *filename;
 94	void (*merge[GCOV_COUNTERS])(gcov_type *, unsigned int);
 95	unsigned int n_functions;
 96	struct gcov_fn_info **functions;
 97};
 98
 99/**
100 * gcov_info_filename - return info filename
101 * @info: profiling data set
102 */
103const char *gcov_info_filename(struct gcov_info *info)
104{
105	return info->filename;
106}
107
108/**
109 * gcov_info_version - return info version
110 * @info: profiling data set
111 */
112unsigned int gcov_info_version(struct gcov_info *info)
113{
114	return info->version;
115}
116
117/**
118 * gcov_info_next - return next profiling data set
119 * @info: profiling data set
120 *
121 * Returns next gcov_info following @info or first gcov_info in the chain if
122 * @info is %NULL.
123 */
124struct gcov_info *gcov_info_next(struct gcov_info *info)
125{
126	if (!info)
127		return gcov_info_head;
128
129	return info->next;
130}
131
132/**
133 * gcov_info_link - link/add profiling data set to the list
134 * @info: profiling data set
135 */
136void gcov_info_link(struct gcov_info *info)
137{
138	info->next = gcov_info_head;
139	gcov_info_head = info;
140}
141
142/**
143 * gcov_info_unlink - unlink/remove profiling data set from the list
144 * @prev: previous profiling data set
145 * @info: profiling data set
146 */
147void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
148{
149	if (prev)
150		prev->next = info->next;
151	else
152		gcov_info_head = info->next;
153}
154
155/**
156 * gcov_info_within_module - check if a profiling data set belongs to a module
157 * @info: profiling data set
158 * @mod: module
159 *
160 * Returns true if profiling data belongs module, false otherwise.
161 */
162bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
163{
164	return within_module((unsigned long)info, mod);
165}
166
167/* Symbolic links to be created for each profiling data file. */
168const struct gcov_link gcov_link[] = {
169	{ OBJ_TREE, "gcno" },	/* Link to .gcno file in $(objtree). */
170	{ 0, NULL},
171};
172
173/*
174 * Determine whether a counter is active. Doesn't change at run-time.
175 */
176static int counter_active(struct gcov_info *info, unsigned int type)
177{
178	return info->merge[type] ? 1 : 0;
179}
180
181/* Determine number of active counters. Based on gcc magic. */
182static unsigned int num_counter_active(struct gcov_info *info)
183{
184	unsigned int i;
185	unsigned int result = 0;
186
187	for (i = 0; i < GCOV_COUNTERS; i++) {
188		if (counter_active(info, i))
189			result++;
190	}
191	return result;
192}
193
194/**
195 * gcov_info_reset - reset profiling data to zero
196 * @info: profiling data set
197 */
198void gcov_info_reset(struct gcov_info *info)
199{
200	struct gcov_ctr_info *ci_ptr;
201	unsigned int fi_idx;
202	unsigned int ct_idx;
203
204	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
205		ci_ptr = info->functions[fi_idx]->ctrs;
206
207		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
208			if (!counter_active(info, ct_idx))
209				continue;
210
211			memset(ci_ptr->values, 0,
212					sizeof(gcov_type) * ci_ptr->num);
213			ci_ptr++;
214		}
215	}
216}
217
218/**
219 * gcov_info_is_compatible - check if profiling data can be added
220 * @info1: first profiling data set
221 * @info2: second profiling data set
222 *
223 * Returns non-zero if profiling data can be added, zero otherwise.
224 */
225int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
226{
227	return (info1->stamp == info2->stamp);
228}
229
230/**
231 * gcov_info_add - add up profiling data
232 * @dest: profiling data set to which data is added
233 * @source: profiling data set which is added
234 *
235 * Adds profiling counts of @source to @dest.
236 */
237void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
238{
239	struct gcov_ctr_info *dci_ptr;
240	struct gcov_ctr_info *sci_ptr;
241	unsigned int fi_idx;
242	unsigned int ct_idx;
243	unsigned int val_idx;
244
245	for (fi_idx = 0; fi_idx < src->n_functions; fi_idx++) {
246		dci_ptr = dst->functions[fi_idx]->ctrs;
247		sci_ptr = src->functions[fi_idx]->ctrs;
248
249		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
250			if (!counter_active(src, ct_idx))
251				continue;
252
253			for (val_idx = 0; val_idx < sci_ptr->num; val_idx++)
254				dci_ptr->values[val_idx] +=
255					sci_ptr->values[val_idx];
256
257			dci_ptr++;
258			sci_ptr++;
259		}
260	}
261}
262
263/**
264 * gcov_info_dup - duplicate profiling data set
265 * @info: profiling data set to duplicate
266 *
267 * Return newly allocated duplicate on success, %NULL on error.
268 */
269struct gcov_info *gcov_info_dup(struct gcov_info *info)
270{
271	struct gcov_info *dup;
272	struct gcov_ctr_info *dci_ptr; /* dst counter info */
273	struct gcov_ctr_info *sci_ptr; /* src counter info */
274	unsigned int active;
275	unsigned int fi_idx; /* function info idx */
276	unsigned int ct_idx; /* counter type idx */
277	size_t fi_size; /* function info size */
278	size_t cv_size; /* counter values size */
279
280	dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
281	if (!dup)
282		return NULL;
283
284	dup->next = NULL;
285	dup->filename = NULL;
286	dup->functions = NULL;
287
288	dup->filename = kstrdup(info->filename, GFP_KERNEL);
289	if (!dup->filename)
290		goto err_free;
291
292	dup->functions = kcalloc(info->n_functions,
293				 sizeof(struct gcov_fn_info *), GFP_KERNEL);
294	if (!dup->functions)
295		goto err_free;
296
297	active = num_counter_active(info);
298	fi_size = sizeof(struct gcov_fn_info);
299	fi_size += sizeof(struct gcov_ctr_info) * active;
300
301	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
302		dup->functions[fi_idx] = kzalloc(fi_size, GFP_KERNEL);
303		if (!dup->functions[fi_idx])
304			goto err_free;
305
306		*(dup->functions[fi_idx]) = *(info->functions[fi_idx]);
307
308		sci_ptr = info->functions[fi_idx]->ctrs;
309		dci_ptr = dup->functions[fi_idx]->ctrs;
310
311		for (ct_idx = 0; ct_idx < active; ct_idx++) {
312
313			cv_size = sizeof(gcov_type) * sci_ptr->num;
314
315			dci_ptr->values = vmalloc(cv_size);
316
317			if (!dci_ptr->values)
318				goto err_free;
319
320			dci_ptr->num = sci_ptr->num;
321			memcpy(dci_ptr->values, sci_ptr->values, cv_size);
322
323			sci_ptr++;
324			dci_ptr++;
325		}
326	}
327
328	return dup;
329err_free:
330	gcov_info_free(dup);
331	return NULL;
332}
333
334/**
335 * gcov_info_free - release memory for profiling data set duplicate
336 * @info: profiling data set duplicate to free
337 */
338void gcov_info_free(struct gcov_info *info)
339{
340	unsigned int active;
341	unsigned int fi_idx;
342	unsigned int ct_idx;
343	struct gcov_ctr_info *ci_ptr;
344
345	if (!info->functions)
346		goto free_info;
347
348	active = num_counter_active(info);
349
350	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
351		if (!info->functions[fi_idx])
352			continue;
353
354		ci_ptr = info->functions[fi_idx]->ctrs;
355
356		for (ct_idx = 0; ct_idx < active; ct_idx++, ci_ptr++)
357			vfree(ci_ptr->values);
358
359		kfree(info->functions[fi_idx]);
360	}
361
362free_info:
363	kfree(info->functions);
364	kfree(info->filename);
365	kfree(info);
366}
367
368#define ITER_STRIDE	PAGE_SIZE
369
370/**
371 * struct gcov_iterator - specifies current file position in logical records
372 * @info: associated profiling data
373 * @buffer: buffer containing file data
374 * @size: size of buffer
375 * @pos: current position in file
376 */
377struct gcov_iterator {
378	struct gcov_info *info;
379	void *buffer;
380	size_t size;
381	loff_t pos;
382};
383
384/**
385 * store_gcov_u32 - store 32 bit number in gcov format to buffer
386 * @buffer: target buffer or NULL
387 * @off: offset into the buffer
388 * @v: value to be stored
389 *
390 * Number format defined by gcc: numbers are recorded in the 32 bit
391 * unsigned binary form of the endianness of the machine generating the
392 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
393 * store anything.
394 */
395static size_t store_gcov_u32(void *buffer, size_t off, u32 v)
396{
397	u32 *data;
398
399	if (buffer) {
400		data = buffer + off;
401		*data = v;
402	}
403
404	return sizeof(*data);
405}
406
407/**
408 * store_gcov_u64 - store 64 bit number in gcov format to buffer
409 * @buffer: target buffer or NULL
410 * @off: offset into the buffer
411 * @v: value to be stored
412 *
413 * Number format defined by gcc: numbers are recorded in the 32 bit
414 * unsigned binary form of the endianness of the machine generating the
415 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
416 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
417 * anything.
418 */
419static size_t store_gcov_u64(void *buffer, size_t off, u64 v)
420{
421	u32 *data;
422
423	if (buffer) {
424		data = buffer + off;
425
426		data[0] = (v & 0xffffffffUL);
427		data[1] = (v >> 32);
428	}
429
430	return sizeof(*data) * 2;
431}
432
433/**
434 * convert_to_gcda - convert profiling data set to gcda file format
435 * @buffer: the buffer to store file data or %NULL if no data should be stored
436 * @info: profiling data set to be converted
437 *
438 * Returns the number of bytes that were/would have been stored into the buffer.
439 */
440static size_t convert_to_gcda(char *buffer, struct gcov_info *info)
441{
442	struct gcov_fn_info *fi_ptr;
443	struct gcov_ctr_info *ci_ptr;
444	unsigned int fi_idx;
445	unsigned int ct_idx;
446	unsigned int cv_idx;
447	size_t pos = 0;
448
449	/* File header. */
450	pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
451	pos += store_gcov_u32(buffer, pos, info->version);
452	pos += store_gcov_u32(buffer, pos, info->stamp);
453
454	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
455		fi_ptr = info->functions[fi_idx];
456
457		/* Function record. */
458		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
459		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION_LENGTH);
460		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
461		pos += store_gcov_u32(buffer, pos, fi_ptr->lineno_checksum);
462		pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
463
464		ci_ptr = fi_ptr->ctrs;
465
466		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
467			if (!counter_active(info, ct_idx))
468				continue;
469
470			/* Counter record. */
471			pos += store_gcov_u32(buffer, pos,
472					      GCOV_TAG_FOR_COUNTER(ct_idx));
473			pos += store_gcov_u32(buffer, pos, ci_ptr->num * 2);
474
475			for (cv_idx = 0; cv_idx < ci_ptr->num; cv_idx++) {
476				pos += store_gcov_u64(buffer, pos,
477						      ci_ptr->values[cv_idx]);
478			}
479
480			ci_ptr++;
481		}
482	}
483
484	return pos;
485}
486
487/**
488 * gcov_iter_new - allocate and initialize profiling data iterator
489 * @info: profiling data set to be iterated
490 *
491 * Return file iterator on success, %NULL otherwise.
492 */
493struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
494{
495	struct gcov_iterator *iter;
496
497	iter = kzalloc(sizeof(struct gcov_iterator), GFP_KERNEL);
498	if (!iter)
499		goto err_free;
500
501	iter->info = info;
502	/* Dry-run to get the actual buffer size. */
503	iter->size = convert_to_gcda(NULL, info);
504	iter->buffer = vmalloc(iter->size);
505	if (!iter->buffer)
506		goto err_free;
507
508	convert_to_gcda(iter->buffer, info);
509
510	return iter;
511
512err_free:
513	kfree(iter);
514	return NULL;
515}
516
517
518/**
519 * gcov_iter_get_info - return profiling data set for given file iterator
520 * @iter: file iterator
521 */
522void gcov_iter_free(struct gcov_iterator *iter)
523{
524	vfree(iter->buffer);
525	kfree(iter);
526}
527
528/**
529 * gcov_iter_get_info - return profiling data set for given file iterator
530 * @iter: file iterator
531 */
532struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
533{
534	return iter->info;
535}
536
537/**
538 * gcov_iter_start - reset file iterator to starting position
539 * @iter: file iterator
540 */
541void gcov_iter_start(struct gcov_iterator *iter)
542{
543	iter->pos = 0;
544}
545
546/**
547 * gcov_iter_next - advance file iterator to next logical record
548 * @iter: file iterator
549 *
550 * Return zero if new position is valid, non-zero if iterator has reached end.
551 */
552int gcov_iter_next(struct gcov_iterator *iter)
553{
554	if (iter->pos < iter->size)
555		iter->pos += ITER_STRIDE;
556
557	if (iter->pos >= iter->size)
558		return -EINVAL;
559
560	return 0;
561}
562
563/**
564 * gcov_iter_write - write data for current pos to seq_file
565 * @iter: file iterator
566 * @seq: seq_file handle
567 *
568 * Return zero on success, non-zero otherwise.
569 */
570int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq)
571{
572	size_t len;
573
574	if (iter->pos >= iter->size)
575		return -EINVAL;
576
577	len = ITER_STRIDE;
578	if (iter->pos + len > iter->size)
579		len = iter->size - iter->pos;
580
581	seq_write(seq, iter->buffer + iter->pos, len);
582
583	return 0;
584}