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/mm.h>
19#include "gcov.h"
20
21#if (__GNUC__ >= 10)
22#define GCOV_COUNTERS			8
23#elif (__GNUC__ >= 7)
24#define GCOV_COUNTERS			9
25#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)
26#define GCOV_COUNTERS			10
27#else
28#define GCOV_COUNTERS			9
29#endif
30
31#define GCOV_TAG_FUNCTION_LENGTH	3
32
33/* Since GCC 12.1 sizes are in BYTES and not in WORDS (4B). */
34#if (__GNUC__ >= 12)
35#define GCOV_UNIT_SIZE				4
36#else
37#define GCOV_UNIT_SIZE				1
38#endif
39
40static struct gcov_info *gcov_info_head;
41
42/**
43 * struct gcov_ctr_info - information about counters for a single function
44 * @num: number of counter values for this type
45 * @values: array of counter values for this type
46 *
47 * This data is generated by gcc during compilation and doesn't change
48 * at run-time with the exception of the values array.
49 */
50struct gcov_ctr_info {
51	unsigned int num;
52	gcov_type *values;
53};
54
55/**
56 * struct gcov_fn_info - profiling meta data per function
57 * @key: comdat key
58 * @ident: unique ident of function
59 * @lineno_checksum: function lineo_checksum
60 * @cfg_checksum: function cfg checksum
61 * @ctrs: instrumented counters
62 *
63 * This data is generated by gcc during compilation and doesn't change
64 * at run-time.
65 *
66 * Information about a single function.  This uses the trailing array
67 * idiom. The number of counters is determined from the merge pointer
68 * array in gcov_info.  The key is used to detect which of a set of
69 * comdat functions was selected -- it points to the gcov_info object
70 * of the object file containing the selected comdat function.
71 */
72struct gcov_fn_info {
73	const struct gcov_info *key;
74	unsigned int ident;
75	unsigned int lineno_checksum;
76	unsigned int cfg_checksum;
77	struct gcov_ctr_info ctrs[];
78};
79
80/**
81 * struct gcov_info - profiling data per object file
82 * @version: gcov version magic indicating the gcc version used for compilation
83 * @next: list head for a singly-linked list
84 * @stamp: uniquifying time stamp
85 * @checksum: unique object checksum
86 * @filename: name of the associated gcov data file
87 * @merge: merge functions (null for unused counter type)
88 * @n_functions: number of instrumented functions
89 * @functions: pointer to pointers to function information
90 *
91 * This data is generated by gcc during compilation and doesn't change
92 * at run-time with the exception of the next pointer.
93 */
94struct gcov_info {
95	unsigned int version;
96	struct gcov_info *next;
97	unsigned int stamp;
98 /* Since GCC 12.1 a checksum field is added. */
99#if (__GNUC__ >= 12)
100	unsigned int checksum;
101#endif
102	const char *filename;
103	void (*merge[GCOV_COUNTERS])(gcov_type *, unsigned int);
104	unsigned int n_functions;
105	struct gcov_fn_info **functions;
106};
107
108/**
109 * gcov_info_filename - return info filename
110 * @info: profiling data set
111 */
112const char *gcov_info_filename(struct gcov_info *info)
113{
114	return info->filename;
115}
116
117/**
118 * gcov_info_version - return info version
119 * @info: profiling data set
120 */
121unsigned int gcov_info_version(struct gcov_info *info)
122{
123	return info->version;
124}
125
126/**
127 * gcov_info_next - return next profiling data set
128 * @info: profiling data set
129 *
130 * Returns next gcov_info following @info or first gcov_info in the chain if
131 * @info is %NULL.
132 */
133struct gcov_info *gcov_info_next(struct gcov_info *info)
134{
135	if (!info)
136		return gcov_info_head;
137
138	return info->next;
139}
140
141/**
142 * gcov_info_link - link/add profiling data set to the list
143 * @info: profiling data set
144 */
145void gcov_info_link(struct gcov_info *info)
146{
147	info->next = gcov_info_head;
148	gcov_info_head = info;
149}
150
151/**
152 * gcov_info_unlink - unlink/remove profiling data set from the list
153 * @prev: previous profiling data set
154 * @info: profiling data set
155 */
156void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
157{
158	if (prev)
159		prev->next = info->next;
160	else
161		gcov_info_head = info->next;
162}
163
164/**
165 * gcov_info_within_module - check if a profiling data set belongs to a module
166 * @info: profiling data set
167 * @mod: module
168 *
169 * Returns true if profiling data belongs module, false otherwise.
170 */
171bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
172{
173	return within_module((unsigned long)info, mod);
174}
175
176/* Symbolic links to be created for each profiling data file. */
177const struct gcov_link gcov_link[] = {
178	{ OBJ_TREE, "gcno" },	/* Link to .gcno file in $(objtree). */
179	{ 0, NULL},
180};
181
182/*
183 * Determine whether a counter is active. Doesn't change at run-time.
184 */
185static int counter_active(struct gcov_info *info, unsigned int type)
186{
187	return info->merge[type] ? 1 : 0;
188}
189
190/* Determine number of active counters. Based on gcc magic. */
191static unsigned int num_counter_active(struct gcov_info *info)
192{
193	unsigned int i;
194	unsigned int result = 0;
195
196	for (i = 0; i < GCOV_COUNTERS; i++) {
197		if (counter_active(info, i))
198			result++;
199	}
200	return result;
201}
202
203/**
204 * gcov_info_reset - reset profiling data to zero
205 * @info: profiling data set
206 */
207void gcov_info_reset(struct gcov_info *info)
208{
209	struct gcov_ctr_info *ci_ptr;
210	unsigned int fi_idx;
211	unsigned int ct_idx;
212
213	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
214		ci_ptr = info->functions[fi_idx]->ctrs;
215
216		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
217			if (!counter_active(info, ct_idx))
218				continue;
219
220			memset(ci_ptr->values, 0,
221					sizeof(gcov_type) * ci_ptr->num);
222			ci_ptr++;
223		}
224	}
225}
226
227/**
228 * gcov_info_is_compatible - check if profiling data can be added
229 * @info1: first profiling data set
230 * @info2: second profiling data set
231 *
232 * Returns non-zero if profiling data can be added, zero otherwise.
233 */
234int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
235{
236	return (info1->stamp == info2->stamp);
237}
238
239/**
240 * gcov_info_add - add up profiling data
241 * @dst: profiling data set to which data is added
242 * @src: profiling data set which is added
243 *
244 * Adds profiling counts of @src to @dst.
245 */
246void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
247{
248	struct gcov_ctr_info *dci_ptr;
249	struct gcov_ctr_info *sci_ptr;
250	unsigned int fi_idx;
251	unsigned int ct_idx;
252	unsigned int val_idx;
253
254	for (fi_idx = 0; fi_idx < src->n_functions; fi_idx++) {
255		dci_ptr = dst->functions[fi_idx]->ctrs;
256		sci_ptr = src->functions[fi_idx]->ctrs;
257
258		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
259			if (!counter_active(src, ct_idx))
260				continue;
261
262			for (val_idx = 0; val_idx < sci_ptr->num; val_idx++)
263				dci_ptr->values[val_idx] +=
264					sci_ptr->values[val_idx];
265
266			dci_ptr++;
267			sci_ptr++;
268		}
269	}
270}
271
272/**
273 * gcov_info_dup - duplicate profiling data set
274 * @info: profiling data set to duplicate
275 *
276 * Return newly allocated duplicate on success, %NULL on error.
277 */
278struct gcov_info *gcov_info_dup(struct gcov_info *info)
279{
280	struct gcov_info *dup;
281	struct gcov_ctr_info *dci_ptr; /* dst counter info */
282	struct gcov_ctr_info *sci_ptr; /* src counter info */
283	unsigned int active;
284	unsigned int fi_idx; /* function info idx */
285	unsigned int ct_idx; /* counter type idx */
286	size_t fi_size; /* function info size */
287	size_t cv_size; /* counter values size */
288
289	dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
290	if (!dup)
291		return NULL;
292
293	dup->next = NULL;
294	dup->filename = NULL;
295	dup->functions = NULL;
296
297	dup->filename = kstrdup(info->filename, GFP_KERNEL);
298	if (!dup->filename)
299		goto err_free;
300
301	dup->functions = kcalloc(info->n_functions,
302				 sizeof(struct gcov_fn_info *), GFP_KERNEL);
303	if (!dup->functions)
304		goto err_free;
305
306	active = num_counter_active(info);
307	fi_size = sizeof(struct gcov_fn_info);
308	fi_size += sizeof(struct gcov_ctr_info) * active;
309
310	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
311		dup->functions[fi_idx] = kzalloc(fi_size, GFP_KERNEL);
312		if (!dup->functions[fi_idx])
313			goto err_free;
314
315		*(dup->functions[fi_idx]) = *(info->functions[fi_idx]);
316
317		sci_ptr = info->functions[fi_idx]->ctrs;
318		dci_ptr = dup->functions[fi_idx]->ctrs;
319
320		for (ct_idx = 0; ct_idx < active; ct_idx++) {
321
322			cv_size = sizeof(gcov_type) * sci_ptr->num;
323
324			dci_ptr->values = kvmalloc(cv_size, GFP_KERNEL);
325
326			if (!dci_ptr->values)
327				goto err_free;
328
329			dci_ptr->num = sci_ptr->num;
330			memcpy(dci_ptr->values, sci_ptr->values, cv_size);
331
332			sci_ptr++;
333			dci_ptr++;
334		}
335	}
336
337	return dup;
338err_free:
339	gcov_info_free(dup);
340	return NULL;
341}
342
343/**
344 * gcov_info_free - release memory for profiling data set duplicate
345 * @info: profiling data set duplicate to free
346 */
347void gcov_info_free(struct gcov_info *info)
348{
349	unsigned int active;
350	unsigned int fi_idx;
351	unsigned int ct_idx;
352	struct gcov_ctr_info *ci_ptr;
353
354	if (!info->functions)
355		goto free_info;
356
357	active = num_counter_active(info);
358
359	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
360		if (!info->functions[fi_idx])
361			continue;
362
363		ci_ptr = info->functions[fi_idx]->ctrs;
364
365		for (ct_idx = 0; ct_idx < active; ct_idx++, ci_ptr++)
366			kvfree(ci_ptr->values);
367
368		kfree(info->functions[fi_idx]);
369	}
370
371free_info:
372	kfree(info->functions);
373	kfree(info->filename);
374	kfree(info);
375}
376
377/**
378 * convert_to_gcda - convert profiling data set to gcda file format
379 * @buffer: the buffer to store file data or %NULL if no data should be stored
380 * @info: profiling data set to be converted
381 *
382 * Returns the number of bytes that were/would have been stored into the buffer.
383 */
384size_t convert_to_gcda(char *buffer, struct gcov_info *info)
385{
386	struct gcov_fn_info *fi_ptr;
387	struct gcov_ctr_info *ci_ptr;
388	unsigned int fi_idx;
389	unsigned int ct_idx;
390	unsigned int cv_idx;
391	size_t pos = 0;
392
393	/* File header. */
394	pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
395	pos += store_gcov_u32(buffer, pos, info->version);
396	pos += store_gcov_u32(buffer, pos, info->stamp);
397
398#if (__GNUC__ >= 12)
399	/* Use zero as checksum of the compilation unit. */
400	pos += store_gcov_u32(buffer, pos, 0);
401#endif
402
403	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
404		fi_ptr = info->functions[fi_idx];
405
406		/* Function record. */
407		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
408		pos += store_gcov_u32(buffer, pos,
409			GCOV_TAG_FUNCTION_LENGTH * GCOV_UNIT_SIZE);
410		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
411		pos += store_gcov_u32(buffer, pos, fi_ptr->lineno_checksum);
412		pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
413
414		ci_ptr = fi_ptr->ctrs;
415
416		for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
417			if (!counter_active(info, ct_idx))
418				continue;
419
420			/* Counter record. */
421			pos += store_gcov_u32(buffer, pos,
422					      GCOV_TAG_FOR_COUNTER(ct_idx));
423			pos += store_gcov_u32(buffer, pos,
424				ci_ptr->num * 2 * GCOV_UNIT_SIZE);
425
426			for (cv_idx = 0; cv_idx < ci_ptr->num; cv_idx++) {
427				pos += store_gcov_u64(buffer, pos,
428						      ci_ptr->values[cv_idx]);
429			}
430
431			ci_ptr++;
432		}
433	}
434
435	return pos;
436}
437