1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2019 Google, Inc.
4 * modified from kernel/gcov/gcc_4_7.c
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 *
16 * LLVM uses profiling data that's deliberately similar to GCC, but has a
17 * very different way of exporting that data.  LLVM calls llvm_gcov_init() once
18 * per module, and provides a couple of callbacks that we can use to ask for
19 * more data.
20 *
21 * We care about the "writeout" callback, which in turn calls back into
22 * compiler-rt/this module to dump all the gathered coverage data to disk:
23 *
24 *    llvm_gcda_start_file()
25 *      llvm_gcda_emit_function()
26 *      llvm_gcda_emit_arcs()
27 *      llvm_gcda_emit_function()
28 *      llvm_gcda_emit_arcs()
29 *      [... repeats for each function ...]
30 *    llvm_gcda_summary_info()
31 *    llvm_gcda_end_file()
32 *
33 * This design is much more stateless and unstructured than gcc's, and is
34 * intended to run at process exit.  This forces us to keep some local state
35 * about which module we're dealing with at the moment.  On the other hand, it
36 * also means we don't depend as much on how LLVM represents profiling data
37 * internally.
38 *
39 * See LLVM's lib/Transforms/Instrumentation/GCOVProfiling.cpp for more
40 * details on how this works, particularly GCOVProfiler::emitProfileArcs(),
41 * GCOVProfiler::insertCounterWriteout(), and
42 * GCOVProfiler::insertFlush().
43 */
44
45#define pr_fmt(fmt)	"gcov: " fmt
46
47#include <linux/kernel.h>
48#include <linux/list.h>
49#include <linux/printk.h>
50#include <linux/ratelimit.h>
51#include <linux/slab.h>
52#include <linux/mm.h>
53#include "gcov.h"
54
55typedef void (*llvm_gcov_callback)(void);
56
57struct gcov_info {
58	struct list_head head;
59
60	const char *filename;
61	unsigned int version;
62	u32 checksum;
63
64	struct list_head functions;
65};
66
67struct gcov_fn_info {
68	struct list_head head;
69
70	u32 ident;
71	u32 checksum;
72	u32 cfg_checksum;
73
74	u32 num_counters;
75	u64 *counters;
76};
77
78static struct gcov_info *current_info;
79
80static LIST_HEAD(clang_gcov_list);
81
82void llvm_gcov_init(llvm_gcov_callback writeout, llvm_gcov_callback flush)
83{
84	struct gcov_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
85
86	if (!info)
87		return;
88
89	INIT_LIST_HEAD(&info->head);
90	INIT_LIST_HEAD(&info->functions);
91
92	mutex_lock(&gcov_lock);
93
94	list_add_tail(&info->head, &clang_gcov_list);
95	current_info = info;
96	writeout();
97	current_info = NULL;
98	if (gcov_events_enabled)
99		gcov_event(GCOV_ADD, info);
100
101	mutex_unlock(&gcov_lock);
102}
103EXPORT_SYMBOL(llvm_gcov_init);
104
105void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum)
106{
107	current_info->filename = orig_filename;
108	current_info->version = version;
109	current_info->checksum = checksum;
110}
111EXPORT_SYMBOL(llvm_gcda_start_file);
112
113void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum)
114{
115	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
116
117	if (!info)
118		return;
119
120	INIT_LIST_HEAD(&info->head);
121	info->ident = ident;
122	info->checksum = func_checksum;
123	info->cfg_checksum = cfg_checksum;
124	list_add_tail(&info->head, &current_info->functions);
125}
126EXPORT_SYMBOL(llvm_gcda_emit_function);
127
128void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
129{
130	struct gcov_fn_info *info = list_last_entry(&current_info->functions,
131			struct gcov_fn_info, head);
132
133	info->num_counters = num_counters;
134	info->counters = counters;
135}
136EXPORT_SYMBOL(llvm_gcda_emit_arcs);
137
138void llvm_gcda_summary_info(void)
139{
140}
141EXPORT_SYMBOL(llvm_gcda_summary_info);
142
143void llvm_gcda_end_file(void)
144{
145}
146EXPORT_SYMBOL(llvm_gcda_end_file);
147
148/**
149 * gcov_info_filename - return info filename
150 * @info: profiling data set
151 */
152const char *gcov_info_filename(struct gcov_info *info)
153{
154	return info->filename;
155}
156
157/**
158 * gcov_info_version - return info version
159 * @info: profiling data set
160 */
161unsigned int gcov_info_version(struct gcov_info *info)
162{
163	return info->version;
164}
165
166/**
167 * gcov_info_next - return next profiling data set
168 * @info: profiling data set
169 *
170 * Returns next gcov_info following @info or first gcov_info in the chain if
171 * @info is %NULL.
172 */
173struct gcov_info *gcov_info_next(struct gcov_info *info)
174{
175	if (!info)
176		return list_first_entry_or_null(&clang_gcov_list,
177				struct gcov_info, head);
178	if (list_is_last(&info->head, &clang_gcov_list))
179		return NULL;
180	return list_next_entry(info, head);
181}
182
183/**
184 * gcov_info_link - link/add profiling data set to the list
185 * @info: profiling data set
186 */
187void gcov_info_link(struct gcov_info *info)
188{
189	list_add_tail(&info->head, &clang_gcov_list);
190}
191
192/**
193 * gcov_info_unlink - unlink/remove profiling data set from the list
194 * @prev: previous profiling data set
195 * @info: profiling data set
196 */
197void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
198{
199	/* Generic code unlinks while iterating. */
200	__list_del_entry(&info->head);
201}
202
203/**
204 * gcov_info_within_module - check if a profiling data set belongs to a module
205 * @info: profiling data set
206 * @mod: module
207 *
208 * Returns true if profiling data belongs module, false otherwise.
209 */
210bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
211{
212	return within_module((unsigned long)info->filename, mod);
213}
214
215/* Symbolic links to be created for each profiling data file. */
216const struct gcov_link gcov_link[] = {
217	{ OBJ_TREE, "gcno" },	/* Link to .gcno file in $(objtree). */
218	{ 0, NULL},
219};
220
221/**
222 * gcov_info_reset - reset profiling data to zero
223 * @info: profiling data set
224 */
225void gcov_info_reset(struct gcov_info *info)
226{
227	struct gcov_fn_info *fn;
228
229	list_for_each_entry(fn, &info->functions, head)
230		memset(fn->counters, 0,
231				sizeof(fn->counters[0]) * fn->num_counters);
232}
233
234/**
235 * gcov_info_is_compatible - check if profiling data can be added
236 * @info1: first profiling data set
237 * @info2: second profiling data set
238 *
239 * Returns non-zero if profiling data can be added, zero otherwise.
240 */
241int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
242{
243	struct gcov_fn_info *fn_ptr1 = list_first_entry_or_null(
244			&info1->functions, struct gcov_fn_info, head);
245	struct gcov_fn_info *fn_ptr2 = list_first_entry_or_null(
246			&info2->functions, struct gcov_fn_info, head);
247
248	if (info1->checksum != info2->checksum)
249		return false;
250	if (!fn_ptr1)
251		return fn_ptr1 == fn_ptr2;
252	while (!list_is_last(&fn_ptr1->head, &info1->functions) &&
253		!list_is_last(&fn_ptr2->head, &info2->functions)) {
254		if (fn_ptr1->checksum != fn_ptr2->checksum)
255			return false;
256		if (fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
257			return false;
258		fn_ptr1 = list_next_entry(fn_ptr1, head);
259		fn_ptr2 = list_next_entry(fn_ptr2, head);
260	}
261	return list_is_last(&fn_ptr1->head, &info1->functions) &&
262		list_is_last(&fn_ptr2->head, &info2->functions);
263}
264
265/**
266 * gcov_info_add - add up profiling data
267 * @dest: profiling data set to which data is added
268 * @source: profiling data set which is added
269 *
270 * Adds profiling counts of @source to @dest.
271 */
272void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
273{
274	struct gcov_fn_info *dfn_ptr;
275	struct gcov_fn_info *sfn_ptr = list_first_entry_or_null(&src->functions,
276			struct gcov_fn_info, head);
277
278	list_for_each_entry(dfn_ptr, &dst->functions, head) {
279		u32 i;
280
281		for (i = 0; i < sfn_ptr->num_counters; i++)
282			dfn_ptr->counters[i] += sfn_ptr->counters[i];
283
284		sfn_ptr = list_next_entry(sfn_ptr, head);
285	}
286}
287
288static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
289{
290	size_t cv_size; /* counter values size */
291	struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),
292			GFP_KERNEL);
293	if (!fn_dup)
294		return NULL;
295	INIT_LIST_HEAD(&fn_dup->head);
296
297	cv_size = fn->num_counters * sizeof(fn->counters[0]);
298	fn_dup->counters = kvmalloc(cv_size, GFP_KERNEL);
299	if (!fn_dup->counters) {
300		kfree(fn_dup);
301		return NULL;
302	}
303
304	memcpy(fn_dup->counters, fn->counters, cv_size);
305
306	return fn_dup;
307}
308
309/**
310 * gcov_info_dup - duplicate profiling data set
311 * @info: profiling data set to duplicate
312 *
313 * Return newly allocated duplicate on success, %NULL on error.
314 */
315struct gcov_info *gcov_info_dup(struct gcov_info *info)
316{
317	struct gcov_info *dup;
318	struct gcov_fn_info *fn;
319
320	dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
321	if (!dup)
322		return NULL;
323	INIT_LIST_HEAD(&dup->head);
324	INIT_LIST_HEAD(&dup->functions);
325	dup->filename = kstrdup(info->filename, GFP_KERNEL);
326	if (!dup->filename)
327		goto err;
328
329	list_for_each_entry(fn, &info->functions, head) {
330		struct gcov_fn_info *fn_dup = gcov_fn_info_dup(fn);
331
332		if (!fn_dup)
333			goto err;
334		list_add_tail(&fn_dup->head, &dup->functions);
335	}
336
337	return dup;
338
339err:
340	gcov_info_free(dup);
341	return NULL;
342}
343
344/**
345 * gcov_info_free - release memory for profiling data set duplicate
346 * @info: profiling data set duplicate to free
347 */
348void gcov_info_free(struct gcov_info *info)
349{
350	struct gcov_fn_info *fn, *tmp;
351
352	list_for_each_entry_safe(fn, tmp, &info->functions, head) {
353		kvfree(fn->counters);
354		list_del(&fn->head);
355		kfree(fn);
356	}
357	kfree(info->filename);
358	kfree(info);
359}
360
361/**
362 * convert_to_gcda - convert profiling data set to gcda file format
363 * @buffer: the buffer to store file data or %NULL if no data should be stored
364 * @info: profiling data set to be converted
365 *
366 * Returns the number of bytes that were/would have been stored into the buffer.
367 */
368size_t convert_to_gcda(char *buffer, struct gcov_info *info)
369{
370	struct gcov_fn_info *fi_ptr;
371	size_t pos = 0;
372
373	/* File header. */
374	pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
375	pos += store_gcov_u32(buffer, pos, info->version);
376	pos += store_gcov_u32(buffer, pos, info->checksum);
377
378	list_for_each_entry(fi_ptr, &info->functions, head) {
379		u32 i;
380
381		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
382		pos += store_gcov_u32(buffer, pos, 3);
383		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
384		pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
385		pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
386		pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
387		pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
388		for (i = 0; i < fi_ptr->num_counters; i++)
389			pos += store_gcov_u64(buffer, pos, fi_ptr->counters[i]);
390	}
391
392	return pos;
393}
394