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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, ¤t_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(¤t_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}