xref: /openbmc/linux/kernel/gcov/clang.c (revision e5bd61e8)
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 
55 typedef void (*llvm_gcov_callback)(void);
56 
57 struct 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 
67 struct 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 
78 static struct gcov_info *current_info;
79 
80 static LIST_HEAD(clang_gcov_list);
81 
82 void 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 }
103 EXPORT_SYMBOL(llvm_gcov_init);
104 
105 void 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 }
111 EXPORT_SYMBOL(llvm_gcda_start_file);
112 
113 void 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 }
126 EXPORT_SYMBOL(llvm_gcda_emit_function);
127 
128 void 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 }
136 EXPORT_SYMBOL(llvm_gcda_emit_arcs);
137 
138 void llvm_gcda_summary_info(void)
139 {
140 }
141 EXPORT_SYMBOL(llvm_gcda_summary_info);
142 
143 void llvm_gcda_end_file(void)
144 {
145 }
146 EXPORT_SYMBOL(llvm_gcda_end_file);
147 
148 /**
149  * gcov_info_filename - return info filename
150  * @info: profiling data set
151  */
152 const 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  */
161 unsigned 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  */
173 struct 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  */
187 void 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  */
197 void 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  */
210 bool 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. */
216 const 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  */
225 void 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  */
241 int 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  */
272 void 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 }
285 
286 static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
287 {
288 	size_t cv_size; /* counter values size */
289 	struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),
290 			GFP_KERNEL);
291 	if (!fn_dup)
292 		return NULL;
293 	INIT_LIST_HEAD(&fn_dup->head);
294 
295 	cv_size = fn->num_counters * sizeof(fn->counters[0]);
296 	fn_dup->counters = kvmalloc(cv_size, GFP_KERNEL);
297 	if (!fn_dup->counters) {
298 		kfree(fn_dup);
299 		return NULL;
300 	}
301 
302 	memcpy(fn_dup->counters, fn->counters, cv_size);
303 
304 	return fn_dup;
305 }
306 
307 /**
308  * gcov_info_dup - duplicate profiling data set
309  * @info: profiling data set to duplicate
310  *
311  * Return newly allocated duplicate on success, %NULL on error.
312  */
313 struct gcov_info *gcov_info_dup(struct gcov_info *info)
314 {
315 	struct gcov_info *dup;
316 	struct gcov_fn_info *fn;
317 
318 	dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
319 	if (!dup)
320 		return NULL;
321 	INIT_LIST_HEAD(&dup->head);
322 	INIT_LIST_HEAD(&dup->functions);
323 	dup->filename = kstrdup(info->filename, GFP_KERNEL);
324 	if (!dup->filename)
325 		goto err;
326 
327 	list_for_each_entry(fn, &info->functions, head) {
328 		struct gcov_fn_info *fn_dup = gcov_fn_info_dup(fn);
329 
330 		if (!fn_dup)
331 			goto err;
332 		list_add_tail(&fn_dup->head, &dup->functions);
333 	}
334 
335 	return dup;
336 
337 err:
338 	gcov_info_free(dup);
339 	return NULL;
340 }
341 
342 /**
343  * gcov_info_free - release memory for profiling data set duplicate
344  * @info: profiling data set duplicate to free
345  */
346 void gcov_info_free(struct gcov_info *info)
347 {
348 	struct gcov_fn_info *fn, *tmp;
349 
350 	list_for_each_entry_safe(fn, tmp, &info->functions, head) {
351 		kvfree(fn->counters);
352 		list_del(&fn->head);
353 		kfree(fn);
354 	}
355 	kfree(info->filename);
356 	kfree(info);
357 }
358 
359 /**
360  * convert_to_gcda - convert profiling data set to gcda file format
361  * @buffer: the buffer to store file data or %NULL if no data should be stored
362  * @info: profiling data set to be converted
363  *
364  * Returns the number of bytes that were/would have been stored into the buffer.
365  */
366 size_t convert_to_gcda(char *buffer, struct gcov_info *info)
367 {
368 	struct gcov_fn_info *fi_ptr;
369 	size_t pos = 0;
370 
371 	/* File header. */
372 	pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
373 	pos += store_gcov_u32(buffer, pos, info->version);
374 	pos += store_gcov_u32(buffer, pos, info->checksum);
375 
376 	list_for_each_entry(fi_ptr, &info->functions, head) {
377 		u32 i;
378 
379 		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
380 		pos += store_gcov_u32(buffer, pos, 3);
381 		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
382 		pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
383 		pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
384 		pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
385 		pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
386 		for (i = 0; i < fi_ptr->num_counters; i++)
387 			pos += store_gcov_u64(buffer, pos, fi_ptr->counters[i]);
388 	}
389 
390 	return pos;
391 }
392