kernel/gcov/clang.c

   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                 sfn_ptr = list_next_entry(sfn_ptr, head);
 285         }
 286 }
 287
 288 static 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  */
 315 struct 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
 339 err:
 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  */
 348 void 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  */
 368 size_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 }