--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Google, Inc.
+ * modified from kernel/gcov/gcc_4_7.c
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ *
+ * LLVM uses profiling data that's deliberately similar to GCC, but has a
+ * very different way of exporting that data. LLVM calls llvm_gcov_init() once
+ * per module, and provides a couple of callbacks that we can use to ask for
+ * more data.
+ *
+ * We care about the "writeout" callback, which in turn calls back into
+ * compiler-rt/this module to dump all the gathered coverage data to disk:
+ *
+ * llvm_gcda_start_file()
+ * llvm_gcda_emit_function()
+ * llvm_gcda_emit_arcs()
+ * llvm_gcda_emit_function()
+ * llvm_gcda_emit_arcs()
+ * [... repeats for each function ...]
+ * llvm_gcda_summary_info()
+ * llvm_gcda_end_file()
+ *
+ * This design is much more stateless and unstructured than gcc's, and is
+ * intended to run at process exit. This forces us to keep some local state
+ * about which module we're dealing with at the moment. On the other hand, it
+ * also means we don't depend as much on how LLVM represents profiling data
+ * internally.
+ *
+ * See LLVM's lib/Transforms/Instrumentation/GCOVProfiling.cpp for more
+ * details on how this works, particularly GCOVProfiler::emitProfileArcs(),
+ * GCOVProfiler::insertCounterWriteout(), and
+ * GCOVProfiler::insertFlush().
+ */
+
+#define pr_fmt(fmt) "gcov: " fmt
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/printk.h>
+#include <linux/ratelimit.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include "gcov.h"
+
+typedef void (*llvm_gcov_callback)(void);
+
+struct gcov_info {
+ struct list_head head;
+
+ const char *filename;
+ unsigned int version;
+ u32 checksum;
+
+ struct list_head functions;
+};
+
+struct gcov_fn_info {
+ struct list_head head;
+
+ u32 ident;
+ u32 checksum;
+ u8 use_extra_checksum;
+ u32 cfg_checksum;
+
+ u32 num_counters;
+ u64 *counters;
+ const char *function_name;
+};
+
+static struct gcov_info *current_info;
+
+static LIST_HEAD(clang_gcov_list);
+
+void llvm_gcov_init(llvm_gcov_callback writeout, llvm_gcov_callback flush)
+{
+ struct gcov_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
+
+ if (!info)
+ return;
+
+ INIT_LIST_HEAD(&info->head);
+ INIT_LIST_HEAD(&info->functions);
+
+ mutex_lock(&gcov_lock);
+
+ list_add_tail(&info->head, &clang_gcov_list);
+ current_info = info;
+ writeout();
+ current_info = NULL;
+ if (gcov_events_enabled)
+ gcov_event(GCOV_ADD, info);
+
+ mutex_unlock(&gcov_lock);
+}
+EXPORT_SYMBOL(llvm_gcov_init);
+
+void llvm_gcda_start_file(const char *orig_filename, const char version[4],
+ u32 checksum)
+{
+ current_info->filename = orig_filename;
+ memcpy(¤t_info->version, version, sizeof(current_info->version));
+ current_info->checksum = checksum;
+}
+EXPORT_SYMBOL(llvm_gcda_start_file);
+
+void llvm_gcda_emit_function(u32 ident, const char *function_name,
+ u32 func_checksum, u8 use_extra_checksum, u32 cfg_checksum)
+{
+ struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
+
+ if (!info)
+ return;
+
+ INIT_LIST_HEAD(&info->head);
+ info->ident = ident;
+ info->checksum = func_checksum;
+ info->use_extra_checksum = use_extra_checksum;
+ info->cfg_checksum = cfg_checksum;
+ if (function_name)
+ info->function_name = kstrdup(function_name, GFP_KERNEL);
+
+ list_add_tail(&info->head, ¤t_info->functions);
+}
+EXPORT_SYMBOL(llvm_gcda_emit_function);
+
+void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
+{
+ struct gcov_fn_info *info = list_last_entry(¤t_info->functions,
+ struct gcov_fn_info, head);
+
+ info->num_counters = num_counters;
+ info->counters = counters;
+}
+EXPORT_SYMBOL(llvm_gcda_emit_arcs);
+
+void llvm_gcda_summary_info(void)
+{
+}
+EXPORT_SYMBOL(llvm_gcda_summary_info);
+
+void llvm_gcda_end_file(void)
+{
+}
+EXPORT_SYMBOL(llvm_gcda_end_file);
+
+/**
+ * gcov_info_filename - return info filename
+ * @info: profiling data set
+ */
+const char *gcov_info_filename(struct gcov_info *info)
+{
+ return info->filename;
+}
+
+/**
+ * gcov_info_version - return info version
+ * @info: profiling data set
+ */
+unsigned int gcov_info_version(struct gcov_info *info)
+{
+ return info->version;
+}
+
+/**
+ * gcov_info_next - return next profiling data set
+ * @info: profiling data set
+ *
+ * Returns next gcov_info following @info or first gcov_info in the chain if
+ * @info is %NULL.
+ */
+struct gcov_info *gcov_info_next(struct gcov_info *info)
+{
+ if (!info)
+ return list_first_entry_or_null(&clang_gcov_list,
+ struct gcov_info, head);
+ if (list_is_last(&info->head, &clang_gcov_list))
+ return NULL;
+ return list_next_entry(info, head);
+}
+
+/**
+ * gcov_info_link - link/add profiling data set to the list
+ * @info: profiling data set
+ */
+void gcov_info_link(struct gcov_info *info)
+{
+ list_add_tail(&info->head, &clang_gcov_list);
+}
+
+/**
+ * gcov_info_unlink - unlink/remove profiling data set from the list
+ * @prev: previous profiling data set
+ * @info: profiling data set
+ */
+void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
+{
+ /* Generic code unlinks while iterating. */
+ __list_del_entry(&info->head);
+}
+
+/**
+ * gcov_info_within_module - check if a profiling data set belongs to a module
+ * @info: profiling data set
+ * @mod: module
+ *
+ * Returns true if profiling data belongs module, false otherwise.
+ */
+bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
+{
+ return within_module((unsigned long)info->filename, mod);
+}
+
+/* Symbolic links to be created for each profiling data file. */
+const struct gcov_link gcov_link[] = {
+ { OBJ_TREE, "gcno" }, /* Link to .gcno file in $(objtree). */
+ { 0, NULL},
+};
+
+/**
+ * gcov_info_reset - reset profiling data to zero
+ * @info: profiling data set
+ */
+void gcov_info_reset(struct gcov_info *info)
+{
+ struct gcov_fn_info *fn;
+
+ list_for_each_entry(fn, &info->functions, head)
+ memset(fn->counters, 0,
+ sizeof(fn->counters[0]) * fn->num_counters);
+}
+
+/**
+ * gcov_info_is_compatible - check if profiling data can be added
+ * @info1: first profiling data set
+ * @info2: second profiling data set
+ *
+ * Returns non-zero if profiling data can be added, zero otherwise.
+ */
+int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
+{
+ struct gcov_fn_info *fn_ptr1 = list_first_entry_or_null(
+ &info1->functions, struct gcov_fn_info, head);
+ struct gcov_fn_info *fn_ptr2 = list_first_entry_or_null(
+ &info2->functions, struct gcov_fn_info, head);
+
+ if (info1->checksum != info2->checksum)
+ return false;
+ if (!fn_ptr1)
+ return fn_ptr1 == fn_ptr2;
+ while (!list_is_last(&fn_ptr1->head, &info1->functions) &&
+ !list_is_last(&fn_ptr2->head, &info2->functions)) {
+ if (fn_ptr1->checksum != fn_ptr2->checksum)
+ return false;
+ if (fn_ptr1->use_extra_checksum != fn_ptr2->use_extra_checksum)
+ return false;
+ if (fn_ptr1->use_extra_checksum &&
+ fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
+ return false;
+ fn_ptr1 = list_next_entry(fn_ptr1, head);
+ fn_ptr2 = list_next_entry(fn_ptr2, head);
+ }
+ return list_is_last(&fn_ptr1->head, &info1->functions) &&
+ list_is_last(&fn_ptr2->head, &info2->functions);
+}
+
+/**
+ * gcov_info_add - add up profiling data
+ * @dest: profiling data set to which data is added
+ * @source: profiling data set which is added
+ *
+ * Adds profiling counts of @source to @dest.
+ */
+void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
+{
+ struct gcov_fn_info *dfn_ptr;
+ struct gcov_fn_info *sfn_ptr = list_first_entry_or_null(&src->functions,
+ struct gcov_fn_info, head);
+
+ list_for_each_entry(dfn_ptr, &dst->functions, head) {
+ u32 i;
+
+ for (i = 0; i < sfn_ptr->num_counters; i++)
+ dfn_ptr->counters[i] += sfn_ptr->counters[i];
+ }
+}
+
+static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
+{
+ size_t cv_size; /* counter values size */
+ struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),
+ GFP_KERNEL);
+ if (!fn_dup)
+ return NULL;
+ INIT_LIST_HEAD(&fn_dup->head);
+
+ fn_dup->function_name = kstrdup(fn->function_name, GFP_KERNEL);
+ if (!fn_dup->function_name)
+ goto err_name;
+
+ cv_size = fn->num_counters * sizeof(fn->counters[0]);
+ fn_dup->counters = vmalloc(cv_size);
+ if (!fn_dup->counters)
+ goto err_counters;
+ memcpy(fn_dup->counters, fn->counters, cv_size);
+
+ return fn_dup;
+
+err_counters:
+ kfree(fn_dup->function_name);
+err_name:
+ kfree(fn_dup);
+ return NULL;
+}
+
+/**
+ * gcov_info_dup - duplicate profiling data set
+ * @info: profiling data set to duplicate
+ *
+ * Return newly allocated duplicate on success, %NULL on error.
+ */
+struct gcov_info *gcov_info_dup(struct gcov_info *info)
+{
+ struct gcov_info *dup;
+ struct gcov_fn_info *fn;
+
+ dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
+ if (!dup)
+ return NULL;
+ INIT_LIST_HEAD(&dup->head);
+ INIT_LIST_HEAD(&dup->functions);
+ dup->filename = kstrdup(info->filename, GFP_KERNEL);
+ if (!dup->filename)
+ goto err;
+
+ list_for_each_entry(fn, &info->functions, head) {
+ struct gcov_fn_info *fn_dup = gcov_fn_info_dup(fn);
+
+ if (!fn_dup)
+ goto err;
+ list_add_tail(&fn_dup->head, &dup->functions);
+ }
+
+ return dup;
+
+err:
+ gcov_info_free(dup);
+ return NULL;
+}
+
+/**
+ * gcov_info_free - release memory for profiling data set duplicate
+ * @info: profiling data set duplicate to free
+ */
+void gcov_info_free(struct gcov_info *info)
+{
+ struct gcov_fn_info *fn, *tmp;
+
+ list_for_each_entry_safe(fn, tmp, &info->functions, head) {
+ kfree(fn->function_name);
+ vfree(fn->counters);
+ list_del(&fn->head);
+ kfree(fn);
+ }
+ kfree(info->filename);
+ kfree(info);
+}
+
+#define ITER_STRIDE PAGE_SIZE
+
+/**
+ * struct gcov_iterator - specifies current file position in logical records
+ * @info: associated profiling data
+ * @buffer: buffer containing file data
+ * @size: size of buffer
+ * @pos: current position in file
+ */
+struct gcov_iterator {
+ struct gcov_info *info;
+ void *buffer;
+ size_t size;
+ loff_t pos;
+};
+
+/**
+ * store_gcov_u32 - store 32 bit number in gcov format to buffer
+ * @buffer: target buffer or NULL
+ * @off: offset into the buffer
+ * @v: value to be stored
+ *
+ * Number format defined by gcc: numbers are recorded in the 32 bit
+ * unsigned binary form of the endianness of the machine generating the
+ * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
+ * store anything.
+ */
+static size_t store_gcov_u32(void *buffer, size_t off, u32 v)
+{
+ u32 *data;
+
+ if (buffer) {
+ data = buffer + off;
+ *data = v;
+ }
+
+ return sizeof(*data);
+}
+
+/**
+ * store_gcov_u64 - store 64 bit number in gcov format to buffer
+ * @buffer: target buffer or NULL
+ * @off: offset into the buffer
+ * @v: value to be stored
+ *
+ * Number format defined by gcc: numbers are recorded in the 32 bit
+ * unsigned binary form of the endianness of the machine generating the
+ * file. 64 bit numbers are stored as two 32 bit numbers, the low part
+ * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
+ * anything.
+ */
+static size_t store_gcov_u64(void *buffer, size_t off, u64 v)
+{
+ u32 *data;
+
+ if (buffer) {
+ data = buffer + off;
+
+ data[0] = (v & 0xffffffffUL);
+ data[1] = (v >> 32);
+ }
+
+ return sizeof(*data) * 2;
+}
+
+/**
+ * convert_to_gcda - convert profiling data set to gcda file format
+ * @buffer: the buffer to store file data or %NULL if no data should be stored
+ * @info: profiling data set to be converted
+ *
+ * Returns the number of bytes that were/would have been stored into the buffer.
+ */
+static size_t convert_to_gcda(char *buffer, struct gcov_info *info)
+{
+ struct gcov_fn_info *fi_ptr;
+ size_t pos = 0;
+
+ /* File header. */
+ pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
+ pos += store_gcov_u32(buffer, pos, info->version);
+ pos += store_gcov_u32(buffer, pos, info->checksum);
+
+ list_for_each_entry(fi_ptr, &info->functions, head) {
+ u32 i;
+ u32 len = 2;
+
+ if (fi_ptr->use_extra_checksum)
+ len++;
+
+ pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
+ pos += store_gcov_u32(buffer, pos, len);
+ pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
+ pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
+ if (fi_ptr->use_extra_checksum)
+ pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
+
+ pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
+ pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
+ for (i = 0; i < fi_ptr->num_counters; i++)
+ pos += store_gcov_u64(buffer, pos, fi_ptr->counters[i]);
+ }
+
+ return pos;
+}
+
+/**
+ * gcov_iter_new - allocate and initialize profiling data iterator
+ * @info: profiling data set to be iterated
+ *
+ * Return file iterator on success, %NULL otherwise.
+ */
+struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
+{
+ struct gcov_iterator *iter;
+
+ iter = kzalloc(sizeof(struct gcov_iterator), GFP_KERNEL);
+ if (!iter)
+ goto err_free;
+
+ iter->info = info;
+ /* Dry-run to get the actual buffer size. */
+ iter->size = convert_to_gcda(NULL, info);
+ iter->buffer = vmalloc(iter->size);
+ if (!iter->buffer)
+ goto err_free;
+
+ convert_to_gcda(iter->buffer, info);
+
+ return iter;
+
+err_free:
+ kfree(iter);
+ return NULL;
+}
+
+
+/**
+ * gcov_iter_get_info - return profiling data set for given file iterator
+ * @iter: file iterator
+ */
+void gcov_iter_free(struct gcov_iterator *iter)
+{
+ vfree(iter->buffer);
+ kfree(iter);
+}
+
+/**
+ * gcov_iter_get_info - return profiling data set for given file iterator
+ * @iter: file iterator
+ */
+struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
+{
+ return iter->info;
+}
+
+/**
+ * gcov_iter_start - reset file iterator to starting position
+ * @iter: file iterator
+ */
+void gcov_iter_start(struct gcov_iterator *iter)
+{
+ iter->pos = 0;
+}
+
+/**
+ * gcov_iter_next - advance file iterator to next logical record
+ * @iter: file iterator
+ *
+ * Return zero if new position is valid, non-zero if iterator has reached end.
+ */
+int gcov_iter_next(struct gcov_iterator *iter)
+{
+ if (iter->pos < iter->size)
+ iter->pos += ITER_STRIDE;
+
+ if (iter->pos >= iter->size)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
+ * gcov_iter_write - write data for current pos to seq_file
+ * @iter: file iterator
+ * @seq: seq_file handle
+ *
+ * Return zero on success, non-zero otherwise.
+ */
+int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq)
+{
+ size_t len;
+
+ if (iter->pos >= iter->size)
+ return -EINVAL;
+
+ len = ITER_STRIDE;
+ if (iter->pos + len > iter->size)
+ len = iter->size - iter->pos;
+
+ seq_write(seq, iter->buffer + iter->pos, len);
+
+ return 0;
+}
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