[PATCH v2][makedumpfile 10/14] Implement kernel module's btf resolving

[Tao Liu]

Signed-off-by: Tao Liu <ltao at redhat.com>
---
 btf.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 btf.h |   2 +
 2 files changed, 123 insertions(+)

diff --git a/btf.c b/btf.c
index ba376cf..5dd2047 100644
--- a/btf.c
+++ b/btf.c
@@ -796,3 +796,124 @@ int init_kernel_btf(void)
 	return ret;
 }
 
+int init_module_btf(void)
+{
+	uint64_t btf_modules, list;
+	struct member_info mi;
+	uint64_t btf = 0, data = 0, module = 0;
+	int data_size = 0;
+	char *btf_buf = NULL;
+	char *modname = NULL;
+
+	btf_modules = get_kallsyms_value_by_name("btf_modules");
+	if (!btf_modules)
+		/* Maybe module is not enabled, this is not an error */
+		return 0;
+
+	INIT_MEMBER_OFF_SIZE(btf_module, list);
+	INIT_MEMBER_OFF_SIZE(btf_module, btf);
+	INIT_MEMBER_OFF_SIZE(btf_module, module);
+	INIT_MEMBER_OFF_SIZE(module, name);
+	INIT_MEMBER_OFF_SIZE(btf, data);
+	INIT_MEMBER_OFF_SIZE(btf, data_size);
+	modname = (char *)malloc(GET_MEMBER_SIZE(module, name));
+	if (!modname) {
+		fprintf(stderr, "%s: Not enough memory!\n", __func__);
+		goto out;
+	}
+
+	for (list = next_list(btf_modules); list != btf_modules; list = next_list(list)) {
+		readmem(VADDR, list - GET_MEMBER_OFF(btf_module, list) +
+				GET_MEMBER_OFF(btf_module, btf),
+			&btf, GET_MEMBER_SIZE(btf_module, btf));
+		readmem(VADDR, list - GET_MEMBER_OFF(btf_module, list) +
+				GET_MEMBER_OFF(btf_module, module),
+			&module, GET_MEMBER_SIZE(btf_module, module));
+		readmem(VADDR, module + GET_MEMBER_OFF(module, name),
+			modname, GET_MEMBER_SIZE(module, name));
+		readmem(VADDR, btf + GET_MEMBER_OFF(btf, data),
+			&data, GET_MEMBER_SIZE(btf, data));
+		readmem(VADDR, btf + GET_MEMBER_OFF(btf, data_size),
+			&data_size, GET_MEMBER_SIZE(btf, data_size));
+		btf_buf = (char *)malloc(data_size);
+		if (!btf_buf) {
+			fprintf(stderr, "%s: Not enough memory!\n", __func__);
+			goto out;
+		}
+		readmem(VADDR, data, btf_buf, data_size);
+		if (init_btf_from_buf(modname, btf_buf, data_size))
+			goto out;
+		free(btf_buf);
+	}
+	return 0;
+out:
+	if (modname)
+		free(modname);
+	if (btf_buf)
+		free(btf_buf);
+	return -1;
+}
+
+void cleanup_btf(void)
+{
+	int bf_index, i;
+	struct btf_file *bf;
+	struct name_entry *en, *en_tmp;
+	DIR *temp_dir;
+	struct dirent *entry;
+	char path[512];
+
+	/* Free no-hashtable-installed elements */
+	for (bf_index = 0; bf_index < btf_files_array_index; bf_index++) {
+		bf = btf_files_array[bf_index];
+		if (bf && bf->array) {
+			for (i = 0; i < bf->array_len; i++) {
+				if (!bf->array[i]->name || !bf->array[i]->name[0])
+					free(bf->array[i]);
+			}
+		}
+	}
+
+	/* Free the hashtable-installed elements */
+	for (i = 0; i < NAME_HASH; i++) {
+		for (en = name_hash_table[i]; en;) {
+			en_tmp = en;
+			en = en->name_hash_next;
+			free(en_tmp);
+		}
+	}
+
+	/* Cleanup anything else */
+	for (bf_index = 0; bf_index < btf_files_array_index; bf_index++) {
+		bf = btf_files_array[bf_index];
+		if (bf && bf->array) {
+			free(bf->array);
+		}
+		if (bf && bf->file_name)
+			free(bf->file_name);
+		if (bf && bf->str_cache)
+			free(bf->str_cache);
+		if (bf)
+			free(bf);
+	}
+
+	if (btf_files_array)
+		free(btf_files_array);
+
+	/* Cleanup the dir /tmp/btf_XXXXXX */
+	temp_dir = opendir(temp);
+	if (!temp_dir)
+		return;
+	while ((entry = readdir(temp_dir)) != NULL) {
+		if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, ".."))
+			continue;
+		snprintf(path, sizeof(path), "%s/%s", temp, entry->d_name);
+		if (remove(path)) {
+			fprintf(stderr, "%s: fail del %s!\n", __func__, path);
+			/* In case too many fail messages of files in the dir */
+			return;
+		}
+	}
+	closedir(temp_dir);
+	rmdir(temp);
+}
\ No newline at end of file
diff --git a/btf.h b/btf.h
index 424e9e0..2fcdfe1 100644
--- a/btf.h
+++ b/btf.h
@@ -166,6 +166,8 @@ void resolve_typedef(struct name_entry *, struct name_entry **, struct btf_type
 int get_btf_type_by_type_id(struct btf_file *, uint32_t,
 			    struct btf_type *, struct name_entry **);
 uint32_t id_to_uniq_id(uint32_t, struct btf_file *);
+int init_module_btf(void);
+void cleanup_btf(void);
 
 static inline uint32_t btf_kind(uint32_t info)
 {
-- 
2.47.0