Commit 240bf8a5 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Andrii Nakryiko
Browse files

libbpf: Replace elf_state->st_ops_* fields with SEC_ST_OPS sec_type 



The next patch would add two new section names for struct_ops maps.
To make working with multiple struct_ops sections more convenient:
- remove fields like elf_state->st_ops_{shndx,link_shndx};
- mark section descriptions hosting struct_ops as
  elf_sec_desc->sec_type == SEC_ST_OPS;

After these changes struct_ops sections could be processed uniformly
by iterating bpf_object->efile.secs entries.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-11-eddyz87@gmail.com
parent 651d49f1

tools/lib/bpf/libbpf.c

+32 −29
Original line number Diff line number Diff line
@@ -612,6 +612,7 @@ enum sec_type { 
	SEC_BSS,

	SEC_DATA,

	SEC_RODATA,

	SEC_ST_OPS,

};



struct elf_sec_desc {
@@ -627,8 +628,6 @@ struct elf_state { 
	Elf *elf;

	Elf64_Ehdr *ehdr;

	Elf_Data *symbols;

	Elf_Data *st_ops_data;

	Elf_Data *st_ops_link_data;

	size_t shstrndx; /* section index for section name strings */

	size_t strtabidx;

	struct elf_sec_desc *secs;
@@ -637,8 +636,7 @@ struct elf_state { 
	__u32 btf_maps_sec_btf_id;

	int text_shndx;

	int symbols_shndx;

	int st_ops_shndx;

	int st_ops_link_shndx;

	bool has_st_ops;

};



struct usdt_manager;
@@ -1266,7 +1264,7 @@ static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj) 
}



static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,

				int shndx, Elf_Data *data, __u32 map_flags)

				int shndx, Elf_Data *data)

{

	const struct btf_type *type, *datasec;

	const struct btf_var_secinfo *vsi;
@@ -1328,7 +1326,7 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name, 
		map->def.key_size = sizeof(int);

		map->def.value_size = type->size;

		map->def.max_entries = 1;

		map->def.map_flags = map_flags;

		map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0 ? BPF_F_LINK : 0;



		map->st_ops = calloc(1, sizeof(*map->st_ops));

		if (!map->st_ops)
@@ -1363,17 +1361,27 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name, 


static int bpf_object_init_struct_ops(struct bpf_object *obj)

{

	int err;

	const char *sec_name;

	int sec_idx, err;



	for (sec_idx = 0; sec_idx < obj->efile.sec_cnt; ++sec_idx) {

		struct elf_sec_desc *desc = &obj->efile.secs[sec_idx];



		if (desc->sec_type != SEC_ST_OPS)

			continue;



	err = init_struct_ops_maps(obj, STRUCT_OPS_SEC, obj->efile.st_ops_shndx,

				   obj->efile.st_ops_data, 0);

	err = err ?: init_struct_ops_maps(obj, STRUCT_OPS_LINK_SEC,

					  obj->efile.st_ops_link_shndx,

					  obj->efile.st_ops_link_data,

					  BPF_F_LINK);

		sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));

		if (!sec_name)

			return -LIBBPF_ERRNO__FORMAT;



		err = init_struct_ops_maps(obj, sec_name, sec_idx, desc->data);

		if (err)

			return err;

	}



	return 0;

}



static struct bpf_object *bpf_object__new(const char *path,

					  const void *obj_buf,

					  size_t obj_buf_sz,
@@ -1409,8 +1417,6 @@ static struct bpf_object *bpf_object__new(const char *path, 
	obj->efile.obj_buf = obj_buf;

	obj->efile.obj_buf_sz = obj_buf_sz;

	obj->efile.btf_maps_shndx = -1;

	obj->efile.st_ops_shndx = -1;

	obj->efile.st_ops_link_shndx = -1;

	obj->kconfig_map_idx = -1;



	obj->kern_version = get_kernel_version();
@@ -1427,8 +1433,6 @@ static void bpf_object__elf_finish(struct bpf_object *obj) 
	elf_end(obj->efile.elf);

	obj->efile.elf = NULL;

	obj->efile.symbols = NULL;

	obj->efile.st_ops_data = NULL;

	obj->efile.st_ops_link_data = NULL;



	zfree(&obj->efile.secs);

	obj->efile.sec_cnt = 0;
@@ -2973,14 +2977,13 @@ static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) 
static bool libbpf_needs_btf(const struct bpf_object *obj)

{

	return obj->efile.btf_maps_shndx >= 0 ||

	       obj->efile.st_ops_shndx >= 0 ||

	       obj->efile.st_ops_link_shndx >= 0 ||

	       obj->efile.has_st_ops ||

	       obj->nr_extern > 0;

}



static bool kernel_needs_btf(const struct bpf_object *obj)

{

	return obj->efile.st_ops_shndx >= 0 || obj->efile.st_ops_link_shndx >= 0;

	return obj->efile.has_st_ops;

}



static int bpf_object__init_btf(struct bpf_object *obj,
@@ -3681,12 +3684,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
				sec_desc->sec_type = SEC_RODATA;

				sec_desc->shdr = sh;

				sec_desc->data = data;

			} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {

				obj->efile.st_ops_data = data;

				obj->efile.st_ops_shndx = idx;

			} else if (strcmp(name, STRUCT_OPS_LINK_SEC) == 0) {

				obj->efile.st_ops_link_data = data;

				obj->efile.st_ops_link_shndx = idx;

			} else if (strcmp(name, STRUCT_OPS_SEC) == 0 ||

				   strcmp(name, STRUCT_OPS_LINK_SEC) == 0) {

				sec_desc->sec_type = SEC_ST_OPS;

				sec_desc->shdr = sh;

				sec_desc->data = data;

				obj->efile.has_st_ops = true;

			} else {

				pr_info("elf: skipping unrecognized data section(%d) %s\n",

					idx, name);
@@ -6999,12 +7002,12 @@ static int bpf_object__collect_relos(struct bpf_object *obj) 
		data = sec_desc->data;

		idx = shdr->sh_info;



		if (shdr->sh_type != SHT_REL) {

		if (shdr->sh_type != SHT_REL || idx < 0 || idx >= obj->efile.sec_cnt) {

			pr_warn("internal error at %d\n", __LINE__);

			return -LIBBPF_ERRNO__INTERNAL;

		}



		if (idx == obj->efile.st_ops_shndx || idx == obj->efile.st_ops_link_shndx)

		if (obj->efile.secs[idx].sec_type == SEC_ST_OPS)

			err = bpf_object__collect_st_ops_relos(obj, shdr, data);

		else if (idx == obj->efile.btf_maps_shndx)

			err = bpf_object__collect_map_relos(obj, shdr, data);