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

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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: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-11-eddyz87@gmail.com
This commit is contained in:
Eduard Zingerman 2024-03-06 12:45:24 +02:00 committed by Andrii Nakryiko
parent 651d49f15b
commit 240bf8a516
1 changed files with 32 additions and 29 deletions
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61
tools/lib/bpf/libbpf.c
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@ -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)
@ -1363,15 +1361,25 @@ 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;
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);
return 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;
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,
@ -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);