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libbpf: Struct_ops in SEC("?.struct_ops") / SEC("?.struct_ops.link")

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Allow using two new section names for struct_ops maps:
- SEC("?.struct_ops")
- SEC("?.struct_ops.link")

To specify maps that have bpf_map->autocreate == false after open.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-12-eddyz87@gmail.com
This commit is contained in:
Eduard Zingerman 2024-03-06 12:45:25 +02:00 committed by Andrii Nakryiko
parent 240bf8a516
commit 5ad0ecbe05
1 changed files with 14 additions and 1 deletions
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15
tools/lib/bpf/libbpf.c
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@ -1322,6 +1322,15 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
return -ENOMEM;
map->btf_value_type_id = type_id;
/* Follow same convention as for programs autoload:
* SEC("?.struct_ops") means map is not created by default.
*/
if (sec_name[0] == '?') {
map->autocreate = false;
/* from now on forget there was ? in section name */
sec_name++;
}
map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
map->def.key_size = sizeof(int);
map->def.value_size = type->size;
@ -3685,7 +3694,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (strcmp(name, STRUCT_OPS_SEC) == 0 ||
strcmp(name, STRUCT_OPS_LINK_SEC) == 0) {
strcmp(name, STRUCT_OPS_LINK_SEC) == 0 ||
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;
@ -3705,6 +3716,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
if (!section_have_execinstr(obj, targ_sec_idx) &&
strcmp(name, ".rel" STRUCT_OPS_SEC) &&
strcmp(name, ".rel" STRUCT_OPS_LINK_SEC) &&
strcmp(name, ".rel?" STRUCT_OPS_SEC) &&
strcmp(name, ".rel?" STRUCT_OPS_LINK_SEC) &&
strcmp(name, ".rel" MAPS_ELF_SEC)) {
pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
idx, name, targ_sec_idx,