This code is heavily borrowed from libbpf and is used in the
subsequent commits porting relocation functions from libbbf.
Signed-off-by: Blaise Boscaccy <bboscaccy@xxxxxxxxxxxxxxxxxxx>
---
kernel/bpf/syscall.c | 110 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 110 insertions(+)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 907cc0b34f822..dc763772b55e5 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5964,6 +5964,116 @@ static struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
return btf_ext;
}
+static int elf_sec_idx_by_name(struct bpf_obj *obj, const char *name)
+{
+ int i;
+ Elf_Shdr *shdr;
+
+ for (i = 1; i < obj->hdr->e_shnum; i++) {
+ shdr = &obj->sechdrs[i];
+ if (strcmp(name, obj->secstrings + shdr->sh_name) == 0)
+ return i;
+ }
+ return -ENOENT;
+}
+
+static const struct btf_var *btf_type_var(const struct btf_type *t)
+{
+ return (const struct btf_var *)(t + 1);
+}
+
+static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
+{
+ const struct btf_type *t;
+ const char *tname;
+ int i, n;
+
+ if (!btf)
+ return -ESRCH;
+
+ n = btf_type_cnt(btf);
+
+ for (i = 1; i < n; i++) {
+ t = btf_type_by_id(btf, i);
+
+ if (!btf_type_is_var(t) && !btf_type_is_func(t))
+ continue;
+
+ tname = btf_str_by_offset(btf, t->name_off);
+ if (strcmp(tname, ext_name))
+ continue;
+
+ if (btf_type_is_var(t) &&
+ btf_type_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+ return -EINVAL;
+
+ if (btf_type_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
+ return -EINVAL;
+
+ return i;
+ }
+
+ return -ENOENT;
+}
+
+static inline struct btf_var_secinfo *
+btf_var_secinfos(const struct btf_type *t)
+{
+ return (struct btf_var_secinfo *)(t + 1);
+}
+
+static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id)
+{
+ const struct btf_var_secinfo *vs;
+ const struct btf_type *t;
+ int i, j, n;
+
+ if (!btf)
+ return -ESRCH;
+
+ n = btf_type_cnt(btf);
+ for (i = 1; i < n; i++) {
+ t = btf_type_by_id(btf, i);
+
+ if (!btf_type_is_datasec(t))
+ continue;
+
+ vs = btf_var_secinfos(t);
+ for (j = 0; j < btf_vlen(t); j++, vs++) {
+ if (vs->type == ext_btf_id)
+ return i;
+ }
+ }
+
+ return -ENOENT;
+}
+
+static bool sym_is_extern(const Elf64_Sym *sym)
+{
+ int bind = ELF64_ST_BIND(sym->st_info);
+ /* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
+ return sym->st_shndx == SHN_UNDEF &&
+ (bind == STB_GLOBAL || bind == STB_WEAK) &&
+ ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
+}
+
+static const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, u32 id, u32 *res_id)
+{
+ const struct btf_type *t = btf_type_by_id(btf, id);
+
+ if (res_id)
+ *res_id = id;
+
+ while (btf_type_is_mod(t) || btf_type_is_typedef(t)) {
+ if (res_id)
+ *res_id = t->type;
+ t = btf_type_by_id(btf, t->type);
+ }
+
+ return t;
+}
+
static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size)
{
union bpf_attr attr;
--
2.47.1
