libbpf: Add multi-prog section support for struct_ops

Adjust struct_ops handling code to work with multi-program ELF sections
properly.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-7-andriin@fb.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ca2b5c9145da646dbd87c360e22a14599cd4c732..2d6bf0af3305f64281c20442014db6632a27bf48 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -73,8 +73,6 @@
 #define __printf(a, b) __attribute__((format(printf, a, b)))
 
 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
-static struct bpf_program *bpf_object__find_prog_by_idx(struct bpf_object *obj,
-                                                       int idx);
 static const struct btf_type *
 skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
 
@@ -3249,20 +3247,6 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
        return 0;
 }
 
-static struct bpf_program *
-bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
-{
-       struct bpf_program *prog;
-       size_t i;
-
-       for (i = 0; i < obj->nr_programs; i++) {
-               prog = &obj->programs[i];
-               if (prog->sec_idx == idx)
-                       return prog;
-       }
-       return NULL;
-}
-
 struct bpf_program *
 bpf_object__find_program_by_title(const struct bpf_object *obj,
                                  const char *title)
@@ -8198,7 +8182,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
        const struct btf *btf;
        struct bpf_map *map;
        Elf_Data *symbols;
-       unsigned int moff;
+       unsigned int moff, insn_idx;
        const char *name;
        __u32 member_idx;
        GElf_Sym sym;
@@ -8243,6 +8227,12 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
                                map->name, (size_t)rel.r_offset, shdr_idx);
                        return -LIBBPF_ERRNO__RELOC;
                }
+               if (sym.st_value % BPF_INSN_SZ) {
+                       pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
+                               map->name, (__u64)sym.st_value);
+                       return -LIBBPF_ERRNO__FORMAT;
+               }
+               insn_idx = sym.st_value / BPF_INSN_SZ;
 
                member = find_member_by_offset(st_ops->type, moff * 8);
                if (!member) {
@@ -8259,7 +8249,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
                        return -EINVAL;
                }
 
-               prog = bpf_object__find_prog_by_idx(obj, shdr_idx);
+               prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
                if (!prog) {
                        pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
                                map->name, shdr_idx, name);