bpf, libbpf: refactor relocation handling

Adjust the code for relocations slightly with no functional changes,
so that upcoming patches that will introduce support for relocations
into the .data, .rodata and .bss sections can be added independent
of these changes.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1ebfe7943d53139ecc8b3a8c3ada54e0b5298e98..6dba0f01673b1e16a2592a2385ed5f57e52969af 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -871,20 +871,20 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
                                obj->efile.symbols = data;
                                obj->efile.strtabidx = sh.sh_link;
                        }
-               } else if ((sh.sh_type == SHT_PROGBITS) &&
-                          (sh.sh_flags & SHF_EXECINSTR) &&
-                          (data->d_size > 0)) {
-                       if (strcmp(name, ".text") == 0)
-                               obj->efile.text_shndx = idx;
-                       err = bpf_object__add_program(obj, data->d_buf,
-                                                     data->d_size, name, idx);
-                       if (err) {
-                               char errmsg[STRERR_BUFSIZE];
-                               char *cp = libbpf_strerror_r(-err, errmsg,
-                                                            sizeof(errmsg));
-
-                               pr_warning("failed to alloc program %s (%s): %s",
-                                          name, obj->path, cp);
+               } else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
+                       if (sh.sh_flags & SHF_EXECINSTR) {
+                               if (strcmp(name, ".text") == 0)
+                                       obj->efile.text_shndx = idx;
+                               err = bpf_object__add_program(obj, data->d_buf,
+                                                             data->d_size, name, idx);
+                               if (err) {
+                                       char errmsg[STRERR_BUFSIZE];
+                                       char *cp = libbpf_strerror_r(-err, errmsg,
+                                                                    sizeof(errmsg));
+
+                                       pr_warning("failed to alloc program %s (%s): %s",
+                                                  name, obj->path, cp);
+                               }
                        }
                } else if (sh.sh_type == SHT_REL) {
                        void *reloc = obj->efile.reloc;
@@ -1046,24 +1046,26 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
                        return -LIBBPF_ERRNO__RELOC;
                }
 
-               /* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
-               for (map_idx = 0; map_idx < nr_maps; map_idx++) {
-                       if (maps[map_idx].offset == sym.st_value) {
-                               pr_debug("relocation: find map %zd (%s) for insn %u\n",
-                                        map_idx, maps[map_idx].name, insn_idx);
-                               break;
+               if (sym.st_shndx == maps_shndx) {
+                       /* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
+                       for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+                               if (maps[map_idx].offset == sym.st_value) {
+                                       pr_debug("relocation: find map %zd (%s) for insn %u\n",
+                                                map_idx, maps[map_idx].name, insn_idx);
+                                       break;
+                               }
                        }
-               }
 
-               if (map_idx >= nr_maps) {
-                       pr_warning("bpf relocation: map_idx %d large than %d\n",
-                                  (int)map_idx, (int)nr_maps - 1);
-                       return -LIBBPF_ERRNO__RELOC;
-               }
+                       if (map_idx >= nr_maps) {
+                               pr_warning("bpf relocation: map_idx %d large than %d\n",
+                                          (int)map_idx, (int)nr_maps - 1);
+                               return -LIBBPF_ERRNO__RELOC;
+                       }
 
-               prog->reloc_desc[i].type = RELO_LD64;
-               prog->reloc_desc[i].insn_idx = insn_idx;
-               prog->reloc_desc[i].map_idx = map_idx;
+                       prog->reloc_desc[i].type = RELO_LD64;
+                       prog->reloc_desc[i].insn_idx = insn_idx;
+                       prog->reloc_desc[i].map_idx = map_idx;
+               }
        }
        return 0;
 }
@@ -1425,7 +1427,7 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
                        }
                        insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
                        insns[insn_idx].imm = obj->maps[map_idx].fd;
-               } else {
+               } else if (prog->reloc_desc[i].type == RELO_CALL) {
                        err = bpf_program__reloc_text(prog, obj,
                                                      &prog->reloc_desc[i]);
                        if (err)