diff options
| -rwxr-xr-x | scripts/gen-btf.sh | 2 | ||||
| -rwxr-xr-x | scripts/link-vmlinux.sh | 2 | ||||
| -rw-r--r-- | tools/bpf/resolve_btfids/main.c | 117 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/Makefile | 2 |
4 files changed, 120 insertions, 3 deletions
diff --git a/scripts/gen-btf.sh b/scripts/gen-btf.sh index 12244dbe097c..0aec86615416 100755 --- a/scripts/gen-btf.sh +++ b/scripts/gen-btf.sh @@ -123,7 +123,7 @@ embed_btf_data() fi local btf_ids="${ELF_FILE}.BTF_ids" if [ -f "${btf_ids}" ]; then - ${OBJCOPY} --update-section .BTF_ids=${btf_ids} ${ELF_FILE} + ${RESOLVE_BTFIDS} --patch_btfids ${btf_ids} ${ELF_FILE} fi } diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index e2207e612ac3..1915adf3249b 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -266,7 +266,7 @@ vmlinux_link "${VMLINUX}" if is_enabled CONFIG_DEBUG_INFO_BTF; then info OBJCOPY ${btfids_vmlinux} - ${OBJCOPY} --update-section .BTF_ids=${btfids_vmlinux} ${VMLINUX} + ${RESOLVE_BTFIDS} --patch_btfids ${btfids_vmlinux} ${VMLINUX} fi mksysmap "${VMLINUX}" System.map diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index 2cbc252259be..df39982f51df 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -862,8 +862,119 @@ static inline int make_out_path(char *buf, u32 buf_sz, const char *in_path, cons return 0; } +/* + * Patch the .BTF_ids section of an ELF file with data from provided file. + * Equivalent to: objcopy --update-section .BTF_ids=<btfids> <elf> + * + * 1. Find .BTF_ids section in the ELF + * 2. Verify that blob file size matches section size + * 3. Update section data buffer with blob data + * 4. Write the ELF file + */ +static int patch_btfids(const char *btfids_path, const char *elf_path) +{ + Elf_Scn *scn = NULL; + FILE *btfids_file; + size_t shdrstrndx; + int fd, err = -1; + Elf_Data *data; + struct stat st; + GElf_Shdr sh; + char *name; + Elf *elf; + + elf_version(EV_CURRENT); + + fd = open(elf_path, O_RDWR, 0666); + if (fd < 0) { + pr_err("FAILED to open %s: %s\n", elf_path, strerror(errno)); + return -1; + } + + elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL); + if (!elf) { + close(fd); + pr_err("FAILED cannot create ELF descriptor: %s\n", elf_errmsg(-1)); + return -1; + } + + elf_flagelf(elf, ELF_C_SET, ELF_F_LAYOUT); + + if (elf_getshdrstrndx(elf, &shdrstrndx) != 0) { + pr_err("FAILED cannot get shdr str ndx\n"); + goto out; + } + + while ((scn = elf_nextscn(elf, scn)) != NULL) { + + if (gelf_getshdr(scn, &sh) != &sh) { + pr_err("FAILED to get section header\n"); + goto out; + } + + name = elf_strptr(elf, shdrstrndx, sh.sh_name); + if (!name) + continue; + + if (strcmp(name, BTF_IDS_SECTION) == 0) + break; + } + + if (!scn) { + pr_err("FAILED: section %s not found in %s\n", BTF_IDS_SECTION, elf_path); + goto out; + } + + data = elf_getdata(scn, NULL); + if (!data) { + pr_err("FAILED to get %s section data from %s\n", BTF_IDS_SECTION, elf_path); + goto out; + } + + if (stat(btfids_path, &st) < 0) { + pr_err("FAILED to stat %s: %s\n", btfids_path, strerror(errno)); + goto out; + } + + if ((size_t)st.st_size != data->d_size) { + pr_err("FAILED: size mismatch - %s section in %s is %zu bytes, %s is %zu bytes\n", + BTF_IDS_SECTION, elf_path, data->d_size, btfids_path, (size_t)st.st_size); + goto out; + } + + btfids_file = fopen(btfids_path, "rb"); + if (!btfids_file) { + pr_err("FAILED to open %s: %s\n", btfids_path, strerror(errno)); + goto out; + } + + pr_debug("Copying data from %s to %s section of %s (%zu bytes)\n", + btfids_path, BTF_IDS_SECTION, elf_path, data->d_size); + + if (fread(data->d_buf, data->d_size, 1, btfids_file) != 1) { + pr_err("FAILED to read %s\n", btfids_path); + fclose(btfids_file); + goto out; + } + fclose(btfids_file); + + elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY); + if (elf_update(elf, ELF_C_WRITE) < 0) { + pr_err("FAILED to update ELF file %s\n", elf_path); + goto out; + } + + err = 0; +out: + elf_end(elf); + close(fd); + + return err; +} + static const char * const resolve_btfids_usage[] = { "resolve_btfids [<options>] <ELF object>", + "resolve_btfids --patch_btfids <.BTF_ids file> <ELF object>", NULL }; @@ -880,6 +991,7 @@ int main(int argc, const char **argv) .funcs = RB_ROOT, .sets = RB_ROOT, }; + const char *btfids_path = NULL; bool fatal_warnings = false; char out_path[PATH_MAX]; @@ -894,6 +1006,8 @@ int main(int argc, const char **argv) "turn warnings into errors"), OPT_BOOLEAN(0, "distill_base", &obj.distill_base, "distill --btf_base and emit .BTF.base section data"), + OPT_STRING(0, "patch_btfids", &btfids_path, "file", + "path to .BTF_ids section data blob to patch into ELF file"), OPT_END() }; int err = -1; @@ -905,6 +1019,9 @@ int main(int argc, const char **argv) obj.path = argv[0]; + if (btfids_path) + return patch_btfids(btfids_path, obj.path); + if (load_btf(&obj)) goto out; diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index f28a32b16ff0..9488d076c740 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -657,7 +657,7 @@ $(TRUNNER_TEST_OBJS): $(TRUNNER_OUTPUT)/%.test.o: \ $$(if $$(TEST_NEEDS_BTFIDS), \ $$(call msg,BTFIDS,$(TRUNNER_BINARY),$$@) \ $(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@; \ - $(OBJCOPY) --update-section .BTF_ids=$$@.BTF_ids $$@) + $(RESOLVE_BTFIDS) --patch_btfids $$@.BTF_ids $$@) $(TRUNNER_TEST_OBJS:.o=.d): $(TRUNNER_OUTPUT)/%.test.d: \ $(TRUNNER_TESTS_DIR)/%.c \ |