From f0187f0b17fad7439f510eff4d65606c9ea1190f Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 7 Dec 2018 16:42:29 -0800 Subject: [PATCH] bpf: libbpf: Refactor and bug fix on the bpf_func_info loading logic This patch refactor and fix a bug in the libbpf's bpf_func_info loading logic. The bug fix and refactoring are targeting the same commit 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections") which is in the bpf-next branch. 1) In bpf_load_program_xattr(), it should retry when errno == E2BIG regardless of log_buf and log_buf_sz. This patch fixes it. 2) btf_ext__reloc_init() and btf_ext__reloc() are essentially the same except btf_ext__reloc_init() always has insns_cnt == 0. Hence, btf_ext__reloc_init() is removed. btf_ext__reloc() is also renamed to btf_ext__reloc_func_info() to get ready for the line_info support in the next patch. 3) Consolidate func_info section logic from "btf_ext_parse_hdr()", "btf_ext_validate_func_info()" and "btf_ext__new()" to a new function "btf_ext_copy_func_info()" such that similar logic can be reused by the later libbpf's line_info patch. 4) The next line_info patch will store line_info_cnt instead of line_info_len in the bpf_program because the kernel is taking line_info_cnt also. It will save a few "len" to "cnt" conversions and will also save some function args. Hence, this patch also makes bpf_program to store func_info_cnt instead of func_info_len. 5) btf_ext depends on btf. e.g. the func_info's type_id in ".BTF.ext" is not useful when ".BTF" is absent. This patch only init the obj->btf_ext pointer after it has successfully init the obj->btf pointer. This can avoid always checking "obj->btf && obj->btf_ext" together for accessing ".BTF.ext". Checking "obj->btf_ext" alone will do. 6) Move "struct btf_sec_func_info" from btf.h to btf.c. There is no external usage outside btf.c. Fixes: 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections") Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/bpf.c | 7 +- tools/lib/bpf/btf.c | 191 ++++++++++++++++------------------------- tools/lib/bpf/btf.h | 17 +--- tools/lib/bpf/libbpf.c | 139 ++++++++++++++++++++---------- 4 files changed, 177 insertions(+), 177 deletions(-) diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 5c3be06bf0dd..9fbbc0ed5952 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -205,7 +205,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr, min(name_len, BPF_OBJ_NAME_LEN - 1)); fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); - if (fd >= 0 || !log_buf || !log_buf_sz) + if (fd >= 0) return fd; /* After bpf_prog_load, the kernel may modify certain attributes @@ -244,10 +244,13 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr, fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); - if (fd >= 0 || !log_buf || !log_buf_sz) + if (fd >= 0) goto done; } + if (!log_buf || !log_buf_sz) + goto done; + /* Try again with log */ attr.log_buf = ptr_to_u64(log_buf); attr.log_size = log_buf_sz; diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 85d6446cf832..aa4fa02b13fc 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -43,6 +43,13 @@ struct btf_ext { __u32 func_info_len; }; +struct btf_sec_func_info { + __u32 sec_name_off; + __u32 num_func_info; + /* Followed by num_func_info number of bpf func_info records */ + __u8 data[0]; +}; + /* The minimum bpf_func_info checked by the loader */ struct bpf_func_info_min { __u32 insn_off; @@ -479,41 +486,66 @@ exit_free: return err; } -static int btf_ext_validate_func_info(const void *finfo, __u32 size, - btf_print_fn_t err_log) +static int btf_ext_copy_func_info(struct btf_ext *btf_ext, + __u8 *data, __u32 data_size, + btf_print_fn_t err_log) { - int sec_hdrlen = sizeof(struct btf_sec_func_info); - __u32 size_left, num_records, record_size; + const struct btf_ext_header *hdr = (struct btf_ext_header *)data; const struct btf_sec_func_info *sinfo; - __u64 total_record_size; + __u32 info_left, record_size; + /* The start of the info sec (including the __u32 record_size). */ + const void *info; + + /* data and data_size do not include btf_ext_header from now on */ + data = data + hdr->hdr_len; + data_size -= hdr->hdr_len; + + if (hdr->func_info_off & 0x03) { + elog("BTF.ext func_info section is not aligned to 4 bytes\n"); + return -EINVAL; + } + + if (data_size < hdr->func_info_off || + hdr->func_info_len > data_size - hdr->func_info_off) { + elog("func_info section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n", + hdr->func_info_off, hdr->func_info_len); + return -EINVAL; + } + + info = data + hdr->func_info_off; + info_left = hdr->func_info_len; /* At least a func_info record size */ - if (size < sizeof(__u32)) { + if (info_left < sizeof(__u32)) { elog("BTF.ext func_info record size not found"); return -EINVAL; } - /* The record size needs to meet below minimum standard */ - record_size = *(__u32 *)finfo; + /* The record size needs to meet the minimum standard */ + record_size = *(__u32 *)info; if (record_size < sizeof(struct bpf_func_info_min) || - record_size % sizeof(__u32)) { + record_size & 0x03) { elog("BTF.ext func_info invalid record size"); return -EINVAL; } - sinfo = finfo + sizeof(__u32); - size_left = size - sizeof(__u32); + sinfo = info + sizeof(__u32); + info_left -= sizeof(__u32); /* If no func_info records, return failure now so .BTF.ext * won't be used. */ - if (!size_left) { + if (!info_left) { elog("BTF.ext no func info records"); return -EINVAL; } - while (size_left) { - if (size_left < sec_hdrlen) { + while (info_left) { + unsigned int sec_hdrlen = sizeof(struct btf_sec_func_info); + __u64 total_record_size; + __u32 num_records; + + if (info_left < sec_hdrlen) { elog("BTF.ext func_info header not found"); return -EINVAL; } @@ -526,15 +558,23 @@ static int btf_ext_validate_func_info(const void *finfo, __u32 size, total_record_size = sec_hdrlen + (__u64)num_records * record_size; - if (size_left < total_record_size) { + if (info_left < total_record_size) { elog("incorrect BTF.ext num_func_info"); return -EINVAL; } - size_left -= total_record_size; + info_left -= total_record_size; sinfo = (void *)sinfo + total_record_size; } + btf_ext->func_info_len = hdr->func_info_len - sizeof(__u32); + btf_ext->func_info_rec_size = record_size; + btf_ext->func_info = malloc(btf_ext->func_info_len); + if (!btf_ext->func_info) + return -ENOMEM; + memcpy(btf_ext->func_info, info + sizeof(__u32), + btf_ext->func_info_len); + return 0; } @@ -542,8 +582,6 @@ static int btf_ext_parse_hdr(__u8 *data, __u32 data_size, btf_print_fn_t err_log) { const struct btf_ext_header *hdr = (struct btf_ext_header *)data; - __u32 meta_left, last_func_info_pos; - void *finfo; if (data_size < offsetof(struct btf_ext_header, func_info_off) || data_size < hdr->hdr_len) { @@ -566,34 +604,12 @@ static int btf_ext_parse_hdr(__u8 *data, __u32 data_size, return -ENOTSUP; } - meta_left = data_size - hdr->hdr_len; - if (!meta_left) { + if (data_size == hdr->hdr_len) { elog("BTF.ext has no data\n"); return -EINVAL; } - if (meta_left < hdr->func_info_off) { - elog("Invalid BTF.ext func_info section offset:%u\n", - hdr->func_info_off); - return -EINVAL; - } - - if (hdr->func_info_off & 0x03) { - elog("BTF.ext func_info section is not aligned to 4 bytes\n"); - return -EINVAL; - } - - last_func_info_pos = hdr->hdr_len + hdr->func_info_off + - hdr->func_info_len; - if (last_func_info_pos > data_size) { - elog("Invalid BTF.ext func_info section size:%u\n", - hdr->func_info_len); - return -EINVAL; - } - - finfo = data + hdr->hdr_len + hdr->func_info_off; - return btf_ext_validate_func_info(finfo, hdr->func_info_len, - err_log); + return 0; } void btf_ext__free(struct btf_ext *btf_ext) @@ -607,10 +623,7 @@ void btf_ext__free(struct btf_ext *btf_ext) struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log) { - const struct btf_ext_header *hdr; struct btf_ext *btf_ext; - void *org_fdata, *fdata; - __u32 hdrlen, size_u32; int err; err = btf_ext_parse_hdr(data, size, err_log); @@ -621,81 +634,18 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log) if (!btf_ext) return ERR_PTR(-ENOMEM); - hdr = (const struct btf_ext_header *)data; - hdrlen = hdr->hdr_len; - size_u32 = sizeof(__u32); - fdata = malloc(hdr->func_info_len - size_u32); - if (!fdata) { - free(btf_ext); - return ERR_PTR(-ENOMEM); + err = btf_ext_copy_func_info(btf_ext, data, size, err_log); + if (err) { + btf_ext__free(btf_ext); + return ERR_PTR(err); } - /* remember record size and copy rest of func_info data */ - org_fdata = data + hdrlen + hdr->func_info_off; - btf_ext->func_info_rec_size = *(__u32 *)org_fdata; - memcpy(fdata, org_fdata + size_u32, hdr->func_info_len - size_u32); - btf_ext->func_info = fdata; - btf_ext->func_info_len = hdr->func_info_len - size_u32; - return btf_ext; } -int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext, - const char *sec_name, void **func_info, - __u32 *func_info_rec_size, __u32 *func_info_len) -{ - __u32 sec_hdrlen = sizeof(struct btf_sec_func_info); - __u32 i, record_size, records_len; - struct btf_sec_func_info *sinfo; - const char *info_sec_name; - __s64 remain_len; - void *data; - - record_size = btf_ext->func_info_rec_size; - sinfo = btf_ext->func_info; - remain_len = btf_ext->func_info_len; - - while (remain_len > 0) { - records_len = sinfo->num_func_info * record_size; - info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off); - if (strcmp(info_sec_name, sec_name)) { - remain_len -= sec_hdrlen + records_len; - sinfo = (void *)sinfo + sec_hdrlen + records_len; - continue; - } - - data = malloc(records_len); - if (!data) - return -ENOMEM; - - memcpy(data, sinfo->data, records_len); - - /* adjust the insn_off, the data in .BTF.ext is - * the actual byte offset, and the kernel expects - * the offset in term of bpf_insn. - * - * adjust the insn offset only, the rest data will - * be passed to kernel. - */ - for (i = 0; i < sinfo->num_func_info; i++) { - struct bpf_func_info_min *record; - - record = data + i * record_size; - record->insn_off /= sizeof(struct bpf_insn); - } - - *func_info = data; - *func_info_len = records_len; - *func_info_rec_size = record_size; - return 0; - } - - return -EINVAL; -} - -int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext, - const char *sec_name, __u32 insns_cnt, - void **func_info, __u32 *func_info_len) +int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext, + const char *sec_name, __u32 insns_cnt, + void **func_info, __u32 *cnt) { __u32 sec_hdrlen = sizeof(struct btf_sec_func_info); __u32 i, record_size, existing_flen, records_len; @@ -716,7 +666,7 @@ int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext, continue; } - existing_flen = *func_info_len; + existing_flen = (*cnt) * record_size; data = realloc(*func_info, existing_flen + records_len); if (!data) return -ENOMEM; @@ -734,9 +684,14 @@ int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext, insns_cnt; } *func_info = data; - *func_info_len = existing_flen + records_len; + *cnt += sinfo->num_func_info; return 0; } - return -EINVAL; + return -ENOENT; +} + +__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext) +{ + return btf_ext->func_info_rec_size; } diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 5336b2f37293..936177a538cd 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -53,13 +53,6 @@ struct btf_ext_header { __u32 func_info_len; }; -struct btf_sec_func_info { - __u32 sec_name_off; - __u32 num_func_info; - /* Followed by num_func_info number of bpf func_info records */ - __u8 data[0]; -}; - typedef int (*btf_print_fn_t)(const char *, ...) __attribute__((format(printf, 1, 2))); @@ -77,12 +70,10 @@ LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log); void btf_ext__free(struct btf_ext *btf_ext); -int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext, - const char *sec_name, void **func_info, - __u32 *func_info_rec_size, __u32 *func_info_len); -int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext, - const char *sec_name, __u32 insns_cnt, void **func_info, - __u32 *func_info_len); +int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext, + const char *sec_name, __u32 insns_cnt, + void **func_info, __u32 *func_info_len); +__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext); #ifdef __cplusplus } /* extern "C" */ diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 59b748ebd15f..4ea3368bf803 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -167,7 +167,7 @@ struct bpf_program { int btf_fd; void *func_info; __u32 func_info_rec_size; - __u32 func_info_len; + __u32 func_info_cnt; struct bpf_capabilities *caps; }; @@ -779,6 +779,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) { Elf *elf = obj->efile.elf; GElf_Ehdr *ep = &obj->efile.ehdr; + Elf_Data *btf_ext_data = NULL; Elf_Scn *scn = NULL; int idx = 0, err = 0; @@ -841,14 +842,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) obj->btf = NULL; } } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) { - obj->btf_ext = btf_ext__new(data->d_buf, data->d_size, - __pr_debug); - if (IS_ERR(obj->btf_ext)) { - pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n", - BTF_EXT_ELF_SEC, - PTR_ERR(obj->btf_ext)); - obj->btf_ext = NULL; - } + btf_ext_data = data; } else if (sh.sh_type == SHT_SYMTAB) { if (obj->efile.symbols) { pr_warning("bpf: multiple SYMTAB in %s\n", @@ -910,6 +904,22 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) pr_warning("Corrupted ELF file: index of strtab invalid\n"); return LIBBPF_ERRNO__FORMAT; } + if (btf_ext_data) { + if (!obj->btf) { + pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n", + BTF_EXT_ELF_SEC, BTF_ELF_SEC); + } else { + obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, + btf_ext_data->d_size, + __pr_debug); + if (IS_ERR(obj->btf_ext)) { + pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n", + BTF_EXT_ELF_SEC, + PTR_ERR(obj->btf_ext)); + obj->btf_ext = NULL; + } + } + } if (obj->efile.maps_shndx >= 0) { err = bpf_object__init_maps(obj, flags); if (err) @@ -1275,6 +1285,69 @@ bpf_object__create_maps(struct bpf_object *obj) return 0; } +static int +check_btf_ext_reloc_err(struct bpf_program *prog, int err, + void *btf_prog_info, const char *info_name) +{ + if (err != -ENOENT) { + pr_warning("Error in loading %s for sec %s.\n", + info_name, prog->section_name); + return err; + } + + /* err == -ENOENT (i.e. prog->section_name not found in btf_ext) */ + + if (btf_prog_info) { + /* + * Some info has already been found but has problem + * in the last btf_ext reloc. Must have to error + * out. + */ + pr_warning("Error in relocating %s for sec %s.\n", + info_name, prog->section_name); + return err; + } + + /* + * Have problem loading the very first info. Ignore + * the rest. + */ + pr_warning("Cannot find %s for main program sec %s. Ignore all %s.\n", + info_name, prog->section_name, info_name); + return 0; +} + +static int +bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj, + const char *section_name, __u32 insn_offset) +{ + int err; + + if (!insn_offset || prog->func_info) { + /* + * !insn_offset => main program + * + * For sub prog, the main program's func_info has to + * be loaded first (i.e. prog->func_info != NULL) + */ + err = btf_ext__reloc_func_info(obj->btf, obj->btf_ext, + section_name, insn_offset, + &prog->func_info, + &prog->func_info_cnt); + if (err) + return check_btf_ext_reloc_err(prog, err, + prog->func_info, + "bpf_func_info"); + + prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext); + } + + if (!insn_offset) + prog->btf_fd = btf__fd(obj->btf); + + return 0; +} + static int bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj, struct reloc_desc *relo) @@ -1306,17 +1379,12 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj, return -ENOMEM; } - if (obj->btf && obj->btf_ext) { - err = btf_ext__reloc(obj->btf, obj->btf_ext, - text->section_name, - prog->insns_cnt, - &prog->func_info, - &prog->func_info_len); - if (err) { - pr_warning("error in btf_ext__reloc for sec %s\n", - text->section_name); + if (obj->btf_ext) { + err = bpf_program_reloc_btf_ext(prog, obj, + text->section_name, + prog->insns_cnt); + if (err) return err; - } } memcpy(new_insn + prog->insns_cnt, text->insns, @@ -1341,18 +1409,11 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj) if (!prog) return 0; - if (obj->btf && obj->btf_ext) { - err = btf_ext__reloc_init(obj->btf, obj->btf_ext, - prog->section_name, - &prog->func_info, - &prog->func_info_rec_size, - &prog->func_info_len); - if (err) { - pr_warning("err in btf_ext__reloc_init for sec %s\n", - prog->section_name); + if (obj->btf_ext) { + err = bpf_program_reloc_btf_ext(prog, obj, + prog->section_name, 0); + if (err) return err; - } - prog->btf_fd = btf__fd(obj->btf); } if (!prog->reloc_desc) @@ -1444,8 +1505,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj) static int load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, - char *license, __u32 kern_version, int *pfd, - __u32 func_info_cnt) + char *license, __u32 kern_version, int *pfd) { struct bpf_load_program_attr load_attr; char *cp, errmsg[STRERR_BUFSIZE]; @@ -1465,8 +1525,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, load_attr.prog_btf_fd = prog->btf_fd >= 0 ? prog->btf_fd : 0; load_attr.func_info = prog->func_info; load_attr.func_info_rec_size = prog->func_info_rec_size; - load_attr.func_info_cnt = func_info_cnt; - + load_attr.func_info_cnt = prog->func_info_cnt; if (!load_attr.insns || !load_attr.insns_cnt) return -EINVAL; @@ -1523,14 +1582,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_version) { - __u32 func_info_cnt; int err = 0, fd, i; - if (prog->func_info_len == 0) - func_info_cnt = 0; - else - func_info_cnt = prog->func_info_len / prog->func_info_rec_size; - if (prog->instances.nr < 0 || !prog->instances.fds) { if (prog->preprocessor) { pr_warning("Internal error: can't load program '%s'\n", @@ -1553,8 +1606,7 @@ bpf_program__load(struct bpf_program *prog, prog->section_name, prog->instances.nr); } err = load_program(prog, prog->insns, prog->insns_cnt, - license, kern_version, &fd, - func_info_cnt); + license, kern_version, &fd); if (!err) prog->instances.fds[0] = fd; goto out; @@ -1584,8 +1636,7 @@ bpf_program__load(struct bpf_program *prog, err = load_program(prog, result.new_insn_ptr, result.new_insn_cnt, - license, kern_version, &fd, - func_info_cnt); + license, kern_version, &fd); if (err) { pr_warning("Loading the %dth instance of program '%s' failed\n", -- 2.30.2