From f90eb70d4489ea6fa6f3a7638aa614e15ad7181f Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 9 Aug 2023 10:34:21 +0200 Subject: libbpf: Add elf_open/elf_close functions Adding elf_open/elf_close functions and using it in elf_find_func_offset_from_file function. It will be used in following changes to save some common code. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230809083440.3209381-10-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/elf.c | 61 +++++++++++++++++++++++++++-------------- tools/lib/bpf/libbpf_internal.h | 8 ++++++ tools/lib/bpf/usdt.c | 30 ++++++-------------- 3 files changed, 57 insertions(+), 42 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c index 735ef10093ac..71363acdeb67 100644 --- a/tools/lib/bpf/elf.c +++ b/tools/lib/bpf/elf.c @@ -10,6 +10,42 @@ #define STRERR_BUFSIZE 128 +int elf_open(const char *binary_path, struct elf_fd *elf_fd) +{ + char errmsg[STRERR_BUFSIZE]; + int fd, ret; + Elf *elf; + + if (elf_version(EV_CURRENT) == EV_NONE) { + pr_warn("elf: failed to init libelf for %s\n", binary_path); + return -LIBBPF_ERRNO__LIBELF; + } + fd = open(binary_path, O_RDONLY | O_CLOEXEC); + if (fd < 0) { + ret = -errno; + pr_warn("elf: failed to open %s: %s\n", binary_path, + libbpf_strerror_r(ret, errmsg, sizeof(errmsg))); + return ret; + } + elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); + if (!elf) { + pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1)); + close(fd); + return -LIBBPF_ERRNO__FORMAT; + } + elf_fd->fd = fd; + elf_fd->elf = elf; + return 0; +} + +void elf_close(struct elf_fd *elf_fd) +{ + if (!elf_fd) + return; + elf_end(elf_fd->elf); + close(elf_fd->fd); +} + /* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */ static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn) { @@ -170,28 +206,13 @@ out: */ long elf_find_func_offset_from_file(const char *binary_path, const char *name) { - char errmsg[STRERR_BUFSIZE]; + struct elf_fd elf_fd; long ret = -ENOENT; - Elf *elf; - int fd; - fd = open(binary_path, O_RDONLY | O_CLOEXEC); - if (fd < 0) { - ret = -errno; - pr_warn("failed to open %s: %s\n", binary_path, - libbpf_strerror_r(ret, errmsg, sizeof(errmsg))); + ret = elf_open(binary_path, &elf_fd); + if (ret) return ret; - } - elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); - if (!elf) { - pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1)); - close(fd); - return -LIBBPF_ERRNO__FORMAT; - } - - ret = elf_find_func_offset(elf, binary_path, name); - elf_end(elf); - close(fd); + ret = elf_find_func_offset(elf_fd.elf, binary_path, name); + elf_close(&elf_fd); return ret; } - diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 44eb63541507..0bbcd8e6fdc5 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -581,4 +581,12 @@ int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts); long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name); long elf_find_func_offset_from_file(const char *binary_path, const char *name); +struct elf_fd { + Elf *elf; + int fd; +}; + +int elf_open(const char *binary_path, struct elf_fd *elf_fd); +void elf_close(struct elf_fd *elf_fd); + #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c index 37455d00b239..8322337ab65b 100644 --- a/tools/lib/bpf/usdt.c +++ b/tools/lib/bpf/usdt.c @@ -946,32 +946,22 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct const char *usdt_provider, const char *usdt_name, __u64 usdt_cookie) { - int i, fd, err, spec_map_fd, ip_map_fd; + int i, err, spec_map_fd, ip_map_fd; LIBBPF_OPTS(bpf_uprobe_opts, opts); struct hashmap *specs_hash = NULL; struct bpf_link_usdt *link = NULL; struct usdt_target *targets = NULL; + struct elf_fd elf_fd; size_t target_cnt; - Elf *elf; spec_map_fd = bpf_map__fd(man->specs_map); ip_map_fd = bpf_map__fd(man->ip_to_spec_id_map); - fd = open(path, O_RDONLY | O_CLOEXEC); - if (fd < 0) { - err = -errno; - pr_warn("usdt: failed to open ELF binary '%s': %d\n", path, err); + err = elf_open(path, &elf_fd); + if (err) return libbpf_err_ptr(err); - } - elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); - if (!elf) { - err = -EBADF; - pr_warn("usdt: failed to parse ELF binary '%s': %s\n", path, elf_errmsg(-1)); - goto err_out; - } - - err = sanity_check_usdt_elf(elf, path); + err = sanity_check_usdt_elf(elf_fd.elf, path); if (err) goto err_out; @@ -984,7 +974,7 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct /* discover USDT in given binary, optionally limiting * activations to a given PID, if pid > 0 */ - err = collect_usdt_targets(man, elf, path, pid, usdt_provider, usdt_name, + err = collect_usdt_targets(man, elf_fd.elf, path, pid, usdt_provider, usdt_name, usdt_cookie, &targets, &target_cnt); if (err <= 0) { err = (err == 0) ? -ENOENT : err; @@ -1069,9 +1059,7 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct free(targets); hashmap__free(specs_hash); - elf_end(elf); - close(fd); - + elf_close(&elf_fd); return &link->link; err_out: @@ -1079,9 +1067,7 @@ err_out: bpf_link__destroy(&link->link); free(targets); hashmap__free(specs_hash); - if (elf) - elf_end(elf); - close(fd); + elf_close(&elf_fd); return libbpf_err_ptr(err); } -- cgit v1.2.3