diff options
Diffstat (limited to 'tools/lib/bpf/btf.c')
-rw-r--r-- | tools/lib/bpf/btf.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 03348c4d6bd4..6139550810a1 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -4,10 +4,12 @@ #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <fcntl.h> #include <unistd.h> #include <errno.h> #include <linux/err.h> #include <linux/btf.h> +#include <gelf.h> #include "btf.h" #include "bpf.h" #include "libbpf.h" @@ -417,6 +419,132 @@ done: return btf; } +static bool btf_check_endianness(const GElf_Ehdr *ehdr) +{ +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ + return ehdr->e_ident[EI_DATA] == ELFDATA2LSB; +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ + return ehdr->e_ident[EI_DATA] == ELFDATA2MSB; +#else +# error "Unrecognized __BYTE_ORDER__" +#endif +} + +struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext) +{ + Elf_Data *btf_data = NULL, *btf_ext_data = NULL; + int err = 0, fd = -1, idx = 0; + struct btf *btf = NULL; + Elf_Scn *scn = NULL; + Elf *elf = NULL; + GElf_Ehdr ehdr; + + if (elf_version(EV_CURRENT) == EV_NONE) { + pr_warning("failed to init libelf for %s\n", path); + return ERR_PTR(-LIBBPF_ERRNO__LIBELF); + } + + fd = open(path, O_RDONLY); + if (fd < 0) { + err = -errno; + pr_warning("failed to open %s: %s\n", path, strerror(errno)); + return ERR_PTR(err); + } + + err = -LIBBPF_ERRNO__FORMAT; + + elf = elf_begin(fd, ELF_C_READ, NULL); + if (!elf) { + pr_warning("failed to open %s as ELF file\n", path); + goto done; + } + if (!gelf_getehdr(elf, &ehdr)) { + pr_warning("failed to get EHDR from %s\n", path); + goto done; + } + if (!btf_check_endianness(&ehdr)) { + pr_warning("non-native ELF endianness is not supported\n"); + goto done; + } + if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) { + pr_warning("failed to get e_shstrndx from %s\n", path); + goto done; + } + + while ((scn = elf_nextscn(elf, scn)) != NULL) { + GElf_Shdr sh; + char *name; + + idx++; + if (gelf_getshdr(scn, &sh) != &sh) { + pr_warning("failed to get section(%d) header from %s\n", + idx, path); + goto done; + } + name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name); + if (!name) { + pr_warning("failed to get section(%d) name from %s\n", + idx, path); + goto done; + } + if (strcmp(name, BTF_ELF_SEC) == 0) { + btf_data = elf_getdata(scn, 0); + if (!btf_data) { + pr_warning("failed to get section(%d, %s) data from %s\n", + idx, name, path); + goto done; + } + continue; + } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) { + btf_ext_data = elf_getdata(scn, 0); + if (!btf_ext_data) { + pr_warning("failed to get section(%d, %s) data from %s\n", + idx, name, path); + goto done; + } + continue; + } + } + + err = 0; + + if (!btf_data) { + err = -ENOENT; + goto done; + } + btf = btf__new(btf_data->d_buf, btf_data->d_size); + if (IS_ERR(btf)) + goto done; + + if (btf_ext && btf_ext_data) { + *btf_ext = btf_ext__new(btf_ext_data->d_buf, + btf_ext_data->d_size); + if (IS_ERR(*btf_ext)) + goto done; + } else if (btf_ext) { + *btf_ext = NULL; + } +done: + if (elf) + elf_end(elf); + close(fd); + + if (err) + return ERR_PTR(err); + /* + * btf is always parsed before btf_ext, so no need to clean up + * btf_ext, if btf loading failed + */ + if (IS_ERR(btf)) + return btf; + if (btf_ext && IS_ERR(*btf_ext)) { + btf__free(btf); + err = PTR_ERR(*btf_ext); + return ERR_PTR(err); + } + return btf; +} + static int compare_vsi_off(const void *_a, const void *_b) { const struct btf_var_secinfo *a = _a; |