[PATCH openEuler-22.09 312/379] libbpf: Use Elf64-specific types explicitly for dealing with ELF

From: Andrii Nakryiko andrii@kernel.org

mainline inclusion from mainline-5.16-rc1 commit ad23b7238474c6319bf692ae6ce037d9696df1d1 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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Minimize the usage of class-agnostic gelf_xxx() APIs from libelf. These APIs require copying ELF data structures into local GElf_xxx structs and have a more cumbersome API. BPF ELF file is defined to be always 64-bit ELF object, even when intended to be run on 32-bit host architectures, so there is no need to do class-agnostic conversions everywhere. BPF static linker implementation within libbpf has been using Elf64-specific types since initial implementation.

Add two simple helpers, elf_sym_by_idx() and elf_rel_by_idx(), for more succinct direct access to ELF symbol and relocation records within ELF data itself and switch all the GElf_xxx usage into Elf64_xxx equivalents. The only remaining place within libbpf.c that's still using gelf API is gelf_getclass(), as there doesn't seem to be a direct way to get underlying ELF bitness.

No functional changes intended.

Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Song Liu songliubraving@fb.com Link: https://lore.kernel.org/bpf/20211021014404.2635234-4-andrii@kernel.org (cherry picked from commit ad23b7238474c6319bf692ae6ce037d9696df1d1) Signed-off-by: Wang Yufen wangyufen@huawei.com --- tools/lib/bpf/libbpf.c | 353 ++++++++++++++++++-------------- tools/lib/bpf/libbpf_internal.h | 4 +- tools/lib/bpf/linker.c | 1 - 3 files changed, 196 insertions(+), 162 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0f8f1e41ff22..9413360be003 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -441,7 +441,7 @@ struct elf_state { const void *obj_buf; size_t obj_buf_sz; Elf *elf; - GElf_Ehdr ehdr; + Elf64_Ehdr *ehdr; Elf_Data *symbols; Elf_Data *data; Elf_Data *rodata; @@ -450,7 +450,7 @@ struct elf_state { size_t shstrndx; /* section index for section name strings */ size_t strtabidx; struct { - GElf_Shdr shdr; + Elf64_Shdr *shdr; Elf_Data *data; } *reloc_sects; int nr_reloc_sects; @@ -525,9 +525,11 @@ static const char *elf_sym_str(const struct bpf_object *obj, size_t off); static const char *elf_sec_str(const struct bpf_object *obj, size_t off); static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx); static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name); -static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr); +static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn); static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn); static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn); +static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx); +static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);

void bpf_program__unload(struct bpf_program *prog) { @@ -669,25 +671,25 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms; int nr_progs, err, i; const char *name; - GElf_Sym sym; + Elf64_Sym *sym;

progs = obj->programs; nr_progs = obj->nr_programs; - nr_syms = symbols->d_size / sizeof(GElf_Sym); + nr_syms = symbols->d_size / sizeof(Elf64_Sym); sec_off = 0;

for (i = 0; i < nr_syms; i++) { - if (!gelf_getsym(symbols, i, &sym)) - continue; - if (sym.st_shndx != sec_idx) + sym = elf_sym_by_idx(obj, i); + + if (sym->st_shndx != sec_idx) continue; - if (GELF_ST_TYPE(sym.st_info) != STT_FUNC) + if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC) continue;

- prog_sz = sym.st_size; - sec_off = sym.st_value; + prog_sz = sym->st_size; + sec_off = sym->st_value;

- name = elf_sym_str(obj, sym.st_name); + name = elf_sym_str(obj, sym->st_name); if (!name) { pr_warn("sec '%s': failed to get symbol name for offset %zu\n", sec_name, sec_off); @@ -700,7 +702,7 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, return -LIBBPF_ERRNO__FORMAT; }

- if (sec_idx != obj->efile.text_shndx && GELF_ST_BIND(sym.st_info) == STB_LOCAL) { + if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) { pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name); return -ENOTSUP; } @@ -733,9 +735,9 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, * as static to enable more permissive BPF verification mode * with more outside context available to BPF verifier */ - if (GELF_ST_BIND(sym.st_info) != STB_LOCAL - && (GELF_ST_VISIBILITY(sym.st_other) == STV_HIDDEN - || GELF_ST_VISIBILITY(sym.st_other) == STV_INTERNAL)) + if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL + && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN + || ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL)) prog->mark_btf_static = true;

nr_progs++; @@ -1175,8 +1177,9 @@ static void bpf_object__elf_finish(struct bpf_object *obj)

static int bpf_object__elf_init(struct bpf_object *obj) { + Elf64_Ehdr *ehdr; int err = 0; - GElf_Ehdr *ep; + Elf *elf;

if (obj->efile.elf) { pr_warn("elf: init internal error\n"); @@ -1188,8 +1191,7 @@ static int bpf_object__elf_init(struct bpf_object *obj) * obj_buf should have been validated by * bpf_object__open_buffer(). */ - obj->efile.elf = elf_memory((char *)obj->efile.obj_buf, - obj->efile.obj_buf_sz); + elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz); } else { obj->efile.fd = open(obj->path, O_RDONLY); if (obj->efile.fd < 0) { @@ -1201,23 +1203,37 @@ static int bpf_object__elf_init(struct bpf_object *obj) return err; }

- obj->efile.elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL); + elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL); }

- if (!obj->efile.elf) { + if (!elf) { pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__LIBELF; goto errout; }

- if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) { + obj->efile.elf = elf; + + if (elf_kind(elf) != ELF_K_ELF) { + err = -LIBBPF_ERRNO__FORMAT; + pr_warn("elf: '%s' is not a proper ELF object\n", obj->path); + goto errout; + } + + if (gelf_getclass(elf) != ELFCLASS64) { + err = -LIBBPF_ERRNO__FORMAT; + pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path); + goto errout; + } + + obj->efile.ehdr = ehdr = elf64_getehdr(elf); + if (!obj->efile.ehdr) { pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; goto errout; } - ep = &obj->efile.ehdr;

- if (elf_getshdrstrndx(obj->efile.elf, &obj->efile.shstrndx)) { + if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) { pr_warn("elf: failed to get section names section index for %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; @@ -1225,7 +1241,7 @@ static int bpf_object__elf_init(struct bpf_object *obj) }

/* Elf is corrupted/truncated, avoid calling elf_strptr. */ - if (!elf_rawdata(elf_getscn(obj->efile.elf, obj->efile.shstrndx), NULL)) { + if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) { pr_warn("elf: failed to get section names strings from %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; @@ -1233,8 +1249,7 @@ static int bpf_object__elf_init(struct bpf_object *obj) }

/* Old LLVM set e_machine to EM_NONE */ - if (ep->e_type != ET_REL || - (ep->e_machine && ep->e_machine != EM_BPF)) { + if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) { pr_warn("elf: %s is not a valid eBPF object file\n", obj->path); err = -LIBBPF_ERRNO__FORMAT; goto errout; @@ -1249,10 +1264,10 @@ static int bpf_object__elf_init(struct bpf_object *obj) static int bpf_object__check_endianness(struct bpf_object *obj) { #if __BYTE_ORDER == __LITTLE_ENDIAN - if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB) + if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB) return 0; #elif __BYTE_ORDER == __BIG_ENDIAN - if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB) + if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB) return 0; #else # error "Unrecognized __BYTE_ORDER__" @@ -1333,23 +1348,20 @@ static int find_elf_var_offset(const struct bpf_object *obj, const char *name, _ if (!name || !off) return -EINVAL;

- for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) { - GElf_Sym sym; + for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) { + Elf64_Sym *sym = elf_sym_by_idx(obj, si);

- if (!gelf_getsym(symbols, si, &sym)) - continue; - if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL || - GELF_ST_TYPE(sym.st_info) != STT_OBJECT) + if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL || + ELF64_ST_TYPE(sym->st_info) != STT_OBJECT) continue;

- sname = elf_sym_str(obj, sym.st_name); + sname = elf_sym_str(obj, sym->st_name); if (!sname) { - pr_warn("failed to get sym name string for var %s\n", - name); + pr_warn("failed to get sym name string for var %s\n", name); return -EIO; } if (strcmp(name, sname) == 0) { - *off = sym.st_value; + *off = sym->st_value; return 0; } } @@ -1836,15 +1848,13 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) * * TODO: Detect array of map and report error. */ - nr_syms = symbols->d_size / sizeof(GElf_Sym); + nr_syms = symbols->d_size / sizeof(Elf64_Sym); for (i = 0; i < nr_syms; i++) { - GElf_Sym sym; + Elf64_Sym *sym = elf_sym_by_idx(obj, i);

- if (!gelf_getsym(symbols, i, &sym)) + if (sym->st_shndx != obj->efile.maps_shndx) continue; - if (sym.st_shndx != obj->efile.maps_shndx) - continue; - if (GELF_ST_TYPE(sym.st_info) == STT_SECTION) + if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION) continue; nr_maps++; } @@ -1861,40 +1871,38 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)

/* Fill obj->maps using data in "maps" section. */ for (i = 0; i < nr_syms; i++) { - GElf_Sym sym; + Elf64_Sym *sym = elf_sym_by_idx(obj, i); const char *map_name; struct bpf_map_def *def; struct bpf_map *map;

- if (!gelf_getsym(symbols, i, &sym)) - continue; - if (sym.st_shndx != obj->efile.maps_shndx) + if (sym->st_shndx != obj->efile.maps_shndx) continue; - if (GELF_ST_TYPE(sym.st_info) == STT_SECTION) + if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION) continue;

map = bpf_object__add_map(obj); if (IS_ERR(map)) return PTR_ERR(map);

- map_name = elf_sym_str(obj, sym.st_name); + map_name = elf_sym_str(obj, sym->st_name); if (!map_name) { pr_warn("failed to get map #%d name sym string for obj %s\n", i, obj->path); return -LIBBPF_ERRNO__FORMAT; }

- if (GELF_ST_BIND(sym.st_info) == STB_LOCAL) { + if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL) { pr_warn("map '%s' (legacy): static maps are not supported\n", map_name); return -ENOTSUP; }

map->libbpf_type = LIBBPF_MAP_UNSPEC; - map->sec_idx = sym.st_shndx; - map->sec_offset = sym.st_value; + map->sec_idx = sym->st_shndx; + map->sec_offset = sym->st_value; pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n", map_name, map->sec_idx, map->sec_offset); - if (sym.st_value + map_def_sz > data->d_size) { + if (sym->st_value + map_def_sz > data->d_size) { pr_warn("corrupted maps section in %s: last map "%s" too small\n", obj->path, map_name); return -EINVAL; @@ -1906,7 +1914,7 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) return -ENOMEM; } pr_debug("map %d is "%s"\n", i, map->name); - def = (struct bpf_map_def *)(data->d_buf + sym.st_value); + def = (struct bpf_map_def *)(data->d_buf + sym->st_value); /* * If the definition of the map in the object file fits in * bpf_map_def, copy it. Any extra fields in our version @@ -2476,12 +2484,13 @@ static int bpf_object__init_maps(struct bpf_object *obj,

static bool section_have_execinstr(struct bpf_object *obj, int idx) { - GElf_Shdr sh; + Elf64_Shdr *sh;

- if (elf_sec_hdr(obj, elf_sec_by_idx(obj, idx), &sh)) + sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx)); + if (!sh) return false;

- return sh.sh_flags & SHF_EXECINSTR; + return sh->sh_flags & SHF_EXECINSTR; }

static bool btf_needs_sanitization(struct bpf_object *obj) @@ -2958,32 +2967,36 @@ static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name) return NULL; }

-static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr) +static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn) { + Elf64_Shdr *shdr; + if (!scn) - return -EINVAL; + return NULL;

- if (gelf_getshdr(scn, hdr) != hdr) { + shdr = elf64_getshdr(scn); + if (!shdr) { pr_warn("elf: failed to get section(%zu) header from %s: %s\n", elf_ndxscn(scn), obj->path, elf_errmsg(-1)); - return -EINVAL; + return NULL; }

- return 0; + return shdr; }

static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn) { const char *name; - GElf_Shdr sh; + Elf64_Shdr *sh;

if (!scn) return NULL;

- if (elf_sec_hdr(obj, scn, &sh)) + sh = elf_sec_hdr(obj, scn); + if (!sh) return NULL;

- name = elf_sec_str(obj, sh.sh_name); + name = elf_sec_str(obj, sh->sh_name); if (!name) { pr_warn("elf: failed to get section(%zu) name from %s: %s\n", elf_ndxscn(scn), obj->path, elf_errmsg(-1)); @@ -3011,13 +3024,29 @@ static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn) return data; }

+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx) +{ + if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym)) + return NULL; + + return (Elf64_Sym *)obj->efile.symbols->d_buf + idx; +} + +static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx) +{ + if (idx >= data->d_size / sizeof(Elf64_Rel)) + return NULL; + + return (Elf64_Rel *)data->d_buf + idx; +} + static bool is_sec_name_dwarf(const char *name) { /* approximation, but the actual list is too long */ return str_has_pfx(name, ".debug_"); }

-static bool ignore_elf_section(GElf_Shdr *hdr, const char *name) +static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name) { /* no special handling of .strtab */ if (hdr->sh_type == SHT_STRTAB) @@ -3072,17 +3101,18 @@ static int bpf_object__elf_collect(struct bpf_object *obj) const char *name; Elf_Data *data; Elf_Scn *scn; - GElf_Shdr sh; + Elf64_Shdr *sh;

/* a bunch of ELF parsing functionality depends on processing symbols, * so do the first pass and find the symbol table */ scn = NULL; while ((scn = elf_nextscn(elf, scn)) != NULL) { - if (elf_sec_hdr(obj, scn, &sh)) + sh = elf_sec_hdr(obj, scn); + if (!sh) return -LIBBPF_ERRNO__FORMAT;

- if (sh.sh_type == SHT_SYMTAB) { + if (sh->sh_type == SHT_SYMTAB) { if (obj->efile.symbols) { pr_warn("elf: multiple symbol tables in %s\n", obj->path); return -LIBBPF_ERRNO__FORMAT; @@ -3094,7 +3124,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj)

obj->efile.symbols = data; obj->efile.symbols_shndx = elf_ndxscn(scn); - obj->efile.strtabidx = sh.sh_link; + obj->efile.strtabidx = sh->sh_link; } }

@@ -3108,14 +3138,15 @@ static int bpf_object__elf_collect(struct bpf_object *obj) while ((scn = elf_nextscn(elf, scn)) != NULL) { idx++;

- if (elf_sec_hdr(obj, scn, &sh)) + sh = elf_sec_hdr(obj, scn); + if (!sh) return -LIBBPF_ERRNO__FORMAT;

- name = elf_sec_str(obj, sh.sh_name); + name = elf_sec_str(obj, sh->sh_name); if (!name) return -LIBBPF_ERRNO__FORMAT;

- if (ignore_elf_section(&sh, name)) + if (ignore_elf_section(sh, name)) continue;

data = elf_sec_data(obj, scn); @@ -3124,8 +3155,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)

pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n", idx, name, (unsigned long)data->d_size, - (int)sh.sh_link, (unsigned long)sh.sh_flags, - (int)sh.sh_type); + (int)sh->sh_link, (unsigned long)sh->sh_flags, + (int)sh->sh_type);

if (strcmp(name, "license") == 0) { err = bpf_object__init_license(obj, data->d_buf, data->d_size); @@ -3143,10 +3174,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj) btf_data = data; } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) { btf_ext_data = data; - } else if (sh.sh_type == SHT_SYMTAB) { + } else if (sh->sh_type == SHT_SYMTAB) { /* already processed during the first pass above */ - } else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) { - if (sh.sh_flags & SHF_EXECINSTR) { + } 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_programs(obj, data, name, idx); @@ -3165,10 +3196,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj) pr_info("elf: skipping unrecognized data section(%d) %s\n", idx, name); } - } else if (sh.sh_type == SHT_REL) { + } else if (sh->sh_type == SHT_REL) { int nr_sects = obj->efile.nr_reloc_sects; void *sects = obj->efile.reloc_sects; - int sec = sh.sh_info; /* points to other section */ + int sec = sh->sh_info; /* points to other section */

/* Only do relo for section with exec instructions */ if (!section_have_execinstr(obj, sec) && @@ -3190,12 +3221,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj)

obj->efile.reloc_sects[nr_sects].shdr = sh; obj->efile.reloc_sects[nr_sects].data = data; - } else if (sh.sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) { + } else if (sh->sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) { obj->efile.bss = data; obj->efile.bss_shndx = idx; } else { pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name, - (size_t)sh.sh_size); + (size_t)sh->sh_size); } }

@@ -3211,19 +3242,19 @@ static int bpf_object__elf_collect(struct bpf_object *obj) return bpf_object__init_btf(obj, btf_data, btf_ext_data); }

-static bool sym_is_extern(const GElf_Sym *sym) +static bool sym_is_extern(const Elf64_Sym *sym) { - int bind = GELF_ST_BIND(sym->st_info); + int bind = ELF64_ST_BIND(sym->st_info); /* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */ return sym->st_shndx == SHN_UNDEF && (bind == STB_GLOBAL || bind == STB_WEAK) && - GELF_ST_TYPE(sym->st_info) == STT_NOTYPE; + ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE; }

-static bool sym_is_subprog(const GElf_Sym *sym, int text_shndx) +static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx) { - int bind = GELF_ST_BIND(sym->st_info); - int type = GELF_ST_TYPE(sym->st_info); + int bind = ELF64_ST_BIND(sym->st_info); + int type = ELF64_ST_TYPE(sym->st_info);

/* in .text section */ if (sym->st_shndx != text_shndx) @@ -3421,30 +3452,31 @@ static int bpf_object__collect_externs(struct bpf_object *obj) int i, n, off, dummy_var_btf_id; const char *ext_name, *sec_name; Elf_Scn *scn; - GElf_Shdr sh; + Elf64_Shdr *sh;

if (!obj->efile.symbols) return 0;

scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx); - if (elf_sec_hdr(obj, scn, &sh)) + sh = elf_sec_hdr(obj, scn); + if (!sh) return -LIBBPF_ERRNO__FORMAT;

dummy_var_btf_id = add_dummy_ksym_var(obj->btf); if (dummy_var_btf_id < 0) return dummy_var_btf_id;

- n = sh.sh_size / sh.sh_entsize; + n = sh->sh_size / sh->sh_entsize; pr_debug("looking for externs among %d symbols...\n", n);

for (i = 0; i < n; i++) { - GElf_Sym sym; + Elf64_Sym *sym = elf_sym_by_idx(obj, i);

- if (!gelf_getsym(obj->efile.symbols, i, &sym)) + if (!sym) return -LIBBPF_ERRNO__FORMAT; - if (!sym_is_extern(&sym)) + if (!sym_is_extern(sym)) continue; - ext_name = elf_sym_str(obj, sym.st_name); + ext_name = elf_sym_str(obj, sym->st_name); if (!ext_name || !ext_name[0]) continue;

@@ -3466,7 +3498,7 @@ static int bpf_object__collect_externs(struct bpf_object *obj) t = btf__type_by_id(obj->btf, ext->btf_id); ext->name = btf__name_by_offset(obj->btf, t->name_off); ext->sym_idx = i; - ext->is_weak = GELF_ST_BIND(sym.st_info) == STB_WEAK; + ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;

ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id); if (ext->sec_btf_id <= 0) { @@ -3706,7 +3738,7 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx) static int bpf_program__record_reloc(struct bpf_program *prog, struct reloc_desc *reloc_desc, __u32 insn_idx, const char *sym_name, - const GElf_Sym *sym, const GElf_Rel *rel) + const Elf64_Sym *sym, const Elf64_Rel *rel) { struct bpf_insn *insn = &prog->insns[insn_idx]; size_t map_idx, nr_maps = prog->obj->nr_maps; @@ -3723,7 +3755,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog, }

if (sym_is_extern(sym)) { - int sym_idx = GELF_R_SYM(rel->r_info); + int sym_idx = ELF64_R_SYM(rel->r_info); int i, n = obj->nr_extern; struct extern_desc *ext;

@@ -3888,9 +3920,8 @@ static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj, }

static int -bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) +bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data) { - Elf_Data *symbols = obj->efile.symbols; const char *relo_sec_name, *sec_name; size_t sec_idx = shdr->sh_info; struct bpf_program *prog; @@ -3900,8 +3931,8 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data __u32 insn_idx; Elf_Scn *scn; Elf_Data *scn_data; - GElf_Sym sym; - GElf_Rel rel; + Elf64_Sym *sym; + Elf64_Rel *rel;

scn = elf_sec_by_idx(obj, sec_idx); scn_data = elf_sec_data(obj, scn); @@ -3916,33 +3947,36 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data nrels = shdr->sh_size / shdr->sh_entsize;

for (i = 0; i < nrels; i++) { - if (!gelf_getrel(data, i, &rel)) { + rel = elf_rel_by_idx(data, i); + if (!rel) { pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i); return -LIBBPF_ERRNO__FORMAT; } - if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { + + sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info)); + if (!sym) { pr_warn("sec '%s': symbol 0x%zx not found for relo #%d\n", - relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i); + relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i); return -LIBBPF_ERRNO__FORMAT; }

- if (rel.r_offset % BPF_INSN_SZ || rel.r_offset >= scn_data->d_size) { + if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) { pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n", - relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i); + relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i); return -LIBBPF_ERRNO__FORMAT; }

- insn_idx = rel.r_offset / BPF_INSN_SZ; + insn_idx = rel->r_offset / BPF_INSN_SZ; /* relocations against static functions are recorded as * relocations against the section that contains a function; * in such case, symbol will be STT_SECTION and sym.st_name * will point to empty string (0), so fetch section name * instead */ - if (GELF_ST_TYPE(sym.st_info) == STT_SECTION && sym.st_name == 0) - sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym.st_shndx)); + if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0) + sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx)); else - sym_name = elf_sym_str(obj, sym.st_name); + sym_name = elf_sym_str(obj, sym->st_name); sym_name = sym_name ?: "<?";

pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n", @@ -3964,7 +3998,7 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data /* adjust insn_idx to local BPF program frame of reference */ insn_idx -= prog->sec_insn_off; err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc], - insn_idx, sym_name, &sym, &rel); + insn_idx, sym_name, sym, rel); if (err) return err;

@@ -5972,10 +6006,10 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path) }

static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, - GElf_Shdr *shdr, Elf_Data *data); + Elf64_Shdr *shdr, Elf_Data *data);

static int bpf_object__collect_map_relos(struct bpf_object *obj, - GElf_Shdr *shdr, Elf_Data *data) + Elf64_Shdr *shdr, Elf_Data *data) { const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *); int i, j, nrels, new_sz; @@ -5984,10 +6018,9 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, struct bpf_map *map = NULL, *targ_map; const struct btf_member *member; const char *name, *mname; - Elf_Data *symbols; unsigned int moff; - GElf_Sym sym; - GElf_Rel rel; + Elf64_Sym *sym; + Elf64_Rel *rel; void *tmp;

if (!obj->efile.btf_maps_sec_btf_id || !obj->btf) @@ -5996,28 +6029,30 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, if (!sec) return -EINVAL;

- symbols = obj->efile.symbols; nrels = shdr->sh_size / shdr->sh_entsize; for (i = 0; i < nrels; i++) { - if (!gelf_getrel(data, i, &rel)) { + rel = elf_rel_by_idx(data, i); + if (!rel) { pr_warn(".maps relo #%d: failed to get ELF relo\n", i); return -LIBBPF_ERRNO__FORMAT; } - if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { + + sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info)); + if (!sym) { pr_warn(".maps relo #%d: symbol %zx not found\n", - i, (size_t)GELF_R_SYM(rel.r_info)); + i, (size_t)ELF64_R_SYM(rel->r_info)); return -LIBBPF_ERRNO__FORMAT; } - name = elf_sym_str(obj, sym.st_name) ?: "<?>"; - if (sym.st_shndx != obj->efile.btf_maps_shndx) { + name = elf_sym_str(obj, sym->st_name) ?: "<?>"; + if (sym->st_shndx != obj->efile.btf_maps_shndx) { pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n", i, name); return -LIBBPF_ERRNO__RELOC; }

- pr_debug(".maps relo #%d: for %zd value %zd rel.r_offset %zu name %d ('%s')\n", - i, (ssize_t)(rel.r_info >> 32), (size_t)sym.st_value, - (size_t)rel.r_offset, sym.st_name, name); + pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n", + i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value, + (size_t)rel->r_offset, sym->st_name, name);

for (j = 0; j < obj->nr_maps; j++) { map = &obj->maps[j]; @@ -6025,13 +6060,13 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, continue;

vi = btf_var_secinfos(sec) + map->btf_var_idx; - if (vi->offset <= rel.r_offset && - rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size) + if (vi->offset <= rel->r_offset && + rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size) break; } if (j == obj->nr_maps) { - pr_warn(".maps relo #%d: cannot find map '%s' at rel.r_offset %zu\n", - i, name, (size_t)rel.r_offset); + pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n", + i, name, (size_t)rel->r_offset); return -EINVAL; }

@@ -6058,10 +6093,10 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, return -EINVAL;

moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8; - if (rel.r_offset - vi->offset < moff) + if (rel->r_offset - vi->offset < moff) return -EINVAL;

- moff = rel.r_offset - vi->offset - moff; + moff = rel->r_offset - vi->offset - moff; /* here we use BPF pointer size, which is always 64 bit, as we * are parsing ELF that was built for BPF target */ @@ -6107,7 +6142,7 @@ static int bpf_object__collect_relos(struct bpf_object *obj) int i, err;

for (i = 0; i < obj->efile.nr_reloc_sects; i++) { - GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr; + Elf64_Shdr *shdr = obj->efile.reloc_sects[i].shdr; Elf_Data *data = obj->efile.reloc_sects[i].data; int idx = shdr->sh_info;

@@ -8336,7 +8371,7 @@ static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,

/* Collect the reloc from ELF and populate the st_ops->progs[] */ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, - GElf_Shdr *shdr, Elf_Data *data) + Elf64_Shdr *shdr, Elf_Data *data) { const struct btf_member *member; struct bpf_struct_ops *st_ops; @@ -8344,58 +8379,58 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, unsigned int shdr_idx; const struct btf *btf; struct bpf_map *map; - Elf_Data *symbols; unsigned int moff, insn_idx; const char *name; __u32 member_idx; - GElf_Sym sym; - GElf_Rel rel; + Elf64_Sym *sym; + Elf64_Rel *rel; int i, nrels;

- symbols = obj->efile.symbols; btf = obj->btf; nrels = shdr->sh_size / shdr->sh_entsize; for (i = 0; i < nrels; i++) { - if (!gelf_getrel(data, i, &rel)) { + rel = elf_rel_by_idx(data, i); + if (!rel) { pr_warn("struct_ops reloc: failed to get %d reloc\n", i); return -LIBBPF_ERRNO__FORMAT; }

- if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { + sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info)); + if (!sym) { pr_warn("struct_ops reloc: symbol %zx not found\n", - (size_t)GELF_R_SYM(rel.r_info)); + (size_t)ELF64_R_SYM(rel->r_info)); return -LIBBPF_ERRNO__FORMAT; }

- name = elf_sym_str(obj, sym.st_name) ?: "<?>"; - map = find_struct_ops_map_by_offset(obj, rel.r_offset); + name = elf_sym_str(obj, sym->st_name) ?: "<?>"; + map = find_struct_ops_map_by_offset(obj, rel->r_offset); if (!map) { - pr_warn("struct_ops reloc: cannot find map at rel.r_offset %zu\n", - (size_t)rel.r_offset); + pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n", + (size_t)rel->r_offset); return -EINVAL; }

- moff = rel.r_offset - map->sec_offset; - shdr_idx = sym.st_shndx; + moff = rel->r_offset - map->sec_offset; + shdr_idx = sym->st_shndx; st_ops = map->st_ops; - pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel.r_offset %zu map->sec_offset %zu name %d ('%s')\n", + pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d ('%s')\n", map->name, - (long long)(rel.r_info >> 32), - (long long)sym.st_value, - shdr_idx, (size_t)rel.r_offset, - map->sec_offset, sym.st_name, name); + (long long)(rel->r_info >> 32), + (long long)sym->st_value, + shdr_idx, (size_t)rel->r_offset, + map->sec_offset, sym->st_name, name);

if (shdr_idx >= SHN_LORESERVE) { - pr_warn("struct_ops reloc %s: rel.r_offset %zu shdr_idx %u unsupported non-static function\n", - map->name, (size_t)rel.r_offset, shdr_idx); + pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n", + map->name, (size_t)rel->r_offset, shdr_idx); return -LIBBPF_ERRNO__RELOC; } - if (sym.st_value % BPF_INSN_SZ) { + if (sym->st_value % BPF_INSN_SZ) { pr_warn("struct_ops reloc %s: invalid target program offset %llu\n", - map->name, (unsigned long long)sym.st_value); + map->name, (unsigned long long)sym->st_value); return -LIBBPF_ERRNO__FORMAT; } - insn_idx = sym.st_value / BPF_INSN_SZ; + insn_idx = sym->st_value / BPF_INSN_SZ;

member = find_member_by_offset(st_ops->type, moff * 8); if (!member) { diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 63d0d4c7ea1d..604a9a26773c 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -52,8 +52,8 @@ #endif

/* Older libelf all end up in this expression, for both 32 and 64 bit */ -#ifndef GELF_ST_VISIBILITY -#define GELF_ST_VISIBILITY(o) ((o) & 0x03) +#ifndef ELF64_ST_VISIBILITY +#define ELF64_ST_VISIBILITY(o) ((o) & 0x03) #endif

#define BTF_INFO_ENC(kind, kind_flag, vlen) \ diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c index f638ba372a9b..db97d3bfdc5e 100644 --- a/tools/lib/bpf/linker.c +++ b/tools/lib/bpf/linker.c @@ -15,7 +15,6 @@ #include <linux/btf.h> #include <elf.h> #include <libelf.h> -#include <gelf.h> #include <fcntl.h> #include "libbpf.h" #include "btf.h"