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libbpf: Use Elf64-specific types explicitly for dealing with ELF 

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
This commit is contained in:
Andrii Nakryiko 2021-10-20 18:43:57 -07:00 коммит произвёл Alexei Starovoitov
Родитель 29a30ff501
Коммит ad23b72384
3 изменённых файлов: 197 добавлений и 163 удалений
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355
tools/lib/bpf/libbpf.c
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@ -467,7 +467,7 @@ 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;
@ -476,7 +476,7 @@ 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;
@ -555,9 +555,11 @@ 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)
{
@ -699,25 +701,25 @@ 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))
sym = elf_sym_by_idx(obj, i);
if (sym->st_shndx != sec_idx)
continue;
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);
@ -730,7 +732,7 @@ 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;
}
@ -763,9 +765,9 @@ 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++;
@ -1205,8 +1207,9 @@ 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");
@ -1218,8 +1221,7 @@ 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) {
@ -1231,23 +1233,37 @@ 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;
@ -1255,7 +1271,7 @@ 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;
@ -1263,8 +1279,7 @@ 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;
@ -1279,10 +1294,10 @@ errout:
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__"
@ -1363,23 +1378,20 @@ 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;
}
}
@ -1866,15 +1878,13 @@ 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++;
}
@ -1891,40 +1901,38 @@ 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))
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;
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;
@ -1936,7 +1944,7 @@ 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
@ -2506,12 +2514,13 @@ 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)
@ -2987,32 +2996,36 @@ 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)
{
if (!scn)
return -EINVAL;
Elf64_Shdr *shdr;
if (gelf_getshdr(scn, hdr) != hdr) {
if (!scn)
return NULL;
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));
@ -3040,13 +3053,29 @@ 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)
@ -3101,17 +3130,18 @@ 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;
@ -3123,7 +3153,7 @@ 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;
}
}
@ -3137,14 +3167,15 @@ 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);
@ -3153,8 +3184,8 @@ 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);
@ -3172,10 +3203,10 @@ 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);
@ -3194,10 +3225,10 @@ 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) &&
@ -3219,12 +3250,12 @@ 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);
}
}
@ -3240,19 +3271,19 @@ 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)
@ -3450,30 +3481,31 @@ 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;
@ -3495,7 +3527,7 @@ 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) {
@ -3730,7 +3762,7 @@ 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;
@ -3747,7 +3779,7 @@ 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;
@ -3912,9 +3944,8 @@ 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;
@ -3924,8 +3955,8 @@ 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);
@ -3940,33 +3971,36 @@ 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",
@ -3988,7 +4022,7 @@ 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;
@ -6036,10 +6070,10 @@ 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;
@ -6048,10 +6082,9 @@ 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)
@ -6060,28 +6093,30 @@ 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];
@ -6089,13 +6124,13 @@ 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;
}
@ -6122,10 +6157,10 @@ 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
*/
@ -6171,7 +6206,7 @@ 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;
@ -8362,7 +8397,7 @@ 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;
@ -8370,58 +8405,58 @@ 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) {

4
tools/lib/bpf/libbpf_internal.h
Просмотреть файл

@ -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) \

1
tools/lib/bpf/linker.c
Просмотреть файл

@ -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"