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libbpf: add support for bpf_call
- recognize relocation emitted by llvm - since all regular function will be kept in .text section and llvm takes care of pc-relative offsets in bpf_call instruction simply copy all of .text to relevant program section while adjusting bpf_call instructions in program section to point to newly copied body of instructions from .text - do so for all programs in the elf file - set all programs types to the one passed to bpf_prog_load() Note for elf files with multiple programs that use different functions in .text section we need to do 'linker' style logic. This work is still TBD Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Alexei Starovoitov
Daniel Borkmann
parent
d98588cef0
commit
48cca7e44f
@ -197,8 +197,14 @@ enum bpf_attach_type {
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*/
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#define BPF_F_STRICT_ALIGNMENT (1U << 0)
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/* when bpf_ldimm64->src_reg == BPF_PSEUDO_MAP_FD, bpf_ldimm64->imm == fd */
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#define BPF_PSEUDO_MAP_FD 1
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/* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
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* offset to another bpf function
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*/
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#define BPF_PSEUDO_CALL 1
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/* flags for BPF_MAP_UPDATE_ELEM command */
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#define BPF_ANY 0 /* create new element or update existing */
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#define BPF_NOEXIST 1 /* create new element if it didn't exist */
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@ -40,7 +40,7 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
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__u32 map_flags);
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/* Recommend log buffer size */
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#define BPF_LOG_BUF_SIZE 65536
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#define BPF_LOG_BUF_SIZE (256 * 1024)
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int bpf_load_program_name(enum bpf_prog_type type, const char *name,
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const struct bpf_insn *insns,
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size_t insns_cnt, const char *license,
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@ -174,12 +174,19 @@ struct bpf_program {
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char *name;
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char *section_name;
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struct bpf_insn *insns;
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size_t insns_cnt;
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size_t insns_cnt, main_prog_cnt;
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enum bpf_prog_type type;
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struct {
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struct reloc_desc {
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enum {
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RELO_LD64,
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RELO_CALL,
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} type;
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int insn_idx;
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int map_idx;
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union {
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int map_idx;
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int text_off;
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};
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} *reloc_desc;
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int nr_reloc;
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@ -234,6 +241,7 @@ struct bpf_object {
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} *reloc;
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int nr_reloc;
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int maps_shndx;
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int text_shndx;
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} efile;
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/*
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* All loaded bpf_object is linked in a list, which is
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@ -375,9 +383,13 @@ bpf_object__init_prog_names(struct bpf_object *obj)
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size_t pi, si;
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for (pi = 0; pi < obj->nr_programs; pi++) {
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char *name = NULL;
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const char *name = NULL;
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prog = &obj->programs[pi];
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if (prog->idx == obj->efile.text_shndx) {
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name = ".text";
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goto skip_search;
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}
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for (si = 0; si < symbols->d_size / sizeof(GElf_Sym) && !name;
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si++) {
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@ -405,7 +417,7 @@ bpf_object__init_prog_names(struct bpf_object *obj)
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prog->section_name);
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return -EINVAL;
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}
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skip_search:
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prog->name = strdup(name);
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if (!prog->name) {
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pr_warning("failed to allocate memory for prog sym %s\n",
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@ -795,6 +807,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
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} else if ((sh.sh_type == SHT_PROGBITS) &&
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(sh.sh_flags & SHF_EXECINSTR) &&
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(data->d_size > 0)) {
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if (strcmp(name, ".text") == 0)
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obj->efile.text_shndx = idx;
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err = bpf_object__add_program(obj, data->d_buf,
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data->d_size, name, idx);
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if (err) {
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@ -856,11 +870,14 @@ bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
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}
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static int
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bpf_program__collect_reloc(struct bpf_program *prog,
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size_t nr_maps, GElf_Shdr *shdr,
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Elf_Data *data, Elf_Data *symbols,
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int maps_shndx, struct bpf_map *maps)
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bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
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Elf_Data *data, struct bpf_object *obj)
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{
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Elf_Data *symbols = obj->efile.symbols;
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int text_shndx = obj->efile.text_shndx;
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int maps_shndx = obj->efile.maps_shndx;
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struct bpf_map *maps = obj->maps;
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size_t nr_maps = obj->nr_maps;
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int i, nrels;
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pr_debug("collecting relocating info for: '%s'\n",
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@ -893,8 +910,10 @@ bpf_program__collect_reloc(struct bpf_program *prog,
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GELF_R_SYM(rel.r_info));
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return -LIBBPF_ERRNO__FORMAT;
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}
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pr_debug("relo for %ld value %ld name %d\n",
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rel.r_info >> 32, sym.st_value, sym.st_name);
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if (sym.st_shndx != maps_shndx) {
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if (sym.st_shndx != maps_shndx && sym.st_shndx != text_shndx) {
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pr_warning("Program '%s' contains non-map related relo data pointing to section %u\n",
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prog->section_name, sym.st_shndx);
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return -LIBBPF_ERRNO__RELOC;
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@ -903,6 +922,17 @@ bpf_program__collect_reloc(struct bpf_program *prog,
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insn_idx = rel.r_offset / sizeof(struct bpf_insn);
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pr_debug("relocation: insn_idx=%u\n", insn_idx);
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if (insns[insn_idx].code == (BPF_JMP | BPF_CALL)) {
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if (insns[insn_idx].src_reg != BPF_PSEUDO_CALL) {
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pr_warning("incorrect bpf_call opcode\n");
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return -LIBBPF_ERRNO__RELOC;
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}
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prog->reloc_desc[i].type = RELO_CALL;
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prog->reloc_desc[i].insn_idx = insn_idx;
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prog->reloc_desc[i].text_off = sym.st_value;
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continue;
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}
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if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
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pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
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insn_idx, insns[insn_idx].code);
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@ -924,6 +954,7 @@ bpf_program__collect_reloc(struct bpf_program *prog,
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return -LIBBPF_ERRNO__RELOC;
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}
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prog->reloc_desc[i].type = RELO_LD64;
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prog->reloc_desc[i].insn_idx = insn_idx;
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prog->reloc_desc[i].map_idx = map_idx;
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}
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@ -962,28 +993,77 @@ bpf_object__create_maps(struct bpf_object *obj)
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return 0;
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}
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static int
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bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
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struct reloc_desc *relo)
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{
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struct bpf_insn *insn, *new_insn;
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struct bpf_program *text;
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size_t new_cnt;
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if (relo->type != RELO_CALL)
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return -LIBBPF_ERRNO__RELOC;
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if (prog->idx == obj->efile.text_shndx) {
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pr_warning("relo in .text insn %d into off %d\n",
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relo->insn_idx, relo->text_off);
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return -LIBBPF_ERRNO__RELOC;
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}
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if (prog->main_prog_cnt == 0) {
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text = bpf_object__find_prog_by_idx(obj, obj->efile.text_shndx);
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if (!text) {
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pr_warning("no .text section found yet relo into text exist\n");
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return -LIBBPF_ERRNO__RELOC;
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}
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new_cnt = prog->insns_cnt + text->insns_cnt;
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new_insn = realloc(prog->insns, new_cnt * sizeof(*insn));
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if (!new_insn) {
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pr_warning("oom in prog realloc\n");
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return -ENOMEM;
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}
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memcpy(new_insn + prog->insns_cnt, text->insns,
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text->insns_cnt * sizeof(*insn));
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prog->insns = new_insn;
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prog->main_prog_cnt = prog->insns_cnt;
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prog->insns_cnt = new_cnt;
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}
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insn = &prog->insns[relo->insn_idx];
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insn->imm += prog->main_prog_cnt - relo->insn_idx;
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pr_debug("added %zd insn from %s to prog %s\n",
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text->insns_cnt, text->section_name, prog->section_name);
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return 0;
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}
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static int
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bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
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{
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int i;
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int i, err;
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if (!prog || !prog->reloc_desc)
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return 0;
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for (i = 0; i < prog->nr_reloc; i++) {
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int insn_idx, map_idx;
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struct bpf_insn *insns = prog->insns;
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if (prog->reloc_desc[i].type == RELO_LD64) {
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struct bpf_insn *insns = prog->insns;
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int insn_idx, map_idx;
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insn_idx = prog->reloc_desc[i].insn_idx;
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map_idx = prog->reloc_desc[i].map_idx;
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insn_idx = prog->reloc_desc[i].insn_idx;
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map_idx = prog->reloc_desc[i].map_idx;
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if (insn_idx >= (int)prog->insns_cnt) {
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pr_warning("relocation out of range: '%s'\n",
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prog->section_name);
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return -LIBBPF_ERRNO__RELOC;
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if (insn_idx >= (int)prog->insns_cnt) {
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pr_warning("relocation out of range: '%s'\n",
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prog->section_name);
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return -LIBBPF_ERRNO__RELOC;
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}
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insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
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insns[insn_idx].imm = obj->maps[map_idx].fd;
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} else {
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err = bpf_program__reloc_text(prog, obj,
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&prog->reloc_desc[i]);
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if (err)
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return err;
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}
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insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
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insns[insn_idx].imm = obj->maps[map_idx].fd;
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}
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zfree(&prog->reloc_desc);
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@ -1026,7 +1106,6 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
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Elf_Data *data = obj->efile.reloc[i].data;
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int idx = shdr->sh_info;
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struct bpf_program *prog;
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size_t nr_maps = obj->nr_maps;
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if (shdr->sh_type != SHT_REL) {
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pr_warning("internal error at %d\n", __LINE__);
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@ -1040,11 +1119,9 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
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return -LIBBPF_ERRNO__RELOC;
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}
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err = bpf_program__collect_reloc(prog, nr_maps,
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err = bpf_program__collect_reloc(prog,
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shdr, data,
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obj->efile.symbols,
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obj->efile.maps_shndx,
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obj->maps);
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obj);
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if (err)
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return err;
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}
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@ -1197,6 +1274,8 @@ bpf_object__load_progs(struct bpf_object *obj)
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int err;
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for (i = 0; i < obj->nr_programs; i++) {
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if (obj->programs[i].idx == obj->efile.text_shndx)
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continue;
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err = bpf_program__load(&obj->programs[i],
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obj->license,
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obj->kern_version);
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@ -1859,7 +1938,7 @@ long libbpf_get_error(const void *ptr)
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int bpf_prog_load(const char *file, enum bpf_prog_type type,
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struct bpf_object **pobj, int *prog_fd)
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{
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struct bpf_program *prog;
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struct bpf_program *prog, *first_prog = NULL;
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struct bpf_object *obj;
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int err;
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@ -1867,25 +1946,30 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
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if (IS_ERR(obj))
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return -ENOENT;
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prog = bpf_program__next(NULL, obj);
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if (!prog) {
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bpf_object__for_each_program(prog, obj) {
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/*
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* If type is not specified, try to guess it based on
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* section name.
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*/
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if (type == BPF_PROG_TYPE_UNSPEC) {
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type = bpf_program__guess_type(prog);
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if (type == BPF_PROG_TYPE_UNSPEC) {
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bpf_object__close(obj);
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return -EINVAL;
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}
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}
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bpf_program__set_type(prog, type);
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if (prog->idx != obj->efile.text_shndx && !first_prog)
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first_prog = prog;
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}
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if (!first_prog) {
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pr_warning("object file doesn't contain bpf program\n");
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bpf_object__close(obj);
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return -ENOENT;
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}
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/*
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* If type is not specified, try to guess it based on
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* section name.
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*/
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if (type == BPF_PROG_TYPE_UNSPEC) {
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type = bpf_program__guess_type(prog);
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if (type == BPF_PROG_TYPE_UNSPEC) {
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bpf_object__close(obj);
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return -EINVAL;
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}
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}
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bpf_program__set_type(prog, type);
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err = bpf_object__load(obj);
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if (err) {
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bpf_object__close(obj);
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@ -1893,6 +1977,6 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
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}
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*pobj = obj;
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*prog_fd = bpf_program__fd(prog);
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*prog_fd = bpf_program__fd(first_prog);
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return 0;
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}
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