diff options
Diffstat (limited to 'lib/librte_bpf/bpf_load_elf.c')
| -rw-r--r-- | lib/librte_bpf/bpf_load_elf.c | 322 |
1 files changed, 322 insertions, 0 deletions
diff --git a/lib/librte_bpf/bpf_load_elf.c b/lib/librte_bpf/bpf_load_elf.c new file mode 100644 index 00000000..96d3630f --- /dev/null +++ b/lib/librte_bpf/bpf_load_elf.c @@ -0,0 +1,322 @@ +/* SPDX-License-Identifier: BSD-3-Clause + * Copyright(c) 2018 Intel Corporation + */ + +#include <stdarg.h> +#include <stdio.h> +#include <string.h> +#include <errno.h> +#include <stdint.h> +#include <unistd.h> +#include <inttypes.h> + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/queue.h> +#include <fcntl.h> + +#include <libelf.h> + +#include <rte_common.h> +#include <rte_log.h> +#include <rte_debug.h> +#include <rte_memory.h> +#include <rte_eal.h> +#include <rte_byteorder.h> +#include <rte_errno.h> + +#include "bpf_impl.h" + +/* To overcome compatibility issue */ +#ifndef EM_BPF +#define EM_BPF 247 +#endif + +static uint32_t +bpf_find_xsym(const char *sn, enum rte_bpf_xtype type, + const struct rte_bpf_xsym fp[], uint32_t fn) +{ + uint32_t i; + + if (sn == NULL || fp == NULL) + return UINT32_MAX; + + for (i = 0; i != fn; i++) { + if (fp[i].type == type && strcmp(sn, fp[i].name) == 0) + break; + } + + return (i != fn) ? i : UINT32_MAX; +} + +/* + * update BPF code at offset *ofs* with a proper address(index) for external + * symbol *sn* + */ +static int +resolve_xsym(const char *sn, size_t ofs, struct ebpf_insn *ins, size_t ins_sz, + const struct rte_bpf_prm *prm) +{ + uint32_t idx, fidx; + enum rte_bpf_xtype type; + + if (ofs % sizeof(ins[0]) != 0 || ofs >= ins_sz) + return -EINVAL; + + idx = ofs / sizeof(ins[0]); + if (ins[idx].code == (BPF_JMP | EBPF_CALL)) + type = RTE_BPF_XTYPE_FUNC; + else if (ins[idx].code == (BPF_LD | BPF_IMM | EBPF_DW) && + ofs < ins_sz - sizeof(ins[idx])) + type = RTE_BPF_XTYPE_VAR; + else + return -EINVAL; + + fidx = bpf_find_xsym(sn, type, prm->xsym, prm->nb_xsym); + if (fidx == UINT32_MAX) + return -ENOENT; + + /* for function we just need an index in our xsym table */ + if (type == RTE_BPF_XTYPE_FUNC) + ins[idx].imm = fidx; + /* for variable we need to store its absolute address */ + else { + ins[idx].imm = (uintptr_t)prm->xsym[fidx].var.val; + ins[idx + 1].imm = + (uint64_t)(uintptr_t)prm->xsym[fidx].var.val >> 32; + } + + return 0; +} + +static int +check_elf_header(const Elf64_Ehdr *eh) +{ + const char *err; + + err = NULL; + +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN + if (eh->e_ident[EI_DATA] != ELFDATA2LSB) +#else + if (eh->e_ident[EI_DATA] != ELFDATA2MSB) +#endif + err = "not native byte order"; + else if (eh->e_ident[EI_OSABI] != ELFOSABI_NONE) + err = "unexpected OS ABI"; + else if (eh->e_type != ET_REL) + err = "unexpected ELF type"; + else if (eh->e_machine != EM_NONE && eh->e_machine != EM_BPF) + err = "unexpected machine type"; + + if (err != NULL) { + RTE_BPF_LOG(ERR, "%s(): %s\n", __func__, err); + return -EINVAL; + } + + return 0; +} + +/* + * helper function, find executable section by name. + */ +static int +find_elf_code(Elf *elf, const char *section, Elf_Data **psd, size_t *pidx) +{ + Elf_Scn *sc; + const Elf64_Ehdr *eh; + const Elf64_Shdr *sh; + Elf_Data *sd; + const char *sn; + int32_t rc; + + eh = elf64_getehdr(elf); + if (eh == NULL) { + rc = elf_errno(); + RTE_BPF_LOG(ERR, "%s(%p, %s) error code: %d(%s)\n", + __func__, elf, section, rc, elf_errmsg(rc)); + return -EINVAL; + } + + if (check_elf_header(eh) != 0) + return -EINVAL; + + /* find given section by name */ + for (sc = elf_nextscn(elf, NULL); sc != NULL; + sc = elf_nextscn(elf, sc)) { + sh = elf64_getshdr(sc); + sn = elf_strptr(elf, eh->e_shstrndx, sh->sh_name); + if (sn != NULL && strcmp(section, sn) == 0 && + sh->sh_type == SHT_PROGBITS && + sh->sh_flags == (SHF_ALLOC | SHF_EXECINSTR)) + break; + } + + sd = elf_getdata(sc, NULL); + if (sd == NULL || sd->d_size == 0 || + sd->d_size % sizeof(struct ebpf_insn) != 0) { + rc = elf_errno(); + RTE_BPF_LOG(ERR, "%s(%p, %s) error code: %d(%s)\n", + __func__, elf, section, rc, elf_errmsg(rc)); + return -EINVAL; + } + + *psd = sd; + *pidx = elf_ndxscn(sc); + return 0; +} + +/* + * helper function to process data from relocation table. + */ +static int +process_reloc(Elf *elf, size_t sym_idx, Elf64_Rel *re, size_t re_sz, + struct ebpf_insn *ins, size_t ins_sz, const struct rte_bpf_prm *prm) +{ + int32_t rc; + uint32_t i, n; + size_t ofs, sym; + const char *sn; + const Elf64_Ehdr *eh; + Elf_Scn *sc; + const Elf_Data *sd; + Elf64_Sym *sm; + + eh = elf64_getehdr(elf); + + /* get symtable by section index */ + sc = elf_getscn(elf, sym_idx); + sd = elf_getdata(sc, NULL); + if (sd == NULL) + return -EINVAL; + sm = sd->d_buf; + + n = re_sz / sizeof(re[0]); + for (i = 0; i != n; i++) { + + ofs = re[i].r_offset; + + /* retrieve index in the symtable */ + sym = ELF64_R_SYM(re[i].r_info); + if (sym * sizeof(sm[0]) >= sd->d_size) + return -EINVAL; + + sn = elf_strptr(elf, eh->e_shstrndx, sm[sym].st_name); + + rc = resolve_xsym(sn, ofs, ins, ins_sz, prm); + if (rc != 0) { + RTE_BPF_LOG(ERR, + "resolve_xsym(%s, %zu) error code: %d\n", + sn, ofs, rc); + return rc; + } + } + + return 0; +} + +/* + * helper function, find relocation information (if any) + * and update bpf code. + */ +static int +elf_reloc_code(Elf *elf, Elf_Data *ed, size_t sidx, + const struct rte_bpf_prm *prm) +{ + Elf64_Rel *re; + Elf_Scn *sc; + const Elf64_Shdr *sh; + const Elf_Data *sd; + int32_t rc; + + rc = 0; + + /* walk through all sections */ + for (sc = elf_nextscn(elf, NULL); sc != NULL && rc == 0; + sc = elf_nextscn(elf, sc)) { + + sh = elf64_getshdr(sc); + + /* relocation data for our code section */ + if (sh->sh_type == SHT_REL && sh->sh_info == sidx) { + sd = elf_getdata(sc, NULL); + if (sd == NULL || sd->d_size == 0 || + sd->d_size % sizeof(re[0]) != 0) + return -EINVAL; + rc = process_reloc(elf, sh->sh_link, + sd->d_buf, sd->d_size, ed->d_buf, ed->d_size, + prm); + } + } + + return rc; +} + +static struct rte_bpf * +bpf_load_elf(const struct rte_bpf_prm *prm, int32_t fd, const char *section) +{ + Elf *elf; + Elf_Data *sd; + size_t sidx; + int32_t rc; + struct rte_bpf *bpf; + struct rte_bpf_prm np; + + elf_version(EV_CURRENT); + elf = elf_begin(fd, ELF_C_READ, NULL); + + rc = find_elf_code(elf, section, &sd, &sidx); + if (rc == 0) + rc = elf_reloc_code(elf, sd, sidx, prm); + + if (rc == 0) { + np = prm[0]; + np.ins = sd->d_buf; + np.nb_ins = sd->d_size / sizeof(struct ebpf_insn); + bpf = rte_bpf_load(&np); + } else { + bpf = NULL; + rte_errno = -rc; + } + + elf_end(elf); + return bpf; +} + +__rte_experimental struct rte_bpf * +rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname, + const char *sname) +{ + int32_t fd, rc; + struct rte_bpf *bpf; + + if (prm == NULL || fname == NULL || sname == NULL) { + rte_errno = EINVAL; + return NULL; + } + + fd = open(fname, O_RDONLY); + if (fd < 0) { + rc = errno; + RTE_BPF_LOG(ERR, "%s(%s) error code: %d(%s)\n", + __func__, fname, rc, strerror(rc)); + rte_errno = EINVAL; + return NULL; + } + + bpf = bpf_load_elf(prm, fd, sname); + close(fd); + + if (bpf == NULL) { + RTE_BPF_LOG(ERR, + "%s(fname=\"%s\", sname=\"%s\") failed, " + "error code: %d\n", + __func__, fname, sname, rte_errno); + return NULL; + } + + RTE_BPF_LOG(INFO, "%s(fname=\"%s\", sname=\"%s\") " + "successfully creates %p(jit={.func=%p,.sz=%zu});\n", + __func__, fname, sname, bpf, bpf->jit.func, bpf->jit.sz); + return bpf; +} |