diff options
Diffstat (limited to 'tools/bpf/bpftool/jit_disasm.c')
| -rw-r--r-- | tools/bpf/bpftool/jit_disasm.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c new file mode 100644 index 000000000..24734f224 --- /dev/null +++ b/tools/bpf/bpftool/jit_disasm.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +/* + * Based on: + * + * Minimal BPF JIT image disassembler + * + * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for + * debugging or verification purposes. + * + * Copyright 2013 Daniel Borkmann <daniel@iogearbox.net> + * Licensed under the GNU General Public License, version 2.0 (GPLv2) + */ + +#define _GNU_SOURCE +#include <stdio.h> +#include <stdarg.h> +#include <stdint.h> +#include <stdlib.h> +#include <assert.h> +#include <unistd.h> +#include <string.h> +#include <bfd.h> +#include <dis-asm.h> +#include <sys/stat.h> +#include <limits.h> +#include <bpf/libbpf.h> + +#include "json_writer.h" +#include "main.h" + +static void get_exec_path(char *tpath, size_t size) +{ + const char *path = "/proc/self/exe"; + ssize_t len; + + len = readlink(path, tpath, size - 1); + assert(len > 0); + tpath[len] = 0; +} + +static int oper_count; +static int fprintf_json(void *out, const char *fmt, ...) +{ + va_list ap; + char *s; + int err; + + va_start(ap, fmt); + err = vasprintf(&s, fmt, ap); + va_end(ap); + if (err < 0) + return -1; + + if (!oper_count) { + int i; + + /* Strip trailing spaces */ + i = strlen(s) - 1; + while (s[i] == ' ') + s[i--] = '\0'; + + jsonw_string_field(json_wtr, "operation", s); + jsonw_name(json_wtr, "operands"); + jsonw_start_array(json_wtr); + oper_count++; + } else if (!strcmp(fmt, ",")) { + /* Skip */ + } else { + jsonw_string(json_wtr, s); + oper_count++; + } + free(s); + return 0; +} + +void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes, + const char *arch, const char *disassembler_options, + const struct btf *btf, + const struct bpf_prog_linfo *prog_linfo, + __u64 func_ksym, unsigned int func_idx, + bool linum) +{ + const struct bpf_line_info *linfo = NULL; + disassembler_ftype disassemble; + struct disassemble_info info; + unsigned int nr_skip = 0; + int count, i, pc = 0; + char tpath[PATH_MAX]; + bfd *bfdf; + + if (!len) + return; + + memset(tpath, 0, sizeof(tpath)); + get_exec_path(tpath, sizeof(tpath)); + + bfdf = bfd_openr(tpath, NULL); + assert(bfdf); + assert(bfd_check_format(bfdf, bfd_object)); + + if (json_output) + init_disassemble_info(&info, stdout, + (fprintf_ftype) fprintf_json); + else + init_disassemble_info(&info, stdout, + (fprintf_ftype) fprintf); + + /* Update architecture info for offload. */ + if (arch) { + const bfd_arch_info_type *inf = bfd_scan_arch(arch); + + if (inf) { + bfdf->arch_info = inf; + } else { + p_err("No libbfd support for %s", arch); + return; + } + } + + info.arch = bfd_get_arch(bfdf); + info.mach = bfd_get_mach(bfdf); + if (disassembler_options) + info.disassembler_options = disassembler_options; + info.buffer = image; + info.buffer_length = len; + + disassemble_init_for_target(&info); + +#ifdef DISASM_FOUR_ARGS_SIGNATURE + disassemble = disassembler(info.arch, + bfd_big_endian(bfdf), + info.mach, + bfdf); +#else + disassemble = disassembler(bfdf); +#endif + assert(disassemble); + + if (json_output) + jsonw_start_array(json_wtr); + do { + if (prog_linfo) { + linfo = bpf_prog_linfo__lfind_addr_func(prog_linfo, + func_ksym + pc, + func_idx, + nr_skip); + if (linfo) + nr_skip++; + } + + if (json_output) { + jsonw_start_object(json_wtr); + oper_count = 0; + if (linfo) + btf_dump_linfo_json(btf, linfo, linum); + jsonw_name(json_wtr, "pc"); + jsonw_printf(json_wtr, "\"0x%x\"", pc); + } else { + if (linfo) + btf_dump_linfo_plain(btf, linfo, "; ", + linum); + printf("%4x:\t", pc); + } + + count = disassemble(pc, &info); + if (json_output) { + /* Operand array, was started in fprintf_json. Before + * that, make sure we have a _null_ value if no operand + * other than operation code was present. + */ + if (oper_count == 1) + jsonw_null(json_wtr); + jsonw_end_array(json_wtr); + } + + if (opcodes) { + if (json_output) { + jsonw_name(json_wtr, "opcodes"); + jsonw_start_array(json_wtr); + for (i = 0; i < count; ++i) + jsonw_printf(json_wtr, "\"0x%02hhx\"", + (uint8_t)image[pc + i]); + jsonw_end_array(json_wtr); + } else { + printf("\n\t"); + for (i = 0; i < count; ++i) + printf("%02x ", + (uint8_t)image[pc + i]); + } + } + if (json_output) + jsonw_end_object(json_wtr); + else + printf("\n"); + + pc += count; + } while (count > 0 && pc < len); + if (json_output) + jsonw_end_array(json_wtr); + + bfd_close(bfdf); +} + +int disasm_init(void) +{ + bfd_init(); + return 0; +} |