1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
5 * Minimal BPF JIT image disassembler
7 * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
8 * debugging or verification purposes.
10 * Copyright 2013 Daniel Borkmann <daniel@iogearbox.net>
11 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
29 #include "json_writer.h"
32 static void get_exec_path(char *tpath, size_t size)
34 const char *path = "/proc/self/exe";
37 len = readlink(path, tpath, size - 1);
42 static int oper_count;
43 static int fprintf_json(void *out, const char *fmt, ...)
49 if (vasprintf(&s, fmt, ap) < 0)
56 /* Strip trailing spaces */
61 jsonw_string_field(json_wtr, "operation", s);
62 jsonw_name(json_wtr, "operands");
63 jsonw_start_array(json_wtr);
65 } else if (!strcmp(fmt, ",")) {
68 jsonw_string(json_wtr, s);
75 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
76 const char *arch, const char *disassembler_options,
77 const struct btf *btf,
78 const struct bpf_prog_linfo *prog_linfo,
79 __u64 func_ksym, unsigned int func_idx,
82 const struct bpf_line_info *linfo = NULL;
83 disassembler_ftype disassemble;
84 struct disassemble_info info;
85 unsigned int nr_skip = 0;
93 memset(tpath, 0, sizeof(tpath));
94 get_exec_path(tpath, sizeof(tpath));
96 bfdf = bfd_openr(tpath, NULL);
98 assert(bfd_check_format(bfdf, bfd_object));
101 init_disassemble_info(&info, stdout,
102 (fprintf_ftype) fprintf_json);
104 init_disassemble_info(&info, stdout,
105 (fprintf_ftype) fprintf);
107 /* Update architecture info for offload. */
109 const bfd_arch_info_type *inf = bfd_scan_arch(arch);
112 bfdf->arch_info = inf;
114 p_err("No libbfd support for %s", arch);
119 info.arch = bfd_get_arch(bfdf);
120 info.mach = bfd_get_mach(bfdf);
121 if (disassembler_options)
122 info.disassembler_options = disassembler_options;
124 info.buffer_length = len;
126 disassemble_init_for_target(&info);
128 #ifdef DISASM_FOUR_ARGS_SIGNATURE
129 disassemble = disassembler(info.arch,
130 bfd_big_endian(bfdf),
134 disassemble = disassembler(bfdf);
139 jsonw_start_array(json_wtr);
142 linfo = bpf_prog_linfo__lfind_addr_func(prog_linfo,
151 jsonw_start_object(json_wtr);
154 btf_dump_linfo_json(btf, linfo, linum);
155 jsonw_name(json_wtr, "pc");
156 jsonw_printf(json_wtr, "\"0x%x\"", pc);
159 btf_dump_linfo_plain(btf, linfo, "; ",
161 printf("%4x:\t", pc);
164 count = disassemble(pc, &info);
166 /* Operand array, was started in fprintf_json. Before
167 * that, make sure we have a _null_ value if no operand
168 * other than operation code was present.
171 jsonw_null(json_wtr);
172 jsonw_end_array(json_wtr);
177 jsonw_name(json_wtr, "opcodes");
178 jsonw_start_array(json_wtr);
179 for (i = 0; i < count; ++i)
180 jsonw_printf(json_wtr, "\"0x%02hhx\"",
181 (uint8_t)image[pc + i]);
182 jsonw_end_array(json_wtr);
185 for (i = 0; i < count; ++i)
187 (uint8_t)image[pc + i]);
191 jsonw_end_object(json_wtr);
196 } while (count > 0 && pc < len);
198 jsonw_end_array(json_wtr);
203 int disasm_init(void)