diff options
Diffstat (limited to 'tools/bpf/bpftool/jit_disasm.c')
| -rw-r--r-- | tools/bpf/bpftool/jit_disasm.c | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c new file mode 100644 index 0000000000..7b8d9ec89e --- /dev/null +++ b/tools/bpf/bpftool/jit_disasm.c @@ -0,0 +1,403 @@ +// 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) + */ + +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif +#include <stdio.h> +#include <stdarg.h> +#include <stdint.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/stat.h> +#include <limits.h> +#include <bpf/libbpf.h> + +#ifdef HAVE_LLVM_SUPPORT +#include <llvm-c/Core.h> +#include <llvm-c/Disassembler.h> +#include <llvm-c/Target.h> +#include <llvm-c/TargetMachine.h> +#endif + +#ifdef HAVE_LIBBFD_SUPPORT +#include <bfd.h> +#include <dis-asm.h> +#include <tools/dis-asm-compat.h> +#endif + +#include "json_writer.h" +#include "main.h" + +static int oper_count; + +#ifdef HAVE_LLVM_SUPPORT +#define DISASM_SPACER + +typedef LLVMDisasmContextRef disasm_ctx_t; + +static int printf_json(char *s) +{ + s = strtok(s, " \t"); + jsonw_string_field(json_wtr, "operation", s); + + jsonw_name(json_wtr, "operands"); + jsonw_start_array(json_wtr); + oper_count = 1; + + while ((s = strtok(NULL, " \t,()")) != 0) { + jsonw_string(json_wtr, s); + oper_count++; + } + return 0; +} + +/* This callback to set the ref_type is necessary to have the LLVM disassembler + * print PC-relative addresses instead of byte offsets for branch instruction + * targets. + */ +static const char * +symbol_lookup_callback(__maybe_unused void *disasm_info, + __maybe_unused uint64_t ref_value, + uint64_t *ref_type, __maybe_unused uint64_t ref_PC, + __maybe_unused const char **ref_name) +{ + *ref_type = LLVMDisassembler_ReferenceType_InOut_None; + return NULL; +} + +static int +init_context(disasm_ctx_t *ctx, const char *arch, + __maybe_unused const char *disassembler_options, + __maybe_unused unsigned char *image, __maybe_unused ssize_t len) +{ + char *triple; + + if (arch) + triple = LLVMNormalizeTargetTriple(arch); + else + triple = LLVMGetDefaultTargetTriple(); + if (!triple) { + p_err("Failed to retrieve triple"); + return -1; + } + *ctx = LLVMCreateDisasm(triple, NULL, 0, NULL, symbol_lookup_callback); + LLVMDisposeMessage(triple); + + if (!*ctx) { + p_err("Failed to create disassembler"); + return -1; + } + + return 0; +} + +static void destroy_context(disasm_ctx_t *ctx) +{ + LLVMDisposeMessage(*ctx); +} + +static int +disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc) +{ + char buf[256]; + int count; + + count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, pc, + buf, sizeof(buf)); + if (json_output) + printf_json(buf); + else + printf("%s", buf); + + return count; +} + +int disasm_init(void) +{ + LLVMInitializeAllTargetInfos(); + LLVMInitializeAllTargetMCs(); + LLVMInitializeAllDisassemblers(); + return 0; +} +#endif /* HAVE_LLVM_SUPPORT */ + +#ifdef HAVE_LIBBFD_SUPPORT +#define DISASM_SPACER "\t" + +typedef struct { + struct disassemble_info *info; + disassembler_ftype disassemble; + bfd *bfdf; +} disasm_ctx_t; + +static int get_exec_path(char *tpath, size_t size) +{ + const char *path = "/proc/self/exe"; + ssize_t len; + + len = readlink(path, tpath, size - 1); + if (len <= 0) + return -1; + + tpath[len] = 0; + + return 0; +} + +static int printf_json(void *out, const char *fmt, va_list ap) +{ + char *s; + int err; + + err = vasprintf(&s, fmt, 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; +} + +static int fprintf_json(void *out, const char *fmt, ...) +{ + va_list ap; + int r; + + va_start(ap, fmt); + r = printf_json(out, fmt, ap); + va_end(ap); + + return r; +} + +static int fprintf_json_styled(void *out, + enum disassembler_style style __maybe_unused, + const char *fmt, ...) +{ + va_list ap; + int r; + + va_start(ap, fmt); + r = printf_json(out, fmt, ap); + va_end(ap); + + return r; +} + +static int init_context(disasm_ctx_t *ctx, const char *arch, + const char *disassembler_options, + unsigned char *image, ssize_t len) +{ + struct disassemble_info *info; + char tpath[PATH_MAX]; + bfd *bfdf; + + memset(tpath, 0, sizeof(tpath)); + if (get_exec_path(tpath, sizeof(tpath))) { + p_err("failed to create disassembler (get_exec_path)"); + return -1; + } + + ctx->bfdf = bfd_openr(tpath, NULL); + if (!ctx->bfdf) { + p_err("failed to create disassembler (bfd_openr)"); + return -1; + } + if (!bfd_check_format(ctx->bfdf, bfd_object)) { + p_err("failed to create disassembler (bfd_check_format)"); + goto err_close; + } + bfdf = ctx->bfdf; + + ctx->info = malloc(sizeof(struct disassemble_info)); + if (!ctx->info) { + p_err("mem alloc failed"); + goto err_close; + } + info = ctx->info; + + if (json_output) + init_disassemble_info_compat(info, stdout, + (fprintf_ftype) fprintf_json, + fprintf_json_styled); + else + init_disassemble_info_compat(info, stdout, + (fprintf_ftype) fprintf, + fprintf_styled); + + /* 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); + goto err_free; + } + } + + 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 + ctx->disassemble = disassembler(info->arch, + bfd_big_endian(bfdf), + info->mach, + bfdf); +#else + ctx->disassemble = disassembler(bfdf); +#endif + if (!ctx->disassemble) { + p_err("failed to create disassembler"); + goto err_free; + } + return 0; + +err_free: + free(info); +err_close: + bfd_close(ctx->bfdf); + return -1; +} + +static void destroy_context(disasm_ctx_t *ctx) +{ + free(ctx->info); + bfd_close(ctx->bfdf); +} + +static int +disassemble_insn(disasm_ctx_t *ctx, __maybe_unused unsigned char *image, + __maybe_unused ssize_t len, int pc) +{ + return ctx->disassemble(pc, ctx->info); +} + +int disasm_init(void) +{ + bfd_init(); + return 0; +} +#endif /* HAVE_LIBBPFD_SUPPORT */ + +int 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; + unsigned int nr_skip = 0; + int count, i, pc = 0; + disasm_ctx_t ctx; + + if (!len) + return -1; + + if (init_context(&ctx, arch, disassembler_options, image, len)) + return -1; + + 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:" DISASM_SPACER, pc); + } + + count = disassemble_insn(&ctx, image, len, pc); + + 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); + + destroy_context(&ctx); + + return 0; +} |