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-rw-r--r--tools/bpf/bpftool/jit_disasm.c208
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;
+}