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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* fdtdump.c - Contributed by Pantelis Antoniou <pantelis.antoniou AT gmail.com>
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <inttypes.h>
#include <libfdt.h>
#include <libfdt_env.h>
#include <fdt.h>
#include "util.h"
#define FDT_MAGIC_SIZE 4
#define MAX_VERSION 17U
#define ALIGN(x, a) (((x) + ((a) - 1)) & ~((a) - 1))
#define PALIGN(p, a) ((void *)(ALIGN((uintptr_t)(p), (a))))
#define GET_CELL(p) (p += 4, *((const fdt32_t *)(p-4)))
static const char *tagname(uint32_t tag)
{
static const char * const names[] = {
#define TN(t) [t] = #t
TN(FDT_BEGIN_NODE),
TN(FDT_END_NODE),
TN(FDT_PROP),
TN(FDT_NOP),
TN(FDT_END),
#undef TN
};
if (tag < ARRAY_SIZE(names))
if (names[tag])
return names[tag];
return "FDT_???";
}
#define dumpf(fmt, args...) \
do { if (debug) printf("// " fmt, ## args); } while (0)
static void dump_blob(void *blob, bool debug)
{
uintptr_t blob_off = (uintptr_t)blob;
struct fdt_header *bph = blob;
uint32_t off_mem_rsvmap = fdt32_to_cpu(bph->off_mem_rsvmap);
uint32_t off_dt = fdt32_to_cpu(bph->off_dt_struct);
uint32_t off_str = fdt32_to_cpu(bph->off_dt_strings);
struct fdt_reserve_entry *p_rsvmap =
(struct fdt_reserve_entry *)((char *)blob + off_mem_rsvmap);
const char *p_struct = (const char *)blob + off_dt;
const char *p_strings = (const char *)blob + off_str;
uint32_t version = fdt32_to_cpu(bph->version);
uint32_t totalsize = fdt32_to_cpu(bph->totalsize);
uint32_t tag;
const char *p, *s, *t;
int depth, sz, shift;
int i;
uint64_t addr, size;
depth = 0;
shift = 4;
printf("/dts-v1/;\n");
printf("// magic:\t\t0x%"PRIx32"\n", fdt32_to_cpu(bph->magic));
printf("// totalsize:\t\t0x%"PRIx32" (%"PRIu32")\n",
totalsize, totalsize);
printf("// off_dt_struct:\t0x%"PRIx32"\n", off_dt);
printf("// off_dt_strings:\t0x%"PRIx32"\n", off_str);
printf("// off_mem_rsvmap:\t0x%"PRIx32"\n", off_mem_rsvmap);
printf("// version:\t\t%"PRIu32"\n", version);
printf("// last_comp_version:\t%"PRIu32"\n",
fdt32_to_cpu(bph->last_comp_version));
if (version >= 2)
printf("// boot_cpuid_phys:\t0x%"PRIx32"\n",
fdt32_to_cpu(bph->boot_cpuid_phys));
if (version >= 3)
printf("// size_dt_strings:\t0x%"PRIx32"\n",
fdt32_to_cpu(bph->size_dt_strings));
if (version >= 17)
printf("// size_dt_struct:\t0x%"PRIx32"\n",
fdt32_to_cpu(bph->size_dt_struct));
printf("\n");
for (i = 0; ; i++) {
addr = fdt64_to_cpu(p_rsvmap[i].address);
size = fdt64_to_cpu(p_rsvmap[i].size);
if (addr == 0 && size == 0)
break;
printf("/memreserve/ %#"PRIx64" %#"PRIx64";\n",
addr, size);
}
p = p_struct;
while ((tag = fdt32_to_cpu(GET_CELL(p))) != FDT_END) {
dumpf("%04"PRIxPTR": tag: 0x%08"PRIx32" (%s)\n",
(uintptr_t)p - blob_off - 4, tag, tagname(tag));
if (tag == FDT_BEGIN_NODE) {
s = p;
p = PALIGN(p + strlen(s) + 1, 4);
if (*s == '\0')
s = "/";
printf("%*s%s {\n", depth * shift, "", s);
depth++;
continue;
}
if (tag == FDT_END_NODE) {
depth--;
printf("%*s};\n", depth * shift, "");
continue;
}
if (tag == FDT_NOP) {
printf("%*s// [NOP]\n", depth * shift, "");
continue;
}
if (tag != FDT_PROP) {
fprintf(stderr, "%*s ** Unknown tag 0x%08"PRIx32"\n", depth * shift, "", tag);
break;
}
sz = fdt32_to_cpu(GET_CELL(p));
s = p_strings + fdt32_to_cpu(GET_CELL(p));
if (version < 16 && sz >= 8)
p = PALIGN(p, 8);
t = p;
p = PALIGN(p + sz, 4);
dumpf("%04"PRIxPTR": string: %s\n", (uintptr_t)s - blob_off, s);
dumpf("%04"PRIxPTR": value\n", (uintptr_t)t - blob_off);
printf("%*s%s", depth * shift, "", s);
utilfdt_print_data(t, sz);
printf(";\n");
}
}
/* Usage related data. */
static const char usage_synopsis[] = "fdtdump [options] <file>";
static const char usage_short_opts[] = "ds" USAGE_COMMON_SHORT_OPTS;
static struct option const usage_long_opts[] = {
{"debug", no_argument, NULL, 'd'},
{"scan", no_argument, NULL, 's'},
USAGE_COMMON_LONG_OPTS
};
static const char * const usage_opts_help[] = {
"Dump debug information while decoding the file",
"Scan for an embedded fdt in file",
USAGE_COMMON_OPTS_HELP
};
static bool valid_header(char *p, size_t len)
{
if (len < sizeof(struct fdt_header) ||
fdt_magic(p) != FDT_MAGIC ||
fdt_version(p) > MAX_VERSION ||
fdt_last_comp_version(p) > MAX_VERSION ||
fdt_totalsize(p) >= len ||
fdt_off_dt_struct(p) >= len ||
fdt_off_dt_strings(p) >= len)
return 0;
else
return 1;
}
int main(int argc, char *argv[])
{
int opt;
const char *file;
char *buf;
bool debug = false;
bool scan = false;
size_t len;
fprintf(stderr, "\n"
"**** fdtdump is a low-level debugging tool, not meant for general use.\n"
"**** If you want to decompile a dtb, you probably want\n"
"**** dtc -I dtb -O dts <filename>\n\n"
);
while ((opt = util_getopt_long()) != EOF) {
switch (opt) {
case_USAGE_COMMON_FLAGS
case 'd':
debug = true;
break;
case 's':
scan = true;
break;
}
}
if (optind != argc - 1)
usage("missing input filename");
file = argv[optind];
buf = utilfdt_read(file, &len);
if (!buf)
die("could not read: %s\n", file);
/* try and locate an embedded fdt in a bigger blob */
if (scan) {
unsigned char smagic[FDT_MAGIC_SIZE];
char *p = buf;
char *endp = buf + len;
fdt32_st(smagic, FDT_MAGIC);
/* poor man's memmem */
while ((endp - p) >= FDT_MAGIC_SIZE) {
p = memchr(p, smagic[0], endp - p - FDT_MAGIC_SIZE);
if (!p)
break;
if (fdt_magic(p) == FDT_MAGIC) {
/* try and validate the main struct */
off_t this_len = endp - p;
if (valid_header(p, this_len))
break;
if (debug)
printf("%s: skipping fdt magic at offset %#tx\n",
file, p - buf);
}
++p;
}
if (!p || (size_t)(endp - p) < sizeof(struct fdt_header))
die("%s: could not locate fdt magic\n", file);
printf("%s: found fdt at offset %#tx\n", file, p - buf);
buf = p;
} else if (!valid_header(buf, len))
die("%s: header is not valid\n", file);
dump_blob(buf, debug);
return 0;
}