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6e7ca70449
BCM4908 CFE bootloader requires kernel to be prepended with a custom header. This simple tool implements support for such headers. Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
128 lines
2.6 KiB
C
128 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
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*/
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#include <byteswap.h>
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#include <endian.h>
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#include <errno.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#if !defined(__BYTE_ORDER)
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#error "Unknown byte order"
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#endif
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#if __BYTE_ORDER == __BIG_ENDIAN
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#define cpu_to_le32(x) bswap_32(x)
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#define le32_to_cpu(x) bswap_32(x)
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#elif __BYTE_ORDER == __LITTLE_ENDIAN
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#define cpu_to_le32(x) (x)
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#define le32_to_cpu(x) (x)
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#else
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#error "Unsupported endianness"
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#endif
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struct bcm4908kernel_header {
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uint32_t unk1;
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uint32_t unk2;
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uint32_t length;
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uint8_t magic[4];
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uint32_t unused;
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};
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static void usage() {
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printf("Usage:\n");
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printf("\n");
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printf("\t-i pathname\t\t\tinput kernel filepath\n");
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printf("\t-o pathname\t\t\toutput kernel filepath\n");
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}
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int main(int argc, char **argv) {
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struct bcm4908kernel_header header;
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uint8_t buf[1024];
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FILE *out = NULL;
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FILE *in = NULL;
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size_t length;
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size_t bytes;
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int err = 0;
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char c;
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if (argc >= 2 && !strcmp(argv[1], "-h")) {
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usage();
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return 0;
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}
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while ((c = getopt(argc, argv, "i:o:")) != -1) {
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switch (c) {
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case 'i':
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in = fopen(optarg, "r");
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break;
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case 'o':
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out = fopen(optarg, "w+");
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break;
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}
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}
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if (!in || !out) {
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fprintf(stderr, "Failed to open input and/or output file\n");
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usage();
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return -EINVAL;
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}
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if (fread(&header, 1, sizeof(header), in) != sizeof(header)) {
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fprintf(stderr, "Failed to read %zu bytes from input file\n", sizeof(header));
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err = -EIO;
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goto err_close;
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}
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if (!memcmp(header.magic, "BRCM", 4)) {
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fprintf(stderr, "Input file already contains BCM4908 kernel header\n");
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err = -EIO;
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goto err_close;
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}
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err = fseek(out, sizeof(header), SEEK_SET);
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if (err) {
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err = -errno;
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fprintf(stderr, "Failed to fseek(): %d\n", err);
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goto err_close;
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}
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length = 0;
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rewind(in);
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while ((bytes = fread(buf, 1, sizeof(buf), in)) > 0) {
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if (fwrite(buf, 1, bytes, out) != bytes) {
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fprintf(stderr, "Failed to write %zu B to the output file\n", bytes);
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err = -EIO;
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goto err_close;
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}
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length += bytes;
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}
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header.unk1 = cpu_to_le32(0x00080000);
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header.unk2 = cpu_to_le32(0x00080000);
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header.length = cpu_to_le32(length);
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header.magic[0] = 'B';
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header.magic[1] = 'R';
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header.magic[2] = 'C';
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header.magic[3] = 'M';
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header.unused = 0;
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fseek(out, 0, SEEK_SET);
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if (fwrite(&header, 1, sizeof(header), out) != sizeof(header)) {
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fprintf(stderr, "Failed to write header to the output file\n");
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err = -EIO;
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goto err_close;
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}
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err_close:
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fclose(out);
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fclose(in);
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return err;
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}
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