1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * mkbrncmdline.c - partially based on OpenWrt's wndr3700.c 4 * 5 * Copyright (C) 2011 Tobias Diedrich <ranma+openwrt@tdiedrich.de> 6 */ 7 8 #include <stdio.h> 9 #include <stdlib.h> 10 #include <stddef.h> 11 #include <unistd.h> 12 #include <errno.h> 13 #include <fcntl.h> 14 #include <sys/mman.h> 15 #include <string.h> 16 #include <netinet/in.h> 17 #include <inttypes.h> 18 19 static void usage(const char *) __attribute__ (( __noreturn__ )); 20 21 static void usage(const char *mess) 22 { 23 fprintf(stderr, "Error: %s\n", mess); 24 fprintf(stderr, "Usage: mkbrncmdline -i input_file -o output_file [-a loadaddress] arg1 [argx ...]\n"); 25 fprintf(stderr, "\n"); 26 exit(1); 27 } 28 29 static char *input_file = NULL; 30 static char *output_file = NULL; 31 static unsigned loadaddr = 0x80002000; 32 33 static void parseopts(int *argc, char ***argv) 34 { 35 char *endptr; 36 int res; 37 38 while ((res = getopt(*argc, *argv, "a:i:o:")) != -1) { 39 switch (res) { 40 default: 41 usage("Unknown option"); 42 break; 43 case 'a': 44 loadaddr = strtoul(optarg, &endptr, 0); 45 if (endptr == optarg || *endptr != 0) 46 usage("loadaddress must be a decimal or hexadecimal 32-bit value"); 47 break; 48 case 'i': 49 input_file = optarg; 50 break; 51 case 'o': 52 output_file = optarg; 53 break; 54 } 55 } 56 *argc -= optind; 57 *argv += optind; 58 } 59 60 static void emitload(int outfd, int reg, unsigned value) 61 { 62 char buf[8] = { 63 0x3c, 0x04 + reg, 64 value >> 24, value >> 16, 65 0x34, 0x84 + reg + (reg << 5), 66 value >> 8, value, 67 }; 68 if (write(outfd, buf, sizeof(buf)) != sizeof(buf)) { 69 fprintf(stderr, "write: %s\n", strerror(errno)); 70 exit(1); 71 } 72 } 73 74 int main(int argc, char **argv) 75 { 76 int outfd; 77 int i; 78 int fd; 79 size_t len, skip, buf_len; 80 unsigned cmdline_addr; 81 unsigned s_ofs; 82 char *buf; 83 84 parseopts(&argc, &argv); 85 86 if (argc < 1) 87 usage("must specify at least one kernel cmdline argument"); 88 89 if (input_file == NULL || output_file == NULL) 90 usage("must specify input and output file"); 91 92 if ((outfd = open(output_file, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1) 93 { 94 fprintf(stderr, "Error opening '%s' for writing: %s\n", output_file, strerror(errno)); 95 exit(1); 96 } 97 98 // mmap input_file 99 if ((fd = open(input_file, O_RDONLY)) < 0 100 || (len = lseek(fd, 0, SEEK_END)) < 0 101 || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1) 102 || close(fd) < 0) 103 { 104 fprintf(stderr, "Error mapping file '%s': %s\n", input_file, strerror(errno)); 105 exit(1); 106 } 107 108 cmdline_addr = loadaddr + len; 109 110 // Kernel args are passed in registers a0,a1,a2 and a3 111 emitload(outfd, 0, 0); /* a0 = 0 */ 112 emitload(outfd, 1, 0); /* a1 = 0 */ 113 emitload(outfd, 2, cmdline_addr); /* a2 = &cmdline */ 114 emitload(outfd, 3, 0); /* a3 = 0 */ 115 skip = lseek(outfd, 0, SEEK_END); 116 117 // write the kernel 118 if (write(outfd, input_file + skip, len - skip) != len -skip) { 119 fprintf(stderr, "write: %s\n", strerror(errno)); 120 exit(1); 121 } 122 123 // write cmdline structure 124 buf_len = (argc + 1) * 4; 125 for (i=0; i<argc; i++) { 126 buf_len += strlen(argv[i]) + 1; 127 } 128 buf = malloc(buf_len + 16); 129 if (!buf) { 130 fprintf(stderr, "Could not allocate memory for cmdline buffer\n"); 131 exit(1); 132 } 133 memset(buf, 0, buf_len); 134 135 s_ofs = 4 * (argc + 1); 136 for (i=0; i<argc; i++) { 137 unsigned s_ptr = cmdline_addr + s_ofs; 138 buf[i * 4 + 0] = s_ptr >> 24; 139 buf[i * 4 + 1] = s_ptr >> 16; 140 buf[i * 4 + 2] = s_ptr >> 8; 141 buf[i * 4 + 3] = s_ptr >> 0; 142 memcpy(&buf[s_ofs], argv[i], strlen(argv[i])); 143 s_ofs += strlen(argv[i]) + 1; 144 } 145 if (write(outfd, buf, buf_len) != buf_len) { 146 fprintf(stderr, "write: %s\n", strerror(errno)); 147 exit(1); 148 } 149 150 151 munmap(input_file, len); 152 close(outfd); 153 free(buf); 154 155 return 0; 156 } 157
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