1 // SPDX-License-Identifier: GPL-2.0-only
3 * mkbrncmdline.c - partially based on OpenWrt's wndr3700.c
5 * Copyright (C) 2011 Tobias Diedrich <ranma+openwrt@tdiedrich.de>
16 #include <netinet/in.h>
19 static void usage(const char *) __attribute__ (( __noreturn__
));
21 static void usage(const char *mess
)
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");
29 static char *input_file
= NULL
;
30 static char *output_file
= NULL
;
31 static unsigned loadaddr
= 0x80002000;
33 static void parseopts(int *argc
, char ***argv
)
38 while ((res
= getopt(*argc
, *argv
, "a:i:o:")) != -1) {
41 usage("Unknown option");
44 loadaddr
= strtoul(optarg
, &endptr
, 0);
45 if (endptr
== optarg
|| *endptr
!= 0)
46 usage("loadaddress must be a decimal or hexadecimal 32-bit value");
60 static void emitload(int outfd
, int reg
, unsigned value
)
64 value
>> 24, value
>> 16,
65 0x34, 0x84 + reg
+ (reg
<< 5),
68 if (write(outfd
, buf
, sizeof(buf
)) != sizeof(buf
)) {
69 fprintf(stderr
, "write: %s\n", strerror(errno
));
74 int main(int argc
, char **argv
)
79 size_t len
, skip
, buf_len
;
80 unsigned cmdline_addr
;
84 parseopts(&argc
, &argv
);
87 usage("must specify at least one kernel cmdline argument");
89 if (input_file
== NULL
|| output_file
== NULL
)
90 usage("must specify input and output file");
92 if ((outfd
= open(output_file
, O_WRONLY
|O_CREAT
|O_TRUNC
, 0644)) == -1)
94 fprintf(stderr
, "Error opening '%s' for writing: %s\n", output_file
, strerror(errno
));
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)
104 fprintf(stderr
, "Error mapping file '%s': %s\n", input_file
, strerror(errno
));
108 cmdline_addr
= loadaddr
+ len
;
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
);
118 if (write(outfd
, input_file
+ skip
, len
- skip
) != len
-skip
) {
119 fprintf(stderr
, "write: %s\n", strerror(errno
));
123 // write cmdline structure
124 buf_len
= (argc
+ 1) * 4;
125 for (i
=0; i
<argc
; i
++) {
126 buf_len
+= strlen(argv
[i
]) + 1;
128 buf
= malloc(buf_len
+ 16);
130 fprintf(stderr
, "Could not allocate memory for cmdline buffer\n");
133 memset(buf
, 0, buf_len
);
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;
145 if (write(outfd
, buf
, buf_len
) != buf_len
) {
146 fprintf(stderr
, "write: %s\n", strerror(errno
));
151 munmap(input_file
, len
);