1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * bootstr.c: Boot string/argument acquisition from the PROM.
4 *
5 * Copyright(C) 1995 David S. Miller (davem@caip.rutgers.edu)
6 */
7
8 #include <linux/string.h>
9 #include <asm/oplib.h>
10 #include <linux/init.h>
11
12 #define BARG_LEN 256
13 static char barg_buf[BARG_LEN] = { 0 };
14 static char fetched __initdata = 0;
15
16 char * __init
17 prom_getbootargs(void)
18 {
19 int iter;
20 char *cp, *arg;
21
22 /* This check saves us from a panic when bootfd patches args. */
23 if (fetched) {
24 return barg_buf;
25 }
26
27 switch (prom_vers) {
28 case PROM_V0:
29 cp = barg_buf;
30 /* Start from 1 and go over fd(0,0,0)kernel */
31 for (iter = 1; iter < 8; iter++) {
32 arg = (*(romvec->pv_v0bootargs))->argv[iter];
33 if (arg == NULL)
34 break;
35 while (*arg != 0) {
36 /* Leave place for space and null. */
37 if (cp >= barg_buf + BARG_LEN - 2)
38 /* We might issue a warning here. */
39 break;
40 *cp++ = *arg++;
41 }
42 *cp++ = ' ';
43 if (cp >= barg_buf + BARG_LEN - 1)
44 /* We might issue a warning here. */
45 break;
46 }
47 *cp = 0;
48 break;
49 case PROM_V2:
50 case PROM_V3:
51 /*
52 * V3 PROM cannot supply as with more than 128 bytes
53 * of an argument. But a smart bootstrap loader can.
54 */
55 strlcpy(barg_buf, *romvec->pv_v2bootargs.bootargs, sizeof(barg_buf));
56 break;
57 default:
58 break;
59 }
60
61 fetched = 1;
62 return barg_buf;
63 }