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
prom_getbootargs(void)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 }
64