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
13static char barg_buf[BARG_LEN] = { 0 };
14static char fetched __initdata = 0;
15
16char * __init
17prom_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		strscpy(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