1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  Copyright 2007-2010 Red Hat, Inc.
4 *  by Peter Jones <pjones@redhat.com>
5 *  Copyright 2007 IBM, Inc.
6 *  by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
7 *  Copyright 2008
8 *  by Konrad Rzeszutek <ketuzsezr@darnok.org>
9 *
10 * This code finds the iSCSI Boot Format Table.
11 */
12
13#include <linux/memblock.h>
14#include <linux/blkdev.h>
15#include <linux/ctype.h>
16#include <linux/device.h>
17#include <linux/efi.h>
18#include <linux/err.h>
19#include <linux/init.h>
20#include <linux/limits.h>
21#include <linux/module.h>
22#include <linux/pci.h>
23#include <linux/stat.h>
24#include <linux/string.h>
25#include <linux/types.h>
26#include <linux/acpi.h>
27#include <linux/iscsi_ibft.h>
28
29#include <asm/mmzone.h>
30
31/*
32 * Physical location of iSCSI Boot Format Table.
33 */
34phys_addr_t ibft_phys_addr;
35EXPORT_SYMBOL_GPL(ibft_phys_addr);
36
37static const struct {
38	char *sign;
39} ibft_signs[] = {
40	{ "iBFT" },
41	{ "BIFT" },	/* Broadcom iSCSI Offload */
42};
43
44#define IBFT_SIGN_LEN 4
45#define VGA_MEM 0xA0000 /* VGA buffer */
46#define VGA_SIZE 0x20000 /* 128kB */
47
48/*
49 * Routine used to find and reserve the iSCSI Boot Format Table
50 */
51void __init reserve_ibft_region(void)
52{
53	unsigned long pos, virt_pos = 0;
54	unsigned int len = 0;
55	void *virt = NULL;
56	int i;
57
58	ibft_phys_addr = 0;
59
60	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
61	 * only use ACPI for this
62	 */
63	if (efi_enabled(EFI_BOOT))
64		return;
65
66	for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
67		/* The table can't be inside the VGA BIOS reserved space,
68		 * so skip that area */
69		if (pos == VGA_MEM)
70			pos += VGA_SIZE;
71
72		/* Map page by page */
73		if (offset_in_page(pos) == 0) {
74			if (virt)
75				early_memunmap(virt, PAGE_SIZE);
76			virt = early_memremap_ro(pos, PAGE_SIZE);
77			virt_pos = pos;
78		}
79
80		for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
81			if (memcmp(virt + (pos - virt_pos), ibft_signs[i].sign,
82				   IBFT_SIGN_LEN) == 0) {
83				unsigned long *addr =
84				    (unsigned long *)(virt + pos - virt_pos + 4);
85				len = *addr;
86				/* if the length of the table extends past 1M,
87				 * the table cannot be valid. */
88				if (pos + len <= (IBFT_END-1)) {
89					ibft_phys_addr = pos;
90					memblock_reserve(ibft_phys_addr, PAGE_ALIGN(len));
91					pr_info("iBFT found at %pa.\n", &ibft_phys_addr);
92					goto out;
93				}
94			}
95		}
96	}
97
98out:
99	early_memunmap(virt, PAGE_SIZE);
100}
101