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  */
34 phys_addr_t ibft_phys_addr;
35 EXPORT_SYMBOL_GPL(ibft_phys_addr);
36 
37 static 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  */
51 void __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 
98 out:
99 	early_memunmap(virt, PAGE_SIZE);
100 }
101