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