drivers/firmware/iscsi_ibft_find.c

   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 }