drivers/firmware/efi/efi-bgrt.c

   1 /*
   2  * Copyright 2012 Intel Corporation
   3  * Author: Josh Triplett <josh@joshtriplett.org>
   4  *
   5  * Based on the bgrt driver:
   6  * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
   7  * Author: Matthew Garrett
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/acpi.h>
  19 #include <linux/efi.h>
  20 #include <linux/efi-bgrt.h>
  21
  22 struct acpi_table_bgrt bgrt_tab;
  23 size_t __initdata bgrt_image_size;
  24
  25 struct bmp_header {
  26         u16 id;
  27         u32 size;
  28 } __packed;
  29
  30 static bool efi_bgrt_addr_valid(u64 addr)
  31 {
  32         efi_memory_desc_t *md;
  33
  34         for_each_efi_memory_desc(md) {
  35                 u64 size;
  36                 u64 end;
  37
  38                 if (md->type != EFI_BOOT_SERVICES_DATA)
  39                         continue;
  40
  41                 size = md->num_pages << EFI_PAGE_SHIFT;
  42                 end = md->phys_addr + size;
  43                 if (addr >= md->phys_addr && addr < end)
  44                         return true;
  45         }
  46
  47         return false;
  48 }
  49
  50 void __init efi_bgrt_init(struct acpi_table_header *table)
  51 {
  52         void *image;
  53         struct bmp_header bmp_header;
  54         struct acpi_table_bgrt *bgrt = &bgrt_tab;
  55
  56         if (acpi_disabled)
  57                 return;
  58
  59         if (!efi_enabled(EFI_MEMMAP))
  60                 return;
  61
  62         if (table->length < sizeof(bgrt_tab)) {
  63                 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
  64                        table->length, sizeof(bgrt_tab));
  65                 return;
  66         }
  67         *bgrt = *(struct acpi_table_bgrt *)table;
  68         if (bgrt->version != 1) {
  69                 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
  70                        bgrt->version);
  71                 goto out;
  72         }
  73         if (bgrt->status & 0xfe) {
  74                 pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n",
  75                        bgrt->status);
  76                 goto out;
  77         }
  78         if (bgrt->image_type != 0) {
  79                 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
  80                        bgrt->image_type);
  81                 goto out;
  82         }
  83         if (!bgrt->image_address) {
  84                 pr_notice("Ignoring BGRT: null image address\n");
  85                 goto out;
  86         }
  87
  88         if (!efi_bgrt_addr_valid(bgrt->image_address)) {
  89                 pr_notice("Ignoring BGRT: invalid image address\n");
  90                 goto out;
  91         }
  92         image = early_memremap(bgrt->image_address, sizeof(bmp_header));
  93         if (!image) {
  94                 pr_notice("Ignoring BGRT: failed to map image header memory\n");
  95                 goto out;
  96         }
  97
  98         memcpy(&bmp_header, image, sizeof(bmp_header));
  99         early_memunmap(image, sizeof(bmp_header));
 100         if (bmp_header.id != 0x4d42) {
 101                 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
 102                         bmp_header.id);
 103                 goto out;
 104         }
 105         bgrt_image_size = bmp_header.size;
 106         efi_mem_reserve(bgrt->image_address, bgrt_image_size);
 107
 108         return;
 109 out:
 110         memset(bgrt, 0, sizeof(bgrt_tab));
 111 }