arch/x86/platform/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 void *__initdata bgrt_image;
  24 size_t __initdata bgrt_image_size;
  25
  26 struct bmp_header {
  27         u16 id;
  28         u32 size;
  29 } __packed;
  30
  31 void __init efi_bgrt_init(void)
  32 {
  33         acpi_status status;
  34         void *image;
  35         struct bmp_header bmp_header;
  36
  37         if (acpi_disabled)
  38                 return;
  39
  40         status = acpi_get_table("BGRT", 0,
  41                                 (struct acpi_table_header **)&bgrt_tab);
  42         if (ACPI_FAILURE(status))
  43                 return;
  44
  45         if (bgrt_tab->header.length < sizeof(*bgrt_tab)) {
  46                 pr_err("Ignoring BGRT: invalid length %u (expected %zu)\n",
  47                        bgrt_tab->header.length, sizeof(*bgrt_tab));
  48                 return;
  49         }
  50         if (bgrt_tab->version != 1) {
  51                 pr_err("Ignoring BGRT: invalid version %u (expected 1)\n",
  52                        bgrt_tab->version);
  53                 return;
  54         }
  55         if (bgrt_tab->status & 0xfe) {
  56                 pr_err("Ignoring BGRT: reserved status bits are non-zero %u\n",
  57                        bgrt_tab->status);
  58                 return;
  59         }
  60         if (bgrt_tab->image_type != 0) {
  61                 pr_err("Ignoring BGRT: invalid image type %u (expected 0)\n",
  62                        bgrt_tab->image_type);
  63                 return;
  64         }
  65         if (!bgrt_tab->image_address) {
  66                 pr_err("Ignoring BGRT: null image address\n");
  67                 return;
  68         }
  69
  70         image = memremap(bgrt_tab->image_address, sizeof(bmp_header), MEMREMAP_WB);
  71         if (!image) {
  72                 pr_err("Ignoring BGRT: failed to map image header memory\n");
  73                 return;
  74         }
  75
  76         memcpy(&bmp_header, image, sizeof(bmp_header));
  77         memunmap(image);
  78         if (bmp_header.id != 0x4d42) {
  79                 pr_err("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
  80                         bmp_header.id);
  81                 return;
  82         }
  83         bgrt_image_size = bmp_header.size;
  84
  85         bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL | __GFP_NOWARN);
  86         if (!bgrt_image) {
  87                 pr_err("Ignoring BGRT: failed to allocate memory for image (wanted %zu bytes)\n",
  88                        bgrt_image_size);
  89                 return;
  90         }
  91
  92         image = memremap(bgrt_tab->image_address, bmp_header.size, MEMREMAP_WB);
  93         if (!image) {
  94                 pr_err("Ignoring BGRT: failed to map image memory\n");
  95                 kfree(bgrt_image);
  96                 bgrt_image = NULL;
  97                 return;
  98         }
  99
 100         memcpy(bgrt_image, image, bgrt_image_size);
 101         memunmap(image);
 102 }