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 void __init efi_bgrt_init(struct acpi_table_header *table)
  31 {
  32         void *image;
  33         struct bmp_header bmp_header;
  34         struct acpi_table_bgrt *bgrt = &bgrt_tab;
  35
  36         if (acpi_disabled)
  37                 return;
  38
  39         if (!efi_enabled(EFI_BOOT))
  40                 return;
  41
  42         if (table->length < sizeof(bgrt_tab)) {
  43                 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
  44                        table->length, sizeof(bgrt_tab));
  45                 return;
  46         }
  47         *bgrt = *(struct acpi_table_bgrt *)table;
  48         if (bgrt->version != 1) {
  49                 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
  50                        bgrt->version);
  51                 goto out;
  52         }
  53         if (bgrt->status & 0xfe) {
  54                 pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n",
  55                        bgrt->status);
  56                 goto out;
  57         }
  58         if (bgrt->image_type != 0) {
  59                 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
  60                        bgrt->image_type);
  61                 goto out;
  62         }
  63         if (!bgrt->image_address) {
  64                 pr_notice("Ignoring BGRT: null image address\n");
  65                 goto out;
  66         }
  67
  68         image = early_memremap(bgrt->image_address, sizeof(bmp_header));
  69         if (!image) {
  70                 pr_notice("Ignoring BGRT: failed to map image header memory\n");
  71                 goto out;
  72         }
  73
  74         memcpy(&bmp_header, image, sizeof(bmp_header));
  75         early_memunmap(image, sizeof(bmp_header));
  76         if (bmp_header.id != 0x4d42) {
  77                 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
  78                         bmp_header.id);
  79                 goto out;
  80         }
  81         bgrt_image_size = bmp_header.size;
  82         efi_mem_reserve(bgrt->image_address, bgrt_image_size);
  83
  84         return;
  85 out:
  86         memset(bgrt, 0, sizeof(bgrt_tab));
  87 }