1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2012 Intel Corporation
4 * Author: Josh Triplett <josh@joshtriplett.org>
5 *
6 * Based on the bgrt driver:
7 * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
8 * Author: Matthew Garrett
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/acpi.h>
16#include <linux/efi.h>
17#include <linux/efi-bgrt.h>
18
19struct acpi_table_bgrt bgrt_tab;
20size_t bgrt_image_size;
21
22struct bmp_header {
23 u16 id;
24 u32 size;
25} __packed;
26
27void __init efi_bgrt_init(struct acpi_table_header *table)
28{
29 void *image;
30 struct bmp_header bmp_header;
31 struct acpi_table_bgrt *bgrt = &bgrt_tab;
32
33 if (acpi_disabled)
34 return;
35
36 if (!efi_enabled(EFI_MEMMAP))
37 return;
38
39 if (table->length < sizeof(bgrt_tab)) {
40 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
41 table->length, sizeof(bgrt_tab));
42 return;
43 }
44 *bgrt = *(struct acpi_table_bgrt *)table;
45 /*
46 * Only version 1 is defined but some older laptops (seen on Lenovo
47 * Ivy Bridge models) have a correct version 1 BGRT table with the
48 * version set to 0, so we accept version 0 and 1.
49 */
50 if (bgrt->version > 1) {
51 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
52 bgrt->version);
53 goto out;
54 }
55 if (bgrt->image_type != 0) {
56 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
57 bgrt->image_type);
58 goto out;
59 }
60 if (!bgrt->image_address) {
61 pr_notice("Ignoring BGRT: null image address\n");
62 goto out;
63 }
64
65 if (efi_mem_type(phys_addr: bgrt->image_address) != EFI_BOOT_SERVICES_DATA) {
66 pr_notice("Ignoring BGRT: invalid image address\n");
67 goto out;
68 }
69 image = early_memremap(phys_addr: bgrt->image_address, size: sizeof(bmp_header));
70 if (!image) {
71 pr_notice("Ignoring BGRT: failed to map image header memory\n");
72 goto out;
73 }
74
75 memcpy(to: &bmp_header, from: image, len: sizeof(bmp_header));
76 early_memunmap(addr: image, size: sizeof(bmp_header));
77 if (bmp_header.id != 0x4d42) {
78 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
79 bmp_header.id);
80 goto out;
81 }
82 bgrt_image_size = bmp_header.size;
83 efi_mem_reserve(addr: bgrt->image_address, size: bgrt_image_size);
84
85 return;
86out:
87 memset(s: bgrt, c: 0, n: sizeof(bgrt_tab));
88}
89