89 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright 2012 Intel Corporation4 * 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 Garrett9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 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 Lenovo47 * Ivy Bridge models) have a correct version 1 BGRT table with the48 * 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(bgrt->image_address) != EFI_BOOT_SERVICES_DATA) {66 pr_notice("Ignoring BGRT: invalid image address\n");67 goto out;68 }69 image = early_memremap(bgrt->image_address, 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(&bmp_header, image, sizeof(bmp_header));76 early_memunmap(image, 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(bgrt->image_address, bgrt_image_size);84 85 return;86out:87 memset(bgrt, 0, sizeof(bgrt_tab));88}89