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 19 struct acpi_table_bgrt bgrt_tab; 20 size_t bgrt_image_size; 21 22 struct bmp_header { 23 u16 id; 24 u32 size; 25 } __packed; 26 27 void __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 int mem_type; 33 34 if (acpi_disabled) 35 return; 36 37 if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT)) 38 return; 39 40 if (table->length < sizeof(bgrt_tab)) { 41 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n", 42 table->length, sizeof(bgrt_tab)); 43 return; 44 } 45 *bgrt = *(struct acpi_table_bgrt *)table; 46 /* 47 * Only version 1 is defined but some older laptops (seen on Lenovo 48 * Ivy Bridge models) have a correct version 1 BGRT table with the 49 * version set to 0, so we accept version 0 and 1. 50 */ 51 if (bgrt->version > 1) { 52 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n", 53 bgrt->version); 54 goto out; 55 } 56 if (bgrt->image_type != 0) { 57 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n", 58 bgrt->image_type); 59 goto out; 60 } 61 if (!bgrt->image_address) { 62 pr_notice("Ignoring BGRT: null image address\n"); 63 goto out; 64 } 65 66 mem_type = efi_mem_type(bgrt->image_address); 67 if (mem_type != EFI_BOOT_SERVICES_DATA && 68 mem_type != EFI_ACPI_RECLAIM_MEMORY) { 69 pr_notice("Ignoring BGRT: invalid image address\n"); 70 goto out; 71 } 72 image = early_memremap(bgrt->image_address, sizeof(bmp_header)); 73 if (!image) { 74 pr_notice("Ignoring BGRT: failed to map image header memory\n"); 75 goto out; 76 } 77 78 memcpy(&bmp_header, image, sizeof(bmp_header)); 79 early_memunmap(image, sizeof(bmp_header)); 80 if (bmp_header.id != 0x4d42) { 81 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n", 82 bmp_header.id); 83 goto out; 84 } 85 bgrt_image_size = bmp_header.size; 86 efi_mem_reserve(bgrt->image_address, bgrt_image_size); 87 88 return; 89 out: 90 memset(bgrt, 0, sizeof(bgrt_tab)); 91 } 92