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 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 if (bgrt->version != 1) { 46 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n", 47 bgrt->version); 48 goto out; 49 } 50 if (bgrt->image_type != 0) { 51 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n", 52 bgrt->image_type); 53 goto out; 54 } 55 if (!bgrt->image_address) { 56 pr_notice("Ignoring BGRT: null image address\n"); 57 goto out; 58 } 59 60 if (efi_mem_type(bgrt->image_address) != EFI_BOOT_SERVICES_DATA) { 61 pr_notice("Ignoring BGRT: invalid image address\n"); 62 goto out; 63 } 64 image = early_memremap(bgrt->image_address, sizeof(bmp_header)); 65 if (!image) { 66 pr_notice("Ignoring BGRT: failed to map image header memory\n"); 67 goto out; 68 } 69 70 memcpy(&bmp_header, image, sizeof(bmp_header)); 71 early_memunmap(image, sizeof(bmp_header)); 72 if (bmp_header.id != 0x4d42) { 73 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n", 74 bmp_header.id); 75 goto out; 76 } 77 bgrt_image_size = bmp_header.size; 78 efi_mem_reserve(bgrt->image_address, bgrt_image_size); 79 80 return; 81 out: 82 memset(bgrt, 0, sizeof(bgrt_tab)); 83 } 84