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 static bool efi_bgrt_addr_valid(u64 addr) 31 { 32 efi_memory_desc_t *md; 33 34 for_each_efi_memory_desc(md) { 35 u64 size; 36 u64 end; 37 38 if (md->type != EFI_BOOT_SERVICES_DATA) 39 continue; 40 41 size = md->num_pages << EFI_PAGE_SHIFT; 42 end = md->phys_addr + size; 43 if (addr >= md->phys_addr && addr < end) 44 return true; 45 } 46 47 return false; 48 } 49 50 void __init efi_bgrt_init(struct acpi_table_header *table) 51 { 52 void *image; 53 struct bmp_header bmp_header; 54 struct acpi_table_bgrt *bgrt = &bgrt_tab; 55 56 if (acpi_disabled) 57 return; 58 59 if (!efi_enabled(EFI_MEMMAP)) 60 return; 61 62 if (table->length < sizeof(bgrt_tab)) { 63 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n", 64 table->length, sizeof(bgrt_tab)); 65 return; 66 } 67 *bgrt = *(struct acpi_table_bgrt *)table; 68 if (bgrt->version != 1) { 69 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n", 70 bgrt->version); 71 goto out; 72 } 73 if (bgrt->status & 0xfe) { 74 pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n", 75 bgrt->status); 76 goto out; 77 } 78 if (bgrt->image_type != 0) { 79 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n", 80 bgrt->image_type); 81 goto out; 82 } 83 if (!bgrt->image_address) { 84 pr_notice("Ignoring BGRT: null image address\n"); 85 goto out; 86 } 87 88 if (!efi_bgrt_addr_valid(bgrt->image_address)) { 89 pr_notice("Ignoring BGRT: invalid image address\n"); 90 goto out; 91 } 92 image = early_memremap(bgrt->image_address, sizeof(bmp_header)); 93 if (!image) { 94 pr_notice("Ignoring BGRT: failed to map image header memory\n"); 95 goto out; 96 } 97 98 memcpy(&bmp_header, image, sizeof(bmp_header)); 99 early_memunmap(image, sizeof(bmp_header)); 100 if (bmp_header.id != 0x4d42) { 101 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n", 102 bmp_header.id); 103 goto out; 104 } 105 bgrt_image_size = bmp_header.size; 106 efi_mem_reserve(bgrt->image_address, bgrt_image_size); 107 108 return; 109 out: 110 memset(bgrt, 0, sizeof(bgrt_tab)); 111 } 112