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1// SPDX-License-Identifier: GPL-2.02/*3 * Support for extracting embedded firmware for peripherals from EFI code,4 *5 * Copyright (c) 2018 Hans de Goede <hdegoede@redhat.com>6 */7 8#include <linux/dmi.h>9#include <linux/efi.h>10#include <linux/efi_embedded_fw.h>11#include <linux/io.h>12#include <linux/slab.h>13#include <linux/types.h>14#include <linux/vmalloc.h>15#include <crypto/sha2.h>16 17/* Exported for use by lib/test_firmware.c only */18LIST_HEAD(efi_embedded_fw_list);19EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_list, TEST_FIRMWARE);20bool efi_embedded_fw_checked;21EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_checked, TEST_FIRMWARE);22 23static const struct dmi_system_id * const embedded_fw_table[] = {24#ifdef CONFIG_TOUCHSCREEN_DMI25 touchscreen_dmi_table,26#endif27 NULL28};29 30/*31 * Note the efi_check_for_embedded_firmwares() code currently makes the32 * following 2 assumptions. This may needs to be revisited if embedded firmware33 * is found where this is not true:34 * 1) The firmware is only found in EFI_BOOT_SERVICES_CODE memory segments35 * 2) The firmware always starts at an offset which is a multiple of 8 bytes36 */37static int __init efi_check_md_for_embedded_firmware(38 efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc)39{40 struct efi_embedded_fw *fw;41 u8 hash[32];42 u64 i, size;43 u8 *map;44 45 size = md->num_pages << EFI_PAGE_SHIFT;46 map = memremap(md->phys_addr, size, MEMREMAP_WB);47 if (!map) {48 pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr);49 return -ENOMEM;50 }51 52 for (i = 0; (i + desc->length) <= size; i += 8) {53 if (memcmp(map + i, desc->prefix, EFI_EMBEDDED_FW_PREFIX_LEN))54 continue;55 56 sha256(map + i, desc->length, hash);57 if (memcmp(hash, desc->sha256, 32) == 0)58 break;59 }60 if ((i + desc->length) > size) {61 memunmap(map);62 return -ENOENT;63 }64 65 pr_info("Found EFI embedded fw '%s'\n", desc->name);66 67 fw = kmalloc(sizeof(*fw), GFP_KERNEL);68 if (!fw) {69 memunmap(map);70 return -ENOMEM;71 }72 73 fw->data = kmemdup(map + i, desc->length, GFP_KERNEL);74 memunmap(map);75 if (!fw->data) {76 kfree(fw);77 return -ENOMEM;78 }79 80 fw->name = desc->name;81 fw->length = desc->length;82 list_add(&fw->list, &efi_embedded_fw_list);83 84 return 0;85}86 87void __init efi_check_for_embedded_firmwares(void)88{89 const struct efi_embedded_fw_desc *fw_desc;90 const struct dmi_system_id *dmi_id;91 efi_memory_desc_t *md;92 int i, r;93 94 for (i = 0; embedded_fw_table[i]; i++) {95 dmi_id = dmi_first_match(embedded_fw_table[i]);96 if (!dmi_id)97 continue;98 99 fw_desc = dmi_id->driver_data;100 101 /*102 * In some drivers the struct driver_data contains may contain103 * other driver specific data after the fw_desc struct; and104 * the fw_desc struct itself may be empty, skip these.105 */106 if (!fw_desc->name)107 continue;108 109 for_each_efi_memory_desc(md) {110 if (md->type != EFI_BOOT_SERVICES_CODE)111 continue;112 113 r = efi_check_md_for_embedded_firmware(md, fw_desc);114 if (r == 0)115 break;116 }117 }118 119 efi_embedded_fw_checked = true;120}121 122int efi_get_embedded_fw(const char *name, const u8 **data, size_t *size)123{124 struct efi_embedded_fw *iter, *fw = NULL;125 126 if (!efi_embedded_fw_checked) {127 pr_warn("Warning %s called while we did not check for embedded fw\n",128 __func__);129 return -ENOENT;130 }131 132 list_for_each_entry(iter, &efi_embedded_fw_list, list) {133 if (strcmp(name, iter->name) == 0) {134 fw = iter;135 break;136 }137 }138 139 if (!fw)140 return -ENOENT;141 142 *data = fw->data;143 *size = fw->length;144 145 return 0;146}147EXPORT_SYMBOL_GPL(efi_get_embedded_fw);148