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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org>4 */5 6#define pr_fmt(fmt) "efi: memattr: " fmt7 8#include <linux/efi.h>9#include <linux/init.h>10#include <linux/io.h>11#include <linux/memblock.h>12 13#include <asm/early_ioremap.h>14 15static int __initdata tbl_size;16unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;17 18/*19 * Reserve the memory associated with the Memory Attributes configuration20 * table, if it exists.21 */22int __init efi_memattr_init(void)23{24 efi_memory_attributes_table_t *tbl;25 26 if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)27 return 0;28 29 tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));30 if (!tbl) {31 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",32 efi_mem_attr_table);33 return -ENOMEM;34 }35 36 if (tbl->version > 2) {37 pr_warn("Unexpected EFI Memory Attributes table version %d\n",38 tbl->version);39 goto unmap;40 }41 42 tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;43 memblock_reserve(efi_mem_attr_table, tbl_size);44 set_bit(EFI_MEM_ATTR, &efi.flags);45 46unmap:47 early_memunmap(tbl, sizeof(*tbl));48 return 0;49}50 51/*52 * Returns a copy @out of the UEFI memory descriptor @in if it is covered53 * entirely by a UEFI memory map entry with matching attributes. The virtual54 * address of @out is set according to the matching entry that was found.55 */56static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)57{58 u64 in_paddr = in->phys_addr;59 u64 in_size = in->num_pages << EFI_PAGE_SHIFT;60 efi_memory_desc_t *md;61 62 *out = *in;63 64 if (in->type != EFI_RUNTIME_SERVICES_CODE &&65 in->type != EFI_RUNTIME_SERVICES_DATA) {66 pr_warn("Entry type should be RuntimeServiceCode/Data\n");67 return false;68 }69 70 if (PAGE_SIZE > EFI_PAGE_SIZE &&71 (!PAGE_ALIGNED(in->phys_addr) ||72 !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {73 /*74 * Since arm64 may execute with page sizes of up to 64 KB, the75 * UEFI spec mandates that RuntimeServices memory regions must76 * be 64 KB aligned. We need to validate this here since we will77 * not be able to tighten permissions on such regions without78 * affecting adjacent regions.79 */80 pr_warn("Entry address region misaligned\n");81 return false;82 }83 84 for_each_efi_memory_desc(md) {85 u64 md_paddr = md->phys_addr;86 u64 md_size = md->num_pages << EFI_PAGE_SHIFT;87 88 if (!(md->attribute & EFI_MEMORY_RUNTIME))89 continue;90 if (md->virt_addr == 0 && md->phys_addr != 0) {91 /* no virtual mapping has been installed by the stub */92 break;93 }94 95 if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)96 continue;97 98 /*99 * This entry covers the start of @in, check whether100 * it covers the end as well.101 */102 if (md_paddr + md_size < in_paddr + in_size) {103 pr_warn("Entry covers multiple EFI memory map regions\n");104 return false;105 }106 107 if (md->type != in->type) {108 pr_warn("Entry type deviates from EFI memory map region type\n");109 return false;110 }111 112 out->virt_addr = in_paddr + (md->virt_addr - md_paddr);113 114 return true;115 }116 117 pr_warn("No matching entry found in the EFI memory map\n");118 return false;119}120 121/*122 * To be called after the EFI page tables have been populated. If a memory123 * attributes table is available, its contents will be used to update the124 * mappings with tightened permissions as described by the table.125 * This requires the UEFI memory map to have already been populated with126 * virtual addresses.127 */128int __init efi_memattr_apply_permissions(struct mm_struct *mm,129 efi_memattr_perm_setter fn)130{131 efi_memory_attributes_table_t *tbl;132 bool has_bti = false;133 int i, ret;134 135 if (tbl_size <= sizeof(*tbl))136 return 0;137 138 /*139 * We need the EFI memory map to be setup so we can use it to140 * lookup the virtual addresses of all entries in the of EFI141 * Memory Attributes table. If it isn't available, this142 * function should not be called.143 */144 if (WARN_ON(!efi_enabled(EFI_MEMMAP)))145 return 0;146 147 tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB);148 if (!tbl) {149 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",150 efi_mem_attr_table);151 return -ENOMEM;152 }153 154 if (tbl->version > 1 &&155 (tbl->flags & EFI_MEMORY_ATTRIBUTES_FLAGS_RT_FORWARD_CONTROL_FLOW_GUARD))156 has_bti = true;157 158 if (efi_enabled(EFI_DBG))159 pr_info("Processing EFI Memory Attributes table:\n");160 161 for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {162 efi_memory_desc_t md;163 unsigned long size;164 bool valid;165 char buf[64];166 167 valid = entry_is_valid(efi_memdesc_ptr(tbl->entry, tbl->desc_size, i),168 &md);169 size = md.num_pages << EFI_PAGE_SHIFT;170 if (efi_enabled(EFI_DBG) || !valid)171 pr_info("%s 0x%012llx-0x%012llx %s\n",172 valid ? "" : "!", md.phys_addr,173 md.phys_addr + size - 1,174 efi_md_typeattr_format(buf, sizeof(buf), &md));175 176 if (valid) {177 ret = fn(mm, &md, has_bti);178 if (ret)179 pr_err("Error updating mappings, skipping subsequent md's\n");180 }181 }182 memunmap(tbl);183 return ret;184}185