1/*
  2 * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org>
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License version 2 as
  6 * published by the Free Software Foundation.
  7 */
  8
  9#define pr_fmt(fmt)	"efi: memattr: " fmt
 10
 11#include <linux/efi.h>
 12#include <linux/init.h>
 13#include <linux/io.h>
 14#include <linux/memblock.h>
 15
 16#include <asm/early_ioremap.h>
 17
 18static int __initdata tbl_size;
 19
 20/*
 21 * Reserve the memory associated with the Memory Attributes configuration
 22 * table, if it exists.
 23 */
 24int __init efi_memattr_init(void)
 25{
 26	efi_memory_attributes_table_t *tbl;
 27
 28	if (efi.mem_attr_table == EFI_INVALID_TABLE_ADDR)
 29		return 0;
 30
 31	tbl = early_memremap(efi.mem_attr_table, sizeof(*tbl));
 32	if (!tbl) {
 33		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
 34		       efi.mem_attr_table);
 35		return -ENOMEM;
 36	}
 37
 38	if (tbl->version > 1) {
 39		pr_warn("Unexpected EFI Memory Attributes table version %d\n",
 40			tbl->version);
 41		goto unmap;
 42	}
 43
 44	tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;
 45	memblock_reserve(efi.mem_attr_table, tbl_size);
 46	set_bit(EFI_MEM_ATTR, &efi.flags);
 47
 48unmap:
 49	early_memunmap(tbl, sizeof(*tbl));
 50	return 0;
 51}
 52
 53/*
 54 * Returns a copy @out of the UEFI memory descriptor @in if it is covered
 55 * entirely by a UEFI memory map entry with matching attributes. The virtual
 56 * address of @out is set according to the matching entry that was found.
 57 */
 58static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)
 59{
 60	u64 in_paddr = in->phys_addr;
 61	u64 in_size = in->num_pages << EFI_PAGE_SHIFT;
 62	efi_memory_desc_t *md;
 63
 64	*out = *in;
 65
 66	if (in->type != EFI_RUNTIME_SERVICES_CODE &&
 67	    in->type != EFI_RUNTIME_SERVICES_DATA) {
 68		pr_warn("Entry type should be RuntimeServiceCode/Data\n");
 69		return false;
 70	}
 71
 72	if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) {
 73		pr_warn("Entry attributes invalid: RO and XP bits both cleared\n");
 74		return false;
 75	}
 76
 77	if (PAGE_SIZE > EFI_PAGE_SIZE &&
 78	    (!PAGE_ALIGNED(in->phys_addr) ||
 79	     !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
 80		/*
 81		 * Since arm64 may execute with page sizes of up to 64 KB, the
 82		 * UEFI spec mandates that RuntimeServices memory regions must
 83		 * be 64 KB aligned. We need to validate this here since we will
 84		 * not be able to tighten permissions on such regions without
 85		 * affecting adjacent regions.
 86		 */
 87		pr_warn("Entry address region misaligned\n");
 88		return false;
 89	}
 90
 91	for_each_efi_memory_desc(md) {
 92		u64 md_paddr = md->phys_addr;
 93		u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
 94
 95		if (!(md->attribute & EFI_MEMORY_RUNTIME))
 96			continue;
 97		if (md->virt_addr == 0) {
 98			/* no virtual mapping has been installed by the stub */
 99			break;
100		}
101
102		if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)
103			continue;
104
105		/*
106		 * This entry covers the start of @in, check whether
107		 * it covers the end as well.
108		 */
109		if (md_paddr + md_size < in_paddr + in_size) {
110			pr_warn("Entry covers multiple EFI memory map regions\n");
111			return false;
112		}
113
114		if (md->type != in->type) {
115			pr_warn("Entry type deviates from EFI memory map region type\n");
116			return false;
117		}
118
119		out->virt_addr = in_paddr + (md->virt_addr - md_paddr);
120
121		return true;
122	}
123
124	pr_warn("No matching entry found in the EFI memory map\n");
125	return false;
126}
127
128/*
129 * To be called after the EFI page tables have been populated. If a memory
130 * attributes table is available, its contents will be used to update the
131 * mappings with tightened permissions as described by the table.
132 * This requires the UEFI memory map to have already been populated with
133 * virtual addresses.
134 */
135int __init efi_memattr_apply_permissions(struct mm_struct *mm,
136					 efi_memattr_perm_setter fn)
137{
138	efi_memory_attributes_table_t *tbl;
139	int i, ret;
140
141	if (tbl_size <= sizeof(*tbl))
142		return 0;
143
144	/*
145	 * We need the EFI memory map to be setup so we can use it to
146	 * lookup the virtual addresses of all entries in the  of EFI
147	 * Memory Attributes table. If it isn't available, this
148	 * function should not be called.
149	 */
150	if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
151		return 0;
152
153	tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB);
154	if (!tbl) {
155		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
156		       efi.mem_attr_table);
157		return -ENOMEM;
158	}
159
160	if (efi_enabled(EFI_DBG))
161		pr_info("Processing EFI Memory Attributes table:\n");
162
163	for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
164		efi_memory_desc_t md;
165		unsigned long size;
166		bool valid;
167		char buf[64];
168
169		valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
170				       &md);
171		size = md.num_pages << EFI_PAGE_SHIFT;
172		if (efi_enabled(EFI_DBG) || !valid)
173			pr_info("%s 0x%012llx-0x%012llx %s\n",
174				valid ? "" : "!", md.phys_addr,
175				md.phys_addr + size - 1,
176				efi_md_typeattr_format(buf, sizeof(buf), &md));
177
178		if (valid) {
179			ret = fn(mm, &md);
180			if (ret)
181				pr_err("Error updating mappings, skipping subsequent md's\n");
182		}
183	}
184	memunmap(tbl);
185	return ret;
186}