2016-04-25 14:06:45 -06:00
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/*
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* Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) "efi: memattr: " fmt
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#include <linux/efi.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/memblock.h>
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#include <asm/early_ioremap.h>
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static int __initdata tbl_size;
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/*
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* Reserve the memory associated with the Memory Attributes configuration
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* table, if it exists.
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*/
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int __init efi_memattr_init(void)
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{
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efi_memory_attributes_table_t *tbl;
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if (efi.mem_attr_table == EFI_INVALID_TABLE_ADDR)
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return 0;
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tbl = early_memremap(efi.mem_attr_table, sizeof(*tbl));
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if (!tbl) {
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pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
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efi.mem_attr_table);
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return -ENOMEM;
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}
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if (tbl->version > 1) {
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pr_warn("Unexpected EFI Memory Attributes table version %d\n",
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tbl->version);
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goto unmap;
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}
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tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;
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memblock_reserve(efi.mem_attr_table, tbl_size);
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2017-01-31 06:21:36 -07:00
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set_bit(EFI_MEM_ATTR, &efi.flags);
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2016-04-25 14:06:45 -06:00
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unmap:
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early_memunmap(tbl, sizeof(*tbl));
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return 0;
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}
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/*
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* Returns a copy @out of the UEFI memory descriptor @in if it is covered
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* entirely by a UEFI memory map entry with matching attributes. The virtual
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* address of @out is set according to the matching entry that was found.
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*/
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static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)
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{
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u64 in_paddr = in->phys_addr;
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u64 in_size = in->num_pages << EFI_PAGE_SHIFT;
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efi_memory_desc_t *md;
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*out = *in;
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if (in->type != EFI_RUNTIME_SERVICES_CODE &&
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in->type != EFI_RUNTIME_SERVICES_DATA) {
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pr_warn("Entry type should be RuntimeServiceCode/Data\n");
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return false;
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}
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if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) {
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pr_warn("Entry attributes invalid: RO and XP bits both cleared\n");
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return false;
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}
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if (PAGE_SIZE > EFI_PAGE_SIZE &&
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(!PAGE_ALIGNED(in->phys_addr) ||
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!PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
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/*
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* Since arm64 may execute with page sizes of up to 64 KB, the
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* UEFI spec mandates that RuntimeServices memory regions must
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* be 64 KB aligned. We need to validate this here since we will
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* not be able to tighten permissions on such regions without
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* affecting adjacent regions.
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*/
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pr_warn("Entry address region misaligned\n");
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return false;
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}
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for_each_efi_memory_desc(md) {
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u64 md_paddr = md->phys_addr;
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u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
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if (!(md->attribute & EFI_MEMORY_RUNTIME))
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continue;
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if (md->virt_addr == 0) {
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/* no virtual mapping has been installed by the stub */
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break;
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}
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if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)
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continue;
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/*
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* This entry covers the start of @in, check whether
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* it covers the end as well.
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*/
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if (md_paddr + md_size < in_paddr + in_size) {
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pr_warn("Entry covers multiple EFI memory map regions\n");
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return false;
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}
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if (md->type != in->type) {
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pr_warn("Entry type deviates from EFI memory map region type\n");
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return false;
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}
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out->virt_addr = in_paddr + (md->virt_addr - md_paddr);
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return true;
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}
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pr_warn("No matching entry found in the EFI memory map\n");
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return false;
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}
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/*
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* To be called after the EFI page tables have been populated. If a memory
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* attributes table is available, its contents will be used to update the
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* mappings with tightened permissions as described by the table.
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* This requires the UEFI memory map to have already been populated with
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* virtual addresses.
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*/
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int __init efi_memattr_apply_permissions(struct mm_struct *mm,
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efi_memattr_perm_setter fn)
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{
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efi_memory_attributes_table_t *tbl;
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int i, ret;
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if (tbl_size <= sizeof(*tbl))
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return 0;
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/*
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* We need the EFI memory map to be setup so we can use it to
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* lookup the virtual addresses of all entries in the of EFI
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* Memory Attributes table. If it isn't available, this
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* function should not be called.
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*/
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if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
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return 0;
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tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB);
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if (!tbl) {
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pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
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efi.mem_attr_table);
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return -ENOMEM;
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}
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if (efi_enabled(EFI_DBG))
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pr_info("Processing EFI Memory Attributes table:\n");
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for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
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efi_memory_desc_t md;
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unsigned long size;
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bool valid;
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char buf[64];
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valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
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&md);
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size = md.num_pages << EFI_PAGE_SHIFT;
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if (efi_enabled(EFI_DBG) || !valid)
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pr_info("%s 0x%012llx-0x%012llx %s\n",
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valid ? "" : "!", md.phys_addr,
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md.phys_addr + size - 1,
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efi_md_typeattr_format(buf, sizeof(buf), &md));
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2017-01-31 06:21:37 -07:00
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if (valid) {
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2016-04-25 14:06:45 -06:00
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ret = fn(mm, &md);
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2017-01-31 06:21:37 -07:00
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if (ret)
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pr_err("Error updating mappings, skipping subsequent md's\n");
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}
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2016-04-25 14:06:45 -06:00
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}
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memunmap(tbl);
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return ret;
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}
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