v4.19.13 snapshot.
diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
new file mode 100644
index 0000000..8986757
--- /dev/null
+++ b/drivers/firmware/efi/memattr.c
@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) "efi: memattr: " fmt
+
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/memblock.h>
+
+#include <asm/early_ioremap.h>
+
+static int __initdata tbl_size;
+
+/*
+ * Reserve the memory associated with the Memory Attributes configuration
+ * table, if it exists.
+ */
+int __init efi_memattr_init(void)
+{
+ efi_memory_attributes_table_t *tbl;
+
+ if (efi.mem_attr_table == EFI_INVALID_TABLE_ADDR)
+ return 0;
+
+ tbl = early_memremap(efi.mem_attr_table, sizeof(*tbl));
+ if (!tbl) {
+ pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
+ efi.mem_attr_table);
+ return -ENOMEM;
+ }
+
+ if (tbl->version > 1) {
+ pr_warn("Unexpected EFI Memory Attributes table version %d\n",
+ tbl->version);
+ goto unmap;
+ }
+
+ tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;
+ memblock_reserve(efi.mem_attr_table, tbl_size);
+ set_bit(EFI_MEM_ATTR, &efi.flags);
+
+unmap:
+ early_memunmap(tbl, sizeof(*tbl));
+ return 0;
+}
+
+/*
+ * Returns a copy @out of the UEFI memory descriptor @in if it is covered
+ * entirely by a UEFI memory map entry with matching attributes. The virtual
+ * address of @out is set according to the matching entry that was found.
+ */
+static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)
+{
+ u64 in_paddr = in->phys_addr;
+ u64 in_size = in->num_pages << EFI_PAGE_SHIFT;
+ efi_memory_desc_t *md;
+
+ *out = *in;
+
+ if (in->type != EFI_RUNTIME_SERVICES_CODE &&
+ in->type != EFI_RUNTIME_SERVICES_DATA) {
+ pr_warn("Entry type should be RuntimeServiceCode/Data\n");
+ return false;
+ }
+
+ if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) {
+ pr_warn("Entry attributes invalid: RO and XP bits both cleared\n");
+ return false;
+ }
+
+ if (PAGE_SIZE > EFI_PAGE_SIZE &&
+ (!PAGE_ALIGNED(in->phys_addr) ||
+ !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
+ /*
+ * Since arm64 may execute with page sizes of up to 64 KB, the
+ * UEFI spec mandates that RuntimeServices memory regions must
+ * be 64 KB aligned. We need to validate this here since we will
+ * not be able to tighten permissions on such regions without
+ * affecting adjacent regions.
+ */
+ pr_warn("Entry address region misaligned\n");
+ return false;
+ }
+
+ for_each_efi_memory_desc(md) {
+ u64 md_paddr = md->phys_addr;
+ u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
+
+ if (!(md->attribute & EFI_MEMORY_RUNTIME))
+ continue;
+ if (md->virt_addr == 0) {
+ /* no virtual mapping has been installed by the stub */
+ break;
+ }
+
+ if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)
+ continue;
+
+ /*
+ * This entry covers the start of @in, check whether
+ * it covers the end as well.
+ */
+ if (md_paddr + md_size < in_paddr + in_size) {
+ pr_warn("Entry covers multiple EFI memory map regions\n");
+ return false;
+ }
+
+ if (md->type != in->type) {
+ pr_warn("Entry type deviates from EFI memory map region type\n");
+ return false;
+ }
+
+ out->virt_addr = in_paddr + (md->virt_addr - md_paddr);
+
+ return true;
+ }
+
+ pr_warn("No matching entry found in the EFI memory map\n");
+ return false;
+}
+
+/*
+ * To be called after the EFI page tables have been populated. If a memory
+ * attributes table is available, its contents will be used to update the
+ * mappings with tightened permissions as described by the table.
+ * This requires the UEFI memory map to have already been populated with
+ * virtual addresses.
+ */
+int __init efi_memattr_apply_permissions(struct mm_struct *mm,
+ efi_memattr_perm_setter fn)
+{
+ efi_memory_attributes_table_t *tbl;
+ int i, ret;
+
+ if (tbl_size <= sizeof(*tbl))
+ return 0;
+
+ /*
+ * We need the EFI memory map to be setup so we can use it to
+ * lookup the virtual addresses of all entries in the of EFI
+ * Memory Attributes table. If it isn't available, this
+ * function should not be called.
+ */
+ if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
+ return 0;
+
+ tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB);
+ if (!tbl) {
+ pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
+ efi.mem_attr_table);
+ return -ENOMEM;
+ }
+
+ if (efi_enabled(EFI_DBG))
+ pr_info("Processing EFI Memory Attributes table:\n");
+
+ for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
+ efi_memory_desc_t md;
+ unsigned long size;
+ bool valid;
+ char buf[64];
+
+ valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
+ &md);
+ size = md.num_pages << EFI_PAGE_SHIFT;
+ if (efi_enabled(EFI_DBG) || !valid)
+ pr_info("%s 0x%012llx-0x%012llx %s\n",
+ valid ? "" : "!", md.phys_addr,
+ md.phys_addr + size - 1,
+ efi_md_typeattr_format(buf, sizeof(buf), &md));
+
+ if (valid) {
+ ret = fn(mm, &md);
+ if (ret)
+ pr_err("Error updating mappings, skipping subsequent md's\n");
+ }
+ }
+ memunmap(tbl);
+ return ret;
+}