1 files changed, 1046 insertions, 0 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
new file mode 100644
index 000000000..e7f19dec1
--- /dev/null
+++ b/arch/x86/platform/efi/efi.c
@@ -0,0 +1,1046 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Common EFI (Extensible Firmware Interface) support functions
+ * Based on Extensible Firmware Interface Specification version 1.0
+ *
+ * Copyright (C) 1999 VA Linux Systems
+ * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
+ * Copyright (C) 1999-2002 Hewlett-Packard Co.
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ *	Stephane Eranian <eranian@hpl.hp.com>
+ * Copyright (C) 2005-2008 Intel Co.
+ *	Fenghua Yu <fenghua.yu@intel.com>
+ *	Bibo Mao <bibo.mao@intel.com>
+ *	Chandramouli Narayanan <mouli@linux.intel.com>
+ *	Huang Ying <ying.huang@intel.com>
+ * Copyright (C) 2013 SuSE Labs
+ *	Borislav Petkov <bp@suse.de> - runtime services VA mapping
+ *
+ * Copied from efi_32.c to eliminate the duplicated code between EFI
+ * 32/64 support code. --ying 2007-10-26
+ *
+ * All EFI Runtime Services are not implemented yet as EFI only
+ * supports physical mode addressing on SoftSDV. This is to be fixed
+ * in a future version.  --drummond 1999-07-20
+ *
+ * Implemented EFI runtime services and virtual mode calls.  --davidm
+ *
+ * Goutham Rao: <goutham.rao@intel.com>
+ *	Skip non-WB memory and ignore empty memory ranges.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/efi.h>
+#include <linux/efi-bgrt.h>
+#include <linux/export.h>
+#include <linux/bootmem.h>
+#include <linux/slab.h>
+#include <linux/memblock.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/time.h>
+#include <linux/io.h>
+#include <linux/reboot.h>
+#include <linux/bcd.h>
+
+#include <asm/setup.h>
+#include <asm/efi.h>
+#include <asm/e820/api.h>
+#include <asm/time.h>
+#include <asm/set_memory.h>
+#include <asm/tlbflush.h>
+#include <asm/x86_init.h>
+#include <asm/uv/uv.h>
+
+static struct efi efi_phys __initdata;
+static efi_system_table_t efi_systab __initdata;
+
+static efi_config_table_type_t arch_tables[] __initdata = {
+#ifdef CONFIG_X86_UV
+	{UV_SYSTEM_TABLE_GUID, "UVsystab", &efi.uv_systab},
+#endif
+	{NULL_GUID, NULL, NULL},
+};
+
+u64 efi_setup;		/* efi setup_data physical address */
+
+static int add_efi_memmap __initdata;
+static int __init setup_add_efi_memmap(char *arg)
+{
+	add_efi_memmap = 1;
+	return 0;
+}
+early_param("add_efi_memmap", setup_add_efi_memmap);
+
+static efi_status_t __init phys_efi_set_virtual_address_map(
+	unsigned long memory_map_size,
+	unsigned long descriptor_size,
+	u32 descriptor_version,
+	efi_memory_desc_t *virtual_map)
+{
+	efi_status_t status;
+	unsigned long flags;
+	pgd_t *save_pgd;
+
+	save_pgd = efi_call_phys_prolog();
+
+	/* Disable interrupts around EFI calls: */
+	local_irq_save(flags);
+	status = efi_call_phys(efi_phys.set_virtual_address_map,
+			       memory_map_size, descriptor_size,
+			       descriptor_version, virtual_map);
+	local_irq_restore(flags);
+
+	efi_call_phys_epilog(save_pgd);
+
+	return status;
+}
+
+void __init efi_find_mirror(void)
+{
+	efi_memory_desc_t *md;
+	u64 mirror_size = 0, total_size = 0;
+
+	for_each_efi_memory_desc(md) {
+		unsigned long long start = md->phys_addr;
+		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
+
+		total_size += size;
+		if (md->attribute & EFI_MEMORY_MORE_RELIABLE) {
+			memblock_mark_mirror(start, size);
+			mirror_size += size;
+		}
+	}
+	if (mirror_size)
+		pr_info("Memory: %lldM/%lldM mirrored memory\n",
+			mirror_size>>20, total_size>>20);
+}
+
+/*
+ * Tell the kernel about the EFI memory map.  This might include
+ * more than the max 128 entries that can fit in the e820 legacy
+ * (zeropage) memory map.
+ */
+
+static void __init do_add_efi_memmap(void)
+{
+	efi_memory_desc_t *md;
+
+	for_each_efi_memory_desc(md) {
+		unsigned long long start = md->phys_addr;
+		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
+		int e820_type;
+
+		switch (md->type) {
+		case EFI_LOADER_CODE:
+		case EFI_LOADER_DATA:
+		case EFI_BOOT_SERVICES_CODE:
+		case EFI_BOOT_SERVICES_DATA:
+		case EFI_CONVENTIONAL_MEMORY:
+			if (md->attribute & EFI_MEMORY_WB)
+				e820_type = E820_TYPE_RAM;
+			else
+				e820_type = E820_TYPE_RESERVED;
+			break;
+		case EFI_ACPI_RECLAIM_MEMORY:
+			e820_type = E820_TYPE_ACPI;
+			break;
+		case EFI_ACPI_MEMORY_NVS:
+			e820_type = E820_TYPE_NVS;
+			break;
+		case EFI_UNUSABLE_MEMORY:
+			e820_type = E820_TYPE_UNUSABLE;
+			break;
+		case EFI_PERSISTENT_MEMORY:
+			e820_type = E820_TYPE_PMEM;
+			break;
+		default:
+			/*
+			 * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
+			 * EFI_RUNTIME_SERVICES_DATA EFI_MEMORY_MAPPED_IO
+			 * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
+			 */
+			e820_type = E820_TYPE_RESERVED;
+			break;
+		}
+		e820__range_add(start, size, e820_type);
+	}
+	e820__update_table(e820_table);
+}
+
+int __init efi_memblock_x86_reserve_range(void)
+{
+	struct efi_info *e = &boot_params.efi_info;
+	struct efi_memory_map_data data;
+	phys_addr_t pmap;
+	int rv;
+
+	if (efi_enabled(EFI_PARAVIRT))
+		return 0;
+
+#ifdef CONFIG_X86_32
+	/* Can't handle data above 4GB at this time */
+	if (e->efi_memmap_hi) {
+		pr_err("Memory map is above 4GB, disabling EFI.\n");
+		return -EINVAL;
+	}
+	pmap =  e->efi_memmap;
+#else
+	pmap = (e->efi_memmap |	((__u64)e->efi_memmap_hi << 32));
+#endif
+	data.phys_map		= pmap;
+	data.size 		= e->efi_memmap_size;
+	data.desc_size		= e->efi_memdesc_size;
+	data.desc_version	= e->efi_memdesc_version;
+
+	rv = efi_memmap_init_early(&data);
+	if (rv)
+		return rv;
+
+	if (add_efi_memmap)
+		do_add_efi_memmap();
+
+	WARN(efi.memmap.desc_version != 1,
+	     "Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
+	     efi.memmap.desc_version);
+
+	memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);
+
+	return 0;
+}
+
+#define OVERFLOW_ADDR_SHIFT	(64 - EFI_PAGE_SHIFT)
+#define OVERFLOW_ADDR_MASK	(U64_MAX << OVERFLOW_ADDR_SHIFT)
+#define U64_HIGH_BIT		(~(U64_MAX >> 1))
+
+static bool __init efi_memmap_entry_valid(const efi_memory_desc_t *md, int i)
+{
+	u64 end = (md->num_pages << EFI_PAGE_SHIFT) + md->phys_addr - 1;
+	u64 end_hi = 0;
+	char buf[64];
+
+	if (md->num_pages == 0) {
+		end = 0;
+	} else if (md->num_pages > EFI_PAGES_MAX ||
+		   EFI_PAGES_MAX - md->num_pages <
+		   (md->phys_addr >> EFI_PAGE_SHIFT)) {
+		end_hi = (md->num_pages & OVERFLOW_ADDR_MASK)
+			>> OVERFLOW_ADDR_SHIFT;
+
+		if ((md->phys_addr & U64_HIGH_BIT) && !(end & U64_HIGH_BIT))
+			end_hi += 1;
+	} else {
+		return true;
+	}
+
+	pr_warn_once(FW_BUG "Invalid EFI memory map entries:\n");
+
+	if (end_hi) {
+		pr_warn("mem%02u: %s range=[0x%016llx-0x%llx%016llx] (invalid)\n",
+			i, efi_md_typeattr_format(buf, sizeof(buf), md),
+			md->phys_addr, end_hi, end);
+	} else {
+		pr_warn("mem%02u: %s range=[0x%016llx-0x%016llx] (invalid)\n",
+			i, efi_md_typeattr_format(buf, sizeof(buf), md),
+			md->phys_addr, end);
+	}
+	return false;
+}
+
+static void __init efi_clean_memmap(void)
+{
+	efi_memory_desc_t *out = efi.memmap.map;
+	const efi_memory_desc_t *in = out;
+	const efi_memory_desc_t *end = efi.memmap.map_end;
+	int i, n_removal;
+
+	for (i = n_removal = 0; in < end; i++) {
+		if (efi_memmap_entry_valid(in, i)) {
+			if (out != in)
+				memcpy(out, in, efi.memmap.desc_size);
+			out = (void *)out + efi.memmap.desc_size;
+		} else {
+			n_removal++;
+		}
+		in = (void *)in + efi.memmap.desc_size;
+	}
+
+	if (n_removal > 0) {
+		u64 size = efi.memmap.nr_map - n_removal;
+
+		pr_warn("Removing %d invalid memory map entries.\n", n_removal);
+		efi_memmap_install(efi.memmap.phys_map, size);
+	}
+}
+
+void __init efi_print_memmap(void)
+{
+	efi_memory_desc_t *md;
+	int i = 0;
+
+	for_each_efi_memory_desc(md) {
+		char buf[64];
+
+		pr_info("mem%02u: %s range=[0x%016llx-0x%016llx] (%lluMB)\n",
+			i++, efi_md_typeattr_format(buf, sizeof(buf), md),
+			md->phys_addr,
+			md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1,
+			(md->num_pages >> (20 - EFI_PAGE_SHIFT)));
+	}
+}
+
+static int __init efi_systab_init(void *phys)
+{
+	if (efi_enabled(EFI_64BIT)) {
+		efi_system_table_64_t *systab64;
+		struct efi_setup_data *data = NULL;
+		u64 tmp = 0;
+
+		if (efi_setup) {
+			data = early_memremap(efi_setup, sizeof(*data));
+			if (!data)
+				return -ENOMEM;
+		}
+		systab64 = early_memremap((unsigned long)phys,
+					 sizeof(*systab64));
+		if (systab64 == NULL) {
+			pr_err("Couldn't map the system table!\n");
+			if (data)
+				early_memunmap(data, sizeof(*data));
+			return -ENOMEM;
+		}
+
+		efi_systab.hdr = systab64->hdr;
+		efi_systab.fw_vendor = data ? (unsigned long)data->fw_vendor :
+					      systab64->fw_vendor;
+		tmp |= data ? data->fw_vendor : systab64->fw_vendor;
+		efi_systab.fw_revision = systab64->fw_revision;
+		efi_systab.con_in_handle = systab64->con_in_handle;
+		tmp |= systab64->con_in_handle;
+		efi_systab.con_in = systab64->con_in;
+		tmp |= systab64->con_in;
+		efi_systab.con_out_handle = systab64->con_out_handle;
+		tmp |= systab64->con_out_handle;
+		efi_systab.con_out = systab64->con_out;
+		tmp |= systab64->con_out;
+		efi_systab.stderr_handle = systab64->stderr_handle;
+		tmp |= systab64->stderr_handle;
+		efi_systab.stderr = systab64->stderr;
+		tmp |= systab64->stderr;
+		efi_systab.runtime = data ?
+				     (void *)(unsigned long)data->runtime :
+				     (void *)(unsigned long)systab64->runtime;
+		tmp |= data ? data->runtime : systab64->runtime;
+		efi_systab.boottime = (void *)(unsigned long)systab64->boottime;
+		tmp |= systab64->boottime;
+		efi_systab.nr_tables = systab64->nr_tables;
+		efi_systab.tables = data ? (unsigned long)data->tables :
+					   systab64->tables;
+		tmp |= data ? data->tables : systab64->tables;
+
+		early_memunmap(systab64, sizeof(*systab64));
+		if (data)
+			early_memunmap(data, sizeof(*data));
+#ifdef CONFIG_X86_32
+		if (tmp >> 32) {
+			pr_err("EFI data located above 4GB, disabling EFI.\n");
+			return -EINVAL;
+		}
+#endif
+	} else {
+		efi_system_table_32_t *systab32;
+
+		systab32 = early_memremap((unsigned long)phys,
+					 sizeof(*systab32));
+		if (systab32 == NULL) {
+			pr_err("Couldn't map the system table!\n");
+			return -ENOMEM;
+		}
+
+		efi_systab.hdr = systab32->hdr;
+		efi_systab.fw_vendor = systab32->fw_vendor;
+		efi_systab.fw_revision = systab32->fw_revision;
+		efi_systab.con_in_handle = systab32->con_in_handle;
+		efi_systab.con_in = systab32->con_in;
+		efi_systab.con_out_handle = systab32->con_out_handle;
+		efi_systab.con_out = systab32->con_out;
+		efi_systab.stderr_handle = systab32->stderr_handle;
+		efi_systab.stderr = systab32->stderr;
+		efi_systab.runtime = (void *)(unsigned long)systab32->runtime;
+		efi_systab.boottime = (void *)(unsigned long)systab32->boottime;
+		efi_systab.nr_tables = systab32->nr_tables;
+		efi_systab.tables = systab32->tables;
+
+		early_memunmap(systab32, sizeof(*systab32));
+	}
+
+	efi.systab = &efi_systab;
+
+	/*
+	 * Verify the EFI Table
+	 */
+	if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
+		pr_err("System table signature incorrect!\n");
+		return -EINVAL;
+	}
+	if ((efi.systab->hdr.revision >> 16) == 0)
+		pr_err("Warning: System table version %d.%02d, expected 1.00 or greater!\n",
+		       efi.systab->hdr.revision >> 16,
+		       efi.systab->hdr.revision & 0xffff);
+
+	return 0;
+}
+
+static int __init efi_runtime_init32(void)
+{
+	efi_runtime_services_32_t *runtime;
+
+	runtime = early_memremap((unsigned long)efi.systab->runtime,
+			sizeof(efi_runtime_services_32_t));
+	if (!runtime) {
+		pr_err("Could not map the runtime service table!\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * We will only need *early* access to the SetVirtualAddressMap
+	 * EFI runtime service. All other runtime services will be called
+	 * via the virtual mapping.
+	 */
+	efi_phys.set_virtual_address_map =
+			(efi_set_virtual_address_map_t *)
+			(unsigned long)runtime->set_virtual_address_map;
+	early_memunmap(runtime, sizeof(efi_runtime_services_32_t));
+
+	return 0;
+}
+
+static int __init efi_runtime_init64(void)
+{
+	efi_runtime_services_64_t *runtime;
+
+	runtime = early_memremap((unsigned long)efi.systab->runtime,
+			sizeof(efi_runtime_services_64_t));
+	if (!runtime) {
+		pr_err("Could not map the runtime service table!\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * We will only need *early* access to the SetVirtualAddressMap
+	 * EFI runtime service. All other runtime services will be called
+	 * via the virtual mapping.
+	 */
+	efi_phys.set_virtual_address_map =
+			(efi_set_virtual_address_map_t *)
+			(unsigned long)runtime->set_virtual_address_map;
+	early_memunmap(runtime, sizeof(efi_runtime_services_64_t));
+
+	return 0;
+}
+
+static int __init efi_runtime_init(void)
+{
+	int rv;
+
+	/*
+	 * Check out the runtime services table. We need to map
+	 * the runtime services table so that we can grab the physical
+	 * address of several of the EFI runtime functions, needed to
+	 * set the firmware into virtual mode.
+	 *
+	 * When EFI_PARAVIRT is in force then we could not map runtime
+	 * service memory region because we do not have direct access to it.
+	 * However, runtime services are available through proxy functions
+	 * (e.g. in case of Xen dom0 EFI implementation they call special
+	 * hypercall which executes relevant EFI functions) and that is why
+	 * they are always enabled.
+	 */
+
+	if (!efi_enabled(EFI_PARAVIRT)) {
+		if (efi_enabled(EFI_64BIT))
+			rv = efi_runtime_init64();
+		else
+			rv = efi_runtime_init32();
+
+		if (rv)
+			return rv;
+	}
+
+	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+
+	return 0;
+}
+
+void __init efi_init(void)
+{
+	efi_char16_t *c16;
+	char vendor[100] = "unknown";
+	int i = 0;
+
+#ifdef CONFIG_X86_32
+	if (boot_params.efi_info.efi_systab_hi ||
+	    boot_params.efi_info.efi_memmap_hi) {
+		pr_info("Table located above 4GB, disabling EFI.\n");
+		return;
+	}
+	efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
+#else
+	efi_phys.systab = (efi_system_table_t *)
+			  (boot_params.efi_info.efi_systab |
+			  ((__u64)boot_params.efi_info.efi_systab_hi<<32));
+#endif
+
+	if (efi_systab_init(efi_phys.systab))
+		return;
+
+	efi.config_table = (unsigned long)efi.systab->tables;
+	efi.fw_vendor	 = (unsigned long)efi.systab->fw_vendor;
+	efi.runtime	 = (unsigned long)efi.systab->runtime;
+
+	/*
+	 * Show what we know for posterity
+	 */
+	c16 = early_memremap_ro(efi.systab->fw_vendor,
+				sizeof(vendor) * sizeof(efi_char16_t));
+	if (c16) {
+		for (i = 0; i < sizeof(vendor) - 1 && c16[i]; ++i)
+			vendor[i] = c16[i];
+		vendor[i] = '\0';
+		early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
+	} else {
+		pr_err("Could not map the firmware vendor!\n");
+	}
+
+	pr_info("EFI v%u.%.02u by %s\n",
+		efi.systab->hdr.revision >> 16,
+		efi.systab->hdr.revision & 0xffff, vendor);
+
+	if (efi_reuse_config(efi.systab->tables, efi.systab->nr_tables))
+		return;
+
+	if (efi_config_init(arch_tables))
+		return;
+
+	/*
+	 * Note: We currently don't support runtime services on an EFI
+	 * that doesn't match the kernel 32/64-bit mode.
+	 */
+
+	if (!efi_runtime_supported())
+		pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
+	else {
+		if (efi_runtime_disabled() || efi_runtime_init()) {
+			efi_memmap_unmap();
+			return;
+		}
+	}
+
+	efi_clean_memmap();
+
+	if (efi_enabled(EFI_DBG))
+		efi_print_memmap();
+}
+
+void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
+{
+	u64 addr, npages;
+
+	addr = md->virt_addr;
+	npages = md->num_pages;
+
+	memrange_efi_to_native(&addr, &npages);
+
+	if (executable)
+		set_memory_x(addr, npages);
+	else
+		set_memory_nx(addr, npages);
+}
+
+void __init runtime_code_page_mkexec(void)
+{
+	efi_memory_desc_t *md;
+
+	/* Make EFI runtime service code area executable */
+	for_each_efi_memory_desc(md) {
+		if (md->type != EFI_RUNTIME_SERVICES_CODE)
+			continue;
+
+		efi_set_executable(md, true);
+	}
+}
+
+void __init efi_memory_uc(u64 addr, unsigned long size)
+{
+	unsigned long page_shift = 1UL << EFI_PAGE_SHIFT;
+	u64 npages;
+
+	npages = round_up(size, page_shift) / page_shift;
+	memrange_efi_to_native(&addr, &npages);
+	set_memory_uc(addr, npages);
+}
+
+void __init old_map_region(efi_memory_desc_t *md)
+{
+	u64 start_pfn, end_pfn, end;
+	unsigned long size;
+	void *va;
+
+	start_pfn = PFN_DOWN(md->phys_addr);
+	size	  = md->num_pages << PAGE_SHIFT;
+	end	  = md->phys_addr + size;
+	end_pfn   = PFN_UP(end);
+
+	if (pfn_range_is_mapped(start_pfn, end_pfn)) {
+		va = __va(md->phys_addr);
+
+		if (!(md->attribute & EFI_MEMORY_WB))
+			efi_memory_uc((u64)(unsigned long)va, size);
+	} else
+		va = efi_ioremap(md->phys_addr, size,
+				 md->type, md->attribute);
+
+	md->virt_addr = (u64) (unsigned long) va;
+	if (!va)
+		pr_err("ioremap of 0x%llX failed!\n",
+		       (unsigned long long)md->phys_addr);
+}
+
+/* Merge contiguous regions of the same type and attribute */
+static void __init efi_merge_regions(void)
+{
+	efi_memory_desc_t *md, *prev_md = NULL;
+
+	for_each_efi_memory_desc(md) {
+		u64 prev_size;
+
+		if (!prev_md) {
+			prev_md = md;
+			continue;
+		}
+
+		if (prev_md->type != md->type ||
+		    prev_md->attribute != md->attribute) {
+			prev_md = md;
+			continue;
+		}
+
+		prev_size = prev_md->num_pages << EFI_PAGE_SHIFT;
+
+		if (md->phys_addr == (prev_md->phys_addr + prev_size)) {
+			prev_md->num_pages += md->num_pages;
+			md->type = EFI_RESERVED_TYPE;
+			md->attribute = 0;
+			continue;
+		}
+		prev_md = md;
+	}
+}
+
+static void __init get_systab_virt_addr(efi_memory_desc_t *md)
+{
+	unsigned long size;
+	u64 end, systab;
+
+	size = md->num_pages << EFI_PAGE_SHIFT;
+	end = md->phys_addr + size;
+	systab = (u64)(unsigned long)efi_phys.systab;
+	if (md->phys_addr <= systab && systab < end) {
+		systab += md->virt_addr - md->phys_addr;
+		efi.systab = (efi_system_table_t *)(unsigned long)systab;
+	}
+}
+
+static void *realloc_pages(void *old_memmap, int old_shift)
+{
+	void *ret;
+
+	ret = (void *)__get_free_pages(GFP_KERNEL, old_shift + 1);
+	if (!ret)
+		goto out;
+
+	/*
+	 * A first-time allocation doesn't have anything to copy.
+	 */
+	if (!old_memmap)
+		return ret;
+
+	memcpy(ret, old_memmap, PAGE_SIZE << old_shift);
+
+out:
+	free_pages((unsigned long)old_memmap, old_shift);
+	return ret;
+}
+
+/*
+ * Iterate the EFI memory map in reverse order because the regions
+ * will be mapped top-down. The end result is the same as if we had
+ * mapped things forward, but doesn't require us to change the
+ * existing implementation of efi_map_region().
+ */
+static inline void *efi_map_next_entry_reverse(void *entry)
+{
+	/* Initial call */
+	if (!entry)
+		return efi.memmap.map_end - efi.memmap.desc_size;
+
+	entry -= efi.memmap.desc_size;
+	if (entry < efi.memmap.map)
+		return NULL;
+
+	return entry;
+}
+
+/*
+ * efi_map_next_entry - Return the next EFI memory map descriptor
+ * @entry: Previous EFI memory map descriptor
+ *
+ * This is a helper function to iterate over the EFI memory map, which
+ * we do in different orders depending on the current configuration.
+ *
+ * To begin traversing the memory map @entry must be %NULL.
+ *
+ * Returns %NULL when we reach the end of the memory map.
+ */
+static void *efi_map_next_entry(void *entry)
+{
+	if (!efi_enabled(EFI_OLD_MEMMAP) && efi_enabled(EFI_64BIT)) {
+		/*
+		 * Starting in UEFI v2.5 the EFI_PROPERTIES_TABLE
+		 * config table feature requires us to map all entries
+		 * in the same order as they appear in the EFI memory
+		 * map. That is to say, entry N must have a lower
+		 * virtual address than entry N+1. This is because the
+		 * firmware toolchain leaves relative references in
+		 * the code/data sections, which are split and become
+		 * separate EFI memory regions. Mapping things
+		 * out-of-order leads to the firmware accessing
+		 * unmapped addresses.
+		 *
+		 * Since we need to map things this way whether or not
+		 * the kernel actually makes use of
+		 * EFI_PROPERTIES_TABLE, let's just switch to this
+		 * scheme by default for 64-bit.
+		 */
+		return efi_map_next_entry_reverse(entry);
+	}
+
+	/* Initial call */
+	if (!entry)
+		return efi.memmap.map;
+
+	entry += efi.memmap.desc_size;
+	if (entry >= efi.memmap.map_end)
+		return NULL;
+
+	return entry;
+}
+
+static bool should_map_region(efi_memory_desc_t *md)
+{
+	/*
+	 * Runtime regions always require runtime mappings (obviously).
+	 */
+	if (md->attribute & EFI_MEMORY_RUNTIME)
+		return true;
+
+	/*
+	 * 32-bit EFI doesn't suffer from the bug that requires us to
+	 * reserve boot services regions, and mixed mode support
+	 * doesn't exist for 32-bit kernels.
+	 */
+	if (IS_ENABLED(CONFIG_X86_32))
+		return false;
+
+	/*
+	 * Map all of RAM so that we can access arguments in the 1:1
+	 * mapping when making EFI runtime calls.
+	 */
+	if (IS_ENABLED(CONFIG_EFI_MIXED) && !efi_is_native()) {
+		if (md->type == EFI_CONVENTIONAL_MEMORY ||
+		    md->type == EFI_LOADER_DATA ||
+		    md->type == EFI_LOADER_CODE)
+			return true;
+	}
+
+	/*
+	 * Map boot services regions as a workaround for buggy
+	 * firmware that accesses them even when they shouldn't.
+	 *
+	 * See efi_{reserve,free}_boot_services().
+	 */
+	if (md->type == EFI_BOOT_SERVICES_CODE ||
+	    md->type == EFI_BOOT_SERVICES_DATA)
+		return true;
+
+	return false;
+}
+
+/*
+ * Map the efi memory ranges of the runtime services and update new_mmap with
+ * virtual addresses.
+ */
+static void * __init efi_map_regions(int *count, int *pg_shift)
+{
+	void *p, *new_memmap = NULL;
+	unsigned long left = 0;
+	unsigned long desc_size;
+	efi_memory_desc_t *md;
+
+	desc_size = efi.memmap.desc_size;
+
+	p = NULL;
+	while ((p = efi_map_next_entry(p))) {
+		md = p;
+
+		if (!should_map_region(md))
+			continue;
+
+		efi_map_region(md);
+		get_systab_virt_addr(md);
+
+		if (left < desc_size) {
+			new_memmap = realloc_pages(new_memmap, *pg_shift);
+			if (!new_memmap)
+				return NULL;
+
+			left += PAGE_SIZE << *pg_shift;
+			(*pg_shift)++;
+		}
+
+		memcpy(new_memmap + (*count * desc_size), md, desc_size);
+
+		left -= desc_size;
+		(*count)++;
+	}
+
+	return new_memmap;
+}
+
+static void __init kexec_enter_virtual_mode(void)
+{
+#ifdef CONFIG_KEXEC_CORE
+	efi_memory_desc_t *md;
+	unsigned int num_pages;
+
+	efi.systab = NULL;
+
+	/*
+	 * We don't do virtual mode, since we don't do runtime services, on
+	 * non-native EFI. With efi=old_map, we don't do runtime services in
+	 * kexec kernel because in the initial boot something else might
+	 * have been mapped at these virtual addresses.
+	 */
+	if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) {
+		efi_memmap_unmap();
+		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+		return;
+	}
+
+	if (efi_alloc_page_tables()) {
+		pr_err("Failed to allocate EFI page tables\n");
+		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+		return;
+	}
+
+	/*
+	* Map efi regions which were passed via setup_data. The virt_addr is a
+	* fixed addr which was used in first kernel of a kexec boot.
+	*/
+	for_each_efi_memory_desc(md) {
+		efi_map_region_fixed(md); /* FIXME: add error handling */
+		get_systab_virt_addr(md);
+	}
+
+	/*
+	 * Unregister the early EFI memmap from efi_init() and install
+	 * the new EFI memory map.
+	 */
+	efi_memmap_unmap();
+
+	if (efi_memmap_init_late(efi.memmap.phys_map,
+				 efi.memmap.desc_size * efi.memmap.nr_map)) {
+		pr_err("Failed to remap late EFI memory map\n");
+		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+		return;
+	}
+
+	BUG_ON(!efi.systab);
+
+	num_pages = ALIGN(efi.memmap.nr_map * efi.memmap.desc_size, PAGE_SIZE);
+	num_pages >>= PAGE_SHIFT;
+
+	if (efi_setup_page_tables(efi.memmap.phys_map, num_pages)) {
+		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+		return;
+	}
+
+	efi_sync_low_kernel_mappings();
+
+	/*
+	 * Now that EFI is in virtual mode, update the function
+	 * pointers in the runtime service table to the new virtual addresses.
+	 *
+	 * Call EFI services through wrapper functions.
+	 */
+	efi.runtime_version = efi_systab.hdr.revision;
+
+	efi_native_runtime_setup();
+
+	efi.set_virtual_address_map = NULL;
+
+	if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX))
+		runtime_code_page_mkexec();
+#endif
+}
+
+/*
+ * This function will switch the EFI runtime services to virtual mode.
+ * Essentially, we look through the EFI memmap and map every region that
+ * has the runtime attribute bit set in its memory descriptor into the
+ * efi_pgd page table.
+ *
+ * The old method which used to update that memory descriptor with the
+ * virtual address obtained from ioremap() is still supported when the
+ * kernel is booted with efi=old_map on its command line. Same old
+ * method enabled the runtime services to be called without having to
+ * thunk back into physical mode for every invocation.
+ *
+ * The new method does a pagetable switch in a preemption-safe manner
+ * so that we're in a different address space when calling a runtime
+ * function. For function arguments passing we do copy the PUDs of the
+ * kernel page table into efi_pgd prior to each call.
+ *
+ * Specially for kexec boot, efi runtime maps in previous kernel should
+ * be passed in via setup_data. In that case runtime ranges will be mapped
+ * to the same virtual addresses as the first kernel, see
+ * kexec_enter_virtual_mode().
+ */
+static void __init __efi_enter_virtual_mode(void)
+{
+	int count = 0, pg_shift = 0;
+	void *new_memmap = NULL;
+	efi_status_t status;
+	unsigned long pa;
+
+	efi.systab = NULL;
+
+	if (efi_alloc_page_tables()) {
+		pr_err("Failed to allocate EFI page tables\n");
+		goto err;
+	}
+
+	efi_merge_regions();
+	new_memmap = efi_map_regions(&count, &pg_shift);
+	if (!new_memmap) {
+		pr_err("Error reallocating memory, EFI runtime non-functional!\n");
+		goto err;
+	}
+
+	pa = __pa(new_memmap);
+
+	/*
+	 * Unregister the early EFI memmap from efi_init() and install
+	 * the new EFI memory map that we are about to pass to the
+	 * firmware via SetVirtualAddressMap().
+	 */
+	efi_memmap_unmap();
+
+	if (efi_memmap_init_late(pa, efi.memmap.desc_size * count)) {
+		pr_err("Failed to remap late EFI memory map\n");
+		goto err;
+	}
+
+	if (efi_enabled(EFI_DBG)) {
+		pr_info("EFI runtime memory map:\n");
+		efi_print_memmap();
+	}
+
+	if (WARN_ON(!efi.systab))
+		goto err;
+
+	if (efi_setup_page_tables(pa, 1 << pg_shift))
+		goto err;
+
+	efi_sync_low_kernel_mappings();
+
+	if (efi_is_native()) {
+		status = phys_efi_set_virtual_address_map(
+				efi.memmap.desc_size * count,
+				efi.memmap.desc_size,
+				efi.memmap.desc_version,
+				(efi_memory_desc_t *)pa);
+	} else {
+		status = efi_thunk_set_virtual_address_map(
+				efi_phys.set_virtual_address_map,
+				efi.memmap.desc_size * count,
+				efi.memmap.desc_size,
+				efi.memmap.desc_version,
+				(efi_memory_desc_t *)pa);
+	}
+
+	if (status != EFI_SUCCESS) {
+		pr_err("Unable to switch EFI into virtual mode (status=%lx)!\n",
+		       status);
+		goto err;
+	}
+
+	/*
+	 * Now that EFI is in virtual mode, update the function
+	 * pointers in the runtime service table to the new virtual addresses.
+	 *
+	 * Call EFI services through wrapper functions.
+	 */
+	efi.runtime_version = efi_systab.hdr.revision;
+
+	if (efi_is_native())
+		efi_native_runtime_setup();
+	else
+		efi_thunk_runtime_setup();
+
+	efi.set_virtual_address_map = NULL;
+
+	/*
+	 * Apply more restrictive page table mapping attributes now that
+	 * SVAM() has been called and the firmware has performed all
+	 * necessary relocation fixups for the new virtual addresses.
+	 */
+	efi_runtime_update_mappings();
+
+	/* clean DUMMY object */
+	efi_delete_dummy_variable();
+	return;
+
+err:
+	clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+}
+
+void __init efi_enter_virtual_mode(void)
+{
+	if (efi_enabled(EFI_PARAVIRT))
+		return;
+
+	if (efi_setup)
+		kexec_enter_virtual_mode();
+	else
+		__efi_enter_virtual_mode();
+
+	efi_dump_pagetable();
+}
+
+static int __init arch_parse_efi_cmdline(char *str)
+{
+	if (!str) {
+		pr_warn("need at least one option\n");
+		return -EINVAL;
+	}
+
+	if (parse_option_str(str, "old_map"))
+		set_bit(EFI_OLD_MEMMAP, &efi.flags);
+
+	return 0;
+}
+early_param("efi", arch_parse_efi_cmdline);