arm64: add EFI runtime services

This patch adds EFI runtime support for arm64. This runtime support allows
the kernel to access various EFI runtime services provided by EFI firmware.
Things like reboot, real time clock, EFI boot variables, and others.

This functionality is supported for little endian kernels only. The UEFI
firmware standard specifies that the firmware be little endian. A future
patch is expected to add support for big endian kernels running with
little endian firmware.

Signed-off-by: Mark Salter <msalter@redhat.com>
[ Remove unnecessary cache/tlb maintenance. ]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

arch/arm64/Kconfig

@@ -280,6 +280,19 @@ config CMDLINE_FORCE
 	  This is useful if you cannot or don't want to change the
 	  command-line options your boot loader passes to the kernel.
 
+config EFI
+	bool "UEFI runtime support"
+	depends on OF && !CPU_BIG_ENDIAN
+	select LIBFDT
+	select UCS2_STRING
+	select EFI_PARAMS_FROM_FDT
+	default y
+	help
+	  This option provides support for runtime services provided
+	  by UEFI firmware (such as non-volatile variables, realtime
+          clock, and platform reset). This is only useful on systems
+	  that have UEFI firmware.
+
 endmenu
 
 menu "Userspace binary formats"
@@ -333,6 +346,8 @@ source "net/Kconfig"
 
 source "drivers/Kconfig"
 
+source "drivers/firmware/Kconfig"
+
 source "fs/Kconfig"
 
 source "arch/arm64/kvm/Kconfig"

arch/arm64/include/asm/efi.h

@@ -0,0 +1,14 @@
+#ifndef _ASM_EFI_H
+#define _ASM_EFI_H
+
+#include <asm/io.h>
+
+#ifdef CONFIG_EFI
+extern void efi_init(void);
+extern void efi_idmap_init(void);
+#else
+#define efi_init()
+#define efi_idmap_init()
+#endif
+
+#endif /* _ASM_EFI_H */

arch/arm64/kernel/Makefile

@@ -22,6 +22,7 @@ arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND)	+= sleep.o suspend.o
 arm64-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
+arm64-obj-$(CONFIG_EFI)			+= efi.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)

arch/arm64/kernel/efi.c

@@ -0,0 +1,466 @@
+/*
+ * Extensible Firmware Interface
+ *
+ * Based on Extensible Firmware Interface Specification version 2.4
+ *
+ * Copyright (C) 2013, 2014 Linaro Ltd.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/efi.h>
+#include <linux/export.h>
+#include <linux/memblock.h>
+#include <linux/bootmem.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <asm/cacheflush.h>
+#include <asm/efi.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+
+struct efi_memory_map memmap;
+
+static efi_runtime_services_t *runtime;
+
+static u64 efi_system_table;
+
+static int uefi_debug __initdata;
+static int __init uefi_debug_setup(char *str)
+{
+	uefi_debug = 1;
+
+	return 0;
+}
+early_param("uefi_debug", uefi_debug_setup);
+
+static int __init is_normal_ram(efi_memory_desc_t *md)
+{
+	if (md->attribute & EFI_MEMORY_WB)
+		return 1;
+	return 0;
+}
+
+static void __init efi_setup_idmap(void)
+{
+	struct memblock_region *r;
+	efi_memory_desc_t *md;
+	u64 paddr, npages, size;
+
+	for_each_memblock(memory, r)
+		create_id_mapping(r->base, r->size, 0);
+
+	/* map runtime io spaces */
+	for_each_efi_memory_desc(&memmap, md) {
+		if (!(md->attribute & EFI_MEMORY_RUNTIME) || is_normal_ram(md))
+			continue;
+		paddr = md->phys_addr;
+		npages = md->num_pages;
+		memrange_efi_to_native(&paddr, &npages);
+		size = npages << PAGE_SHIFT;
+		create_id_mapping(paddr, size, 1);
+	}
+}
+
+static int __init uefi_init(void)
+{
+	efi_char16_t *c16;
+	char vendor[100] = "unknown";
+	int i, retval;
+
+	efi.systab = early_memremap(efi_system_table,
+				    sizeof(efi_system_table_t));
+	if (efi.systab == NULL) {
+		pr_warn("Unable to map EFI system table.\n");
+		return -ENOMEM;
+	}
+
+	set_bit(EFI_BOOT, &efi.flags);
+	set_bit(EFI_64BIT, &efi.flags);
+
+	/*
+	 * 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) < 2)
+		pr_warn("Warning: EFI system table version %d.%02d, expected 2.00 or greater\n",
+			efi.systab->hdr.revision >> 16,
+			efi.systab->hdr.revision & 0xffff);
+
+	/* Show what we know for posterity */
+	c16 = early_memremap(efi.systab->fw_vendor,
+			     sizeof(vendor));
+	if (c16) {
+		for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
+			vendor[i] = c16[i];
+		vendor[i] = '\0';
+	}
+
+	pr_info("EFI v%u.%.02u by %s\n",
+		efi.systab->hdr.revision >> 16,
+		efi.systab->hdr.revision & 0xffff, vendor);
+
+	retval = efi_config_init(NULL);
+	if (retval == 0)
+		set_bit(EFI_CONFIG_TABLES, &efi.flags);
+
+	early_memunmap(c16, sizeof(vendor));
+	early_memunmap(efi.systab,  sizeof(efi_system_table_t));
+
+	return retval;
+}
+
+static __initdata char memory_type_name[][32] = {
+	{"Reserved"},
+	{"Loader Code"},
+	{"Loader Data"},
+	{"Boot Code"},
+	{"Boot Data"},
+	{"Runtime Code"},
+	{"Runtime Data"},
+	{"Conventional Memory"},
+	{"Unusable Memory"},
+	{"ACPI Reclaim Memory"},
+	{"ACPI Memory NVS"},
+	{"Memory Mapped I/O"},
+	{"MMIO Port Space"},
+	{"PAL Code"},
+};
+
+/*
+ * Return true for RAM regions we want to permanently reserve.
+ */
+static __init int is_reserve_region(efi_memory_desc_t *md)
+{
+	if (!is_normal_ram(md))
+		return 0;
+
+	if (md->attribute & EFI_MEMORY_RUNTIME)
+		return 1;
+
+	if (md->type == EFI_ACPI_RECLAIM_MEMORY ||
+	    md->type == EFI_RESERVED_TYPE)
+		return 1;
+
+	return 0;
+}
+
+static __init void reserve_regions(void)
+{
+	efi_memory_desc_t *md;
+	u64 paddr, npages, size;
+
+	if (uefi_debug)
+		pr_info("Processing EFI memory map:\n");
+
+	for_each_efi_memory_desc(&memmap, md) {
+		paddr = md->phys_addr;
+		npages = md->num_pages;
+
+		if (uefi_debug)
+			pr_info("  0x%012llx-0x%012llx [%s]",
+				paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
+				memory_type_name[md->type]);
+
+		memrange_efi_to_native(&paddr, &npages);
+		size = npages << PAGE_SHIFT;
+
+		if (is_normal_ram(md))
+			early_init_dt_add_memory_arch(paddr, size);
+
+		if (is_reserve_region(md) ||
+		    md->type == EFI_BOOT_SERVICES_CODE ||
+		    md->type == EFI_BOOT_SERVICES_DATA) {
+			memblock_reserve(paddr, size);
+			if (uefi_debug)
+				pr_cont("*");
+		}
+
+		if (uefi_debug)
+			pr_cont("\n");
+	}
+}
+
+
+static u64 __init free_one_region(u64 start, u64 end)
+{
+	u64 size = end - start;
+
+	if (uefi_debug)
+		pr_info("  EFI freeing: 0x%012llx-0x%012llx\n",	start, end - 1);
+
+	free_bootmem_late(start, size);
+	return size;
+}
+
+static u64 __init free_region(u64 start, u64 end)
+{
+	u64 map_start, map_end, total = 0;
+
+	if (end <= start)
+		return total;
+
+	map_start = (u64)memmap.phys_map;
+	map_end = PAGE_ALIGN(map_start + (memmap.map_end - memmap.map));
+	map_start &= PAGE_MASK;
+
+	if (start < map_end && end > map_start) {
+		/* region overlaps UEFI memmap */
+		if (start < map_start)
+			total += free_one_region(start, map_start);
+
+		if (map_end < end)
+			total += free_one_region(map_end, end);
+	} else
+		total += free_one_region(start, end);
+
+	return total;
+}
+
+static void __init free_boot_services(void)
+{
+	u64 total_freed = 0;
+	u64 keep_end, free_start, free_end;
+	efi_memory_desc_t *md;
+
+	/*
+	 * If kernel uses larger pages than UEFI, we have to be careful
+	 * not to inadvertantly free memory we want to keep if there is
+	 * overlap at the kernel page size alignment. We do not want to
+	 * free is_reserve_region() memory nor the UEFI memmap itself.
+	 *
+	 * The memory map is sorted, so we keep track of the end of
+	 * any previous region we want to keep, remember any region
+	 * we want to free and defer freeing it until we encounter
+	 * the next region we want to keep. This way, before freeing
+	 * it, we can clip it as needed to avoid freeing memory we
+	 * want to keep for UEFI.
+	 */
+
+	keep_end = 0;
+	free_start = 0;
+
+	for_each_efi_memory_desc(&memmap, md) {
+		u64 paddr, npages, size;
+
+		if (is_reserve_region(md)) {
+			/*
+			 * We don't want to free any memory from this region.
+			 */
+			if (free_start) {
+				/* adjust free_end then free region */
+				if (free_end > md->phys_addr)
+					free_end -= PAGE_SIZE;
+				total_freed += free_region(free_start, free_end);
+				free_start = 0;
+			}
+			keep_end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT);
+			continue;
+		}
+
+		if (md->type != EFI_BOOT_SERVICES_CODE &&
+		    md->type != EFI_BOOT_SERVICES_DATA) {
+			/* no need to free this region */
+			continue;
+		}
+
+		/*
+		 * We want to free memory from this region.
+		 */
+		paddr = md->phys_addr;
+		npages = md->num_pages;
+		memrange_efi_to_native(&paddr, &npages);
+		size = npages << PAGE_SHIFT;
+
+		if (free_start) {
+			if (paddr <= free_end)
+				free_end = paddr + size;
+			else {
+				total_freed += free_region(free_start, free_end);
+				free_start = paddr;
+				free_end = paddr + size;
+			}
+		} else {
+			free_start = paddr;
+			free_end = paddr + size;
+		}
+		if (free_start < keep_end) {
+			free_start += PAGE_SIZE;
+			if (free_start >= free_end)
+				free_start = 0;
+		}
+	}
+	if (free_start)
+		total_freed += free_region(free_start, free_end);
+
+	if (total_freed)
+		pr_info("Freed 0x%llx bytes of EFI boot services memory",
+			total_freed);
+}
+
+void __init efi_init(void)
+{
+	struct efi_fdt_params params;
+
+	/* Grab UEFI information placed in FDT by stub */
+	if (!efi_get_fdt_params(&params, uefi_debug))
+		return;
+
+	efi_system_table = params.system_table;
+
+	memblock_reserve(params.mmap & PAGE_MASK,
+			 PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
+	memmap.phys_map = (void *)params.mmap;
+	memmap.map = early_memremap(params.mmap, params.mmap_size);
+	memmap.map_end = memmap.map + params.mmap_size;
+	memmap.desc_size = params.desc_size;
+	memmap.desc_version = params.desc_ver;
+
+	if (uefi_init() < 0)
+		return;
+
+	reserve_regions();
+}
+
+void __init efi_idmap_init(void)
+{
+	/* boot time idmap_pg_dir is incomplete, so fill in missing parts */
+	efi_setup_idmap();
+}
+
+static int __init remap_region(efi_memory_desc_t *md, void **new)
+{
+	u64 paddr, vaddr, npages, size;
+
+	paddr = md->phys_addr;
+	npages = md->num_pages;
+	memrange_efi_to_native(&paddr, &npages);
+	size = npages << PAGE_SHIFT;
+
+	if (is_normal_ram(md))
+		vaddr = (__force u64)ioremap_cache(paddr, size);
+	else
+		vaddr = (__force u64)ioremap(paddr, size);
+
+	if (!vaddr) {
+		pr_err("Unable to remap 0x%llx pages @ %p\n",
+		       npages, (void *)paddr);
+		return 0;
+	}
+
+	/* adjust for any rounding when EFI and system pagesize differs */
+	md->virt_addr = vaddr + (md->phys_addr - paddr);
+
+	if (uefi_debug)
+		pr_info("  EFI remap 0x%012llx => %p\n",
+			md->phys_addr, (void *)md->virt_addr);
+
+	memcpy(*new, md, memmap.desc_size);
+	*new += memmap.desc_size;
+
+	return 1;
+}
+
+/*
+ * Switch UEFI from an identity map to a kernel virtual map
+ */
+static int __init arm64_enter_virtual_mode(void)
+{
+	efi_memory_desc_t *md;
+	phys_addr_t virtmap_phys;
+	void *virtmap, *virt_md;
+	efi_status_t status;
+	u64 mapsize;
+	int count = 0;
+	unsigned long flags;
+
+	if (!efi_enabled(EFI_BOOT)) {
+		pr_info("EFI services will not be available.\n");
+		return -1;
+	}
+
+	pr_info("Remapping and enabling EFI services.\n");
+
+	/* replace early memmap mapping with permanent mapping */
+	mapsize = memmap.map_end - memmap.map;
+	early_memunmap(memmap.map, mapsize);
+	memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
+						   mapsize);
+	memmap.map_end = memmap.map + mapsize;
+
+	efi.memmap = &memmap;
+
+	/* Map the runtime regions */
+	virtmap = kmalloc(mapsize, GFP_KERNEL);
+	if (!virtmap) {
+		pr_err("Failed to allocate EFI virtual memmap\n");
+		return -1;
+	}
+	virtmap_phys = virt_to_phys(virtmap);
+	virt_md = virtmap;
+
+	for_each_efi_memory_desc(&memmap, md) {
+		if (!(md->attribute & EFI_MEMORY_RUNTIME))
+			continue;
+		if (remap_region(md, &virt_md))
+			++count;
+	}
+
+	efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table);
+	if (efi.systab)
+		set_bit(EFI_SYSTEM_TABLES, &efi.flags);
+
+	local_irq_save(flags);
+	cpu_switch_mm(idmap_pg_dir, &init_mm);
+
+	/* Call SetVirtualAddressMap with the physical address of the map */
+	runtime = efi.systab->runtime;
+	efi.set_virtual_address_map = runtime->set_virtual_address_map;
+
+	status = efi.set_virtual_address_map(count * memmap.desc_size,
+					     memmap.desc_size,
+					     memmap.desc_version,
+					     (efi_memory_desc_t *)virtmap_phys);
+	cpu_set_reserved_ttbr0();
+	flush_tlb_all();
+	local_irq_restore(flags);
+
+	kfree(virtmap);
+
+	free_boot_services();
+
+	if (status != EFI_SUCCESS) {
+		pr_err("Failed to set EFI virtual address map! [%lx]\n",
+			status);
+		return -1;
+	}
+
+	/* Set up runtime services function pointers */
+	runtime = efi.systab->runtime;
+	efi.get_time = runtime->get_time;
+	efi.set_time = runtime->set_time;
+	efi.get_wakeup_time = runtime->get_wakeup_time;
+	efi.set_wakeup_time = runtime->set_wakeup_time;
+	efi.get_variable = runtime->get_variable;
+	efi.get_next_variable = runtime->get_next_variable;
+	efi.set_variable = runtime->set_variable;
+	efi.query_variable_info = runtime->query_variable_info;
+	efi.update_capsule = runtime->update_capsule;
+	efi.query_capsule_caps = runtime->query_capsule_caps;
+	efi.get_next_high_mono_count = runtime->get_next_high_mono_count;
+	efi.reset_system = runtime->reset_system;
+
+	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+
+	return 0;
+}
+early_initcall(arm64_enter_virtual_mode);

arch/arm64/kernel/setup.c

@@ -41,6 +41,7 @@
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
+#include <linux/efi.h>
 
 #include <asm/fixmap.h>
 #include <asm/cputype.h>
@@ -55,6 +56,7 @@
 #include <asm/traps.h>
 #include <asm/memblock.h>
 #include <asm/psci.h>
+#include <asm/efi.h>
 
 unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);
@@ -366,11 +368,14 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
+	efi_init();
 	arm64_memblock_init();
 
 	paging_init();
 	request_standard_resources();
 
+	efi_idmap_init();
+
 	unflatten_device_tree();
 
 	psci_init();