efi.c

/*
 * 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/atomic.h>
#include <linux/dmi.h>
#include <linux/efi.h>
#include <linux/export.h>
#include <linux/memblock.h>
#include <linux/mm_types.h>
#include <linux/bootmem.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/preempt.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <asm/cacheflush.h>
#include <asm/efi.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>

struct efi_memory_map memmap;

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);
	}
}

/*
 * Translate a EFI virtual address into a physical address: this is necessary,
 * as some data members of the EFI system table are virtually remapped after
 * SetVirtualAddressMap() has been called.
 */
static phys_addr_t efi_to_phys(unsigned long addr)
{
	efi_memory_desc_t *md;

	for_each_efi_memory_desc(&memmap, md) {
		if (!(md->attribute & EFI_MEMORY_RUNTIME))
			continue;
		if (md->virt_addr == 0)
			/* no virtual mapping has been installed by the stub */
			break;
		if (md->virt_addr <= addr &&
		    (addr - md->virt_addr) < (md->num_pages << EFI_PAGE_SHIFT))
			return md->phys_addr + addr - md->virt_addr;
	}
	return addr;
}

static int __init uefi_init(void)
{
	efi_char16_t *c16;
	void *config_tables;
	u64 table_size;
	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");
		retval = -EINVAL;
		goto out;
	}
	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_to_phys(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';
		early_memunmap(c16, sizeof(vendor));
	}

	pr_info("EFI v%u.%.02u by %s\n",
		efi.systab->hdr.revision >> 16,
		efi.systab->hdr.revision & 0xffff, vendor);

	table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
	config_tables = early_memremap(efi_to_phys(efi.systab->tables),
				       table_size);

	retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
					 sizeof(efi_config_table_64_t), NULL);

	early_memunmap(config_tables, table_size);
out:
	early_memunmap(efi.systab,  sizeof(efi_system_table_t));
	return retval;
}

/*
 * Return true for RAM regions we want to permanently reserve.
 */
static __init int is_reserve_region(efi_memory_desc_t *md)
{
	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:
		return 0;
	default:
		break;
	}
	return is_normal_ram(md);
}

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) {
			char buf[64];

			pr_info("  0x%012llx-0x%012llx %s",
				paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
				efi_md_typeattr_format(buf, sizeof(buf), md));
		}

		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");
	}

	set_bit(EFI_MEMMAP, &efi.flags);
}


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)
{
	if (!efi_enabled(EFI_BOOT))
		return;

	/* boot time idmap_pg_dir is incomplete, so fill in missing parts */
	efi_setup_idmap();
	early_memunmap(memmap.map, memmap.map_end - memmap.map);
}

/*
 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 * non-early mapping of the UEFI system table and virtual mappings for all
 * EFI_MEMORY_RUNTIME regions.
 */
static int __init arm64_enable_runtime_services(void)
{
	u64 mapsize;

	if (!efi_enabled(EFI_BOOT)) {
		pr_info("EFI services will not be available.\n");
		return -1;
	}

	mapsize = memmap.map_end - memmap.map;

	if (efi_runtime_disabled()) {
		pr_info("EFI runtime services will be disabled.\n");
		return -1;
	}

	pr_info("Remapping and enabling EFI services.\n");
	/* replace early memmap mapping with permanent mapping */
	memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
						   mapsize);
	memmap.map_end = memmap.map + mapsize;

	efi.memmap = &memmap;

	efi.systab = (__force void *)ioremap_cache(efi_system_table,
						   sizeof(efi_system_table_t));
	if (!efi.systab) {
		pr_err("Failed to remap EFI System Table\n");
		return -1;
	}
	set_bit(EFI_SYSTEM_TABLES, &efi.flags);

	free_boot_services();

	if (!efi_enabled(EFI_VIRTMAP)) {
		pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
		return -1;
	}

	/* Set up runtime services function pointers */
	efi_native_runtime_setup();
	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);

	efi.runtime_version = efi.systab->hdr.revision;

	return 0;
}
early_initcall(arm64_enable_runtime_services);

static int __init arm64_dmi_init(void)
{
	/*
	 * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
	 * be called early because dmi_id_init(), which is an arch_initcall
	 * itself, depends on dmi_scan_machine() having been called already.
	 */
	dmi_scan_machine();
	if (dmi_available)
		dmi_set_dump_stack_arch_desc();
	return 0;
}
core_initcall(arm64_dmi_init);

static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;

static struct mm_struct efi_mm = {
	.mm_rb			= RB_ROOT,
	.pgd			= efi_pgd,
	.mm_users		= ATOMIC_INIT(2),
	.mm_count		= ATOMIC_INIT(1),
	.mmap_sem		= __RWSEM_INITIALIZER(efi_mm.mmap_sem),
	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
	INIT_MM_CONTEXT(efi_mm)
};

static void efi_set_pgd(struct mm_struct *mm)
{
	cpu_switch_mm(mm->pgd, mm);
	flush_tlb_all();
	if (icache_is_aivivt())
		__flush_icache_all();
}

void efi_virtmap_load(void)
{
	preempt_disable();
	efi_set_pgd(&efi_mm);
}

void efi_virtmap_unload(void)
{
	efi_set_pgd(current->active_mm);
	preempt_enable();
}

void __init efi_virtmap_init(void)
{
	efi_memory_desc_t *md;

	if (!efi_enabled(EFI_BOOT))
		return;

	for_each_efi_memory_desc(&memmap, md) {
		u64 paddr, npages, size;
		pgprot_t prot;

		if (!(md->attribute & EFI_MEMORY_RUNTIME))
			continue;
		if (WARN(md->virt_addr == 0,
			 "UEFI virtual mapping incomplete or missing -- no entry found for 0x%llx\n",
			 md->phys_addr))
			return;

		paddr = md->phys_addr;
		npages = md->num_pages;
		memrange_efi_to_native(&paddr, &npages);
		size = npages << PAGE_SHIFT;

		pr_info("  EFI remap 0x%016llx => %p\n",
			md->phys_addr, (void *)md->virt_addr);

		/*
		 * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
		 * executable, everything else can be mapped with the XN bits
		 * set.
		 */
		if (!is_normal_ram(md))
			prot = __pgprot(PROT_DEVICE_nGnRE);
		else if (md->type == EFI_RUNTIME_SERVICES_CODE)
			prot = PAGE_KERNEL_EXEC;
		else
			prot = PAGE_KERNEL;

		create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
	}
	set_bit(EFI_VIRTMAP, &efi.flags);
}