kernel-fxtec-pro1x/arch/arm64/kernel/efi.c
Will Deacon 130c93fd10 arm64: efi: don't restore TTBR0 if active_mm points at init_mm
init_mm isn't a normal mm: it has swapper_pg_dir as its pgd (which
contains kernel mappings) and is used as the active_mm for the idle
thread.

When restoring the pgd after an EFI call, we write current->active_mm
into TTBR0. If the current task is actually the idle thread (e.g. when
initialising the EFI RTC before entering userspace), then the TLB can
erroneously populate itself with junk global entries as a result of
speculative table walks.

When we do eventually return to userspace, the task can end up hitting
these junk mappings leading to lockups, corruption or crashes.

This patch fixes the problem in the same way as the CPU suspend code by
ensuring that we never switch to the init_mm in efi_set_pgd and instead
point TTBR0 at the zero page. A check is also added to cpu_switch_mm to
BUG if we get passed swapper_pg_dir.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Fixes: f3cdfd239d ("arm64/efi: move SetVirtualAddressMap() to UEFI stub")
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-03-20 17:05:16 +00:00

369 lines
8.6 KiB
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 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 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;
}
/*
* 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)) {
memblock_reserve(paddr, size);
if (uefi_debug)
pr_cont("*");
}
if (uefi_debug)
pr_cont("\n");
}
set_bit(EFI_MEMMAP, &efi.flags);
}
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();
early_memunmap(memmap.map, params.mmap_size);
}
static bool __init efi_virtmap_init(void)
{
efi_memory_desc_t *md;
for_each_efi_memory_desc(&memmap, md) {
u64 paddr, npages, size;
pgprot_t prot;
if (!(md->attribute & EFI_MEMORY_RUNTIME))
continue;
if (md->virt_addr == 0)
return false;
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);
}
return true;
}
/*
* 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;
}
if (efi_runtime_disabled()) {
pr_info("EFI runtime services will be disabled.\n");
return -1;
}
pr_info("Remapping and enabling EFI services.\n");
mapsize = memmap.map_end - memmap.map;
memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
mapsize);
if (!memmap.map) {
pr_err("Failed to remap EFI memory map\n");
return -1;
}
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);
if (!efi_virtmap_init()) {
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 void efi_set_pgd(struct mm_struct *mm)
{
if (mm == &init_mm)
cpu_set_reserved_ttbr0();
else
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();
}
/*
* UpdateCapsule() depends on the system being shutdown via
* ResetSystem().
*/
bool efi_poweroff_required(void)
{
return efi_enabled(EFI_RUNTIME_SERVICES);
}