linux-stable/drivers/firmware/efi/arm-runtime.c
Ard Biesheuvel d1eb98143c efi/arm: Fix boot crash with CONFIG_CPUMASK_OFFSTACK=y
On ARM and arm64, we use a dedicated mm_struct to map the UEFI
Runtime Services regions, which allows us to map those regions
on demand, and in a way that is guaranteed to be compatible
with incoming kernels across kexec.

As it turns out, we don't fully initialize the mm_struct in the
same way as process mm_structs are initialized on fork(), which
results in the following crash on ARM if CONFIG_CPUMASK_OFFSTACK=y
is enabled:

  ...
  EFI Variables Facility v0.08 2004-May-17
  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  [...]
  Process swapper/0 (pid: 1)
  ...
  __memzero()
  check_and_switch_context()
  virt_efi_get_next_variable()
  efivar_init()
  efivars_sysfs_init()
  do_one_initcall()
  ...

This is due to a missing call to mm_init_cpumask(), so add it.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: <stable@vger.kernel.org> # v4.5+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1488395154-29786-1-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:11:19 +01:00

168 lines
3.9 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/efi.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/mm_types.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/mmu.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
extern u64 efi_system_table;
static struct mm_struct efi_mm = {
.mm_rb = RB_ROOT,
.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),
};
#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
#include <asm/ptdump.h>
static struct ptdump_info efi_ptdump_info = {
.mm = &efi_mm,
.markers = (struct addr_marker[]){
{ 0, "UEFI runtime start" },
{ TASK_SIZE_64, "UEFI runtime end" }
},
.base_addr = 0,
};
static int __init ptdump_init(void)
{
return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
}
device_initcall(ptdump_init);
#endif
static bool __init efi_virtmap_init(void)
{
efi_memory_desc_t *md;
bool systab_found;
efi_mm.pgd = pgd_alloc(&efi_mm);
mm_init_cpumask(&efi_mm);
init_new_context(NULL, &efi_mm);
systab_found = false;
for_each_efi_memory_desc(md) {
phys_addr_t phys = md->phys_addr;
int ret;
if (!(md->attribute & EFI_MEMORY_RUNTIME))
continue;
if (md->virt_addr == 0)
return false;
ret = efi_create_mapping(&efi_mm, md);
if (!ret) {
pr_info(" EFI remap %pa => %p\n",
&phys, (void *)(unsigned long)md->virt_addr);
} else {
pr_warn(" EFI remap %pa: failed to create mapping (%d)\n",
&phys, ret);
return false;
}
/*
* If this entry covers the address of the UEFI system table,
* calculate and record its virtual address.
*/
if (efi_system_table >= phys &&
efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
efi.systab = (void *)(unsigned long)(efi_system_table -
phys + md->virt_addr);
systab_found = true;
}
}
if (!systab_found) {
pr_err("No virtual mapping found for the UEFI System Table\n");
return false;
}
if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
return false;
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 arm_enable_runtime_services(void)
{
u64 mapsize;
if (!efi_enabled(EFI_BOOT)) {
pr_info("EFI services will not be available.\n");
return 0;
}
if (efi_runtime_disabled()) {
pr_info("EFI runtime services will be disabled.\n");
return 0;
}
if (efi_enabled(EFI_RUNTIME_SERVICES)) {
pr_info("EFI runtime services access via paravirt.\n");
return 0;
}
pr_info("Remapping and enabling EFI services.\n");
mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
pr_err("Failed to remap EFI memory map\n");
return -ENOMEM;
}
if (!efi_virtmap_init()) {
pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
return -ENOMEM;
}
/* Set up runtime services function pointers */
efi_native_runtime_setup();
set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
return 0;
}
early_initcall(arm_enable_runtime_services);
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();
}