#define pr_fmt(fmt) "efi: " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/types.h>
#include <linux/efi.h>
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <asm/efi.h>
#include <asm/uv/uv.h>
#define EFI_MIN_RESERVE 5120
#define EFI_DUMMY_GUID \
EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
static bool efi_no_storage_paranoia;
/*
* Some firmware implementations refuse to boot if there's insufficient
* space in the variable store. The implementation of garbage collection
* in some FW versions causes stale (deleted) variables to take up space
* longer than intended and space is only freed once the store becomes
* almost completely full.
*
* Enabling this option disables the space checks in
* efi_query_variable_store() and forces garbage collection.
*
* Only enable this option if deleting EFI variables does not free up
* space in your variable store, e.g. if despite deleting variables
* you're unable to create new ones.
*/
static int __init setup_storage_paranoia(char *arg)
{
efi_no_storage_paranoia = true;
return 0;
}
early_param("efi_no_storage_paranoia", setup_storage_paranoia);
/*
* Deleting the dummy variable which kicks off garbage collection
*/
void efi_delete_dummy_variable(void)
{
efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
EFI_VARIABLE_NON_VOLATILE |
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS,
0, NULL);
}
/*
* In the nonblocking case we do not attempt to perform garbage
* collection if we do not have enough free space. Rather, we do the
* bare minimum check and give up immediately if the available space
* is below EFI_MIN_RESERVE.
*
* This function is intended to be small and simple because it is
* invoked from crash handler paths.
*/
static efi_status_t
query_variable_store_nonblocking(u32 attributes, unsigned long size)
{
efi_status_t status;
u64 storage_size, remaining_size, max_size;
status = efi.query_variable_info_nonblocking(attributes, &storage_size,
&remaining_size,
&max_size);
if (status != EFI_SUCCESS)
return status;
if (remaining_size - size < EFI_MIN_RESERVE)
return EFI_OUT_OF_RESOURCES;
return EFI_SUCCESS;
}
/*
* Some firmware implementations refuse to boot if there's insufficient space
* in the variable store. Ensure that we never use more than a safe limit.
*
* Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
* store.
*/
efi_status_t efi_query_variable_store(u32 attributes, unsigned long size,
bool nonblocking)
{
efi_status_t status;
u64 storage_size, remaining_size, max_size;
if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
return 0;
if (nonblocking)
return query_variable_store_nonblocking(attributes, size);
status = efi.query_variable_info(attributes, &storage_size,
&remaining_size, &max_size);
if (status != EFI_SUCCESS)
return status;
/*
* We account for that by refusing the write if permitting it would
* reduce the available space to under 5KB. This figure was provided by
* Samsung, so should be safe.
*/
if ((remaining_size - size < EFI_MIN_RESERVE) &&
!efi_no_storage_paranoia) {
/*
* Triggering garbage collection may require that the firmware
* generate a real EFI_OUT_OF_RESOURCES error. We can force
* that by attempting to use more space than is available.
*/
unsigned long dummy_size = remaining_size + 1024;
void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
if (!dummy)
return EFI_OUT_OF_RESOURCES;
status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
EFI_VARIABLE_NON_VOLATILE |
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS,
dummy_size, dummy);
if (status == EFI_SUCCESS) {
/*
* This should have failed, so if it didn't make sure
* that we delete it...
*/
efi_delete_dummy_variable();
}
kfree(dummy);
/*
* The runtime code may now have triggered a garbage collection
* run, so check the variable info again
*/
status = efi.query_variable_info(attributes, &storage_size,
&remaining_size, &max_size);
if (status != EFI_SUCCESS)
return status;
/*
* There still isn't enough room, so return an error
*/
if (remaining_size - size < EFI_MIN_RESERVE)
return EFI_OUT_OF_RESOURCES;
}
return EFI_SUCCESS;
}
EXPORT_SYMBOL_GPL(efi_query_variable_store);
/*
* Helper function for efi_reserve_boot_services() to figure out if we
* can free regions in efi_free_boot_services().
*
* Use this function to ensure we do not free regions owned by somebody
* else. We must only reserve (and then free) regions:
*
* - Not within any part of the kernel
* - Not the BIOS reserved area (E820_RESERVED, E820_NVS, etc)
*/
static bool can_free_region(u64 start, u64 size)
{
if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end))
return false;
if (!e820_all_mapped(start, start+size, E820_RAM))
return false;
return true;
}
/*
* The UEFI specification makes it clear that the operating system is free to do
* whatever it wants with boot services code after ExitBootServices() has been
* called. Ignoring this recommendation a significant bunch of EFI implementations
* continue calling into boot services code (SetVirtualAddressMap). In order to
* work around such buggy implementations we reserve boot services region during
* EFI init and make sure it stays executable. Then, after SetVirtualAddressMap(), it
* is discarded.
*/
void __init efi_reserve_boot_services(void)
{
void *p;
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
efi_memory_desc_t *md = p;
u64 start = md->phys_addr;
u64 size = md->num_pages << EFI_PAGE_SHIFT;
bool already_reserved;
if (md->type != EFI_BOOT_SERVICES_CODE &&
md->type != EFI_BOOT_SERVICES_DATA)
continue;
already_reserved = memblock_is_region_reserved(start, size);
/*
* Because the following memblock_reserve() is paired
* with free_bootmem_late() for this region in
* efi_free_boot_services(), we must be extremely
* careful not to reserve, and subsequently free,
* critical regions of memory (like the kernel image) or
* those regions that somebody else has already
* reserved.
*
* A good example of a critical region that must not be
* freed is page zero (first 4Kb of memory), which may
* contain boot services code/data but is marked
* E820_RESERVED by trim_bios_range().
*/
if (!already_reserved) {
memblock_reserve(start, size);
/*
* If we are the first to reserve the region, no
* one else cares about it. We own it and can
* free it later.
*/
if (can_free_region(start, size))
continue;
}
/*
* We don't own the region. We must not free it.
*
* Setting this bit for a boot services region really
* doesn't make sense as far as the firmware is
* concerned, but it does provide us with a way to tag
* those regions that must not be paired with
* free_bootmem_late().
*/
md->attribute |= EFI_MEMORY_RUNTIME;
}
}
void __init efi_free_boot_services(void)
{
void *p;
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
efi_memory_desc_t *md = p;
unsigned long long start = md->phys_addr;
unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
if (md->type != EFI_BOOT_SERVICES_CODE &&
md->type != EFI_BOOT_SERVICES_DATA)
continue;
/* Do not free, someone else owns it: */
if (md->attribute & EFI_MEMORY_RUNTIME)
continue;
free_bootmem_late(start, size);
}
efi_unmap_memmap();
}
/*
* A number of config table entries get remapped to virtual addresses
* after entering EFI virtual mode. However, the kexec kernel requires
* their physical addresses therefore we pass them via setup_data and
* correct those entries to their respective physical addresses here.
*
* Currently only handles smbios which is necessary for some firmware
* implementation.
*/
int __init efi_reuse_config(u64 tables, int nr_tables)
{
int i, sz, ret = 0;
void *p, *tablep;
struct efi_setup_data *data;
if (!efi_setup)
return 0;
if (!efi_enabled(EFI_64BIT))
return 0;
data = early_memremap(efi_setup, sizeof(*data));
if (!data) {
ret = -ENOMEM;
goto out;
}
if (!data->smbios)
goto out_memremap;
sz = sizeof(efi_config_table_64_t);
p = tablep = early_memremap(tables, nr_tables * sz);
if (!p) {
pr_err("Could not map Configuration table!\n");
ret = -ENOMEM;
goto out_memremap;
}
for (i = 0; i < efi.systab->nr_tables; i++) {
efi_guid_t guid;
guid = ((efi_config_table_64_t *)p)->guid;
if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
((efi_config_table_64_t *)p)->table = data->smbios;
p += sz;
}
early_memunmap(tablep, nr_tables * sz);
out_memremap:
early_memunmap(data, sizeof(*data));
out:
return ret;
}
static const struct dmi_system_id sgi_uv1_dmi[] = {
{ NULL, "SGI UV1",
{ DMI_MATCH(DMI_PRODUCT_NAME, "Stoutland Platform"),
DMI_MATCH(DMI_PRODUCT_VERSION, "1.0"),
DMI_MATCH(DMI_BIOS_VENDOR, "SGI.COM"),
}
},
{ } /* NULL entry stops DMI scanning */
};
void __init efi_apply_memmap_quirks(void)
{
/*
* Once setup is done earlier, unmap the EFI memory map on mismatched
* firmware/kernel architectures since there is no support for runtime
* services.
*/
if (!efi_runtime_supported()) {
pr_info("Setup done, disabling due to 32/64-bit mismatch\n");
efi_unmap_memmap();
}
/* UV2+ BIOS has a fix for this issue. UV1 still needs the quirk. */
if (dmi_check_system(sgi_uv1_dmi))
set_bit(EFI_OLD_MEMMAP, &efi.flags);
}
/*
* For most modern platforms the preferred method of powering off is via
* ACPI. However, there are some that are known to require the use of
* EFI runtime services and for which ACPI does not work at all.
*
* Using EFI is a last resort, to be used only if no other option
* exists.
*/
bool efi_reboot_required(void)
{
if (!acpi_gbl_reduced_hardware)
return false;
efi_reboot_quirk_mode = EFI_RESET_WARM;
return true;
}
bool efi_poweroff_required(void)
{
return !!acpi_gbl_reduced_hardware;
}
