arch/x86/platform/efi/quirks.c

   1 #include <linux/init.h>
   2 #include <linux/kernel.h>
   3 #include <linux/string.h>
   4 #include <linux/time.h>
   5 #include <linux/types.h>
   6 #include <linux/efi.h>
   7 #include <linux/slab.h>
   8 #include <linux/memblock.h>
   9 #include <linux/bootmem.h>
  10 #include <linux/acpi.h>
  11 #include <asm/efi.h>
  12 #include <asm/uv/uv.h>
  13
  14 #define EFI_MIN_RESERVE 5120
  15
  16 #define EFI_DUMMY_GUID \
  17         EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
  18
  19 static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
  20
  21 static bool efi_no_storage_paranoia;
  22
  23 /*
  24  * Some firmware implementations refuse to boot if there's insufficient
  25  * space in the variable store. The implementation of garbage collection
  26  * in some FW versions causes stale (deleted) variables to take up space
  27  * longer than intended and space is only freed once the store becomes
  28  * almost completely full.
  29  *
  30  * Enabling this option disables the space checks in
  31  * efi_query_variable_store() and forces garbage collection.
  32  *
  33  * Only enable this option if deleting EFI variables does not free up
  34  * space in your variable store, e.g. if despite deleting variables
  35  * you're unable to create new ones.
  36  */
  37 static int __init setup_storage_paranoia(char *arg)
  38 {
  39         efi_no_storage_paranoia = true;
  40         return 0;
  41 }
  42 early_param("efi_no_storage_paranoia", setup_storage_paranoia);
  43
  44 /*
  45  * Deleting the dummy variable which kicks off garbage collection
  46 */
  47 void efi_delete_dummy_variable(void)
  48 {
  49         efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
  50                          EFI_VARIABLE_NON_VOLATILE |
  51                          EFI_VARIABLE_BOOTSERVICE_ACCESS |
  52                          EFI_VARIABLE_RUNTIME_ACCESS,
  53                          0, NULL);
  54 }
  55
  56 /*
  57  * Some firmware implementations refuse to boot if there's insufficient space
  58  * in the variable store. Ensure that we never use more than a safe limit.
  59  *
  60  * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
  61  * store.
  62  */
  63 efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
  64 {
  65         efi_status_t status;
  66         u64 storage_size, remaining_size, max_size;
  67
  68         if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
  69                 return 0;
  70
  71         status = efi.query_variable_info(attributes, &storage_size,
  72                                          &remaining_size, &max_size);
  73         if (status != EFI_SUCCESS)
  74                 return status;
  75
  76         /*
  77          * We account for that by refusing the write if permitting it would
  78          * reduce the available space to under 5KB. This figure was provided by
  79          * Samsung, so should be safe.
  80          */
  81         if ((remaining_size - size < EFI_MIN_RESERVE) &&
  82                 !efi_no_storage_paranoia) {
  83
  84                 /*
  85                  * Triggering garbage collection may require that the firmware
  86                  * generate a real EFI_OUT_OF_RESOURCES error. We can force
  87                  * that by attempting to use more space than is available.
  88                  */
  89                 unsigned long dummy_size = remaining_size + 1024;
  90                 void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
  91
  92                 if (!dummy)
  93                         return EFI_OUT_OF_RESOURCES;
  94
  95                 status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
  96                                           EFI_VARIABLE_NON_VOLATILE |
  97                                           EFI_VARIABLE_BOOTSERVICE_ACCESS |
  98                                           EFI_VARIABLE_RUNTIME_ACCESS,
  99                                           dummy_size, dummy);
 100
 101                 if (status == EFI_SUCCESS) {
 102                         /*
 103                          * This should have failed, so if it didn't make sure
 104                          * that we delete it...
 105                          */
 106                         efi_delete_dummy_variable();
 107                 }
 108
 109                 kfree(dummy);
 110
 111                 /*
 112                  * The runtime code may now have triggered a garbage collection
 113                  * run, so check the variable info again
 114                  */
 115                 status = efi.query_variable_info(attributes, &storage_size,
 116                                                  &remaining_size, &max_size);
 117
 118                 if (status != EFI_SUCCESS)
 119                         return status;
 120
 121                 /*
 122                  * There still isn't enough room, so return an error
 123                  */
 124                 if (remaining_size - size < EFI_MIN_RESERVE)
 125                         return EFI_OUT_OF_RESOURCES;
 126         }
 127
 128         return EFI_SUCCESS;
 129 }
 130 EXPORT_SYMBOL_GPL(efi_query_variable_store);
 131
 132 /*
 133  * The UEFI specification makes it clear that the operating system is free to do
 134  * whatever it wants with boot services code after ExitBootServices() has been
 135  * called. Ignoring this recommendation a significant bunch of EFI implementations
 136  * continue calling into boot services code (SetVirtualAddressMap). In order to
 137  * work around such buggy implementations we reserve boot services region during
 138  * EFI init and make sure it stays executable. Then, after SetVirtualAddressMap(), it
 139 * is discarded.
 140 */
 141 void __init efi_reserve_boot_services(void)
 142 {
 143         void *p;
 144
 145         for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
 146                 efi_memory_desc_t *md = p;
 147                 u64 start = md->phys_addr;
 148                 u64 size = md->num_pages << EFI_PAGE_SHIFT;
 149
 150                 if (md->type != EFI_BOOT_SERVICES_CODE &&
 151                     md->type != EFI_BOOT_SERVICES_DATA)
 152                         continue;
 153                 /* Only reserve where possible:
 154                  * - Not within any already allocated areas
 155                  * - Not over any memory area (really needed, if above?)
 156                  * - Not within any part of the kernel
 157                  * - Not the bios reserved area
 158                 */
 159                 if ((start + size > __pa_symbol(_text)
 160                                 && start <= __pa_symbol(_end)) ||
 161                         !e820_all_mapped(start, start+size, E820_RAM) ||
 162                         memblock_is_region_reserved(start, size)) {
 163                         /* Could not reserve, skip it */
 164                         md->num_pages = 0;
 165                         memblock_dbg("Could not reserve boot range [0x%010llx-0x%010llx]\n",
 166                                      start, start+size-1);
 167                 } else
 168                         memblock_reserve(start, size);
 169         }
 170 }
 171
 172 void __init efi_free_boot_services(void)
 173 {
 174         void *p;
 175
 176         for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
 177                 efi_memory_desc_t *md = p;
 178                 unsigned long long start = md->phys_addr;
 179                 unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
 180
 181                 if (md->type != EFI_BOOT_SERVICES_CODE &&
 182                     md->type != EFI_BOOT_SERVICES_DATA)
 183                         continue;
 184
 185                 /* Could not reserve boot area */
 186                 if (!size)
 187                         continue;
 188
 189                 free_bootmem_late(start, size);
 190         }
 191
 192         efi_unmap_memmap();
 193 }
 194
 195 /*
 196  * A number of config table entries get remapped to virtual addresses
 197  * after entering EFI virtual mode. However, the kexec kernel requires
 198  * their physical addresses therefore we pass them via setup_data and
 199  * correct those entries to their respective physical addresses here.
 200  *
 201  * Currently only handles smbios which is necessary for some firmware
 202  * implementation.
 203  */
 204 int __init efi_reuse_config(u64 tables, int nr_tables)
 205 {
 206         int i, sz, ret = 0;
 207         void *p, *tablep;
 208         struct efi_setup_data *data;
 209
 210         if (!efi_setup)
 211                 return 0;
 212
 213         if (!efi_enabled(EFI_64BIT))
 214                 return 0;
 215
 216         data = early_memremap(efi_setup, sizeof(*data));
 217         if (!data) {
 218                 ret = -ENOMEM;
 219                 goto out;
 220         }
 221
 222         if (!data->smbios)
 223                 goto out_memremap;
 224
 225         sz = sizeof(efi_config_table_64_t);
 226
 227         p = tablep = early_memremap(tables, nr_tables * sz);
 228         if (!p) {
 229                 pr_err("Could not map Configuration table!\n");
 230                 ret = -ENOMEM;
 231                 goto out_memremap;
 232         }
 233
 234         for (i = 0; i < efi.systab->nr_tables; i++) {
 235                 efi_guid_t guid;
 236
 237                 guid = ((efi_config_table_64_t *)p)->guid;
 238
 239                 if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
 240                         ((efi_config_table_64_t *)p)->table = data->smbios;
 241                 p += sz;
 242         }
 243         early_memunmap(tablep, nr_tables * sz);
 244
 245 out_memremap:
 246         early_memunmap(data, sizeof(*data));
 247 out:
 248         return ret;
 249 }
 250
 251 void __init efi_apply_memmap_quirks(void)
 252 {
 253         /*
 254          * Once setup is done earlier, unmap the EFI memory map on mismatched
 255          * firmware/kernel architectures since there is no support for runtime
 256          * services.
 257          */
 258         if (!efi_runtime_supported()) {
 259                 pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");
 260                 efi_unmap_memmap();
 261         }
 262
 263         /*
 264          * UV doesn't support the new EFI pagetable mapping yet.
 265          */
 266         if (is_uv_system())
 267                 set_bit(EFI_OLD_MEMMAP, &efi.flags);
 268 }
 269
 270 /*
 271  * For most modern platforms the preferred method of powering off is via
 272  * ACPI. However, there are some that are known to require the use of
 273  * EFI runtime services and for which ACPI does not work at all.
 274  *
 275  * Using EFI is a last resort, to be used only if no other option
 276  * exists.
 277  */
 278 bool efi_reboot_required(void)
 279 {
 280         if (!acpi_gbl_reduced_hardware)
 281                 return false;
 282
 283         efi_reboot_quirk_mode = EFI_RESET_WARM;
 284         return true;
 285 }
 286
 287 bool efi_poweroff_required(void)
 288 {
 289         return !!acpi_gbl_reduced_hardware;
 290 }