cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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quirks.c (22027B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2#define pr_fmt(fmt) "efi: " fmt
      3
      4#include <linux/init.h>
      5#include <linux/kernel.h>
      6#include <linux/string.h>
      7#include <linux/time.h>
      8#include <linux/types.h>
      9#include <linux/efi.h>
     10#include <linux/slab.h>
     11#include <linux/memblock.h>
     12#include <linux/acpi.h>
     13#include <linux/dmi.h>
     14
     15#include <asm/e820/api.h>
     16#include <asm/efi.h>
     17#include <asm/uv/uv.h>
     18#include <asm/cpu_device_id.h>
     19#include <asm/realmode.h>
     20#include <asm/reboot.h>
     21
     22#define EFI_MIN_RESERVE 5120
     23
     24#define EFI_DUMMY_GUID \
     25	EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
     26
     27#define QUARK_CSH_SIGNATURE		0x5f435348	/* _CSH */
     28#define QUARK_SECURITY_HEADER_SIZE	0x400
     29
     30/*
     31 * Header prepended to the standard EFI capsule on Quark systems the are based
     32 * on Intel firmware BSP.
     33 * @csh_signature:	Unique identifier to sanity check signed module
     34 * 			presence ("_CSH").
     35 * @version:		Current version of CSH used. Should be one for Quark A0.
     36 * @modulesize:		Size of the entire module including the module header
     37 * 			and payload.
     38 * @security_version_number_index: Index of SVN to use for validation of signed
     39 * 			module.
     40 * @security_version_number: Used to prevent against roll back of modules.
     41 * @rsvd_module_id:	Currently unused for Clanton (Quark).
     42 * @rsvd_module_vendor:	Vendor Identifier. For Intel products value is
     43 * 			0x00008086.
     44 * @rsvd_date:		BCD representation of build date as yyyymmdd, where
     45 * 			yyyy=4 digit year, mm=1-12, dd=1-31.
     46 * @headersize:		Total length of the header including including any
     47 * 			padding optionally added by the signing tool.
     48 * @hash_algo:		What Hash is used in the module signing.
     49 * @cryp_algo:		What Crypto is used in the module signing.
     50 * @keysize:		Total length of the key data including including any
     51 * 			padding optionally added by the signing tool.
     52 * @signaturesize:	Total length of the signature including including any
     53 * 			padding optionally added by the signing tool.
     54 * @rsvd_next_header:	32-bit pointer to the next Secure Boot Module in the
     55 * 			chain, if there is a next header.
     56 * @rsvd:		Reserved, padding structure to required size.
     57 *
     58 * See also QuartSecurityHeader_t in
     59 * Quark_EDKII_v1.2.1.1/QuarkPlatformPkg/Include/QuarkBootRom.h
     60 * from https://downloadcenter.intel.com/download/23197/Intel-Quark-SoC-X1000-Board-Support-Package-BSP
     61 */
     62struct quark_security_header {
     63	u32 csh_signature;
     64	u32 version;
     65	u32 modulesize;
     66	u32 security_version_number_index;
     67	u32 security_version_number;
     68	u32 rsvd_module_id;
     69	u32 rsvd_module_vendor;
     70	u32 rsvd_date;
     71	u32 headersize;
     72	u32 hash_algo;
     73	u32 cryp_algo;
     74	u32 keysize;
     75	u32 signaturesize;
     76	u32 rsvd_next_header;
     77	u32 rsvd[2];
     78};
     79
     80static const efi_char16_t efi_dummy_name[] = L"DUMMY";
     81
     82static bool efi_no_storage_paranoia;
     83
     84/*
     85 * Some firmware implementations refuse to boot if there's insufficient
     86 * space in the variable store. The implementation of garbage collection
     87 * in some FW versions causes stale (deleted) variables to take up space
     88 * longer than intended and space is only freed once the store becomes
     89 * almost completely full.
     90 *
     91 * Enabling this option disables the space checks in
     92 * efi_query_variable_store() and forces garbage collection.
     93 *
     94 * Only enable this option if deleting EFI variables does not free up
     95 * space in your variable store, e.g. if despite deleting variables
     96 * you're unable to create new ones.
     97 */
     98static int __init setup_storage_paranoia(char *arg)
     99{
    100	efi_no_storage_paranoia = true;
    101	return 0;
    102}
    103early_param("efi_no_storage_paranoia", setup_storage_paranoia);
    104
    105/*
    106 * Deleting the dummy variable which kicks off garbage collection
    107*/
    108void efi_delete_dummy_variable(void)
    109{
    110	efi.set_variable_nonblocking((efi_char16_t *)efi_dummy_name,
    111				     &EFI_DUMMY_GUID,
    112				     EFI_VARIABLE_NON_VOLATILE |
    113				     EFI_VARIABLE_BOOTSERVICE_ACCESS |
    114				     EFI_VARIABLE_RUNTIME_ACCESS, 0, NULL);
    115}
    116
    117/*
    118 * In the nonblocking case we do not attempt to perform garbage
    119 * collection if we do not have enough free space. Rather, we do the
    120 * bare minimum check and give up immediately if the available space
    121 * is below EFI_MIN_RESERVE.
    122 *
    123 * This function is intended to be small and simple because it is
    124 * invoked from crash handler paths.
    125 */
    126static efi_status_t
    127query_variable_store_nonblocking(u32 attributes, unsigned long size)
    128{
    129	efi_status_t status;
    130	u64 storage_size, remaining_size, max_size;
    131
    132	status = efi.query_variable_info_nonblocking(attributes, &storage_size,
    133						     &remaining_size,
    134						     &max_size);
    135	if (status != EFI_SUCCESS)
    136		return status;
    137
    138	if (remaining_size - size < EFI_MIN_RESERVE)
    139		return EFI_OUT_OF_RESOURCES;
    140
    141	return EFI_SUCCESS;
    142}
    143
    144/*
    145 * Some firmware implementations refuse to boot if there's insufficient space
    146 * in the variable store. Ensure that we never use more than a safe limit.
    147 *
    148 * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
    149 * store.
    150 */
    151efi_status_t efi_query_variable_store(u32 attributes, unsigned long size,
    152				      bool nonblocking)
    153{
    154	efi_status_t status;
    155	u64 storage_size, remaining_size, max_size;
    156
    157	if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
    158		return 0;
    159
    160	if (nonblocking)
    161		return query_variable_store_nonblocking(attributes, size);
    162
    163	status = efi.query_variable_info(attributes, &storage_size,
    164					 &remaining_size, &max_size);
    165	if (status != EFI_SUCCESS)
    166		return status;
    167
    168	/*
    169	 * We account for that by refusing the write if permitting it would
    170	 * reduce the available space to under 5KB. This figure was provided by
    171	 * Samsung, so should be safe.
    172	 */
    173	if ((remaining_size - size < EFI_MIN_RESERVE) &&
    174		!efi_no_storage_paranoia) {
    175
    176		/*
    177		 * Triggering garbage collection may require that the firmware
    178		 * generate a real EFI_OUT_OF_RESOURCES error. We can force
    179		 * that by attempting to use more space than is available.
    180		 */
    181		unsigned long dummy_size = remaining_size + 1024;
    182		void *dummy = kzalloc(dummy_size, GFP_KERNEL);
    183
    184		if (!dummy)
    185			return EFI_OUT_OF_RESOURCES;
    186
    187		status = efi.set_variable((efi_char16_t *)efi_dummy_name,
    188					  &EFI_DUMMY_GUID,
    189					  EFI_VARIABLE_NON_VOLATILE |
    190					  EFI_VARIABLE_BOOTSERVICE_ACCESS |
    191					  EFI_VARIABLE_RUNTIME_ACCESS,
    192					  dummy_size, dummy);
    193
    194		if (status == EFI_SUCCESS) {
    195			/*
    196			 * This should have failed, so if it didn't make sure
    197			 * that we delete it...
    198			 */
    199			efi_delete_dummy_variable();
    200		}
    201
    202		kfree(dummy);
    203
    204		/*
    205		 * The runtime code may now have triggered a garbage collection
    206		 * run, so check the variable info again
    207		 */
    208		status = efi.query_variable_info(attributes, &storage_size,
    209						 &remaining_size, &max_size);
    210
    211		if (status != EFI_SUCCESS)
    212			return status;
    213
    214		/*
    215		 * There still isn't enough room, so return an error
    216		 */
    217		if (remaining_size - size < EFI_MIN_RESERVE)
    218			return EFI_OUT_OF_RESOURCES;
    219	}
    220
    221	return EFI_SUCCESS;
    222}
    223EXPORT_SYMBOL_GPL(efi_query_variable_store);
    224
    225/*
    226 * The UEFI specification makes it clear that the operating system is
    227 * free to do whatever it wants with boot services code after
    228 * ExitBootServices() has been called. Ignoring this recommendation a
    229 * significant bunch of EFI implementations continue calling into boot
    230 * services code (SetVirtualAddressMap). In order to work around such
    231 * buggy implementations we reserve boot services region during EFI
    232 * init and make sure it stays executable. Then, after
    233 * SetVirtualAddressMap(), it is discarded.
    234 *
    235 * However, some boot services regions contain data that is required
    236 * by drivers, so we need to track which memory ranges can never be
    237 * freed. This is done by tagging those regions with the
    238 * EFI_MEMORY_RUNTIME attribute.
    239 *
    240 * Any driver that wants to mark a region as reserved must use
    241 * efi_mem_reserve() which will insert a new EFI memory descriptor
    242 * into efi.memmap (splitting existing regions if necessary) and tag
    243 * it with EFI_MEMORY_RUNTIME.
    244 */
    245void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
    246{
    247	struct efi_memory_map_data data = { 0 };
    248	struct efi_mem_range mr;
    249	efi_memory_desc_t md;
    250	int num_entries;
    251	void *new;
    252
    253	if (efi_mem_desc_lookup(addr, &md) ||
    254	    md.type != EFI_BOOT_SERVICES_DATA) {
    255		pr_err("Failed to lookup EFI memory descriptor for %pa\n", &addr);
    256		return;
    257	}
    258
    259	if (addr + size > md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT)) {
    260		pr_err("Region spans EFI memory descriptors, %pa\n", &addr);
    261		return;
    262	}
    263
    264	size += addr % EFI_PAGE_SIZE;
    265	size = round_up(size, EFI_PAGE_SIZE);
    266	addr = round_down(addr, EFI_PAGE_SIZE);
    267
    268	mr.range.start = addr;
    269	mr.range.end = addr + size - 1;
    270	mr.attribute = md.attribute | EFI_MEMORY_RUNTIME;
    271
    272	num_entries = efi_memmap_split_count(&md, &mr.range);
    273	num_entries += efi.memmap.nr_map;
    274
    275	if (efi_memmap_alloc(num_entries, &data) != 0) {
    276		pr_err("Could not allocate boot services memmap\n");
    277		return;
    278	}
    279
    280	new = early_memremap_prot(data.phys_map, data.size,
    281				  pgprot_val(pgprot_encrypted(FIXMAP_PAGE_NORMAL)));
    282	if (!new) {
    283		pr_err("Failed to map new boot services memmap\n");
    284		return;
    285	}
    286
    287	efi_memmap_insert(&efi.memmap, new, &mr);
    288	early_memunmap(new, data.size);
    289
    290	efi_memmap_install(&data);
    291	e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED);
    292	e820__update_table(e820_table);
    293}
    294
    295/*
    296 * Helper function for efi_reserve_boot_services() to figure out if we
    297 * can free regions in efi_free_boot_services().
    298 *
    299 * Use this function to ensure we do not free regions owned by somebody
    300 * else. We must only reserve (and then free) regions:
    301 *
    302 * - Not within any part of the kernel
    303 * - Not the BIOS reserved area (E820_TYPE_RESERVED, E820_TYPE_NVS, etc)
    304 */
    305static __init bool can_free_region(u64 start, u64 size)
    306{
    307	if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end))
    308		return false;
    309
    310	if (!e820__mapped_all(start, start+size, E820_TYPE_RAM))
    311		return false;
    312
    313	return true;
    314}
    315
    316void __init efi_reserve_boot_services(void)
    317{
    318	efi_memory_desc_t *md;
    319
    320	if (!efi_enabled(EFI_MEMMAP))
    321		return;
    322
    323	for_each_efi_memory_desc(md) {
    324		u64 start = md->phys_addr;
    325		u64 size = md->num_pages << EFI_PAGE_SHIFT;
    326		bool already_reserved;
    327
    328		if (md->type != EFI_BOOT_SERVICES_CODE &&
    329		    md->type != EFI_BOOT_SERVICES_DATA)
    330			continue;
    331
    332		already_reserved = memblock_is_region_reserved(start, size);
    333
    334		/*
    335		 * Because the following memblock_reserve() is paired
    336		 * with memblock_free_late() for this region in
    337		 * efi_free_boot_services(), we must be extremely
    338		 * careful not to reserve, and subsequently free,
    339		 * critical regions of memory (like the kernel image) or
    340		 * those regions that somebody else has already
    341		 * reserved.
    342		 *
    343		 * A good example of a critical region that must not be
    344		 * freed is page zero (first 4Kb of memory), which may
    345		 * contain boot services code/data but is marked
    346		 * E820_TYPE_RESERVED by trim_bios_range().
    347		 */
    348		if (!already_reserved) {
    349			memblock_reserve(start, size);
    350
    351			/*
    352			 * If we are the first to reserve the region, no
    353			 * one else cares about it. We own it and can
    354			 * free it later.
    355			 */
    356			if (can_free_region(start, size))
    357				continue;
    358		}
    359
    360		/*
    361		 * We don't own the region. We must not free it.
    362		 *
    363		 * Setting this bit for a boot services region really
    364		 * doesn't make sense as far as the firmware is
    365		 * concerned, but it does provide us with a way to tag
    366		 * those regions that must not be paired with
    367		 * memblock_free_late().
    368		 */
    369		md->attribute |= EFI_MEMORY_RUNTIME;
    370	}
    371}
    372
    373/*
    374 * Apart from having VA mappings for EFI boot services code/data regions,
    375 * (duplicate) 1:1 mappings were also created as a quirk for buggy firmware. So,
    376 * unmap both 1:1 and VA mappings.
    377 */
    378static void __init efi_unmap_pages(efi_memory_desc_t *md)
    379{
    380	pgd_t *pgd = efi_mm.pgd;
    381	u64 pa = md->phys_addr;
    382	u64 va = md->virt_addr;
    383
    384	/*
    385	 * EFI mixed mode has all RAM mapped to access arguments while making
    386	 * EFI runtime calls, hence don't unmap EFI boot services code/data
    387	 * regions.
    388	 */
    389	if (efi_is_mixed())
    390		return;
    391
    392	if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages))
    393		pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa);
    394
    395	if (kernel_unmap_pages_in_pgd(pgd, va, md->num_pages))
    396		pr_err("Failed to unmap VA mapping for 0x%llx\n", va);
    397}
    398
    399void __init efi_free_boot_services(void)
    400{
    401	struct efi_memory_map_data data = { 0 };
    402	efi_memory_desc_t *md;
    403	int num_entries = 0;
    404	void *new, *new_md;
    405
    406	/* Keep all regions for /sys/kernel/debug/efi */
    407	if (efi_enabled(EFI_DBG))
    408		return;
    409
    410	for_each_efi_memory_desc(md) {
    411		unsigned long long start = md->phys_addr;
    412		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
    413		size_t rm_size;
    414
    415		if (md->type != EFI_BOOT_SERVICES_CODE &&
    416		    md->type != EFI_BOOT_SERVICES_DATA) {
    417			num_entries++;
    418			continue;
    419		}
    420
    421		/* Do not free, someone else owns it: */
    422		if (md->attribute & EFI_MEMORY_RUNTIME) {
    423			num_entries++;
    424			continue;
    425		}
    426
    427		/*
    428		 * Before calling set_virtual_address_map(), EFI boot services
    429		 * code/data regions were mapped as a quirk for buggy firmware.
    430		 * Unmap them from efi_pgd before freeing them up.
    431		 */
    432		efi_unmap_pages(md);
    433
    434		/*
    435		 * Nasty quirk: if all sub-1MB memory is used for boot
    436		 * services, we can get here without having allocated the
    437		 * real mode trampoline.  It's too late to hand boot services
    438		 * memory back to the memblock allocator, so instead
    439		 * try to manually allocate the trampoline if needed.
    440		 *
    441		 * I've seen this on a Dell XPS 13 9350 with firmware
    442		 * 1.4.4 with SGX enabled booting Linux via Fedora 24's
    443		 * grub2-efi on a hard disk.  (And no, I don't know why
    444		 * this happened, but Linux should still try to boot rather
    445		 * panicking early.)
    446		 */
    447		rm_size = real_mode_size_needed();
    448		if (rm_size && (start + rm_size) < (1<<20) && size >= rm_size) {
    449			set_real_mode_mem(start);
    450			start += rm_size;
    451			size -= rm_size;
    452		}
    453
    454		/*
    455		 * Don't free memory under 1M for two reasons:
    456		 * - BIOS might clobber it
    457		 * - Crash kernel needs it to be reserved
    458		 */
    459		if (start + size < SZ_1M)
    460			continue;
    461		if (start < SZ_1M) {
    462			size -= (SZ_1M - start);
    463			start = SZ_1M;
    464		}
    465
    466		memblock_free_late(start, size);
    467	}
    468
    469	if (!num_entries)
    470		return;
    471
    472	if (efi_memmap_alloc(num_entries, &data) != 0) {
    473		pr_err("Failed to allocate new EFI memmap\n");
    474		return;
    475	}
    476
    477	new = memremap(data.phys_map, data.size, MEMREMAP_WB);
    478	if (!new) {
    479		pr_err("Failed to map new EFI memmap\n");
    480		return;
    481	}
    482
    483	/*
    484	 * Build a new EFI memmap that excludes any boot services
    485	 * regions that are not tagged EFI_MEMORY_RUNTIME, since those
    486	 * regions have now been freed.
    487	 */
    488	new_md = new;
    489	for_each_efi_memory_desc(md) {
    490		if (!(md->attribute & EFI_MEMORY_RUNTIME) &&
    491		    (md->type == EFI_BOOT_SERVICES_CODE ||
    492		     md->type == EFI_BOOT_SERVICES_DATA))
    493			continue;
    494
    495		memcpy(new_md, md, efi.memmap.desc_size);
    496		new_md += efi.memmap.desc_size;
    497	}
    498
    499	memunmap(new);
    500
    501	if (efi_memmap_install(&data) != 0) {
    502		pr_err("Could not install new EFI memmap\n");
    503		return;
    504	}
    505}
    506
    507/*
    508 * A number of config table entries get remapped to virtual addresses
    509 * after entering EFI virtual mode. However, the kexec kernel requires
    510 * their physical addresses therefore we pass them via setup_data and
    511 * correct those entries to their respective physical addresses here.
    512 *
    513 * Currently only handles smbios which is necessary for some firmware
    514 * implementation.
    515 */
    516int __init efi_reuse_config(u64 tables, int nr_tables)
    517{
    518	int i, sz, ret = 0;
    519	void *p, *tablep;
    520	struct efi_setup_data *data;
    521
    522	if (nr_tables == 0)
    523		return 0;
    524
    525	if (!efi_setup)
    526		return 0;
    527
    528	if (!efi_enabled(EFI_64BIT))
    529		return 0;
    530
    531	data = early_memremap(efi_setup, sizeof(*data));
    532	if (!data) {
    533		ret = -ENOMEM;
    534		goto out;
    535	}
    536
    537	if (!data->smbios)
    538		goto out_memremap;
    539
    540	sz = sizeof(efi_config_table_64_t);
    541
    542	p = tablep = early_memremap(tables, nr_tables * sz);
    543	if (!p) {
    544		pr_err("Could not map Configuration table!\n");
    545		ret = -ENOMEM;
    546		goto out_memremap;
    547	}
    548
    549	for (i = 0; i < nr_tables; i++) {
    550		efi_guid_t guid;
    551
    552		guid = ((efi_config_table_64_t *)p)->guid;
    553
    554		if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
    555			((efi_config_table_64_t *)p)->table = data->smbios;
    556		p += sz;
    557	}
    558	early_memunmap(tablep, nr_tables * sz);
    559
    560out_memremap:
    561	early_memunmap(data, sizeof(*data));
    562out:
    563	return ret;
    564}
    565
    566void __init efi_apply_memmap_quirks(void)
    567{
    568	/*
    569	 * Once setup is done earlier, unmap the EFI memory map on mismatched
    570	 * firmware/kernel architectures since there is no support for runtime
    571	 * services.
    572	 */
    573	if (!efi_runtime_supported()) {
    574		pr_info("Setup done, disabling due to 32/64-bit mismatch\n");
    575		efi_memmap_unmap();
    576	}
    577}
    578
    579/*
    580 * For most modern platforms the preferred method of powering off is via
    581 * ACPI. However, there are some that are known to require the use of
    582 * EFI runtime services and for which ACPI does not work at all.
    583 *
    584 * Using EFI is a last resort, to be used only if no other option
    585 * exists.
    586 */
    587bool efi_reboot_required(void)
    588{
    589	if (!acpi_gbl_reduced_hardware)
    590		return false;
    591
    592	efi_reboot_quirk_mode = EFI_RESET_WARM;
    593	return true;
    594}
    595
    596bool efi_poweroff_required(void)
    597{
    598	return acpi_gbl_reduced_hardware || acpi_no_s5;
    599}
    600
    601#ifdef CONFIG_EFI_CAPSULE_QUIRK_QUARK_CSH
    602
    603static int qrk_capsule_setup_info(struct capsule_info *cap_info, void **pkbuff,
    604				  size_t hdr_bytes)
    605{
    606	struct quark_security_header *csh = *pkbuff;
    607
    608	/* Only process data block that is larger than the security header */
    609	if (hdr_bytes < sizeof(struct quark_security_header))
    610		return 0;
    611
    612	if (csh->csh_signature != QUARK_CSH_SIGNATURE ||
    613	    csh->headersize != QUARK_SECURITY_HEADER_SIZE)
    614		return 1;
    615
    616	/* Only process data block if EFI header is included */
    617	if (hdr_bytes < QUARK_SECURITY_HEADER_SIZE +
    618			sizeof(efi_capsule_header_t))
    619		return 0;
    620
    621	pr_debug("Quark security header detected\n");
    622
    623	if (csh->rsvd_next_header != 0) {
    624		pr_err("multiple Quark security headers not supported\n");
    625		return -EINVAL;
    626	}
    627
    628	*pkbuff += csh->headersize;
    629	cap_info->total_size = csh->headersize;
    630
    631	/*
    632	 * Update the first page pointer to skip over the CSH header.
    633	 */
    634	cap_info->phys[0] += csh->headersize;
    635
    636	/*
    637	 * cap_info->capsule should point at a virtual mapping of the entire
    638	 * capsule, starting at the capsule header. Our image has the Quark
    639	 * security header prepended, so we cannot rely on the default vmap()
    640	 * mapping created by the generic capsule code.
    641	 * Given that the Quark firmware does not appear to care about the
    642	 * virtual mapping, let's just point cap_info->capsule at our copy
    643	 * of the capsule header.
    644	 */
    645	cap_info->capsule = &cap_info->header;
    646
    647	return 1;
    648}
    649
    650static const struct x86_cpu_id efi_capsule_quirk_ids[] = {
    651	X86_MATCH_VENDOR_FAM_MODEL(INTEL, 5, INTEL_FAM5_QUARK_X1000,
    652				   &qrk_capsule_setup_info),
    653	{ }
    654};
    655
    656int efi_capsule_setup_info(struct capsule_info *cap_info, void *kbuff,
    657			   size_t hdr_bytes)
    658{
    659	int (*quirk_handler)(struct capsule_info *, void **, size_t);
    660	const struct x86_cpu_id *id;
    661	int ret;
    662
    663	if (hdr_bytes < sizeof(efi_capsule_header_t))
    664		return 0;
    665
    666	cap_info->total_size = 0;
    667
    668	id = x86_match_cpu(efi_capsule_quirk_ids);
    669	if (id) {
    670		/*
    671		 * The quirk handler is supposed to return
    672		 *  - a value > 0 if the setup should continue, after advancing
    673		 *    kbuff as needed
    674		 *  - 0 if not enough hdr_bytes are available yet
    675		 *  - a negative error code otherwise
    676		 */
    677		quirk_handler = (typeof(quirk_handler))id->driver_data;
    678		ret = quirk_handler(cap_info, &kbuff, hdr_bytes);
    679		if (ret <= 0)
    680			return ret;
    681	}
    682
    683	memcpy(&cap_info->header, kbuff, sizeof(cap_info->header));
    684
    685	cap_info->total_size += cap_info->header.imagesize;
    686
    687	return __efi_capsule_setup_info(cap_info);
    688}
    689
    690#endif
    691
    692/*
    693 * If any access by any efi runtime service causes a page fault, then,
    694 * 1. If it's efi_reset_system(), reboot through BIOS.
    695 * 2. If any other efi runtime service, then
    696 *    a. Return error status to the efi caller process.
    697 *    b. Disable EFI Runtime Services forever and
    698 *    c. Freeze efi_rts_wq and schedule new process.
    699 *
    700 * @return: Returns, if the page fault is not handled. This function
    701 * will never return if the page fault is handled successfully.
    702 */
    703void efi_crash_gracefully_on_page_fault(unsigned long phys_addr)
    704{
    705	if (!IS_ENABLED(CONFIG_X86_64))
    706		return;
    707
    708	/*
    709	 * If we get an interrupt/NMI while processing an EFI runtime service
    710	 * then this is a regular OOPS, not an EFI failure.
    711	 */
    712	if (in_interrupt())
    713		return;
    714
    715	/*
    716	 * Make sure that an efi runtime service caused the page fault.
    717	 * READ_ONCE() because we might be OOPSing in a different thread,
    718	 * and we don't want to trip KTSAN while trying to OOPS.
    719	 */
    720	if (READ_ONCE(efi_rts_work.efi_rts_id) == EFI_NONE ||
    721	    current_work() != &efi_rts_work.work)
    722		return;
    723
    724	/*
    725	 * Address range 0x0000 - 0x0fff is always mapped in the efi_pgd, so
    726	 * page faulting on these addresses isn't expected.
    727	 */
    728	if (phys_addr <= 0x0fff)
    729		return;
    730
    731	/*
    732	 * Print stack trace as it might be useful to know which EFI Runtime
    733	 * Service is buggy.
    734	 */
    735	WARN(1, FW_BUG "Page fault caused by firmware at PA: 0x%lx\n",
    736	     phys_addr);
    737
    738	/*
    739	 * Buggy efi_reset_system() is handled differently from other EFI
    740	 * Runtime Services as it doesn't use efi_rts_wq. Although,
    741	 * native_machine_emergency_restart() says that machine_real_restart()
    742	 * could fail, it's better not to complicate this fault handler
    743	 * because this case occurs *very* rarely and hence could be improved
    744	 * on a need by basis.
    745	 */
    746	if (efi_rts_work.efi_rts_id == EFI_RESET_SYSTEM) {
    747		pr_info("efi_reset_system() buggy! Reboot through BIOS\n");
    748		machine_real_restart(MRR_BIOS);
    749		return;
    750	}
    751
    752	/*
    753	 * Before calling EFI Runtime Service, the kernel has switched the
    754	 * calling process to efi_mm. Hence, switch back to task_mm.
    755	 */
    756	arch_efi_call_virt_teardown();
    757
    758	/* Signal error status to the efi caller process */
    759	efi_rts_work.status = EFI_ABORTED;
    760	complete(&efi_rts_work.efi_rts_comp);
    761
    762	clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
    763	pr_info("Froze efi_rts_wq and disabled EFI Runtime Services\n");
    764
    765	/*
    766	 * Call schedule() in an infinite loop, so that any spurious wake ups
    767	 * will never run efi_rts_wq again.
    768	 */
    769	for (;;) {
    770		set_current_state(TASK_IDLE);
    771		schedule();
    772	}
    773}