| // SPDX-License-Identifier: GPL-2.0-only |
| #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/acpi.h> |
| #include <linux/dmi.h> |
| |
| #include <asm/e820/api.h> |
| #include <asm/efi.h> |
| #include <asm/uv/uv.h> |
| #include <asm/cpu_device_id.h> |
| #include <asm/reboot.h> |
| |
| #define EFI_MIN_RESERVE 5120 |
| |
| #define EFI_DUMMY_GUID \ |
| EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9) |
| |
| #define QUARK_CSH_SIGNATURE 0x5f435348 /* _CSH */ |
| #define QUARK_SECURITY_HEADER_SIZE 0x400 |
| |
| /* |
| * Header prepended to the standard EFI capsule on Quark systems the are based |
| * on Intel firmware BSP. |
| * @csh_signature: Unique identifier to sanity check signed module |
| * presence ("_CSH"). |
| * @version: Current version of CSH used. Should be one for Quark A0. |
| * @modulesize: Size of the entire module including the module header |
| * and payload. |
| * @security_version_number_index: Index of SVN to use for validation of signed |
| * module. |
| * @security_version_number: Used to prevent against roll back of modules. |
| * @rsvd_module_id: Currently unused for Clanton (Quark). |
| * @rsvd_module_vendor: Vendor Identifier. For Intel products value is |
| * 0x00008086. |
| * @rsvd_date: BCD representation of build date as yyyymmdd, where |
| * yyyy=4 digit year, mm=1-12, dd=1-31. |
| * @headersize: Total length of the header including including any |
| * padding optionally added by the signing tool. |
| * @hash_algo: What Hash is used in the module signing. |
| * @cryp_algo: What Crypto is used in the module signing. |
| * @keysize: Total length of the key data including including any |
| * padding optionally added by the signing tool. |
| * @signaturesize: Total length of the signature including including any |
| * padding optionally added by the signing tool. |
| * @rsvd_next_header: 32-bit pointer to the next Secure Boot Module in the |
| * chain, if there is a next header. |
| * @rsvd: Reserved, padding structure to required size. |
| * |
| * See also QuartSecurityHeader_t in |
| * Quark_EDKII_v1.2.1.1/QuarkPlatformPkg/Include/QuarkBootRom.h |
| * from https://downloadcenter.intel.com/download/23197/Intel-Quark-SoC-X1000-Board-Support-Package-BSP |
| */ |
| struct quark_security_header { |
| u32 csh_signature; |
| u32 version; |
| u32 modulesize; |
| u32 security_version_number_index; |
| u32 security_version_number; |
| u32 rsvd_module_id; |
| u32 rsvd_module_vendor; |
| u32 rsvd_date; |
| u32 headersize; |
| u32 hash_algo; |
| u32 cryp_algo; |
| u32 keysize; |
| u32 signaturesize; |
| u32 rsvd_next_header; |
| u32 rsvd[2]; |
| }; |
| |
| static const efi_char16_t efi_dummy_name[] = L"DUMMY"; |
| |
| 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_nonblocking((efi_char16_t *)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_KERNEL); |
| |
| if (!dummy) |
| return EFI_OUT_OF_RESOURCES; |
| |
| status = efi.set_variable((efi_char16_t *)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); |
| |
| /* |
| * 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. |
| * |
| * However, some boot services regions contain data that is required |
| * by drivers, so we need to track which memory ranges can never be |
| * freed. This is done by tagging those regions with the |
| * EFI_MEMORY_RUNTIME attribute. |
| * |
| * Any driver that wants to mark a region as reserved must use |
| * efi_mem_reserve() which will insert a new EFI memory descriptor |
| * into efi.memmap (splitting existing regions if necessary) and tag |
| * it with EFI_MEMORY_RUNTIME. |
| */ |
| void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size) |
| { |
| phys_addr_t new_phys, new_size; |
| struct efi_mem_range mr; |
| efi_memory_desc_t md; |
| int num_entries; |
| void *new; |
| |
| if (efi_mem_desc_lookup(addr, &md) || |
| md.type != EFI_BOOT_SERVICES_DATA) { |
| pr_err("Failed to lookup EFI memory descriptor for %pa\n", &addr); |
| return; |
| } |
| |
| if (addr + size > md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT)) { |
| pr_err("Region spans EFI memory descriptors, %pa\n", &addr); |
| return; |
| } |
| |
| size += addr % EFI_PAGE_SIZE; |
| size = round_up(size, EFI_PAGE_SIZE); |
| addr = round_down(addr, EFI_PAGE_SIZE); |
| |
| mr.range.start = addr; |
| mr.range.end = addr + size - 1; |
| mr.attribute = md.attribute | EFI_MEMORY_RUNTIME; |
| |
| num_entries = efi_memmap_split_count(&md, &mr.range); |
| num_entries += efi.memmap.nr_map; |
| |
| new_size = efi.memmap.desc_size * num_entries; |
| |
| new_phys = efi_memmap_alloc(num_entries); |
| if (!new_phys) { |
| pr_err("Could not allocate boot services memmap\n"); |
| return; |
| } |
| |
| new = early_memremap(new_phys, new_size); |
| if (!new) { |
| pr_err("Failed to map new boot services memmap\n"); |
| return; |
| } |
| |
| efi_memmap_insert(&efi.memmap, new, &mr); |
| early_memunmap(new, new_size); |
| |
| efi_memmap_install(new_phys, num_entries); |
| e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED); |
| e820__update_table(e820_table); |
| } |
| |
| /* |
| * 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_TYPE_RESERVED, E820_TYPE_NVS, etc) |
| */ |
| static __init bool can_free_region(u64 start, u64 size) |
| { |
| if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end)) |
| return false; |
| |
| if (!e820__mapped_all(start, start+size, E820_TYPE_RAM)) |
| return false; |
| |
| return true; |
| } |
| |
| void __init efi_reserve_boot_services(void) |
| { |
| efi_memory_desc_t *md; |
| |
| for_each_efi_memory_desc(md) { |
| 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 memblock_free_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_TYPE_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 |
| * memblock_free_late(). |
| */ |
| md->attribute |= EFI_MEMORY_RUNTIME; |
| } |
| } |
| |
| /* |
| * Apart from having VA mappings for EFI boot services code/data regions, |
| * (duplicate) 1:1 mappings were also created as a quirk for buggy firmware. So, |
| * unmap both 1:1 and VA mappings. |
| */ |
| static void __init efi_unmap_pages(efi_memory_desc_t *md) |
| { |
| pgd_t *pgd = efi_mm.pgd; |
| u64 pa = md->phys_addr; |
| u64 va = md->virt_addr; |
| |
| /* |
| * To Do: Remove this check after adding functionality to unmap EFI boot |
| * services code/data regions from direct mapping area because |
| * "efi=old_map" maps EFI regions in swapper_pg_dir. |
| */ |
| if (efi_enabled(EFI_OLD_MEMMAP)) |
| return; |
| |
| /* |
| * EFI mixed mode has all RAM mapped to access arguments while making |
| * EFI runtime calls, hence don't unmap EFI boot services code/data |
| * regions. |
| */ |
| if (!efi_is_native()) |
| return; |
| |
| if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages)) |
| pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa); |
| |
| if (kernel_unmap_pages_in_pgd(pgd, va, md->num_pages)) |
| pr_err("Failed to unmap VA mapping for 0x%llx\n", va); |
| } |
| |
| void __init efi_free_boot_services(void) |
| { |
| phys_addr_t new_phys, new_size; |
| efi_memory_desc_t *md; |
| int num_entries = 0; |
| void *new, *new_md; |
| |
| for_each_efi_memory_desc(md) { |
| unsigned long long start = md->phys_addr; |
| unsigned long long size = md->num_pages << EFI_PAGE_SHIFT; |
| size_t rm_size; |
| |
| if (md->type != EFI_BOOT_SERVICES_CODE && |
| md->type != EFI_BOOT_SERVICES_DATA) { |
| num_entries++; |
| continue; |
| } |
| |
| /* Do not free, someone else owns it: */ |
| if (md->attribute & EFI_MEMORY_RUNTIME) { |
| num_entries++; |
| continue; |
| } |
| |
| /* |
| * Before calling set_virtual_address_map(), EFI boot services |
| * code/data regions were mapped as a quirk for buggy firmware. |
| * Unmap them from efi_pgd before freeing them up. |
| */ |
| efi_unmap_pages(md); |
| |
| /* |
| * Nasty quirk: if all sub-1MB memory is used for boot |
| * services, we can get here without having allocated the |
| * real mode trampoline. It's too late to hand boot services |
| * memory back to the memblock allocator, so instead |
| * try to manually allocate the trampoline if needed. |
| * |
| * I've seen this on a Dell XPS 13 9350 with firmware |
| * 1.4.4 with SGX enabled booting Linux via Fedora 24's |
| * grub2-efi on a hard disk. (And no, I don't know why |
| * this happened, but Linux should still try to boot rather |
| * panicing early.) |
| */ |
| rm_size = real_mode_size_needed(); |
| if (rm_size && (start + rm_size) < (1<<20) && size >= rm_size) { |
| set_real_mode_mem(start); |
| start += rm_size; |
| size -= rm_size; |
| } |
| |
| memblock_free_late(start, size); |
| } |
| |
| if (!num_entries) |
| return; |
| |
| new_size = efi.memmap.desc_size * num_entries; |
| new_phys = efi_memmap_alloc(num_entries); |
| if (!new_phys) { |
| pr_err("Failed to allocate new EFI memmap\n"); |
| return; |
| } |
| |
| new = memremap(new_phys, new_size, MEMREMAP_WB); |
| if (!new) { |
| pr_err("Failed to map new EFI memmap\n"); |
| return; |
| } |
| |
| /* |
| * Build a new EFI memmap that excludes any boot services |
| * regions that are not tagged EFI_MEMORY_RUNTIME, since those |
| * regions have now been freed. |
| */ |
| new_md = new; |
| for_each_efi_memory_desc(md) { |
| if (!(md->attribute & EFI_MEMORY_RUNTIME) && |
| (md->type == EFI_BOOT_SERVICES_CODE || |
| md->type == EFI_BOOT_SERVICES_DATA)) |
| continue; |
| |
| memcpy(new_md, md, efi.memmap.desc_size); |
| new_md += efi.memmap.desc_size; |
| } |
| |
| memunmap(new); |
| |
| if (efi_memmap_install(new_phys, num_entries)) { |
| pr_err("Could not install new EFI memmap\n"); |
| return; |
| } |
| } |
| |
| /* |
| * 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 (nr_tables == 0) |
| return 0; |
| |
| 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_memmap_unmap(); |
| } |
| |
| /* 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 || acpi_no_s5; |
| } |
| |
| #ifdef CONFIG_EFI_CAPSULE_QUIRK_QUARK_CSH |
| |
| static int qrk_capsule_setup_info(struct capsule_info *cap_info, void **pkbuff, |
| size_t hdr_bytes) |
| { |
| struct quark_security_header *csh = *pkbuff; |
| |
| /* Only process data block that is larger than the security header */ |
| if (hdr_bytes < sizeof(struct quark_security_header)) |
| return 0; |
| |
| if (csh->csh_signature != QUARK_CSH_SIGNATURE || |
| csh->headersize != QUARK_SECURITY_HEADER_SIZE) |
| return 1; |
| |
| /* Only process data block if EFI header is included */ |
| if (hdr_bytes < QUARK_SECURITY_HEADER_SIZE + |
| sizeof(efi_capsule_header_t)) |
| return 0; |
| |
| pr_debug("Quark security header detected\n"); |
| |
| if (csh->rsvd_next_header != 0) { |
| pr_err("multiple Quark security headers not supported\n"); |
| return -EINVAL; |
| } |
| |
| *pkbuff += csh->headersize; |
| cap_info->total_size = csh->headersize; |
| |
| /* |
| * Update the first page pointer to skip over the CSH header. |
| */ |
| cap_info->phys[0] += csh->headersize; |
| |
| /* |
| * cap_info->capsule should point at a virtual mapping of the entire |
| * capsule, starting at the capsule header. Our image has the Quark |
| * security header prepended, so we cannot rely on the default vmap() |
| * mapping created by the generic capsule code. |
| * Given that the Quark firmware does not appear to care about the |
| * virtual mapping, let's just point cap_info->capsule at our copy |
| * of the capsule header. |
| */ |
| cap_info->capsule = &cap_info->header; |
| |
| return 1; |
| } |
| |
| #define ICPU(family, model, quirk_handler) \ |
| { X86_VENDOR_INTEL, family, model, X86_FEATURE_ANY, \ |
| (unsigned long)&quirk_handler } |
| |
| static const struct x86_cpu_id efi_capsule_quirk_ids[] = { |
| ICPU(5, 9, qrk_capsule_setup_info), /* Intel Quark X1000 */ |
| { } |
| }; |
| |
| int efi_capsule_setup_info(struct capsule_info *cap_info, void *kbuff, |
| size_t hdr_bytes) |
| { |
| int (*quirk_handler)(struct capsule_info *, void **, size_t); |
| const struct x86_cpu_id *id; |
| int ret; |
| |
| if (hdr_bytes < sizeof(efi_capsule_header_t)) |
| return 0; |
| |
| cap_info->total_size = 0; |
| |
| id = x86_match_cpu(efi_capsule_quirk_ids); |
| if (id) { |
| /* |
| * The quirk handler is supposed to return |
| * - a value > 0 if the setup should continue, after advancing |
| * kbuff as needed |
| * - 0 if not enough hdr_bytes are available yet |
| * - a negative error code otherwise |
| */ |
| quirk_handler = (typeof(quirk_handler))id->driver_data; |
| ret = quirk_handler(cap_info, &kbuff, hdr_bytes); |
| if (ret <= 0) |
| return ret; |
| } |
| |
| memcpy(&cap_info->header, kbuff, sizeof(cap_info->header)); |
| |
| cap_info->total_size += cap_info->header.imagesize; |
| |
| return __efi_capsule_setup_info(cap_info); |
| } |
| |
| #endif |
| |
| /* |
| * If any access by any efi runtime service causes a page fault, then, |
| * 1. If it's efi_reset_system(), reboot through BIOS. |
| * 2. If any other efi runtime service, then |
| * a. Return error status to the efi caller process. |
| * b. Disable EFI Runtime Services forever and |
| * c. Freeze efi_rts_wq and schedule new process. |
| * |
| * @return: Returns, if the page fault is not handled. This function |
| * will never return if the page fault is handled successfully. |
| */ |
| void efi_recover_from_page_fault(unsigned long phys_addr) |
| { |
| if (!IS_ENABLED(CONFIG_X86_64)) |
| return; |
| |
| /* |
| * Make sure that an efi runtime service caused the page fault. |
| * "efi_mm" cannot be used to check if the page fault had occurred |
| * in the firmware context because efi=old_map doesn't use efi_pgd. |
| */ |
| if (efi_rts_work.efi_rts_id == EFI_NONE) |
| return; |
| |
| /* |
| * Address range 0x0000 - 0x0fff is always mapped in the efi_pgd, so |
| * page faulting on these addresses isn't expected. |
| */ |
| if (phys_addr <= 0x0fff) |
| return; |
| |
| /* |
| * Print stack trace as it might be useful to know which EFI Runtime |
| * Service is buggy. |
| */ |
| WARN(1, FW_BUG "Page fault caused by firmware at PA: 0x%lx\n", |
| phys_addr); |
| |
| /* |
| * Buggy efi_reset_system() is handled differently from other EFI |
| * Runtime Services as it doesn't use efi_rts_wq. Although, |
| * native_machine_emergency_restart() says that machine_real_restart() |
| * could fail, it's better not to compilcate this fault handler |
| * because this case occurs *very* rarely and hence could be improved |
| * on a need by basis. |
| */ |
| if (efi_rts_work.efi_rts_id == EFI_RESET_SYSTEM) { |
| pr_info("efi_reset_system() buggy! Reboot through BIOS\n"); |
| machine_real_restart(MRR_BIOS); |
| return; |
| } |
| |
| /* |
| * Before calling EFI Runtime Service, the kernel has switched the |
| * calling process to efi_mm. Hence, switch back to task_mm. |
| */ |
| arch_efi_call_virt_teardown(); |
| |
| /* Signal error status to the efi caller process */ |
| efi_rts_work.status = EFI_ABORTED; |
| complete(&efi_rts_work.efi_rts_comp); |
| |
| clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); |
| pr_info("Froze efi_rts_wq and disabled EFI Runtime Services\n"); |
| |
| /* |
| * Call schedule() in an infinite loop, so that any spurious wake ups |
| * will never run efi_rts_wq again. |
| */ |
| for (;;) { |
| set_current_state(TASK_IDLE); |
| schedule(); |
| } |
| |
| return; |
| } |