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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Extensible Firmware Interface
- *
- * Based on Extensible Firmware Interface Specification version 2.4
- *
- * Copyright (C) 2013, 2014 Linaro Ltd.
- */
- #include <linux/efi.h>
- #include <linux/init.h>
- #include <asm/efi.h>
- /*
- * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
- * executable, everything else can be mapped with the XN bits
- * set. Also take the new (optional) RO/XP bits into account.
- */
- static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
- {
- u64 attr = md->attribute;
- u32 type = md->type;
- if (type == EFI_MEMORY_MAPPED_IO)
- return PROT_DEVICE_nGnRE;
- if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
- "UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
- /*
- * If the region is not aligned to the page size of the OS, we
- * can not use strict permissions, since that would also affect
- * the mapping attributes of the adjacent regions.
- */
- return pgprot_val(PAGE_KERNEL_EXEC);
- /* R-- */
- if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
- (EFI_MEMORY_XP | EFI_MEMORY_RO))
- return pgprot_val(PAGE_KERNEL_RO);
- /* R-X */
- if (attr & EFI_MEMORY_RO)
- return pgprot_val(PAGE_KERNEL_ROX);
- /* RW- */
- if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
- EFI_MEMORY_XP) ||
- type != EFI_RUNTIME_SERVICES_CODE)
- return pgprot_val(PAGE_KERNEL);
- /* RWX */
- return pgprot_val(PAGE_KERNEL_EXEC);
- }
- /* we will fill this structure from the stub, so don't put it in .bss */
- struct screen_info screen_info __section(".data");
- int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
- {
- pteval_t prot_val = create_mapping_protection(md);
- bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE ||
- md->type == EFI_RUNTIME_SERVICES_DATA);
- if (!PAGE_ALIGNED(md->phys_addr) ||
- !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) {
- /*
- * If the end address of this region is not aligned to page
- * size, the mapping is rounded up, and may end up sharing a
- * page frame with the next UEFI memory region. If we create
- * a block entry now, we may need to split it again when mapping
- * the next region, and support for that is going to be removed
- * from the MMU routines. So avoid block mappings altogether in
- * that case.
- */
- page_mappings_only = true;
- }
- create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
- md->num_pages << EFI_PAGE_SHIFT,
- __pgprot(prot_val | PTE_NG), page_mappings_only);
- return 0;
- }
- static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
- {
- efi_memory_desc_t *md = data;
- pte_t pte = READ_ONCE(*ptep);
- if (md->attribute & EFI_MEMORY_RO)
- pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
- if (md->attribute & EFI_MEMORY_XP)
- pte = set_pte_bit(pte, __pgprot(PTE_PXN));
- set_pte(ptep, pte);
- return 0;
- }
- int __init efi_set_mapping_permissions(struct mm_struct *mm,
- efi_memory_desc_t *md)
- {
- BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
- md->type != EFI_RUNTIME_SERVICES_DATA);
- /*
- * Calling apply_to_page_range() is only safe on regions that are
- * guaranteed to be mapped down to pages. Since we are only called
- * for regions that have been mapped using efi_create_mapping() above
- * (and this is checked by the generic Memory Attributes table parsing
- * routines), there is no need to check that again here.
- */
- return apply_to_page_range(mm, md->virt_addr,
- md->num_pages << EFI_PAGE_SHIFT,
- set_permissions, md);
- }
- /*
- * UpdateCapsule() depends on the system being shutdown via
- * ResetSystem().
- */
- bool efi_poweroff_required(void)
- {
- return efi_enabled(EFI_RUNTIME_SERVICES);
- }
- asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
- {
- pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);
- return s;
- }
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