bd264d046a
To avoid triggering diagnostics in the MMU code that are finicky about splitting block mappings into more granular mappings, ensure that regions that are likely to appear in the Memory Attributes table as well as the UEFI memory map are always mapped down to pages. This way, we can use apply_to_page_range() instead of create_pgd_mapping() for the second pass, which cannot split or merge block entries, and operates strictly on PTEs. Note that this aligns the arm64 Memory Attributes table handling code with the ARM code, which already uses apply_to_page_range() to set the strict permissions. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
128 lines
3.6 KiB
C
128 lines
3.6 KiB
C
/*
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* Extensible Firmware Interface
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*
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* Based on Extensible Firmware Interface Specification version 2.4
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*
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* Copyright (C) 2013, 2014 Linaro Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/dmi.h>
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#include <linux/efi.h>
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#include <linux/init.h>
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#include <asm/efi.h>
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/*
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* Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
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* executable, everything else can be mapped with the XN bits
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* set. Also take the new (optional) RO/XP bits into account.
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*/
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static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
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{
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u64 attr = md->attribute;
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u32 type = md->type;
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if (type == EFI_MEMORY_MAPPED_IO)
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return PROT_DEVICE_nGnRE;
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if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
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"UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
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/*
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* If the region is not aligned to the page size of the OS, we
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* can not use strict permissions, since that would also affect
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* the mapping attributes of the adjacent regions.
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*/
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return pgprot_val(PAGE_KERNEL_EXEC);
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/* R-- */
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if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
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(EFI_MEMORY_XP | EFI_MEMORY_RO))
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return pgprot_val(PAGE_KERNEL_RO);
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/* R-X */
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if (attr & EFI_MEMORY_RO)
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return pgprot_val(PAGE_KERNEL_ROX);
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/* RW- */
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if (attr & EFI_MEMORY_XP || type != EFI_RUNTIME_SERVICES_CODE)
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return pgprot_val(PAGE_KERNEL);
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/* RWX */
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return pgprot_val(PAGE_KERNEL_EXEC);
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}
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/* we will fill this structure from the stub, so don't put it in .bss */
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struct screen_info screen_info __section(.data);
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int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
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{
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pteval_t prot_val = create_mapping_protection(md);
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bool allow_block_mappings = (md->type != EFI_RUNTIME_SERVICES_CODE &&
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md->type != EFI_RUNTIME_SERVICES_DATA);
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create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
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md->num_pages << EFI_PAGE_SHIFT,
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__pgprot(prot_val | PTE_NG), allow_block_mappings);
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return 0;
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}
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static int __init set_permissions(pte_t *ptep, pgtable_t token,
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unsigned long addr, void *data)
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{
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efi_memory_desc_t *md = data;
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pte_t pte = *ptep;
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if (md->attribute & EFI_MEMORY_RO)
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pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
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if (md->attribute & EFI_MEMORY_XP)
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pte = set_pte_bit(pte, __pgprot(PTE_PXN));
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set_pte(ptep, pte);
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return 0;
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}
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int __init efi_set_mapping_permissions(struct mm_struct *mm,
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efi_memory_desc_t *md)
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{
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BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
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md->type != EFI_RUNTIME_SERVICES_DATA);
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/*
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* Calling apply_to_page_range() is only safe on regions that are
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* guaranteed to be mapped down to pages. Since we are only called
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* for regions that have been mapped using efi_create_mapping() above
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* (and this is checked by the generic Memory Attributes table parsing
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* routines), there is no need to check that again here.
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*/
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return apply_to_page_range(mm, md->virt_addr,
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md->num_pages << EFI_PAGE_SHIFT,
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set_permissions, md);
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}
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static int __init arm64_dmi_init(void)
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{
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/*
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* On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
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* be called early because dmi_id_init(), which is an arch_initcall
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* itself, depends on dmi_scan_machine() having been called already.
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*/
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dmi_scan_machine();
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if (dmi_available)
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dmi_set_dump_stack_arch_desc();
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return 0;
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}
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core_initcall(arm64_dmi_init);
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/*
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* UpdateCapsule() depends on the system being shutdown via
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* ResetSystem().
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*/
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bool efi_poweroff_required(void)
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{
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return efi_enabled(EFI_RUNTIME_SERVICES);
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}
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