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9fc68b717c
Recent UEFI versions expose permission attributes for runtime services memory regions, either in the UEFI memory map or in the separate memory attributes table. This allows the kernel to map these regions with stricter permissions, rather than the RWX permissions that are used by default. So wire this up in our mapping routine. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Leif Lindholm <leif.lindholm@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1461614832-17633-11-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
/*
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* Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
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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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#include <linux/efi.h>
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#include <asm/efi.h>
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#include <asm/mach/map.h>
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#include <asm/mmu_context.h>
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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(L_PTE_RDONLY));
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if (md->attribute & EFI_MEMORY_XP)
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pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
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set_pte_ext(ptep, pte, PTE_EXT_NG);
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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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unsigned long base, size;
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base = md->virt_addr;
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size = md->num_pages << EFI_PAGE_SHIFT;
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/*
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* We can only use apply_to_page_range() if we can guarantee that the
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* entire region was mapped using pages. This should be the case if the
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* region does not cover any naturally aligned SECTION_SIZE sized
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* blocks.
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*/
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if (round_down(base + size, SECTION_SIZE) <
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round_up(base, SECTION_SIZE) + SECTION_SIZE)
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return apply_to_page_range(mm, base, size, set_permissions, md);
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return 0;
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}
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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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struct map_desc desc = {
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.virtual = md->virt_addr,
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.pfn = __phys_to_pfn(md->phys_addr),
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.length = md->num_pages * EFI_PAGE_SIZE,
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};
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/*
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* Order is important here: memory regions may have all of the
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* bits below set (and usually do), so we check them in order of
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* preference.
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*/
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if (md->attribute & EFI_MEMORY_WB)
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desc.type = MT_MEMORY_RWX;
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else if (md->attribute & EFI_MEMORY_WT)
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desc.type = MT_MEMORY_RWX_NONCACHED;
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else if (md->attribute & EFI_MEMORY_WC)
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desc.type = MT_DEVICE_WC;
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else
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desc.type = MT_DEVICE;
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create_mapping_late(mm, &desc, true);
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/*
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* If stricter permissions were specified, apply them now.
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*/
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if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
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return efi_set_mapping_permissions(mm, md);
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return 0;
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}
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