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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efi.c (2004B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
      4 */
      5
      6#include <linux/efi.h>
      7#include <asm/efi.h>
      8#include <asm/mach/map.h>
      9#include <asm/mmu_context.h>
     10
     11static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
     12{
     13	efi_memory_desc_t *md = data;
     14	pte_t pte = *ptep;
     15
     16	if (md->attribute & EFI_MEMORY_RO)
     17		pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
     18	if (md->attribute & EFI_MEMORY_XP)
     19		pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
     20	set_pte_ext(ptep, pte, PTE_EXT_NG);
     21	return 0;
     22}
     23
     24int __init efi_set_mapping_permissions(struct mm_struct *mm,
     25				       efi_memory_desc_t *md)
     26{
     27	unsigned long base, size;
     28
     29	base = md->virt_addr;
     30	size = md->num_pages << EFI_PAGE_SHIFT;
     31
     32	/*
     33	 * We can only use apply_to_page_range() if we can guarantee that the
     34	 * entire region was mapped using pages. This should be the case if the
     35	 * region does not cover any naturally aligned SECTION_SIZE sized
     36	 * blocks.
     37	 */
     38	if (round_down(base + size, SECTION_SIZE) <
     39	    round_up(base, SECTION_SIZE) + SECTION_SIZE)
     40		return apply_to_page_range(mm, base, size, set_permissions, md);
     41
     42	return 0;
     43}
     44
     45int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
     46{
     47	struct map_desc desc = {
     48		.virtual	= md->virt_addr,
     49		.pfn		= __phys_to_pfn(md->phys_addr),
     50		.length		= md->num_pages * EFI_PAGE_SIZE,
     51	};
     52
     53	/*
     54	 * Order is important here: memory regions may have all of the
     55	 * bits below set (and usually do), so we check them in order of
     56	 * preference.
     57	 */
     58	if (md->attribute & EFI_MEMORY_WB)
     59		desc.type = MT_MEMORY_RWX;
     60	else if (md->attribute & EFI_MEMORY_WT)
     61		desc.type = MT_MEMORY_RWX_NONCACHED;
     62	else if (md->attribute & EFI_MEMORY_WC)
     63		desc.type = MT_DEVICE_WC;
     64	else
     65		desc.type = MT_DEVICE;
     66
     67	create_mapping_late(mm, &desc, true);
     68
     69	/*
     70	 * If stricter permissions were specified, apply them now.
     71	 */
     72	if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
     73		return efi_set_mapping_permissions(mm, md);
     74	return 0;
     75}