131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
// 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");
|
|
EXPORT_SYMBOL(screen_info);
|
|
|
|
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;
|
|
}
|