[linux-2.6-block.git] / arch / arm64 / kernel / efi.c

/*
 * Extensible Firmware Interface
 *
 * Based on Extensible Firmware Interface Specification version 2.4
 *
 * Copyright (C) 2013, 2014 Linaro Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#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, pgtable_t token,
				  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);
}
Commit	Line	Data
f84d0275 MS	1	/*
	2	* Extensible Firmware Interface
	3	*
	4	* Based on Extensible Firmware Interface Specification version 2.4
	5	*
	6	* Copyright (C) 2013, 2014 Linaro Ltd.
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*
	12	*/
	13
	14	#include <linux/efi.h>
e5bc22a4	15	#include <linux/init.h>
f84d0275	16
f84d0275	17	#include <asm/efi.h>
d1ae8c00	18
1fd55a9a AB	19	/*
	20	* Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
	21	* executable, everything else can be mapped with the XN bits
	22	* set. Also take the new (optional) RO/XP bits into account.
	23	*/
	24	static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
f7d92489	25	{
1fd55a9a AB	26	u64 attr = md->attribute;
1fd55a9a AB	27	u32 type = md->type;
f7d92489	28
1fd55a9a AB	29	if (type == EFI_MEMORY_MAPPED_IO)
	30	return PROT_DEVICE_nGnRE;
	31
	32	if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
	33	"UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
	34	/*
	35	* If the region is not aligned to the page size of the OS, we
	36	* can not use strict permissions, since that would also affect
	37	* the mapping attributes of the adjacent regions.
	38	*/
	39	return pgprot_val(PAGE_KERNEL_EXEC);
	40
	41	/* R-- */
	42	if ((attr & (EFI_MEMORY_XP \| EFI_MEMORY_RO)) ==
	43	(EFI_MEMORY_XP \| EFI_MEMORY_RO))
	44	return pgprot_val(PAGE_KERNEL_RO);
	45
	46	/* R-X */
	47	if (attr & EFI_MEMORY_RO)
	48	return pgprot_val(PAGE_KERNEL_ROX);
	49
	50	/* RW- */
1e9de1d2 AB	51	if (((attr & (EFI_MEMORY_RP \| EFI_MEMORY_WP \| EFI_MEMORY_XP)) ==
	52	EFI_MEMORY_XP) \|\|
	53	type != EFI_RUNTIME_SERVICES_CODE)
1fd55a9a AB	54	return pgprot_val(PAGE_KERNEL);
	55
	56	/* RWX */
	57	return pgprot_val(PAGE_KERNEL_EXEC);
	58	}
	59
57fdb89a AB	60	/* we will fill this structure from the stub, so don't put it in .bss */
	61	struct screen_info screen_info __section(.data);
	62
1fd55a9a AB	63	int __init efi_create_mapping(struct mm_struct mm, efi_memory_desc_t md)
	64	{
	65	pteval_t prot_val = create_mapping_protection(md);
f14c66ce AB	66	bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE \|\|
f14c66ce AB	67	md->type == EFI_RUNTIME_SERVICES_DATA);
f7d92489	68
74c102c9 AB	69	if (!PAGE_ALIGNED(md->phys_addr) \|\|
	70	!PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) {
	71	/*
	72	* If the end address of this region is not aligned to page
	73	* size, the mapping is rounded up, and may end up sharing a
	74	* page frame with the next UEFI memory region. If we create
	75	* a block entry now, we may need to split it again when mapping
	76	* the next region, and support for that is going to be removed
	77	* from the MMU routines. So avoid block mappings altogether in
	78	* that case.
	79	*/
f14c66ce	80	page_mappings_only = true;
74c102c9 AB	81	}
74c102c9 AB	82
f7d92489 AB	83	create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
f7d92489 AB	84	md->num_pages << EFI_PAGE_SHIFT,
f14c66ce	85	__pgprot(prot_val \| PTE_NG), page_mappings_only);
f7d92489 AB	86	return 0;
	87	}
	88
bd264d04 AB	89	static int __init set_permissions(pte_t *ptep, pgtable_t token,
	90	unsigned long addr, void *data)
	91	{
	92	efi_memory_desc_t *md = data;
20a004e7	93	pte_t pte = READ_ONCE(*ptep);
bd264d04 AB	94
	95	if (md->attribute & EFI_MEMORY_RO)
	96	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
	97	if (md->attribute & EFI_MEMORY_XP)
	98	pte = set_pte_bit(pte, __pgprot(PTE_PXN));
	99	set_pte(ptep, pte);
	100	return 0;
	101	}
	102
	103	int __init efi_set_mapping_permissions(struct mm_struct *mm,
	104	efi_memory_desc_t *md)
	105	{
	106	BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
	107	md->type != EFI_RUNTIME_SERVICES_DATA);
	108
	109	/*
	110	* Calling apply_to_page_range() is only safe on regions that are
	111	* guaranteed to be mapped down to pages. Since we are only called
	112	* for regions that have been mapped using efi_create_mapping() above
	113	* (and this is checked by the generic Memory Attributes table parsing
	114	* routines), there is no need to check that again here.
	115	*/
	116	return apply_to_page_range(mm, md->virt_addr,
	117	md->num_pages << EFI_PAGE_SHIFT,
	118	set_permissions, md);
	119	}
	120
60c0d45a AB	121	/*
	122	* UpdateCapsule() depends on the system being shutdown via
	123	* ResetSystem().
	124	*/
	125	bool efi_poweroff_required(void)
	126	{
	127	return efi_enabled(EFI_RUNTIME_SERVICES);
	128	}