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RISC-V: Add EFI runtime services

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This patch adds EFI runtime service support for RISC-V.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
[ardb: - Remove the page check]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Atish Patra 2020-09-17 15:37:15 -07:00 • committed by Palmer Dabbelt
parent d7071743db
commit b91540d52a
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11 changed files with 287 additions and 4 deletions
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96
arch/riscv/kernel/efi.c Normal file
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
* Adapted from arch/arm64/kernel/efi.c
*/
#include <linux/efi.h>
#include <linux/init.h>
#include <asm/efi.h>
#include <asm/pgtable.h>
#include <asm/pgtable-bits.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 pgprot_t efimem_to_pgprot_map(efi_memory_desc_t *md)
{
u64 attr = md->attribute;
u32 type = md->type;
if (type == EFI_MEMORY_MAPPED_IO)
return PAGE_KERNEL;
/* R-- */
if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
(EFI_MEMORY_XP | EFI_MEMORY_RO))
return PAGE_KERNEL_READ;
/* R-X */
if (attr & EFI_MEMORY_RO)
return PAGE_KERNEL_READ_EXEC;
/* RW- */
if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
EFI_MEMORY_XP) ||
type != EFI_RUNTIME_SERVICES_CODE)
return PAGE_KERNEL;
/* RWX */
return PAGE_KERNEL_EXEC;
}
int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
{
pgprot_t prot = __pgprot(pgprot_val(efimem_to_pgprot_map(md)) &
~(_PAGE_GLOBAL));
int i;
/* RISC-V maps one page at a time */
for (i = 0; i < md->num_pages; i++)
create_pgd_mapping(mm->pgd, md->virt_addr + i * PAGE_SIZE,
md->phys_addr + i * PAGE_SIZE,
PAGE_SIZE, prot);
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);
unsigned long val;
if (md->attribute & EFI_MEMORY_RO) {
val = pte_val(pte) & ~_PAGE_WRITE;
val = pte_val(pte) | _PAGE_READ;
pte = __pte(val);
}
if (md->attribute & EFI_MEMORY_XP) {
val = pte_val(pte) & ~_PAGE_EXEC;
pte = __pte(val);
}
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);
}