[PATCH 08/26] x86/efi: handle p4d in EFI pagetables

From: Kirill A. Shutemov
Date: Mon Mar 13 2017 - 01:52:56 EST


Allocate additional page table level and change efi_sync_low_kernel_mappings()
to make syncing logic work with additional page table level.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/platform/efi/efi_64.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 8544dae3d1b4..34d019f75239 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -135,6 +135,7 @@ static pgd_t *efi_pgd;
int __init efi_alloc_page_tables(void)
{
pgd_t *pgd;
+ p4d_t *p4d;
pud_t *pud;
gfp_t gfp_mask;

@@ -147,15 +148,20 @@ int __init efi_alloc_page_tables(void)
return -ENOMEM;

pgd = efi_pgd + pgd_index(EFI_VA_END);
+ p4d = p4d_alloc(&init_mm, pgd, EFI_VA_END);
+ if (!p4d) {
+ free_page((unsigned long)efi_pgd);
+ return -ENOMEM;
+ }

- pud = pud_alloc_one(NULL, 0);
+ pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
if (!pud) {
+ if (CONFIG_PGTABLE_LEVELS > 4)
+ free_page((unsigned long) pgd_page_vaddr(*pgd));
free_page((unsigned long)efi_pgd);
return -ENOMEM;
}

- pgd_populate(NULL, pgd, pud);
-
return 0;
}

@@ -190,6 +196,18 @@ void efi_sync_low_kernel_mappings(void)
num_entries = pgd_index(EFI_VA_END) - pgd_index(PAGE_OFFSET);
memcpy(pgd_efi, pgd_k, sizeof(pgd_t) * num_entries);

+ /* The same story as with PGD entries */
+ BUILD_BUG_ON(p4d_index(EFI_VA_END) != p4d_index(MODULES_END));
+ BUILD_BUG_ON((EFI_VA_START & P4D_MASK) != (EFI_VA_END & P4D_MASK));
+
+ pgd_efi = efi_pgd + pgd_index(EFI_VA_END);
+ pgd_k = pgd_offset_k(EFI_VA_END);
+ p4d_efi = p4d_offset(pgd_efi, 0);
+ p4d_k = p4d_offset(pgd_k, 0);
+
+ num_entries = p4d_index(EFI_VA_END);
+ memcpy(p4d_efi, p4d_k, sizeof(p4d_t) * num_entries);
+
/*
* We share all the PUD entries apart from those that map the
* EFI regions. Copy around them.
@@ -197,20 +215,15 @@ void efi_sync_low_kernel_mappings(void)
BUILD_BUG_ON((EFI_VA_START & ~PUD_MASK) != 0);
BUILD_BUG_ON((EFI_VA_END & ~PUD_MASK) != 0);

- pgd_efi = efi_pgd + pgd_index(EFI_VA_END);
- p4d_efi = p4d_offset(pgd_efi, 0);
+ p4d_efi = p4d_offset(pgd_efi, EFI_VA_END);
+ p4d_k = p4d_offset(pgd_k, EFI_VA_END);
pud_efi = pud_offset(p4d_efi, 0);
-
- pgd_k = pgd_offset_k(EFI_VA_END);
- p4d_k = p4d_offset(pgd_k, 0);
pud_k = pud_offset(p4d_k, 0);

num_entries = pud_index(EFI_VA_END);
memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries);

- p4d_efi = p4d_offset(pgd_efi, EFI_VA_START);
pud_efi = pud_offset(p4d_efi, EFI_VA_START);
- p4d_k = p4d_offset(pgd_k, EFI_VA_START);
pud_k = pud_offset(p4d_k, EFI_VA_START);

num_entries = PTRS_PER_PUD - pud_index(EFI_VA_START);
--
2.11.0