From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx>
As part of the preparation for the EFI_MEMORY_RO flag added in the UEFI
2.5 specification, we need the ability to map pages in kernel page
tables without _PAGE_RW being set.
Modify kernel_map_pages_in_pgd() to require its callers to pass _PAGE_RW
if the pages need to be mapped read/write. Otherwise, we'll map the
pages as read-only.
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "Lee, Chun-Yi" <jlee@xxxxxxxx>
Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx>
Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/pageattr.c | 3 +++
arch/x86/platform/efi/efi_64.c | 8 ++++----
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index bf312da41a6d..14c38ae80409 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1971,6 +1971,9 @@ int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
if (!(page_flags & _PAGE_NX))
cpa.mask_clr = __pgprot(_PAGE_NX);
+ if (!(page_flags & _PAGE_RW))
+ cpa.mask_clr = __pgprot(_PAGE_RW);
+
cpa.mask_set = __pgprot(_PAGE_PRESENT | page_flags);
retval = __change_page_attr_set_clr(&cpa, 0);
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index b492521503fe..b0965b27e47f 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -233,7 +233,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
* phys_efi_set_virtual_address_map().
*/
pfn = pa_memmap >> PAGE_SHIFT;
- if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX)) {
+ if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX | _PAGE_RW)) {
pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);
return 1;
}
@@ -262,7 +262,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
pfn = md->phys_addr >> PAGE_SHIFT;
npages = md->num_pages;
- if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, npages, 0)) {
+ if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, npages, _PAGE_RW)) {
pr_err("Failed to map 1:1 memory\n");
return 1;
}
@@ -279,7 +279,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
text = __pa(_text);
pfn = text >> PAGE_SHIFT;
- if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) {
+ if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, _PAGE_RW)) {
pr_err("Failed to map kernel text 1:1\n");
return 1;
}
@@ -294,7 +294,7 @@ void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages)
static void __init __map_region(efi_memory_desc_t *md, u64 va)
{
- unsigned long flags = 0;
+ unsigned long flags = _PAGE_RW;
unsigned long pfn;
pgd_t *pgd = efi_pgd;
--
2.6.2
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
