[PATCH 1/6] x86/mm/pageattr: Ensure cpa->pfn only contains page frame numbers

Matt Fleming
2015-11-12T15:42:28Z

The x86 pageattr code is confused about the data that is stored
cpa->pfn, sometimes it's treated as a page fram number and sometimes
it's treated as an unshifted physical address.

The result of this is that the mapping functions do not map the
intended physical address.

This isn't a problem in practice because most of the addresses we're
mapping in the EFI code paths are already mapped in 'trampoline_pgd'
and so the pageattr mappings functions don't actually do anything in
this case. But when we move to using a separate page table for the EFI
runtime this will be an issue.

Cc: Borislav Petkov <bp@alien8.de>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
arch/x86/mm/pageattr.c | 12 ++++++------
arch/x86/platform/efi/efi_64.c | 33 ++++++++++++++++++++++-----------
2 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 9abe0c9b1098..893921b12272 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -890,10 +890,10 @@ static void populate_pte(struct cpa_data *cpa,
if (!(pgprot_val(pgprot) & _PAGE_NX))
cpa->pfn &= ~_PAGE_NX;

- set_pte(pte, pfn_pte(cpa->pfn >> PAGE_SHIFT, pgprot));
+ set_pte(pte, pfn_pte(cpa->pfn, pgprot));

start += PAGE_SIZE;
- cpa->pfn += PAGE_SIZE;
+ cpa->pfn++;
pte++;
}
}
@@ -949,11 +949,11 @@ static int populate_pmd(struct cpa_data *cpa,

pmd = pmd_offset(pud, start);

- set_pmd(pmd, __pmd(cpa->pfn | _PAGE_PSE |
+ set_pmd(pmd, __pmd(cpa->pfn << PAGE_SHIFT | _PAGE_PSE |
massage_pgprot(pmd_pgprot)));

start += PMD_SIZE;
- cpa->pfn += PMD_SIZE;
+ cpa->pfn += PMD_SIZE >> PAGE_SHIFT;
cur_pages += PMD_SIZE >> PAGE_SHIFT;
}

@@ -1022,11 +1022,11 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd,
* Map everything starting from the Gb boundary, possibly with 1G pages
*/
while (end - start >= PUD_SIZE) {
- set_pud(pud, __pud(cpa->pfn | _PAGE_PSE |
+ set_pud(pud, __pud(cpa->pfn << PAGE_SHIFT | _PAGE_PSE |
massage_pgprot(pud_pgprot)));

start += PUD_SIZE;
- cpa->pfn += PUD_SIZE;
+ cpa->pfn += PUD_SIZE >> PAGE_SHIFT;
cur_pages += PUD_SIZE >> PAGE_SHIFT;
pud++;
}
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index a0ac0f9c307f..c8b58ac47b77 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -143,7 +143,7 @@ void efi_sync_low_kernel_mappings(void)

int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
- unsigned long text;
+ unsigned long pfn, text;
struct page *page;
unsigned npages;
pgd_t *pgd;
@@ -160,7 +160,8 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
* and ident-map those pages containing the map before calling
* phys_efi_set_virtual_address_map().
*/
- if (kernel_map_pages_in_pgd(pgd, pa_memmap, pa_memmap, num_pages, _PAGE_NX)) {
+ pfn = pa_memmap >> PAGE_SHIFT;
+ if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX)) {
pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);
return 1;
}
@@ -176,21 +177,29 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
if (!IS_ENABLED(CONFIG_EFI_MIXED))
return 0;

+ npages = (_end - _text) >> PAGE_SHIFT;
+ text = __pa(_text);
+ pfn = text >> PAGE_SHIFT;
+
+ if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) {
+ pr_err("Failed to map kernel text 1:1\n");
+ return 1;
+ }
+
page = alloc_page(GFP_KERNEL|__GFP_DMA32);
if (!page)
panic("Unable to allocate EFI runtime stack < 4GB\n");

efi_scratch.phys_stack = virt_to_phys(page_address(page));
- efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */
-
- npages = (_end - _text) >> PAGE_SHIFT;
- text = __pa(_text);
+ pfn = page_to_pfn(page);

- if (kernel_map_pages_in_pgd(pgd, text >> PAGE_SHIFT, text, npages, 0)) {
- pr_err("Failed to map kernel text 1:1\n");
+ if (kernel_map_pages_in_pgd(pgd, pfn, efi_scratch.phys_stack, 1, 0)) {
+ pr_err("Failed to map mixed mode stack\n");
return 1;
}

+ efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */
+
return 0;
}

@@ -204,12 +213,14 @@ 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)
{
pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
- unsigned long pf = 0;
+ unsigned long flags = 0;
+ unsigned long pfn;

if (!(md->attribute & EFI_MEMORY_WB))
- pf |= _PAGE_PCD;
+ flags |= _PAGE_PCD;

- if (kernel_map_pages_in_pgd(pgd, md->phys_addr, va, md->num_pages, pf))
+ pfn = md->phys_addr >> PAGE_SHIFT;
+ if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
md->phys_addr, va);
}
--
2.6.2