[tip:x86/efi] x86/mm/pat: Ensure cpa-> pfn only contains page frame numbers

[tip-bot for Matt Fleming]

Commit-ID:  edc3b9129cecd0f0857112136f5b8b1bc1d45918
Gitweb:     http://git.kernel.org/tip/edc3b9129cecd0f0857112136f5b8b1bc1d45918
Author:     Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 27 Nov 2015 21:09:31 +0000
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 29 Nov 2015 09:15:42 +0100

x86/mm/pat: Ensure cpa->pfn only contains page frame numbers

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

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 mapping 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.

Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1448658575-17029-3-git-send-email-matt@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/mm/pageattr.c         | 17 ++++++-----------
 arch/x86/platform/efi/efi_64.c | 16 ++++++++++------
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index a3137a4..c70e420 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -905,15 +905,10 @@ static void populate_pte(struct cpa_data *cpa,
 	pte = pte_offset_kernel(pmd, start);
 
 	while (num_pages-- && start < end) {
-
-		/* deal with the NX bit */
-		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++;
 	}
 }
@@ -969,11 +964,11 @@ 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;
 	}
 
@@ -1042,11 +1037,11 @@ 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 a0ac0f9..5aa186d 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;
 	}
@@ -185,8 +186,9 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 
 	npages = (_end - _text) >> PAGE_SHIFT;
 	text = __pa(_text);
+	pfn = text >> PAGE_SHIFT;
 
-	if (kernel_map_pages_in_pgd(pgd, text >> PAGE_SHIFT, text, npages, 0)) {
+	if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) {
 		pr_err("Failed to map kernel text 1:1\n");
 		return 1;
 	}
@@ -204,12 +206,14 @@ 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);
 }
--
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