From: Sai Praneeth Date: Wed, 17 Feb 2016 12:35:56 +0000 (+0000) Subject: x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=397630150632639b3ca5b4414accd5011c45e276;p=linux-beck.git x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings Since EFI page tables can be treated as kernel page tables they should be global. All the other page mapping functions in pageattr.c set the _PAGE_GLOBAL bit and we want to avoid inconsistencies when we map a page in the EFI code paths, for example when that page is split in __split_large_page(), etc. It also makes it easier to validate that the EFI region mappings have the correct attributes because there are fewer differences compared with regular kernel mappings. Signed-off-by: Sai Praneeth Prakhya Signed-off-by: Matt Fleming Cc: Andrew Morton Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Hugh Dickins Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Ricardo Neri Cc: Thomas Gleixner Cc: Toshi Kani Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1455712566-16727-4-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 632d34d20237..bf312da41a6d 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -909,6 +909,20 @@ static void populate_pte(struct cpa_data *cpa, pte = pte_offset_kernel(pmd, start); + /* + * Set the GLOBAL flags only if the PRESENT flag is + * set otherwise pte_present will return true even on + * a non present pte. The canon_pgprot will clear + * _PAGE_GLOBAL for the ancient hardware that doesn't + * support it. + */ + if (pgprot_val(pgprot) & _PAGE_PRESENT) + pgprot_val(pgprot) |= _PAGE_GLOBAL; + else + pgprot_val(pgprot) &= ~_PAGE_GLOBAL; + + pgprot = canon_pgprot(pgprot); + while (num_pages-- && start < end) { set_pte(pte, pfn_pte(cpa->pfn, pgprot));