| From | Matt Fleming <> | Subject | [PATCH 03/13] x86/mm/pageattr: Use _PAGE_GLOBAL bit for EFI page table mappings | Date | Wed, 17 Feb 2016 12:35:56 +0000 |
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From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
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 <sai.praneeth.prakhya@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> --- arch/x86/mm/pageattr.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
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)); -- 2.6.2
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