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[28/39] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text()

Message ID 1531906876-13451-29-git-send-email-joro@8bytes.org (mailing list archive)
State New, archived
Headers show

Commit Message

Joerg Roedel July 18, 2018, 9:41 a.m. UTC
From: Joerg Roedel <jroedel@suse.de>

Mapping the kernel text area to user-space makes only sense
if it has the same permissions as in the kernel page-table.
If permissions are different this will cause a TLB reload
when using the kernel page-table, which is as good as not
mapping it at all.

On 64-bit kernels this patch makes no difference, as the
whole range cloned by pti_clone_kernel_text() is mapped RO
anyway. On 32 bit there are writeable mappings in the range,
so just keep the permissions as they are.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
 arch/x86/mm/pti.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 4f6e933..fc77054 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -482,7 +482,7 @@  void pti_clone_kernel_text(void)
 	 * pti_set_kernel_image_nonglobal() did to clear the
 	 * global bit.
-	pti_clone_pmds(start, end, _PAGE_RW);
+	pti_clone_pmds(start, end, 0);