[PATCH 28/39] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text()
- Date: Wed, 11 Jul 2018 13:29:35 +0200
- From: Joerg Roedel <joro@xxxxxxxxxx>
- Subject: [PATCH 28/39] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text()
From: Joerg Roedel <jroedel@xxxxxxx>
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@xxxxxxx>
arch/x86/mm/pti.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 4f6e933..fc77054 100644
@@ -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);