[PATCH 2/3] x86/mm/pti: Don't clear permissions in pti_clone_pmd()

[Joerg Roedel]

From: Joerg Roedel <jroe...@suse.de>

The function sets the global-bit on cloned PMD entries,
which only makes sense when the permissions are identical
between the user and the kernel page-table.

Further, only write-permissions are cleared for entry-text
and kernel-text sections, which are not writeable anyway.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 arch/x86/mm/pti.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 113ba14..5164c98 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -291,7 +291,7 @@ static void __init pti_setup_vsyscall(void) { }
 #endif
 
 static void
-pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
+pti_clone_pmds(unsigned long start, unsigned long end)
 {
        unsigned long addr;
 
@@ -352,7 +352,7 @@ pti_clone_pmds(unsigned long start, unsigned long end, 
pmdval_t clear)
                 * tables will share the last-level page tables of this
                 * address range
                 */
-               *target_pmd = pmd_clear_flags(*pmd, clear);
+               *target_pmd = *pmd;
        }
 }
 
@@ -398,7 +398,7 @@ static void __init pti_clone_user_shared(void)
        start = CPU_ENTRY_AREA_BASE;
        end   = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES);
 
-       pti_clone_pmds(start, end, 0);
+       pti_clone_pmds(start, end);
 }
 #endif /* CONFIG_X86_64 */
 
@@ -418,8 +418,7 @@ static void __init pti_setup_espfix64(void)
 static void pti_clone_entry_text(void)
 {
        pti_clone_pmds((unsigned long) __entry_text_start,
-                       (unsigned long) __irqentry_text_end,
-                      _PAGE_RW);
+                      (unsigned long) __irqentry_text_end);
 }
 
 /*
@@ -501,7 +500,7 @@ static void pti_clone_kernel_text(void)
         * pti_set_kernel_image_nonglobal() did to clear the
         * global bit.
         */
-       pti_clone_pmds(start, end_clone, _PAGE_RW);
+       pti_clone_pmds(start, end_clone);
 
        /*
         * pti_clone_pmds() will set the global bit in any PMDs
-- 
2.7.4