x86: adjust vmalloc_sync_all() for Xen (2nd try)

Since the fourth PDPT entry cannot be shared under Xen,
vmalloc_sync_all() must iterate over pmd-s rather than pgd-s here.
Luckily, the code isn't used for native PAE (SHARED_KERNEL_PMD is 1)
and the change is benign to non-PAE.

Also do a little more cleanup in that function.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>

1 files changed, 6 insertions, 8 deletions

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 455f3fe67b42..356ed2dec3a6 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -915,15 +915,15 @@ LIST_HEAD(pgd_list);
 
 void vmalloc_sync_all(void)
 {
-#ifdef CONFIG_X86_32
-        unsigned long start = VMALLOC_START & PGDIR_MASK;
         unsigned long address;
 
+#ifdef CONFIG_X86_32
         if (SHARED_KERNEL_PMD)
                 return;
 
-        BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
-        for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
+        for (address = VMALLOC_START & PMD_MASK;
+             address >= TASK_SIZE && address < FIXADDR_TOP;
+             address += PMD_SIZE) {
                 unsigned long flags;
                 struct page *page;
 
@@ -936,10 +936,8 @@ void vmalloc_sync_all(void)
                 spin_unlock_irqrestore(&pgd_lock, flags);
         }
 #else /* CONFIG_X86_64 */
-        unsigned long start = VMALLOC_START & PGDIR_MASK;
-        unsigned long address;
-
-        for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
+        for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END;
+             address += PGDIR_SIZE) {
                 const pgd_t *pgd_ref = pgd_offset_k(address);
                 unsigned long flags;
                 struct page *page;