[PATCH 01/19] x86, mm: Align start address to correct big page size

[Yinghai Lu <yinghai@kernel.org>]

We are going to use buffer in BRK to pre-map page table buffer.

Page table buffer could be only page aligned, but range around it are
ram too, we could use bigger page to map it to avoid small pages.

We will adjust page_size_mask in next patch to use big page size for
small ram range.

Before that, this patch will make start address to be aligned down
according to bigger page size, otherwise entry in page page will
not have correct value.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 arch/x86/mm/init_32.c |    1 +
 arch/x86/mm/init_64.c |    5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 11a5800..27f7fc6 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -310,6 +310,7 @@ repeat:
 					__pgprot(PTE_IDENT_ATTR |
 						 _PAGE_PSE);
 
+				pfn &= PMD_MASK >> PAGE_SHIFT;
 				addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
 					PAGE_OFFSET + PAGE_SIZE-1;
 
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ab558eb..f40f383 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -461,7 +461,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
 			pages++;
 			spin_lock(&init_mm.page_table_lock);
 			set_pte((pte_t *)pmd,
-				pfn_pte(address >> PAGE_SHIFT,
+				pfn_pte((address & PMD_MASK) >> PAGE_SHIFT,
 					__pgprot(pgprot_val(prot) | _PAGE_PSE)));
 			spin_unlock(&init_mm.page_table_lock);
 			last_map_addr = next;
@@ -536,7 +536,8 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
 			pages++;
 			spin_lock(&init_mm.page_table_lock);
 			set_pte((pte_t *)pud,
-				pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
+				pfn_pte((addr & PUD_MASK) >> PAGE_SHIFT,
+					PAGE_KERNEL_LARGE));
 			spin_unlock(&init_mm.page_table_lock);
 			last_map_addr = next;
 			continue;
-- 
1.7.7