[PATCH v2 23/28] ARM: mmu: Make sure that address is 1M aligned in arm_create_pte()

[Andrey Smirnov]

If address passed arm_create_pte() is not 1M (PGDIR_SIZE) aligned,
page table that is created will end up having unexpected mapping
offset, breaking "1:1 mapping" assumption and leading to bugs that are
not immediately obvious in their nature.

To prevent this and because all of the callers already do said
alignement in-place, move the alignment code to be a part of
are_create_pte().

Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
 arch/arm/cpu/mmu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index eeab0a749..94388f11a 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -92,6 +92,8 @@ static u32 *arm_create_pte(unsigned long virt, uint32_t flags)
 	u32 *table;
 	int i;
 
+	virt = ALIGN_DOWN(virt, PGDIR_SIZE);
+
 	table = xmemalign(PTRS_PER_PTE * sizeof(u32),
 			  PTRS_PER_PTE * sizeof(u32));
 
@@ -291,8 +293,7 @@ static void create_vector_table(unsigned long adr)
 		vectors = xmemalign(PAGE_SIZE, PAGE_SIZE);
 		pr_debug("Creating vector table, virt = 0x%p, phys = 0x%08lx\n",
 			 vectors, adr);
-		exc = arm_create_pte(ALIGN_DOWN(adr, PGDIR_SIZE),
-				     pte_flags_uncached);
+		exc = arm_create_pte(adr, pte_flags_uncached);
 		idx = (adr & (PGDIR_SIZE - 1)) >> PAGE_SHIFT;
 		exc[idx] = (u32)vectors | PTE_TYPE_SMALL | pte_flags_cached;
 	}
-- 
2.17.0