[PATCH 1/2] arm64: mm: detect bad __create_mapping uses
Mark Rutland
mark.rutland at arm.com
Fri Nov 20 07:35:23 PST 2015
If a caller of __create_mapping provides a PA and VA which have
different sub-page offsets, it is not clear which offset they expect to
apply to the mapping, and is indicative of a bad caller.
Disallow calls with differing sub-page offsets, and WARN when they are
encountered, so that we can detect and fix such cases.
Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Catalin Marinas <caralin.marinas at arm.com>
Cc: Laura Abbott <labbott at fedoraproject.org>
Cc: Steve Capper <steve.capper at linaro.org>
Cc: Will Deacon <will.deacon at arm.com>
---
arch/arm64/mm/mmu.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e3f563c..3b06afa 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -300,6 +300,13 @@ static void __create_mapping(struct mm_struct *mm, pgd_t *pgd,
{
unsigned long addr, length, end, next;
+ /*
+ * If the virtual and physical address don't have the same offset
+ * within a page, we cannot map the region as the caller expects.
+ */
+ if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
+ return;
+
addr = virt & PAGE_MASK;
length = PAGE_ALIGN(size + (virt & ~PAGE_MASK));
--
1.9.1
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