ARM: pxa: fix page table corruption on resume

Before this patch, the following error would sometimes occur after a
resume on pxa3xx:

    /path/to/mm/memory.c:144: bad pmd 8040542e.

The problem was that a temporary page table mapping was being improperly
restored.

The PXA3xx resume code creates a temporary mapping of resume_turn_on_mmu
to avoid a prefetch abort.  The pxa3xx_resume_after_mmu code requires
that the r1 register holding the address of this mapping not be
modified, however, resume_turn_on_mmu does modify it. It is mostly
correct in that r1 receives the base table address, but it may also
get other bits in 13:0.  This results in pxa3xx_resume_after_mmu
restoring the original mapping to the wrong place, corrupting memory
and leaving the temporary mapping in place.

Signed-off-by: Matt Reimer <mreimer@sdgsystems.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

diff --git a/arch/arm/mach-pxa/sleep.S b/arch/arm/mach-pxa/sleep.S
index 52c30b0..ae00811 100644 (file)
--- a/arch/arm/mach-pxa/sleep.S
+++ b/arch/arm/mach-pxa/sleep.S
@@ -353,8 +353,8 @@ resume_turn_on_mmu:
 
        @ Let us ensure we jump to resume_after_mmu only when the mcr above
        @ actually took effect.  They call it the "cpwait" operation.
-       mrc     p15, 0, r1, c2, c0, 0           @ queue a dependency on CP15
-       sub     pc, r2, r1, lsr #32             @ jump to virtual addr
+       mrc     p15, 0, r0, c2, c0, 0           @ queue a dependency on CP15
+       sub     pc, r2, r0, lsr #32             @ jump to virtual addr
        nop
        nop
        nop