Re: [PATCH] ARM: decompressor: Flush tlb before swiching domain 0to client mode

From: Santosh Shilimkar
Date: Wed Dec 12 2012 - 05:09:36 EST

On Wednesday 12 December 2012 02:41 AM, Arve HjÃnnevÃg wrote:
If the bootloader used a page table that is incompatible with domain 0
in client mode, then swithing domain 0 to client mode causes a fault
if we don't flush the tlb after updating the page table pointer.

Signed-off-by: Arve HjÃnnevÃg <arve@xxxxxxxxxxx>
arch/arm/boot/compressed/head.S | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 90275f0..9c8034c 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -704,6 +704,7 @@ __armv7_mmu_cache_on:
bic r6, r6, #1 << 31 @ 32-bit translation system
bic r6, r6, #3 << 0 @ use only ttbr0
mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer
+ mcrne p15, 0, r0, c8, c7, 0 @ flush I,D TLBs
mcrne p15, 0, r1, c3, c0, 0 @ load domain access control
mcrne p15, 0, r6, c2, c0, 2 @ load ttb control

The TLB's are already flushed few lines above so above patching
shouldn't help if it was really dirty TLB entry issue. I suspect that
your boot-loader clean-up [1] function may not be taking care of
flushing caches which could potetially lead to the issue.

Have you checked that ?


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at