Re: [PATCH] arm:lpae: build TTB control register value from scratch in v7_ttb_setup
From: Robin Murphy
Date: Fri Aug 04 2017 - 06:05:03 EST
On 04/08/17 07:07, Hoeun Ryu wrote:
> Hello, Russell King.
> The following patch has not merged yet.
> Do you have a plan to accept and merge this patch ?
This should probably go through the ARM tree, so please submit it to
Russell's patch-tracking system here:
> Thank you.
> On Mon, 2017-06-12 at 10:47 +0900, Hoeun Ryu wrote:
>> Reading TTBCR in early boot stage might return the value of the previous
>> kernel's configuration, especially in case of kexec. For example, if
>> normal kernel (first kernel) had run on a configuration of PHYS_OFFSET <=
>> PAGE_OFFSET and crash kernel (second kernel) is running on a configuration
>> PHYS_OFFSET > PAGE_OFFSET, which can happen because it depends on the
>> reserved area for crash kernel, reading TTBCR and using the value to OR
>> other bit fields might be risky because it doesn't have a reset value for
>> Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
>> Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
>> Signed-off-by: Hoeun Ryu <hoeun.ryu@xxxxxxxxx>
>> * add Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
>> * v1: amended based on
>> - "[PATCHv2] arm: LPAE: kexec: clear TTBCR.T1SZ explicitly when
>> PHYS_OFFSET > PAGE_OFFSET"
>> - https://lkml.org/lkml/2017/6/5/239
>> arch/arm/mm/proc-v7-3level.S | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>> diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
>> index 5e5720e..7d16bbc 100644
>> --- a/arch/arm/mm/proc-v7-3level.S
>> +++ b/arch/arm/mm/proc-v7-3level.S
>> @@ -129,8 +129,7 @@ ENDPROC(cpu_v7_set_pte_ext)
>> .macro v7_ttb_setup, zero, ttbr0l, ttbr0h, ttbr1, tmp
>> ldr \tmp, =swapper_pg_dir @ swapper_pg_dir virtual address
>> cmp \ttbr1, \tmp, lsr #12 @ PHYS_OFFSET > PAGE_OFFSET?
>> - mrc p15, 0, \tmp, c2, c0, 2 @ TTB control egister
>> - orr \tmp, \tmp, #TTB_EAE
>> + mov \tmp, #TTB_EAE @ for TTB control egister
>> ALT_SMP(orr \tmp, \tmp, #TTB_FLAGS_SMP)
>> ALT_UP(orr \tmp, \tmp, #TTB_FLAGS_UP)
>> ALT_SMP(orr \tmp, \tmp, #TTB_FLAGS_SMP << 16)