Re: [PATCH] arm:lpae: build TTB control register value from scratch in v7_ttb_setup
From: Hoeun Ryu
Date: Fri Aug 04 2017 - 02:12:28 EST
Hello, Russell King.
The following patch has not merged yet.
Do you have a plan to accept and merge this patch ?
On Mon, 2017-06-12 at 10:47 +0900, Hoeun Ryu wrote:
> ÂReading 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>
> Â* add Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> Â* v1: amended based on
> ÂÂÂÂÂ- "[PATCHv2] arm: LPAE: kexec: clear TTBCR.T1SZ explicitly when
> ÂÂÂÂÂÂÂÂPHYS_OFFSET > PAGE_OFFSET"
> ÂÂÂÂÂ- https://lkml.org/lkml/2017/6/5/239
> Âarch/arm/mm/proc-v7-3level.S | 3 +--
> Â1 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)
> Â .macro v7_ttb_setup, zero, ttbr0l, ttbr0h, ttbr1, tmp
> Â ldr \tmp, =swapper_pg_dir @ swapper_pg_dir virtual address
> Â 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
> Â ALT_SMP(orr \tmp, \tmp, #TTB_FLAGS_SMP)
> Â ALT_UP(orr \tmp, \tmp, #TTB_FLAGS_UP)
> Â ALT_SMP(orr \tmp, \tmp, #TTB_FLAGS_SMP << 16)