Re: [PATCH v4 27/39] arm64: kasan: Enable in-kernel MTE

From: Catalin Marinas
Date: Fri Oct 02 2020 - 10:00:25 EST


On Fri, Oct 02, 2020 at 01:10:28AM +0200, Andrey Konovalov wrote:
> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> index 23c326a06b2d..6c1a6621d769 100644
> --- a/arch/arm64/mm/proc.S
> +++ b/arch/arm64/mm/proc.S
> @@ -40,9 +40,15 @@
> #define TCR_CACHE_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA
>
> #ifdef CONFIG_KASAN_SW_TAGS
> -#define TCR_KASAN_FLAGS TCR_TBI1
> +#define TCR_KASAN_SW_FLAGS TCR_TBI1
> #else
> -#define TCR_KASAN_FLAGS 0
> +#define TCR_KASAN_SW_FLAGS 0
> +#endif
> +
> +#ifdef CONFIG_KASAN_HW_TAGS
> +#define TCR_KASAN_HW_FLAGS SYS_TCR_EL1_TCMA1
> +#else
> +#define TCR_KASAN_HW_FLAGS 0
> #endif
>
> /*
> @@ -427,6 +433,10 @@ SYM_FUNC_START(__cpu_setup)
> */
> mov_q x5, MAIR_EL1_SET
> #ifdef CONFIG_ARM64_MTE
> + mte_tcr .req x20
> +
> + mov mte_tcr, #0
> +
> /*
> * Update MAIR_EL1, GCR_EL1 and TFSR*_EL1 if MTE is supported
> * (ID_AA64PFR1_EL1[11:8] > 1).
> @@ -447,6 +457,9 @@ SYM_FUNC_START(__cpu_setup)
> /* clear any pending tag check faults in TFSR*_EL1 */
> msr_s SYS_TFSR_EL1, xzr
> msr_s SYS_TFSRE0_EL1, xzr
> +
> + /* set the TCR_EL1 bits */
> + mov_q mte_tcr, TCR_KASAN_HW_FLAGS
> 1:
> #endif
> msr mair_el1, x5
> @@ -456,7 +469,11 @@ SYM_FUNC_START(__cpu_setup)
> */
> mov_q x10, TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
> TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
> - TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
> + TCR_TBI0 | TCR_A1 | TCR_KASAN_SW_FLAGS
> +#ifdef CONFIG_ARM64_MTE
> + orr x10, x10, mte_tcr
> + .unreq mte_tcr
> +#endif

Don't we miss the TBI1 bit here? I think the v3 version of this patch
was better.

--
Catalin