Subject: Re: [PATCH v9 32/44] arm64: mte: Switch GCR_EL1 in kernel entry and exit

From: Catalin Marinas <[email-masked]>
Date: Thu, 12 Nov 2020 09:39:09 +0000

On Tue, Nov 10, 2020 at 11:10:29PM +0100, Andrey Konovalov wrote:
> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
> index 664c968dc43c..dbda6598c19d 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -129,6 +131,26 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
>  	return ptr;
>  }
>  
> +void mte_init_tags(u64 max_tag)
> +{
> +	static bool gcr_kernel_excl_initialized = false;
> +
> +	if (!gcr_kernel_excl_initialized) {
> +		/*
> +		 * The format of the tags in KASAN is 0xFF and in MTE is 0xF.
> +		 * This conversion extracts an MTE tag from a KASAN tag.
> +		 */
> +		u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT,
> +					     max_tag), 0);
> +
> +		gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK;
> +		gcr_kernel_excl_initialized = true;
> +	}
> +
> +	/* Enable the kernel exclude mask for random tags generation. */
> +	write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1);
> +}

I don't think this function belongs to this patch. There is an earlier
patch that talks about mte_init_tags() but no trace of it until this
patch.

-- 
Catalin

_______________________________________________
linux-arm-kernel mailing list
[email-masked]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel