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

[Vincenzo Frascino]

On 11/12/20 9:39 AM, Catalin Marinas wrote:
> 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.
> 

Could you please point out to which patch are you referring to?

-- 
Regards,
Vincenzo