Re: [PATCH v2 1/6] linux-user/aarch64: Extend PR_SET_TAGGED_ADDR_CTRL for FEAT_MTE3

[Richard Henderson <richard.henderson@linaro.org>]

On 2/7/24 00:23, Peter Maydell wrote:
>> +++ b/linux-user/aarch64/target_prctl.h
>> @@ -173,21 +173,22 @@ static abi_long do_prctl_set_tagged_addr_ctrl(CPUArchState *env, abi_long arg2)
>>       env->tagged_addr_enable = arg2 & PR_TAGGED_ADDR_ENABLE;
>>
>>       if (cpu_isar_feature(aa64_mte, cpu)) {
>> -        switch (arg2 & PR_MTE_TCF_MASK) {
>> -        case PR_MTE_TCF_NONE:
>> -        case PR_MTE_TCF_SYNC:
>> -        case PR_MTE_TCF_ASYNC:
>> -            break;
>> -        default:
>> -            return -EINVAL;
>> -        }
> 
> We should probably check here and reject unknown bits being
> set in arg2, as set_tagged_addr_ctrl() does; but the old
> code didn't get that right either.

This is done higher up in this function:

     if (arg2 & ~valid_mask) {
         return -TARGET_EINVAL;
     }

The rejection of ASYNC | SYNC here was either a bug in my original implementation, or the 
kernel API changed since the initial implementation in June 2020 (not worth digging to 
find out).


r~