Re: [Qemu-devel] [PATCH v1] target/s390x: Add support for the TEST BLOCK instruction

[Thomas Huth <thuth@redhat.com>]

On 16.05.2017 21:06, Richard Henderson wrote:
> On 05/16/2017 02:28 AM, Thomas Huth wrote:
>> +void HELPER(testblock)(CPUS390XState *env, uint64_t addr)
>> +{
>> +    CPUState *cs = CPU(s390_env_get_cpu(env));
>> +    int i;
>> +
>> +    addr = get_address(env, 0, 0, addr) & ~0xfffULL;
>> +    for (i = 0; i < TARGET_PAGE_SIZE; i += 8) {
>> +        stq_phys(cs->as, addr + i, 0);
>> +    }
>> +    env->cc_op = 0;
>> +}
> 
> This needs several changes: check that the physical page does indeed
> exist, "low address protection", return the cc code.

Ok, ... but if we care about "low address protection", shouldn't we also
add that to the other CPU instructions, too? (As far as I can see, it is
not supported by the TCG code at all yet)

>> +DEF_HELPER_2(testblock, void, env, i64)
> 
> With cc returned, this becomes
> 
>   DEF_HELPER_FLAGS_2(testblock, TCG_CALL_NO_RWG, i32, env, i64)

Ok, thanks ... I'm still learning the details of writing TCG code ... ;-)

 Thomas