On 12.08.19 09:12, Thomas Huth wrote:
> On 8/5/19 5:29 PM, David Hildenbrand wrote:
>> Let's select the ASC before calling the function and use MMU_DATA_LOAD.
>> This is a preparation to:
>> - Remove the ASC magic depending on the access mode from mmu_translate
>> - Implement IEP support, where we could run into access exceptions
>> trying to fetch instructions
>>
>> Signed-off-by: David Hildenbrand <da...@redhat.com>
>> ---
>> target/s390x/helper.c | 10 +++++++++-
>> 1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/target/s390x/helper.c b/target/s390x/helper.c
>> index 13ae9909ad..08166558a0 100644
>> --- a/target/s390x/helper.c
>> +++ b/target/s390x/helper.c
>> @@ -58,7 +58,15 @@ hwaddr s390_cpu_get_phys_page_debug(CPUState *cs, vaddr
>> vaddr)
>> vaddr &= 0x7fffffff;
>> }
>>
>> - if (mmu_translate(env, vaddr, MMU_INST_FETCH, asc, &raddr, &prot,
>> false)) {
>> + /*
>> + * We want to read the code, however, not run into access exceptions
>
> Is this really a safe assumption here that we always use this to
> translate code addresses and not data addresses? ... I don't think so.
> For example with the "gva2gpa" HMP command, I'd rather expect that it
> also works with the secondary space mode...?
Well, it's what current code does. I am not changing that behavior.
While it is in general broken to have a single interface to debug
code+data (which is only a problem on s390x), it makes a lot of sense if
you think about single-stepping through disassembled code using the
gdbstub. Or dumping code where you crashed.
In Linux, code+data will luckily usually have the same virtual->physical
tables, so it's not a real issue.
>
> So maybe we need a proper MemTxAttrs bit or something similar for
> distinguishing instruction accesses from data accesses here?
There would first have to be a way to ask "get_phys_page_debug" to get
code or data for this to make sense. Right now we used it to get code.
Thanks.
--
Thanks,
David / dhildenb
