On 25.09.19 21:25, Richard Henderson wrote:
> On 9/25/19 5:52 AM, David Hildenbrand wrote:
>> +static inline int read_table_entry(hwaddr gaddr, uint64_t *entry)
>> +{
>> + /*
>> + * According to the PoP, these table addresses are "unpredictably real
>> + * or absolute". Also, "it is unpredictable whether the address wraps
>> + * or an addressing exception is recognized".
>> + *
>> + * We treat them as absolute addresses and don't wrap them.
>> + */
>> + if (unlikely(address_space_read(&address_space_memory, gaddr,
>> + MEMTXATTRS_UNSPECIFIED, (uint8_t *)entry, sizeof(*entry))
>> !=
>> + MEMTX_OK)) {
>> + return -EFAULT;
>> + }
>> + *entry = be64_to_cpu(*entry);
>> + return 0;
>> +}
>
> Maybe I've been away from the kernel too long, but I don't find returning
> -EFAULT helpful. I would return true/false for success/failure so that...
>
>
>> + if (read_table_entry(origin + offs, &pt_entry)) {
>> + return PGM_ADDRESSING;
>> + }
>
> ... this gets written
>
> if (!read_table_entry(...)) {
> return PGM_ADDRESSING;
> }
>
> This statement, to me, reads "If we did not read_table_entry, return an
> addressing exception."
>
> If you *really* want to return non-zero on failure, I would prefer returning
> PGM_ADDRESSING instead of the out-of-context -EFAULT.
I'll go for your suggestion with a bool!
>
>> - new_entry = ldq_phys(cs->as, origin + offs);
>> + if (read_table_entry(origin + offs, &new_entry)) {
>
> Do you really want to replace cs->as with address_space_memory?
>
I guess it shouldn't make a difference (unless I am missing something),
but I can just keep using cs->as.
Thanks!
>
> r~
>
--
Thanks,
David / dhildenb
