[OpenBIOS] sparc64's get_physical_address_code should not fault on TTE's with V=0
Jakub Jermar
jakub at jermar.eu
Mon Jan 12 23:03:48 CET 2009
Blue Swirl wrote:
> On 1/12/09, Jakub Jermar <jakub at jermar.eu> wrote:
>> Hi,
>>
>> when I make the following change to helper.c, get_physical_address_code:
>>
>> - // ctx match, vaddr match?
>> + // ctx match, vaddr match, valid?
>> if (env->dmmuregs[1] == (env->itlb_tag[i] & 0x1fff) &&
>> - (address & mask) == (env->itlb_tag[i] & ~0x1fffULL)) {
>> - // valid, access ok?
>> - if ((env->itlb_tte[i] & 0x8000000000000000ULL) == 0 ||
>> - ((env->itlb_tte[i] & 0x4) && is_user)) {
>> + (address & mask) == (env->itlb_tag[i] & ~0x1fffULL) &&
>> + env->itlb_tte[i] & 0x8000000000000000ULL) {
>> + // access ok?
>> + if ((env->itlb_tte[i] & 0x4) && is_user) {
>>
>> HelenOS gets a little bit further than without this change and seems
>> to panic more or less gracefully later.
>>
>> In short, non-valid entries should be skipped by the loop in
>> get_physical_address_code instead of causing TFAULT, because
>> the ITLB can contain a valid entry for the same address. The
>> same is true for DTLB.
>>
>> Can you confirm this?
>
> Yes, this looks correct. I'll apply a fix.
Thanks!
With this fix in place, HelenOS most of the time panics on:
Kernel panic: Cannot find property 'screen'.
I.e. it searches property 'screen' in /aliases and doesn't
find any. If it is not there already, could you please add
it (together with keyboard) to openbios?
Thanks,
Jakub
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