[Skiboot] [PATCH skiboot] phb3: Deprecate reading the PHB status

[Alexey Kardashevskiy]

On 10/01/2019 12:03, Andrew Donnellan wrote:
> On 10/1/19 11:50 am, Alexey Kardashevskiy wrote:
>> The OPAL_PCI_EEH_FREEZE_STATUS call takes a bunch of parameters, one of
>> them is @phb_status. It is defined as __be64* and always NULL in
>> the current Linux upstream but if anyone ever decides to read that
>> status,
>> then the PHB3's handler will assume it is struct OpalIoPhb3ErrorData*
>> (which is a lot bigger than 8 bytes) and zero it causing the stack
>> corruption.
>>
>> This makes @phb_status deprecated by copying the error message from PHB4.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> 
> Looks like p7ioc does the same thing. If the API is obviously wrong
> here, should we move the deprecation warning to core/pci-opal.c and just
> get rid of phb_status from the internal API?


May be. I am just not so sure how Stewart deprecates things in skiboot
exactly :)


> 
>> ---
>>   hw/phb3.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/hw/phb3.c b/hw/phb3.c
>> index 771ccfc..38b8f46 100644
>> --- a/hw/phb3.c
>> +++ b/hw/phb3.c
>> @@ -2772,8 +2772,7 @@ static int64_t phb3_eeh_freeze_status(struct phb
>> *phb, uint64_t pe_number,
>>     bail:
>>       if (phb_status)
>> -        phb3_read_phb_status(p,
>> -            (struct OpalIoPhb3ErrorData *)phb_status);
>> +        PHBERR(p, "%s: deprecated PHB status\n", __func__);
>>         return OPAL_SUCCESS;
>>   }
>>
> 

-- 
Alexey