Re: [PATCH for-8.2 0/4] rtc devices: Avoid putting time_t in 32-bit variables

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 21/7/23 11:46, Peter Maydell wrote:
> On Fri, 21 Jul 2023 at 10:16, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>>
>> Hi Peter,
>>
>> On 20/7/23 17:58, Peter Maydell wrote:
>>> This patchset was prompted by a couple of Coverity warnings
>>> (CID 1507157, 1517772) which note that in the m48t59 RTC device model
>>> we keep an offset in a time_t variable but then truncate it by
>>> passing it to qemu_get_timedate(), which currently uses an 'int'
>>> argument for its offset parameter.
>>>
>>> We can fix the Coverity complaint by making qemu_get_timedate()
>>> take a time_t; we should also correspondingly make the
>>> qemu_timedate_diff() function return a time_t. However this
>>> will only push the issue out to callers of qemu_timedate_diff()
>>> if they are putting the result in a 32-bit variable or doing
>>> 32-bit arithmetic on it.
>>>
>>> Luckily there aren't that many callers of qemu_timedate_diff()
>>> and most of them already use either time_t or int64_t for the
>>> calculations they do on its return value. The first three
>>> patches fix devices which weren't doing that; patch four then
>>> fixes the rtc.c functions. If I missed any callsites in devices
>>> then hopefully Coverity will point them out.
>>
>> PL031State::tick_offset is uint32_t, and pl031_get_count() also
>> returns that type. Is that expected?
> 
> I think those fall into the category of "the device we are
> modelling does not support 64-bit timestamps" -- the PL031
> RTC_DR register is only 32 bits.

Good, thanks for confirming.