Re: [PATCH v2 2/6] gdbserver: Add PID parameter to linux_get_auxv and linux_get_hwcap

[Simon Marchi <simark@simark.ca>]

On 11/28/22 06:50, Luis Machado via Gdb-patches wrote:
> Hi,
> 
> On 11/26/22 02:04, Thiago Jung Bauermann wrote:
>> This patch doesn't change gdbserver behaviour, but after later changes are
>> made it avoids a null pointer dereference when HWCAP needs to be obtained
>> for a specific process while current_thread is nullptr.
>>
>> Fixing linux_read_auxv, linux_get_hwcap and linux_get_hwcap2 to take a PID
>> parameter seems more correct than setting current_thread in one particular
>> code path.
> 
> I'm wondering if passing the pid is needed at all in gdbserver for the purposes of fetching the hwcap entries from auxv.
> 
> While current thread can be nullptr, I suppose current_process will never be nullptr if we have a valid inferior. And the auxv entries are per-process rather than per-thread.
> 
> There is a bit of a corner case when we have extended-remote without a live process and we need to fetch the hwcap bits to determine a particular feature to report via qSupported. But I suppose this is not what this change is trying to address, is it?
> 
> If not, it may be the case that we don't need these changes, and we can just use current_process.

Even if we could just use current_process, this patch is going in the
general direction I like, which is to reduce referring to the global
state everywhere, try to fetch it only at the entry points and then pass
the necessary context down by parameters.

Simon