[PATCH 1/2] ntdll/tests: Check that creating huge thread stacks should work.

[Rémi Bernon]

On 5/7/21 1:58 PM, Rémi Bernon wrote:
> On 5/7/21 1:56 PM, Gabriel Ivăncescu wrote:
>> On 07/05/2021 14:44, Rémi Bernon wrote:
>>> On 5/7/21 1:38 PM, Gabriel Ivăncescu wrote:
>>>> On 07/05/2021 13:20, Rémi Bernon wrote:
>>>>> On 5/7/21 12:08 PM, Rémi Bernon wrote:
>>>>>> Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
>>>>>> ---
>>>>>>
>>>>>> I'm not completely sure what 789c1db18a4e192425da3771cac4726cda77130b
>>>>>> was for, but it seems to be causing spurious failures. This fix is
>>>>>> trying to keep the current behavior, but it may be better to 
>>>>>> completely
>>>>>> revert the commit as, although less likely, TEB allocation could also
>>>>>> fail much more often.
>>>>>>
>>>>>>   dlls/ntdll/tests/virtual.c | 10 ++++++++++
>>>>>>   1 file changed, 10 insertions(+)
>>>>>>
>>>>>> diff --git a/dlls/ntdll/tests/virtual.c b/dlls/ntdll/tests/virtual.c
>>>>>> index 8f5b0092bea..686b4076801 100644
>>>>>> --- a/dlls/ntdll/tests/virtual.c
>>>>>> +++ b/dlls/ntdll/tests/virtual.c
>>>>>> @@ -488,6 +488,11 @@ static DWORD WINAPI 
>>>>>> test_stack_size_thread(void *ptr)
>>>>>>       return 0;
>>>>>>   }
>>>>>> +static DWORD WINAPI test_stack_size_dummy_thread(void *ptr)
>>>>>> +{
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>>   static void test_RtlCreateUserStack(void)
>>>>>>   {
>>>>>>       IMAGE_NT_HEADERS *nt = RtlImageNtHeader( 
>>>>>> NtCurrentTeb()->Peb->ImageBaseAddress );
>>>>>> @@ -563,6 +568,11 @@ static void test_RtlCreateUserStack(void)
>>>>>>       thread = CreateThread(NULL, 0x3ff000, 
>>>>>> test_stack_size_thread, &args, STACK_SIZE_PARAM_IS_A_RESERVATION, 
>>>>>> NULL);
>>>>>>       WaitForSingleObject(thread, INFINITE);
>>>>>>       CloseHandle(thread);
>>>>>> +
>>>>>> +    thread = CreateThread(NULL, 0x80000000, 
>>>>>> test_stack_size_dummy_thread, NULL, 
>>>>>> STACK_SIZE_PARAM_IS_A_RESERVATION, NULL);
>>>>>> +    todo_wine ok(thread != NULL, "CreateThread with huge stack 
>>>>>> failed\n");
>>>>>> +    WaitForSingleObject(thread, INFINITE);
>>>>>> +    CloseHandle(thread);
>>>>>>   }
>>>>>>   static void test_NtMapViewOfSection(void)
>>>>>>
>>>>>
>>>>> Eh obviously that fails on 32bit. Anyway, I'm not sure at all about 
>>>>> the fix, it's maybe something related to allocations that should be 
>>>>> bottom-up by default?
>>>>
>>>> There's a wine-staging patch that does this and fixes some bugs:
>>>>
>>>> ntdll-ForceBottomUpAlloc
>>>>
>>>> Does it help? Also what happens on Windows if you force top-down 
>>>> allocation?
>>>
>>> It doesn't help with the regression, because we now forcefully limit 
>>> the address space where the thread stack / teb can be allocated.
>>>
>>> What I meant was that although I don't know why it's been added, and 
>>> if the reason was to make sure early threads are allocated on low 
>>> addresses, maybe making default allocation strategy bottom-up is the 
>>> correct fix (instead of trying to forcefully put them in the low 2G).
>>>
>>> I think that patch set has been sent already before but it was 
>>> considered a bit over complicated.
>>
>> Yeah, but if all allocations are forced bottom-up, not just the thread 
>> stack/TEB, then the staging patch should already fix this, implicitly.
>>
> 
> I think it makes things ever worse as more things will be allocated in 
> the low address space?
> 
>> An interesting thing is if you forced top-down allocation on Windows, 
>> do they get allocated in low 2G? Info here:
>>
>> https://tedwvc.wordpress.com/2013/07/16/porting-win32-code-to-64-bit-watch-out-for-pointers/ 
>>
>>
>> I think that would explain Windows behavior and whether it special 
>> cases them or not.
> 
> I don't understand, you can't control thread stack allocation strategy. 
> At least not using CreateThread.

Oh sorry, just reading that link now. I guess you can.
-- 
Rémi Bernon <rbernon at codeweavers.com>