Re: [PATCH] aarch64: Check PIC instead of SHARED in start.S

["H.J. Lu" <hjl dot tools at gmail dot com>]

On 10/3/17, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
> On 03/10/17 11:39, Szabolcs Nagy wrote:
>> On 02/10/17 12:20, H.J. Lu wrote:
>>> On 10/2/17, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
>>>> On 29/09/17 22:32, H.J. Lu wrote:
>>>>> Since start.o may be compiled as PIC, we should check PIC instead of
>>>>> SHARED.
>>>>>
>>>>> OK for master?
>>>>>
>>>>
>>>> i believe that the compile/link tests worked..
>>>
>>> Does static PIE of hjl/pie/static branch run on arm and aarch64?
>>>
>>
>> no, if i build with --enable-static-pie the install step
>> fails when the static linked sln runs.
>>
>> there are relative relocs against the func ptrs that are
>> loaded from GOT in the startup code, but execution fails
>> even before those are used because there are R*_JUMP_SLOT
>> and R*_GLOB_DAT relocs which are not processed correctly.
>>
>> in particular in
>>   if (__pthread_initialize_minimal != NULL)
>>     __pthread_initialize_minimal ();
>> the symbol value loaded from GOT is non-NULL even though
>> there is no pthread linked in, that is probably a linker bug.
>>
>
> it seems weak extern symbol is accessed via got and at
> link time that is not relaxed to 0 with -static -pie
> and the got entry is not initialized to 0 either.

Please try the current hjl/pie/static branch.  I added Pcrt1.o to
to create static PIE.  There is no weak extern symbol anymore.
As long as there is no dynamic relocation before
_dl_relocate_static_pie relocates static PIE, it should work.

> as far as i can see the startup code and weak symbols
> are the remaining issues on aarch64 for static pie.
>
>


-- 
H.J.