PATCH: PR ld/10270: IFUNC local symbol

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

On Fri, Jun 12, 2009 at 11:01 PM, Ulrich Drepper<drepper@redhat.com> wrote:
>
>> The other issue can be seen with:
>> gcc -O2 -fpic -shared -o ifunc3lib1.{so,c}
>> gcc -O2 -o ifunc3 ./ifunc3lib1.so
>> ./ifunc3lib1
>> Here, &lib1t3 in the binary resolves to a .plt slot in the binary, while
>> &lib1t3 in the shared library resolves to the actual address the ifunc
>> returned.
>> Not sure what exactly we want to do here, but the function pointers should
>> be the same.
>
> It's tricky alright. ?There really isn't a good answer for this. ?The
> existing behavior is the only sensible solution. ?One could try to make
> things more complicated by changing the linker to associate the symbol
> with the PLT slot and somehow allow ld.so to recognize such symbols, but
> I think it's not worth it.
>
> This all comes about only because IFUNCs are used in situations where
> they really were not meant to be used. ?IFUNC are supposed to be
> definitions in DSOs which can be used in place of FUNC symbols. ?This
> will work without changes to any semantics.
>
> In your test case you're creating and IFUNC symbol in the executable.
> While I have no problem with supporting it this does mean the program
> author take responsibility for doing this. ?I think we can in this case
> very well live with the difference in function addresses.
>
> Therefore I suggest to leave this case and just document it.
>

Hi,

I am checking in this patch to disallow dynamic IFUNC pointer in
non-shared object.


-- 
H.J.
---
bfd/

2009-06-14  H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/10270
	* elf32-i386.c (elf_i386_allocate_dynrelocs): Disallow
	dynamic IFUNC pointer in non-shared object.  Use .got.plt
	for IFUNC definition in PIE.
	(elf_i386_allocate_dynrelocs): Resolve IFUNC definition in
	PIE locally.

	* elf64-x86-64.c (elf64_x86_64_allocate_dynrelocs): Disallow
	dynamic IFUNC pointer in non-shared object.  Use .got.plt
	for IFUNC definition in PIE.
	(elf64_x86_64_relocate_section): Resolve IFUNC definition in
	PIE locally.

ld/testsuite/

2009-06-14  H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/10270
	* ld-ifunc/ifunc-9-x86.d: New.
	* ld-ifunc/ifunc-9-x86.s: Likewise.

Attachment: ld-pr10270-2.patch
Description: Text document