On Mon, Aug 17, 2015 at 02:19:34PM -0700, H.J. Lu wrote: > On Tue, Jun 23, 2015 at 9:18 PM, Rich Felker <dal...@libc.org> wrote: > > For background on the static PIE model I'm working with, see the > > following post to the GCC list: > > > > https://gcc.gnu.org/ml/gcc/2015-06/msg00008.html > > > > So far, I've been prototyping static PIE support by having GCC pass > > the following options to ld instead of -static -pie: > > > > -static -shared -Bsymbolic > > > > This partly works, but since ld does not know it's producing a main > > executable, it misses important details, including the ability to link > > initial-exec and local-exec model TLS code correctly, as well as > > various linking optimizations. So I think the right way forward is > > making ld accept -static and -pie together to do the right thing. > > > > In elflink.c, _bfd_elf_link_create_dynamic_sections assumes that > > executables should always have a .interp section. > > bfd_elf_size_dynamic_sections asserts this assumption again, and the > > individual elf??-*.c files also do so in *_elf_size_dynamic_sections > > where they set a default interpreter. (Is this even useful? Most of > > the names are out of touch with reality, and GCC always passes an > > explicit -dynamic-linker anyway, so I think this code should just be > > removed.) > > > > Now I have a working prototype by changing the info->executable > > condition to info->executable && info->dynamic, and having lexsup.c > > store the value of input_flags.dynamic in link_info.dynamic after > > processing the command line, but I'm not sure if this is the right > > approach. > > It is OK to use -static/-Bstatic/-non_shared with -shared and -pie. > I think you want --no-dynamic-linker.
I see two overall approaches to making the option to omit .interp: 1. In elflink.c, make the creation of the .interp section conditional on a new field in link_info. 2. In ld code (ldlang.c? elf32.em?), check the command line option and remove the .interp section before it can be processed. I think option 1 is a lot cleaner, but it's also going to be a lot more invasive, because every single target arch (elf32-*.c and elf64-*.c) has its own ASSERT that the .interp section exists. These would also need to be updated to either check the new field in link_info, or to replace the ASSERT with a conditional. Before I spend a lot of time implementing one or the other, do you have any feelings on which way would be appropriate? Rich
