On Tue, Aug 18, 2015 at 08:56:00AM -0700, H.J. Lu wrote: > On Mon, Aug 17, 2015 at 8:44 PM, Rich Felker <dal...@libc.org> wrote: > > On Mon, Aug 17, 2015 at 10:42:56PM -0400, Rich Felker wrote: > >> 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? > > > > I went ahead and did option 1 modulo all the target code except sh > > which is where I'm testing it. My work-in-progress patch is attached. > > This is obviously not ready to submit but I would appreciate any > > feedback that's possible at this stage. > > + case OPTION_NO_DYNAMIC_LINKER: > + command_line.interpreter = NULL; > + link_info.nointerp = 1; > > No need to clear command_line.interpreter and please add a simple > testcase to verify it works correctly.
OK. Do I also need to update it to be against the new output_type stuff you just committed? Rich
