Commit Graph

7 Commits

Author SHA1 Message Date
Fangrui Song cf783be8d7 Reland D114783/D115603 [ELF] Split scanRelocations into scanRelocations/postScanRelocations
(Fixed an issue about GOT on a copy relocated alias.)
(Fixed an issue about not creating r_addend=0 IRELATIVE for unreferenced non-preemptible ifunc.)

The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:

* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make GOT deduplication feasible
* Make parallel relocation scanning feasible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice

Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.

For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.

Reviewed By: peter.smith, ikudrin

Differential Revision: https://reviews.llvm.org/D114783
2021-12-14 16:28:41 -08:00
Fangrui Song ea15b862d7 Revert D114783 [ELF] Split scanRelocations into scanRelocations/postScanRelocations
May cause a failure for non-preemptible `bcmp` in a glibc -static link.
2021-12-14 14:33:50 -08:00
Fangrui Song e7a95b0674 Reland [ELF] Split scanRelocations into scanRelocations/postScanRelocations
(Fixed an issue about GOT on a copy relocated alias.)

The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:

* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make GOT deduplication feasible
* Make parallel relocation scanning feasible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice

Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.

For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.

Reviewed By: peter.smith, ikudrin

Differential Revision: https://reviews.llvm.org/D114783
2021-12-13 20:11:24 -08:00
Fangrui Song 0b8b86e30f Revert "[ELF] Split scanRelocations into scanRelocations/postScanRelocations"
This reverts commit fc33861d48.

`replaceWithDefined` should copy needsGot, otherwise an alias for a copy
relocated symbol may not have GOT entry if its needsGot was originally true.
2021-12-13 19:29:53 -08:00
Fangrui Song fc33861d48 [ELF] Split scanRelocations into scanRelocations/postScanRelocations
The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:

* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make parallel relocation scanning possible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice
* Make GOT deduplication feasible

Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.

For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.

Reviewed By: peter.smith, ikudrin

Differential Revision: https://reviews.llvm.org/D114783
2021-12-13 09:56:52 -08:00
Fangrui Song 40a9f2251b [ELF] Replace unused output filenames with /dev/null in tests
Post commit review at rLLD335992

llvm-svn: 336129
2018-07-02 17:48:23 +00:00
Rui Ueyama f9e8034c9c Add `-z nocopyreloc` option.
This option disable creating copy relocations. ld.bfd and ld.gold
have the same option.

llvm-svn: 295772
2017-02-21 21:41:50 +00:00