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| author | H.J. Lu <hjl.tools@gmail.com> | 2024-01-04 20:19:39 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2024-01-05 05:49:49 -0800 |
| commit | 848746e88ec2aa22e8dea25f2110e2b2c59c712e (patch) | |
| tree | 33db2fa3d1b4dc68fec06609cb6bacc4d680a38e /elf/dynamic-link.h | |
| parent | 520b1df08de68a3de328b65a25b86300a7ddf512 (diff) | |
| download | glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.tar.gz glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.tar.xz glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.zip | |
elf: Add ELF_DYNAMIC_AFTER_RELOC to rewrite PLT
Add ELF_DYNAMIC_AFTER_RELOC to allow target specific processing after relocation. For x86-64, add #define DT_X86_64_PLT (DT_LOPROC + 0) #define DT_X86_64_PLTSZ (DT_LOPROC + 1) #define DT_X86_64_PLTENT (DT_LOPROC + 3) 1. DT_X86_64_PLT: The address of the procedure linkage table. 2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage table. 3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table entry. With the r_addend field of the R_X86_64_JUMP_SLOT relocation set to the memory offset of the indirect branch instruction. Define ELF_DYNAMIC_AFTER_RELOC for x86-64 to rewrite the PLT section with direct branch after relocation when the lazy binding is disabled. PLT rewrite is disabled by default since SELinux may disallow modifying code pages and ld.so can't detect it in all cases. Use $ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1 to enable PLT rewrite with 32-bit direct jump at run-time or $ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2 to enable PLT rewrite with 32-bit direct jump and on APX processors with 64-bit absolute jump at run-time. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Diffstat (limited to 'elf/dynamic-link.h')
| -rw-r--r-- | elf/dynamic-link.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index 8cdf7bde09..83d834ecaf 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -177,6 +177,10 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], } \ } while (0); +# ifndef ELF_DYNAMIC_AFTER_RELOC +# define ELF_DYNAMIC_AFTER_RELOC(map, lazy) +# endif + /* This can't just be an inline function because GCC is too dumb to inline functions containing inlines themselves. */ # ifdef RTLD_BOOTSTRAP @@ -192,6 +196,7 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], ELF_DYNAMIC_DO_RELR (map); \ ELF_DYNAMIC_DO_REL ((map), (scope), edr_lazy, skip_ifunc); \ ELF_DYNAMIC_DO_RELA ((map), (scope), edr_lazy, skip_ifunc); \ + ELF_DYNAMIC_AFTER_RELOC ((map), (edr_lazy)); \ } while (0) #endif |