diff options
| author | Dmitry Chestnykh <dm.chestnykh@gmail.com> | 2024-02-06 09:13:41 +0300 |
|---|---|---|
| committer | Waldemar Brodkorb <wbx@openadk.org> | 2024-02-07 13:47:28 +0100 |
| commit | 395f920c0a29dd565a66b268ea00fc444ae64086 (patch) | |
| tree | 78e0c6905d3f98b1e53c5c562dea9f99c4e69983 /ldso/include | |
| parent | 0fef8e7e0661daa17a9ca17b087f55dcb752b378 (diff) | |
ld.so: Add support of DT_RELR relocation format.
Nowadays modern libcs like Glibc and musl currently
support processing of RELATIVE relocations compressed
with DT_RELR format. However I have noticed that uClibc-ng
doesn't support this feature and if the source will be linked with
`-Wl,-z,pack-relative-relos` (bfd) or `-Wl,--pack-dyn-relocs=relr`
(lld) then ld.so cannot properly load the produced DSO.
This patch is intended to fix this issue and adds applying
of DT_RELR relative relocation.
Signed-off-by: Dmitry Chestnykh <dm.chestnykh@gmail.com>
Diffstat (limited to 'ldso/include')
| -rw-r--r-- | ldso/include/dl-elf.h | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h index 2b99958d9..7d514c0f5 100644 --- a/ldso/include/dl-elf.h +++ b/ldso/include/dl-elf.h @@ -250,5 +250,46 @@ unsigned int __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info (((X) & PF_W) ? PROT_WRITE : 0) | \ (((X) & PF_X) ? PROT_EXEC : 0)) +/* FDPIC ABI don't use relative relocations */ +#if !defined(__FDPIC__) +/* Apply relocations in DT_RELR format */ +#define DL_DO_RELOCATE_RELR(load_addr, relr_start, relr_end) \ + do { \ + const ElfW(Relr) *relr = 0; \ + ElfW(Addr) *reloc_addr = 0; \ + for (relr = relr_start; relr < relr_end; relr++) { \ + ElfW(Relr) relr_entry = *relr; \ + if (!(relr_entry & 1)) \ + { \ + reloc_addr = (ElfW(Addr) *)DL_RELOC_ADDR(load_addr, relr_entry); \ + *reloc_addr = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr); \ + reloc_addr++; \ + } \ + else \ + { \ + for (long int i = 0; (relr_entry >>= 1) != 0; ++i) { \ + if ((relr_entry & 1) != 0) \ + reloc_addr[i] = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr[i]); \ + } \ + reloc_addr += CHAR_BIT * sizeof(ElfW(Relr)) - 1; \ + } \ + } \ + } while (0); + +/* The macro to prepare data for the above DL_DO_RELOCATE_RELR */ +#define DL_RELOCATE_RELR(dyn) \ + do { \ + if (dyn->dynamic_info[DT_RELRENT]) \ + _dl_assert(dyn->dynamic_info[DT_RELRENT] == sizeof(ElfW(Relr))); \ + if (dyn->dynamic_info[DT_RELR] && \ + dyn->dynamic_info[DT_RELRSZ]) { \ + ElfW(Relr) *relr_start = (ElfW(Relr) *)((ElfW(Addr))dyn->loadaddr + (ElfW(Addr))dyn->dynamic_info[DT_RELR]); \ + ElfW(Relr) *relr_end = (ElfW(Relr) *)((const char *)relr_start + dyn->dynamic_info[DT_RELRSZ]); \ + _dl_if_debug_dprint("Relocating DT_RELR in %s: start:%p, end:%p\n", \ + dyn->libname, (void *)relr_start, (void *)relr_end); \ + DL_DO_RELOCATE_RELR(dyn->loadaddr, relr_start, relr_end); \ + } \ + } while (0); +#endif /* __FDPIC__ */ #endif /* _DL_ELF_H */ |