diff options
Diffstat (limited to 'arch/arm64/kernel/module-plts.c')
| -rw-r--r-- | arch/arm64/kernel/module-plts.c | 46 |
1 files changed, 43 insertions, 3 deletions
diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index 65b08a74aec6..0ce3a28e3347 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -253,6 +253,40 @@ static unsigned int count_plts(Elf64_Sym *syms, Elf64_Rela *rela, int num, return ret; } +static bool branch_rela_needs_plt(Elf64_Sym *syms, Elf64_Rela *rela, + Elf64_Word dstidx) +{ + + Elf64_Sym *s = syms + ELF64_R_SYM(rela->r_info); + + if (s->st_shndx == dstidx) + return false; + + return ELF64_R_TYPE(rela->r_info) == R_AARCH64_JUMP26 || + ELF64_R_TYPE(rela->r_info) == R_AARCH64_CALL26; +} + +/* Group branch PLT relas at the front end of the array. */ +static int partition_branch_plt_relas(Elf64_Sym *syms, Elf64_Rela *rela, + int numrels, Elf64_Word dstidx) +{ + int i = 0, j = numrels - 1; + + if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + return 0; + + while (i < j) { + if (branch_rela_needs_plt(syms, &rela[i], dstidx)) + i++; + else if (branch_rela_needs_plt(syms, &rela[j], dstidx)) + swap(rela[i], rela[j]); + else + j--; + } + + return i; +} + int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod) { @@ -290,7 +324,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, for (i = 0; i < ehdr->e_shnum; i++) { Elf64_Rela *rels = (void *)ehdr + sechdrs[i].sh_offset; - int numrels = sechdrs[i].sh_size / sizeof(Elf64_Rela); + int nents, numrels = sechdrs[i].sh_size / sizeof(Elf64_Rela); Elf64_Shdr *dstsec = sechdrs + sechdrs[i].sh_info; if (sechdrs[i].sh_type != SHT_RELA) @@ -300,8 +334,14 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, if (!(dstsec->sh_flags & SHF_EXECINSTR)) continue; - /* sort by type, symbol index and addend */ - sort(rels, numrels, sizeof(Elf64_Rela), cmp_rela, NULL); + /* + * sort branch relocations requiring a PLT by type, symbol index + * and addend + */ + nents = partition_branch_plt_relas(syms, rels, numrels, + sechdrs[i].sh_info); + if (nents) + sort(rels, nents, sizeof(Elf64_Rela), cmp_rela, NULL); if (!str_has_prefix(secstrings + dstsec->sh_name, ".init")) core_plts += count_plts(syms, rels, numrels, |