diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/arm64/kernel/module-plts.c | 56 |
1 files changed, 48 insertions, 8 deletions
diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index 65b08a74aec6..5a0a8f552a61 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -37,7 +37,8 @@ struct plt_entry get_plt_entry(u64 dst, void *pc) return plt; } -bool plt_entries_equal(const struct plt_entry *a, const struct plt_entry *b) +static bool plt_entries_equal(const struct plt_entry *a, + const struct plt_entry *b) { u64 p, q; @@ -131,7 +132,7 @@ u64 module_emit_veneer_for_adrp(struct module *mod, Elf64_Shdr *sechdrs, } #endif -#define cmp_3way(a,b) ((a) < (b) ? -1 : (a) > (b)) +#define cmp_3way(a, b) ((a) < (b) ? -1 : (a) > (b)) static int cmp_rela(const void *a, const void *b) { @@ -220,7 +221,7 @@ static unsigned int count_plts(Elf64_Sym *syms, Elf64_Rela *rela, int num, * increasing the section's alignment so that the * resulting address of this instruction is guaranteed * to equal the offset in that particular bit (as well - * as all less signficant bits). This ensures that the + * as all less significant bits). This ensures that the * address modulo 4 KB != 0xfff8 or 0xfffc (which would * have all ones in bits [11:3]) */ @@ -253,6 +254,40 @@ 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) { @@ -271,8 +306,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, mod->arch.core.plt_shndx = i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) mod->arch.init.plt_shndx = i; - else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && - !strcmp(secstrings + sechdrs[i].sh_name, + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".text.ftrace_trampoline")) tramp = sechdrs + i; else if (sechdrs[i].sh_type == SHT_SYMTAB) @@ -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, |