diff options
author | Jessica Yu <jeyu@kernel.org> | 2018-11-05 19:53:23 +0100 |
---|---|---|
committer | Will Deacon <will.deacon@arm.com> | 2018-11-20 11:38:26 +0000 |
commit | c8ebf64eab743130fe404dc6679c2ff0cbc01615 (patch) | |
tree | 5fbae96f2dbb03d1ea65fa778ba96455c3ac4eab /arch/arm64/kernel/module-plts.c | |
parent | c55191e96caa9d787e8f682c5e525b7f8172a3b4 (diff) | |
download | linux-c8ebf64eab743130fe404dc6679c2ff0cbc01615.tar.bz2 |
arm64/module: use plt section indices for relocations
Instead of saving a pointer to the .plt and .init.plt sections to apply
plt-based relocations, save and use their section indices instead.
The mod->arch.{core,init}.plt pointers were problematic for livepatch
because they pointed within temporary section headers (provided by the
module loader via info->sechdrs) that would be freed after module load.
Since livepatch modules may need to apply relocations post-module-load
(for example, to patch a module that is loaded later), using section
indices to offset into the section headers (instead of accessing them
through a saved pointer) allows livepatch modules on arm64 to pass in
their own copy of the section headers to apply_relocate_add() to apply
delayed relocations.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/module-plts.c')
-rw-r--r-- | arch/arm64/kernel/module-plts.c | 36 |
1 files changed, 20 insertions, 16 deletions
diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index f0690c2ca3e0..a0efe30211d6 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -16,12 +16,13 @@ static bool in_init(const struct module *mod, void *loc) return (u64)loc - (u64)mod->init_layout.base < mod->init_layout.size; } -u64 module_emit_plt_entry(struct module *mod, void *loc, const Elf64_Rela *rela, +u64 module_emit_plt_entry(struct module *mod, Elf64_Shdr *sechdrs, + void *loc, const Elf64_Rela *rela, Elf64_Sym *sym) { struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core : &mod->arch.init; - struct plt_entry *plt = (struct plt_entry *)pltsec->plt->sh_addr; + struct plt_entry *plt = (struct plt_entry *)sechdrs[pltsec->plt_shndx].sh_addr; int i = pltsec->plt_num_entries; u64 val = sym->st_value + rela->r_addend; @@ -43,11 +44,12 @@ u64 module_emit_plt_entry(struct module *mod, void *loc, const Elf64_Rela *rela, } #ifdef CONFIG_ARM64_ERRATUM_843419 -u64 module_emit_veneer_for_adrp(struct module *mod, void *loc, u64 val) +u64 module_emit_veneer_for_adrp(struct module *mod, Elf64_Shdr *sechdrs, + void *loc, u64 val) { struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core : &mod->arch.init; - struct plt_entry *plt = (struct plt_entry *)pltsec->plt->sh_addr; + struct plt_entry *plt = (struct plt_entry *)sechdrs[pltsec->plt_shndx].sh_addr; int i = pltsec->plt_num_entries++; u32 mov0, mov1, mov2, br; int rd; @@ -202,7 +204,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, unsigned long core_plts = 0; unsigned long init_plts = 0; Elf64_Sym *syms = NULL; - Elf_Shdr *tramp = NULL; + Elf_Shdr *pltsec, *tramp = NULL; int i; /* @@ -211,9 +213,9 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, */ for (i = 0; i < ehdr->e_shnum; i++) { if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) - mod->arch.core.plt = sechdrs + i; + mod->arch.core.plt_shndx = i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) - mod->arch.init.plt = sechdrs + i; + mod->arch.init.plt_shndx = i; else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && !strcmp(secstrings + sechdrs[i].sh_name, ".text.ftrace_trampoline")) @@ -222,7 +224,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, syms = (Elf64_Sym *)sechdrs[i].sh_addr; } - if (!mod->arch.core.plt || !mod->arch.init.plt) { + if (!mod->arch.core.plt_shndx || !mod->arch.init.plt_shndx) { pr_err("%s: module PLT section(s) missing\n", mod->name); return -ENOEXEC; } @@ -254,17 +256,19 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, sechdrs[i].sh_info, dstsec); } - mod->arch.core.plt->sh_type = SHT_NOBITS; - mod->arch.core.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC; - mod->arch.core.plt->sh_addralign = L1_CACHE_BYTES; - mod->arch.core.plt->sh_size = (core_plts + 1) * sizeof(struct plt_entry); + pltsec = sechdrs + mod->arch.core.plt_shndx; + pltsec->sh_type = SHT_NOBITS; + pltsec->sh_flags = SHF_EXECINSTR | SHF_ALLOC; + pltsec->sh_addralign = L1_CACHE_BYTES; + pltsec->sh_size = (core_plts + 1) * sizeof(struct plt_entry); mod->arch.core.plt_num_entries = 0; mod->arch.core.plt_max_entries = core_plts; - mod->arch.init.plt->sh_type = SHT_NOBITS; - mod->arch.init.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC; - mod->arch.init.plt->sh_addralign = L1_CACHE_BYTES; - mod->arch.init.plt->sh_size = (init_plts + 1) * sizeof(struct plt_entry); + pltsec = sechdrs + mod->arch.init.plt_shndx; + pltsec->sh_type = SHT_NOBITS; + pltsec->sh_flags = SHF_EXECINSTR | SHF_ALLOC; + pltsec->sh_addralign = L1_CACHE_BYTES; + pltsec->sh_size = (init_plts + 1) * sizeof(struct plt_entry); mod->arch.init.plt_num_entries = 0; mod->arch.init.plt_max_entries = init_plts; |