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authorJessica Yu <jeyu@kernel.org>2018-11-05 19:53:23 +0100
committerWill Deacon <will.deacon@arm.com>2018-11-20 11:38:26 +0000
commitc8ebf64eab743130fe404dc6679c2ff0cbc01615 (patch)
tree5fbae96f2dbb03d1ea65fa778ba96455c3ac4eab /arch/arm64/kernel/module-plts.c
parentc55191e96caa9d787e8f682c5e525b7f8172a3b4 (diff)
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.c36
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;