From 529c0f36d2dad7dd4bcec3815f821547d9e9643c Mon Sep 17 00:00:00 2001 From: Xi Ruoyao Date: Tue, 30 Aug 2022 18:48:05 +0800 Subject: [PATCH] LoongArch: Support PC-relative relocations in modules Binutils >= 2.40 uses R_LARCH_B26 instead of R_LARCH_SOP_PUSH_PLT_PCREL, and R_LARCH_PCALA* instead of R_LARCH_SOP_PUSH_PCREL. Handle R_LARCH_B26 and R_LARCH_PCALA* in the module loader. For R_LARCH_B26, also create a PLT entry as needed. Signed-off-by: Xi Ruoyao --- arch/loongarch/kernel/module-sections.c | 7 ++- arch/loongarch/kernel/module.c | 67 +++++++++++++++++++++++++ 2 files changed, 73 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c index 6d498288977d2a..c67b9cb220eb31 100644 --- a/arch/loongarch/kernel/module-sections.c +++ b/arch/loongarch/kernel/module-sections.c @@ -56,9 +56,14 @@ static void count_max_entries(Elf_Rela *relas, int num, unsigned int *plts) for (i = 0; i < num; i++) { type = ELF_R_TYPE(relas[i].r_info); - if (type == R_LARCH_SOP_PUSH_PLT_PCREL) { + switch (type) { + case R_LARCH_SOP_PUSH_PLT_PCREL: + case R_LARCH_B26: if (!duplicate_rela(relas, i)) (*plts)++; + break; + default: + /* Do nothing. */ } } } diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c index 755d91ef8d856d..c09ddbe5ed8bed 100644 --- a/arch/loongarch/kernel/module.c +++ b/arch/loongarch/kernel/module.c @@ -281,6 +281,71 @@ static int apply_r_larch_add_sub(struct module *mod, u32 *location, Elf_Addr v, } } +static int apply_r_larch_b26(struct module *mod, u32 *location, Elf_Addr v, + s64 *rela_stack, size_t *rela_stack_top, unsigned int type) +{ + ptrdiff_t offset = (void *)v - (void *)location; + union loongarch_instruction *insn = (union loongarch_instruction *)location; + + if (offset >= SZ_128M) + v = module_emit_plt_entry(mod, v); + + if (offset < -SZ_128M) + v = module_emit_plt_entry(mod, v); + + offset = (void *)v - (void *)location; + + if (offset & 3) { + pr_err("module %s: jump offset = 0x%llx unaligned! dangerous R_LARCH_B26 (%u) relocation\n", + mod->name, (long long)offset, type); + return -ENOEXEC; + } + + if (!signed_imm_check(offset, 28)) { + pr_err("module %s: jump offset = 0x%llx overflow! dangerous R_LARCH_B26 (%u) relocation\n", + mod->name, (long long)offset, type); + return -ENOEXEC; + } + + offset >>= 2; + insn->reg0i26_format.immediate_l = offset & 0xffff; + insn->reg0i26_format.immediate_h = (offset >> 16) & 0x3ff; + return 0; +} + +static int apply_r_larch_pcala(struct module *mod, u32 *location, Elf_Addr v, + s64 *rela_stack, size_t *rela_stack_top, unsigned int type) +{ + union loongarch_instruction *insn = (union loongarch_instruction *)location; + /* Use s32 for a sign-extension deliberately. */ + s32 offset_hi20 = (void *)((v + 0x800) & ~0xfff) - + (void *)((Elf_Addr)location & ~0xfff); + Elf_Addr anchor = (((Elf_Addr)location) & ~0xfff) + offset_hi20; + ptrdiff_t offset_rem = (void *)v - (void *)anchor; + + switch (type) { + case R_LARCH_PCALA_HI20: + v = offset_hi20 >> 12; + insn->reg1i20_format.immediate = v & 0xfffff; + break; + case R_LARCH_PCALA64_LO20: + v = offset_rem >> 32; + insn->reg1i20_format.immediate = v & 0xfffff; + break; + case R_LARCH_PCALA64_HI12: + v = offset_rem >> 52; + /* fall through */ + case R_LARCH_PCALA_LO12: + insn->reg2i12_format.immediate = v & 0xfff; + break; + default: + pr_err("%s: Unsupport relocation type %u\n", mod->name, type); + return -EINVAL; + } + + return 0; +} + /* * reloc_handlers_rela() - Apply a particular relocation to a module * @mod: the module to apply the reloc to @@ -310,6 +375,8 @@ static reloc_rela_handler reloc_rela_handlers[] = { [R_LARCH_SOP_SUB ... R_LARCH_SOP_IF_ELSE] = apply_r_larch_sop, [R_LARCH_SOP_POP_32_S_10_5 ... R_LARCH_SOP_POP_32_U] = apply_r_larch_sop_imm_field, [R_LARCH_ADD32 ... R_LARCH_SUB64] = apply_r_larch_add_sub, + [R_LARCH_B26] = apply_r_larch_b26, + [R_LARCH_PCALA_HI20...R_LARCH_PCALA64_HI12] = apply_r_larch_pcala, }; int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,