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LoongArch: Support PC-relative relocations in modules

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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.

Tested-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Xi Ruoyao 2022-10-12 16:36:14 +08:00 committed by Huacai Chen
parent 0a75e5d1a1
commit 9bd1e38032
2 changed files with 75 additions and 1 deletions
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7
arch/loongarch/kernel/module-sections.c
View File

@ -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:
break; /* Do nothing. */
}
}
}

69
arch/loongarch/kernel/module.c
View File

@ -281,6 +281,73 @@ 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_LO12:
insn->reg2i12_format.immediate = v & 0xfff;
break;
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;
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 +377,8 @@ 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,