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.

Tested-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c
index 6d49828..e25c2cc 100644 (file)
--- 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:
+                       break; /* Do nothing. */
                }
        }
 }

diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 755d91e..543ab2d 100644 (file)
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -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,