objtool: Handle different entry size of rodata

In the most cases, the entry size of rodata is 8 bytes because the
relocation type is 64 bit. There are also 32 bit relocation types,
the entry size of rodata should be 4 bytes in this case.

Add an arch-specific function arch_reloc_size() to assign the entry
size of rodata for x86, powerpc and LoongArch.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-3-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Author: seehearfeel

tools/objtool/arch/loongarch/decode.c

@@ -363,3 +363,14 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state)
 	state->cfa.base = CFI_SP;
 	state->cfa.offset = 0;
 }
+
+unsigned int arch_reloc_size(struct reloc *reloc)
+{
+	switch (reloc_type(reloc)) {
+	case R_LARCH_32:
+	case R_LARCH_32_PCREL:
+		return 4;
+	default:
+		return 8;
+	}
+}

tools/objtool/arch/powerpc/decode.c

@@ -106,3 +106,17 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state)
 	state->regs[CFI_RA].base = CFI_CFA;
 	state->regs[CFI_RA].offset = 0;
 }
+
+unsigned int arch_reloc_size(struct reloc *reloc)
+{
+	switch (reloc_type(reloc)) {
+	case R_PPC_REL32:
+	case R_PPC_ADDR32:
+	case R_PPC_UADDR32:
+	case R_PPC_PLT32:
+	case R_PPC_PLTREL32:
+		return 4;
+	default:
+		return 8;
+	}
+}

tools/objtool/arch/x86/decode.c

@@ -852,3 +852,16 @@ bool arch_is_embedded_insn(struct symbol *sym)
 	return !strcmp(sym->name, "retbleed_return_thunk") ||
 	       !strcmp(sym->name, "srso_safe_ret");
 }
+
+unsigned int arch_reloc_size(struct reloc *reloc)
+{
+	switch (reloc_type(reloc)) {
+	case R_X86_64_32:
+	case R_X86_64_32S:
+	case R_X86_64_PC32:
+	case R_X86_64_PLT32:
+		return 4;
+	default:
+		return 8;
+	}
+}

tools/objtool/check.c

@@ -1969,7 +1969,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 			break;
 
 		/* Make sure the table entries are consecutive: */
-		if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
+		if (prev_offset && reloc_offset(reloc) != prev_offset + arch_reloc_size(reloc))
 			break;
 
 		sym_offset = reloc->sym->offset + reloc_addend(reloc);

tools/objtool/include/objtool/arch.h

@@ -97,4 +97,6 @@ int arch_rewrite_retpolines(struct objtool_file *file);
 
 bool arch_pc_relative_reloc(struct reloc *reloc);
 
+unsigned int arch_reloc_size(struct reloc *reloc);
+
 #endif /* _ARCH_H */