LoongArch: Support R_LARCH_GOT_PC_{LO12,HI20} in modules

GCC >= 13 and GNU assembler >= 2.40 use these relocations to address
external symbols, so we need to add them.

Let the module loader emit GOT entries for data symbols so we would be
able to handle GOT relocations. The GOT entry is just the data's symbol
address.

In module.lds, emit a stub .got section for a section header entry. The
actual content of the section entry will be filled at runtime by module_
frob_arch_sections().

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

2 files changed, 26 insertions, 2 deletions

diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include/asm/module.h
index 9f6718df1854..b29b19a46f42 100644
--- a/arch/loongarch/include/asm/module.h
+++ b/arch/loongarch/include/asm/module.h
@@ -17,10 +17,15 @@ struct mod_section {
 };
 
 struct mod_arch_specific {
+	struct mod_section got;
 	struct mod_section plt;
 	struct mod_section plt_idx;
 };
 
+struct got_entry {
+	Elf_Addr symbol_addr;
+};
+
 struct plt_entry {
 	u32 inst_lu12iw;
 	u32 inst_lu32id;
@@ -29,10 +34,16 @@ struct plt_entry {
 };
 
 struct plt_idx_entry {
-	unsigned long symbol_addr;
+	Elf_Addr symbol_addr;
 };
 
-Elf_Addr module_emit_plt_entry(struct module *mod, unsigned long val);
+Elf_Addr module_emit_got_entry(struct module *mod, Elf_Addr val);
+Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Addr val);
+
+static inline struct got_entry emit_got_entry(Elf_Addr val)
+{
+	return (struct got_entry) { val };
+}
 
 static inline struct plt_entry emit_plt_entry(unsigned long val)
 {
@@ -77,4 +88,16 @@ static inline struct plt_entry *get_plt_entry(unsigned long val,
 	return plt + plt_idx;
 }
 
+static inline struct got_entry *get_got_entry(Elf_Addr val,
+					      const struct mod_section *sec)
+{
+	struct got_entry *got = (struct got_entry *)sec->shdr->sh_addr;
+	int i;
+
+	for (i = 0; i < sec->num_entries; i++)
+		if (got[i].symbol_addr == val)
+			return &got[i];
+	return NULL;
+}
+
 #endif /* _ASM_MODULE_H */
diff --git a/arch/loongarch/include/asm/module.lds.h b/arch/loongarch/include/asm/module.lds.h
index 31c1c0db11a3..a3d1bc0fcc72 100644
--- a/arch/loongarch/include/asm/module.lds.h
+++ b/arch/loongarch/include/asm/module.lds.h
@@ -2,6 +2,7 @@
 /* Copyright (C) 2020-2022 Loongson Technology Corporation Limited */
 SECTIONS {
 	. = ALIGN(4);
+	.got : { BYTE(0) }
 	.plt : { BYTE(0) }
 	.plt.idx : { BYTE(0) }
 }