ARM: module: clean up handling of ELF unwind tables

There's no need to keep pointers to the ELF sections available while
the module is loaded - we only need the section pointers while we're
finding and registering the unwind tables, which can all be done during
the finalize stage of loading.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/module.h

@@ -8,11 +8,6 @@
 struct unwind_table;
 
 #ifdef CONFIG_ARM_UNWIND
-struct arm_unwind_mapping {
-	Elf_Shdr *unw_sec;
-	Elf_Shdr *sec_text;
-	struct unwind_table *unwind;
-};
 enum {
 	ARM_SEC_INIT,
 	ARM_SEC_DEVINIT,
@@ -21,13 +16,13 @@ enum {
 	ARM_SEC_DEVEXIT,
 	ARM_SEC_MAX,
 };
+#endif
+
 struct mod_arch_specific {
-	struct arm_unwind_mapping map[ARM_SEC_MAX];
-};
-#else
-struct mod_arch_specific {
-};
+#ifdef CONFIG_ARM_UNWIND
+	struct unwind_table *unwind[ARM_SEC_MAX];
 #endif
+};
 
 /*
  * Include the ARM architecture version.

arch/arm/kernel/module.c

@@ -67,35 +67,6 @@ int module_frob_arch_sections(Elf_Ehdr *hdr,
 			      char *secstrings,
 			      struct module *mod)
 {
-#ifdef CONFIG_ARM_UNWIND
-	Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
-	struct arm_unwind_mapping *maps = mod->arch.map;
-
-	for (s = sechdrs; s < sechdrs_end; s++) {
-		char const *secname = secstrings + s->sh_name;
-
-		if (strcmp(".ARM.exidx.init.text", secname) == 0)
-			maps[ARM_SEC_INIT].unw_sec = s;
-		else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
-			maps[ARM_SEC_DEVINIT].unw_sec = s;
-		else if (strcmp(".ARM.exidx", secname) == 0)
-			maps[ARM_SEC_CORE].unw_sec = s;
-		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
-			maps[ARM_SEC_EXIT].unw_sec = s;
-		else if (strcmp(".ARM.exidx.devexit.text", secname) == 0)
-			maps[ARM_SEC_DEVEXIT].unw_sec = s;
-		else if (strcmp(".init.text", secname) == 0)
-			maps[ARM_SEC_INIT].sec_text = s;
-		else if (strcmp(".devinit.text", secname) == 0)
-			maps[ARM_SEC_DEVINIT].sec_text = s;
-		else if (strcmp(".text", secname) == 0)
-			maps[ARM_SEC_CORE].sec_text = s;
-		else if (strcmp(".exit.text", secname) == 0)
-			maps[ARM_SEC_EXIT].sec_text = s;
-		else if (strcmp(".devexit.text", secname) == 0)
-			maps[ARM_SEC_DEVEXIT].sec_text = s;
-	}
-#endif
 	return 0;
 }
 
@@ -300,41 +271,66 @@ apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 	return -ENOEXEC;
 }
 
-#ifdef CONFIG_ARM_UNWIND
-static void register_unwind_tables(struct module *mod)
+struct mod_unwind_map {
+	const Elf_Shdr *unw_sec;
+	const Elf_Shdr *txt_sec;
+};
+
+int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
+		    struct module *mod)
 {
+#ifdef CONFIG_ARM_UNWIND
+	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+	const Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
+	struct mod_unwind_map maps[ARM_SEC_MAX];
 	int i;
-	for (i = 0; i < ARM_SEC_MAX; ++i) {
-		struct arm_unwind_mapping *map = &mod->arch.map[i];
-		if (map->unw_sec && map->sec_text)
-			map->unwind = unwind_table_add(map->unw_sec->sh_addr,
-						       map->unw_sec->sh_size,
-						       map->sec_text->sh_addr,
-						       map->sec_text->sh_size);
+
+	memset(maps, 0, sizeof(maps));
+
+	for (s = sechdrs; s < sechdrs_end; s++) {
+		const char *secname = secstrs + s->sh_name;
+
+		if (strcmp(".ARM.exidx.init.text", secname) == 0)
+			maps[ARM_SEC_INIT].unw_sec = s;
+		else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
+			maps[ARM_SEC_DEVINIT].unw_sec = s;
+		else if (strcmp(".ARM.exidx", secname) == 0)
+			maps[ARM_SEC_CORE].unw_sec = s;
+		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
+			maps[ARM_SEC_EXIT].unw_sec = s;
+		else if (strcmp(".ARM.exidx.devexit.text", secname) == 0)
+			maps[ARM_SEC_DEVEXIT].unw_sec = s;
+		else if (strcmp(".init.text", secname) == 0)
+			maps[ARM_SEC_INIT].txt_sec = s;
+		else if (strcmp(".devinit.text", secname) == 0)
+			maps[ARM_SEC_DEVINIT].txt_sec = s;
+		else if (strcmp(".text", secname) == 0)
+			maps[ARM_SEC_CORE].txt_sec = s;
+		else if (strcmp(".exit.text", secname) == 0)
+			maps[ARM_SEC_EXIT].txt_sec = s;
+		else if (strcmp(".devexit.text", secname) == 0)
+			maps[ARM_SEC_DEVEXIT].txt_sec = s;
 	}
-}
 
-static void unregister_unwind_tables(struct module *mod)
-{
-	int i = ARM_SEC_MAX;
-	while (--i >= 0)
-		unwind_table_del(mod->arch.map[i].unwind);
-}
-#else
-static inline void register_unwind_tables(struct module *mod) { }
-static inline void unregister_unwind_tables(struct module *mod) { }
+	for (i = 0; i < ARM_SEC_MAX; i++)
+		if (maps[i].unw_sec && maps[i].txt_sec)
+			mod->arch.unwind[i] =
+				unwind_table_add(maps[i].unw_sec->sh_addr,
+					         maps[i].unw_sec->sh_size,
+					         maps[i].txt_sec->sh_addr,
+					         maps[i].txt_sec->sh_size);
 #endif
-
-int
-module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
-		struct module *module)
-{
-	register_unwind_tables(module);
 	return 0;
 }
 
 void
 module_arch_cleanup(struct module *mod)
 {
-	unregister_unwind_tables(mod);
+#ifdef CONFIG_ARM_UNWIND
+	int i;
+
+	for (i = 0; i < ARM_SEC_MAX; i++)
+		if (mod->arch.unwind[i])
+			unwind_table_del(mod->arch.unwind[i]);
+#endif
 }