objtool: Clean up elf_write() condition

With there being multiple ways to change the ELF data, let's more
concisely track modification.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

tools/objtool/check.c

@@ -2740,7 +2740,7 @@ int check(const char *_objname, bool orc)
 
 	objname = _objname;
 
-	file.elf = elf_open_read(objname, orc ? O_RDWR : O_RDONLY);
+	file.elf = elf_open_read(objname, O_RDWR);
 	if (!file.elf)
 		return 1;
 
@@ -2801,7 +2801,9 @@ int check(const char *_objname, bool orc)
 		ret = create_orc_sections(&file);
 		if (ret < 0)
 			goto out;
+	}
 
+	if (file.elf->changed) {
 		ret = elf_write(file.elf);
 		if (ret < 0)
 			goto out;

tools/objtool/elf.c

@@ -713,6 +713,8 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
 	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 
+	elf->changed = true;
+
 	return sec;
 }
 
@@ -746,7 +748,7 @@ struct section *elf_create_rela_section(struct elf *elf, struct section *base)
 	return sec;
 }
 
-int elf_rebuild_rela_section(struct section *sec)
+int elf_rebuild_rela_section(struct elf *elf, struct section *sec)
 {
 	struct rela *rela;
 	int nr, idx = 0, size;
@@ -763,6 +765,9 @@ int elf_rebuild_rela_section(struct section *sec)
 		return -1;
 	}
 
+	sec->changed = true;
+	elf->changed = true;
+
 	sec->data->d_buf = relas;
 	sec->data->d_size = size;
 
@@ -779,7 +784,7 @@ int elf_rebuild_rela_section(struct section *sec)
 	return 0;
 }
 
-int elf_write(const struct elf *elf)
+int elf_write(struct elf *elf)
 {
 	struct section *sec;
 	Elf_Scn *s;
@@ -796,6 +801,8 @@ int elf_write(const struct elf *elf)
 				WARN_ELF("gelf_update_shdr");
 				return -1;
 			}
+
+			sec->changed = false;
 		}
 	}
 
@@ -808,6 +815,8 @@ int elf_write(const struct elf *elf)
 		return -1;
 	}
 
+	elf->changed = false;
+
 	return 0;
 }
 

tools/objtool/elf.h

@@ -76,6 +76,7 @@ struct elf {
 	Elf *elf;
 	GElf_Ehdr ehdr;
 	int fd;
+	bool changed;
 	char *name;
 	struct list_head sections;
 	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
@@ -118,7 +119,7 @@ struct elf *elf_open_read(const char *name, int flags);
 struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr);
 struct section *elf_create_rela_section(struct elf *elf, struct section *base);
 void elf_add_rela(struct elf *elf, struct rela *rela);
-int elf_write(const struct elf *elf);
+int elf_write(struct elf *elf);
 void elf_close(struct elf *elf);
 
 struct section *find_section_by_name(const struct elf *elf, const char *name);
@@ -130,7 +131,7 @@ struct rela *find_rela_by_dest(const struct elf *elf, struct section *sec, unsig
 struct rela *find_rela_by_dest_range(const struct elf *elf, struct section *sec,
 				     unsigned long offset, unsigned int len);
 struct symbol *find_func_containing(struct section *sec, unsigned long offset);
-int elf_rebuild_rela_section(struct section *sec);
+int elf_rebuild_rela_section(struct elf *elf, struct section *sec);
 
 #define for_each_sec(file, sec)						\
 	list_for_each_entry(sec, &file->elf->sections, list)

tools/objtool/orc_gen.c

@@ -222,7 +222,7 @@ int create_orc_sections(struct objtool_file *file)
 		}
 	}
 
-	if (elf_rebuild_rela_section(ip_relasec))
+	if (elf_rebuild_rela_section(file->elf, ip_relasec))
 		return -1;
 
 	return 0;