objtool: Track init section

For future usage of .init.text exclusion track the init section in the
instruction decoder and use the result in retpoline validation.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111145.910334431@infradead.org

tools/objtool/check.c

@@ -382,6 +382,15 @@ static int decode_instructions(struct objtool_file *file)
 		    !strncmp(sec->name, ".text.__x86.", 12))
 			sec->noinstr = true;
 
+		/*
+		 * .init.text code is ran before userspace and thus doesn't
+		 * strictly need retpolines, except for modules which are
+		 * loaded late, they very much do need retpoline in their
+		 * .init.text
+		 */
+		if (!strcmp(sec->name, ".init.text") && !opts.module)
+			sec->init = true;
+
 		for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
 			insn = malloc(sizeof(*insn));
 			if (!insn) {
@@ -3748,13 +3757,7 @@ static int validate_retpoline(struct objtool_file *file)
 		if (insn->retpoline_safe)
 			continue;
 
-		/*
-		 * .init.text code is ran before userspace and thus doesn't
-		 * strictly need retpolines, except for modules which are
-		 * loaded late, they very much do need retpoline in their
-		 * .init.text
-		 */
-		if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
+		if (insn->sec->init)
 			continue;
 
 		if (insn->type == INSN_RETURN) {

tools/objtool/include/objtool/elf.h

@@ -38,7 +38,7 @@ struct section {
 	Elf_Data *data;
 	char *name;
 	int idx;
-	bool changed, text, rodata, noinstr;
+	bool changed, text, rodata, noinstr, init;
 };
 
 struct symbol {