linux-kernel - [PATCH v3 29/59] objtool: Track init section

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Message-ID: <20220915111145.910334431@infradead.org>
Date:   Thu, 15 Sep 2022 13:11:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org, x86@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Johannes Wikner <kwikner@...z.ch>,
        Alyssa Milburn <alyssa.milburn@...ux.intel.com>,
        Jann Horn <jannh@...gle.com>, "H.J. Lu" <hjl.tools@...il.com>,
        Joao Moreira <joao.moreira@...el.com>,
        Joseph Nuzman <joseph.nuzman@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Juergen Gross <jgross@...e.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v3 29/59] objtool: Track init section

From: Peter Zijlstra <peterz@...radead.org>

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@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 tools/objtool/check.c               |   17 ++++++++++-------
 tools/objtool/include/objtool/elf.h |    2 +-
 2 files changed, 11 insertions(+), 8 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -380,6 +380,15 @@ static int decode_instructions(struct ob
 		    !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) {
@@ -3720,13 +3729,7 @@ static int validate_retpoline(struct obj
 		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) {
--- a/tools/objtool/include/objtool/elf.h
+++ b/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 {