linux-kernel - [tip: x86/core] objtool: Read the NOENDBR annotation

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Date:   Wed, 09 Mar 2022 07:54:42 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/core] objtool: Read the NOENDBR annotation

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     51727f8e4a1ae15770ac30f05a90536c4aa3b2d8
Gitweb:        https://git.kernel.org/tip/51727f8e4a1ae15770ac30f05a90536c4aa3b2d8
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Tue, 08 Mar 2022 16:30:52 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 08 Mar 2022 23:53:38 +01:00

objtool: Read the NOENDBR annotation

Read the new NOENDBR annotation. While there, attempt to not bloat
struct instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>
Link: https://lore.kernel.org/r/20220308154319.586815435@infradead.org
---
 tools/objtool/check.c                 | 27 ++++++++++++++++++++++++++-
 tools/objtool/include/objtool/check.h | 13 ++++++++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index aee6246..3f28ca4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1865,6 +1865,29 @@ static int read_unwind_hints(struct objtool_file *file)
 	return 0;
 }
 
+static int read_noendbr_hints(struct objtool_file *file)
+{
+	struct section *sec;
+	struct instruction *insn;
+	struct reloc *reloc;
+
+	sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
+	if (!sec)
+		return 0;
+
+	list_for_each_entry(reloc, &sec->reloc_list, list) {
+		insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
+		if (!insn) {
+			WARN("bad .discard.noendbr entry");
+			return -1;
+		}
+
+		insn->noendbr = 1;
+	}
+
+	return 0;
+}
+
 static int read_retpoline_hints(struct objtool_file *file)
 {
 	struct section *sec;
@@ -2098,6 +2121,10 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
+	ret = read_noendbr_hints(file);
+	if (ret)
+		return ret;
+
 	/*
 	 * Must be before add_{jump_call}_destination.
 	 */
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 6cfff07..f10d737 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -45,11 +45,18 @@ struct instruction {
 	unsigned int len;
 	enum insn_type type;
 	unsigned long immediate;
-	bool dead_end, ignore, ignore_alts;
-	bool hint;
-	bool retpoline_safe;
+
+	u8 dead_end	: 1,
+	   ignore	: 1,
+	   ignore_alts	: 1,
+	   hint		: 1,
+	   retpoline_safe : 1,
+	   noendbr	: 1;
+		/* 2 bit hole */
 	s8 instr;
 	u8 visited;
+	/* u8 hole */
+
 	struct alt_group *alt_group;
 	struct symbol *call_dest;
 	struct instruction *jump_dest;