linux-kernel - [tip: objtool/core] objtool: Uniquely identify alternative instruction groups

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Date:   Fri, 01 May 2020 18:22:23 -0000
From:   "tip-bot2 for Alexandre Chartre" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Alexandre Chartre <alexandre.chartre@...cle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: objtool/core] objtool: Uniquely identify alternative instruction groups

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

Commit-ID:     13fab06d9a3ad3afdfd51c7f8f87f2ae28444648
Gitweb:        https://git.kernel.org/tip/13fab06d9a3ad3afdfd51c7f8f87f2ae28444648
Author:        Alexandre Chartre <alexandre.chartre@...cle.com>
AuthorDate:    Tue, 14 Apr 2020 12:36:11 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 30 Apr 2020 20:14:31 +02:00

objtool: Uniquely identify alternative instruction groups

Assign a unique identifier to every alternative instruction group in
order to be able to tell which instructions belong to what
alternative.

[peterz: extracted from a larger patch]
Signed-off-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
---
 tools/objtool/check.c | 6 +++++-
 tools/objtool/check.h | 3 ++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index cc52da6..4da6bfb 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -752,7 +752,9 @@ static int handle_group_alt(struct objtool_file *file,
 			    struct instruction *orig_insn,
 			    struct instruction **new_insn)
 {
+	static unsigned int alt_group_next_index = 1;
 	struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
+	unsigned int alt_group = alt_group_next_index++;
 	unsigned long dest_off;
 
 	last_orig_insn = NULL;
@@ -761,7 +763,7 @@ static int handle_group_alt(struct objtool_file *file,
 		if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
 			break;
 
-		insn->alt_group = true;
+		insn->alt_group = alt_group;
 		last_orig_insn = insn;
 	}
 
@@ -795,6 +797,7 @@ static int handle_group_alt(struct objtool_file *file,
 	}
 
 	last_new_insn = NULL;
+	alt_group = alt_group_next_index++;
 	insn = *new_insn;
 	sec_for_each_insn_from(file, insn) {
 		if (insn->offset >= special_alt->new_off + special_alt->new_len)
@@ -804,6 +807,7 @@ static int handle_group_alt(struct objtool_file *file,
 
 		insn->ignore = orig_insn->ignore_alts;
 		insn->func = orig_insn->func;
+		insn->alt_group = alt_group;
 
 		/*
 		 * Since alternative replacement code is copy/pasted by the
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 12a9660..2428022 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -30,12 +30,13 @@ struct instruction {
 	unsigned int len;
 	enum insn_type type;
 	unsigned long immediate;
-	bool alt_group, dead_end, ignore, ignore_alts;
+	bool dead_end, ignore, ignore_alts;
 	bool hint;
 	bool retpoline_safe;
 	s8 instr;
 	u8 visited;
 	u8 ret_offset;
+	int alt_group;
 	struct symbol *call_dest;
 	struct instruction *jump_dest;
 	struct instruction *first_jump_src;