linux-kernel - [PATCH v3 33/64] objtool: Resurrect --backup option

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Message-ID: <a38a84c7202384d3842af3fab9d03f6f889a6121.1750980517.git.jpoimboe@kernel.org>
Date: Thu, 26 Jun 2025 16:55:20 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org,
	Song Liu <song@...nel.org>,
	laokz <laokz@...mail.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Weinan Liu <wnliu@...gle.com>,
	Fazla Mehrab <a.mehrab@...edance.com>,
	Chen Zhongjin <chenzhongjin@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>,
	Dylan Hatch <dylanbhatch@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v3 33/64] objtool: Resurrect --backup option

The --backup option was removed with the following commit:

  aa8b3e64fd39 ("objtool: Create backup on error and print args")

... which tied the backup functionality to --verbose, and only for
warnings/errors.

It's a bit inelegant and out of scope to tie that to --verbose.

Bring back the old --backup option, but with the new behavior: only on
warnings/errors, and print the args to make it easier to recreate.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/builtin-check.c           | 25 +++++++++++--------------
 tools/objtool/check.c                   |  4 +++-
 tools/objtool/include/objtool/builtin.h |  3 ++-
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 43139143edf8..a8c349f2273d 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -91,6 +91,7 @@ static const struct option check_options[] = {
 
 	OPT_GROUP("Options:"),
 	OPT_BOOLEAN(0,   "backtrace", &opts.backtrace, "unwind on error"),
+	OPT_BOOLEAN(0,   "backup", &opts.backup, "create backup (.orig) file on warning/error"),
 	OPT_BOOLEAN(0,   "dry-run", &opts.dryrun, "don't write modifications"),
 	OPT_BOOLEAN(0,   "link", &opts.link, "object is a linked object"),
 	OPT_BOOLEAN(0,   "module", &opts.module, "object is part of a kernel module"),
@@ -244,12 +245,9 @@ static void save_argv(int argc, const char **argv)
 	};
 }
 
-void print_args(void)
+int make_backup(void)
 {
-	char *backup = NULL;
-
-	if (opts.output || opts.dryrun)
-		goto print;
+	char *backup;
 
 	/*
 	 * Make a backup before kbuild deletes the file so the error
@@ -258,33 +256,32 @@ void print_args(void)
 	backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
 	if (!backup) {
 		ERROR_GLIBC("malloc");
-		goto print;
+		return 1;
 	}
 
 	strcpy(backup, objname);
 	strcat(backup, ORIG_SUFFIX);
-	if (copy_file(objname, backup)) {
-		backup = NULL;
-		goto print;
-	}
+	if (copy_file(objname, backup))
+		return 1;
 
-print:
 	/*
-	 * Print the cmdline args to make it easier to recreate.  If '--output'
-	 * wasn't used, add it to the printed args with the backup as input.
+	 * Print the cmdline args to make it easier to recreate.
 	 */
+
 	fprintf(stderr, "%s", orig_argv[0]);
 
 	for (int i = 1; i < orig_argc; i++) {
 		char *arg = orig_argv[i];
 
-		if (backup && !strcmp(arg, objname))
+		/* Modify the printed args to use the backup */
+		if (!opts.output && !strcmp(arg, objname))
 			fprintf(stderr, " %s -o %s", backup, objname);
 		else
 			fprintf(stderr, " %s", arg);
 	}
 
 	fprintf(stderr, "\n");
+	return 0;
 }
 
 int objtool_run(int argc, const char **argv)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 87d2ba7739d5..46ace2c80317 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4745,9 +4745,11 @@ int check(struct objtool_file *file)
 	if (opts.verbose) {
 		if (opts.werror && warnings)
 			WARN("%d warning(s) upgraded to errors", warnings);
-		print_args();
 		disas_warned_funcs(file);
 	}
 
+	if (opts.backup && make_backup())
+		return 1;
+
 	return ret;
 }
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 6b08666fa69d..de6c08f8e060 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -29,6 +29,7 @@ struct opts {
 
 	/* options: */
 	bool backtrace;
+	bool backup;
 	bool dryrun;
 	bool link;
 	bool mnop;
@@ -47,6 +48,6 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
 
 int objtool_run(int argc, const char **argv);
 
-void print_args(void);
+int make_backup(void);
 
 #endif /* _BUILTIN_H */
-- 
2.49.0