Merge tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - The biggest change is the new option to automatically fail the build
   on objtool warnings: CONFIG_OBJTOOL_WERROR.

   While there are no currently known unfixed false positives left, such
   an expansion in the severity of objtool warnings inevitably creates a
   risk of build failures, so it's disabled by default and depends on
   !COMPILE_TEST, so it shouldn't be enabled on
   allyesconfig/allmodconfig builds and won't be forced on people who
   just accept build-time defaults in 'make oldconfig'.

   While the option is strongly recommended, only people who enable it
   explicitly should see it.

   (Josh Poimboeuf)

 - Disable branch profiling in noinstr code with a broad brush that
   includes all of arch/x86/ and kernel/sched/. (Josh Poimboeuf)

 - Create backup object files on objtool errors and print exact objtool
   arguments to make failure analysis easier (Josh Poimboeuf)

 - Improve noreturn handling (Josh Poimboeuf)

 - Improve rodata handling (Tiezhu Yang)

 - Support jump tables, switch tables and goto tables on LoongArch
   (Tiezhu Yang)

 - Misc cleanups and fixes (Josh Poimboeuf, David Engraf, Ingo Molnar)

* tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  tracing: Disable branch profiling in noinstr code
  objtool: Use O_CREAT with explicit mode mask
  objtool: Add CONFIG_OBJTOOL_WERROR
  objtool: Create backup on error and print args
  objtool: Change "warning:" to "error:" for --Werror
  objtool: Add --Werror option
  objtool: Add --output option
  objtool: Upgrade "Linked object detected" warning to error
  objtool: Consolidate option validation
  objtool: Remove --unret dependency on --rethunk
  objtool: Increase per-function WARN_FUNC() rate limit
  objtool: Update documentation
  objtool: Improve __noreturn annotation warning
  objtool: Fix error handling inconsistencies in check()
  x86/traps: Make exc_double_fault() consistently noreturn
  LoongArch: Enable jump table for objtool
  objtool/LoongArch: Add support for goto table
  objtool/LoongArch: Add support for switch table
  objtool: Handle PC relative relocation type
  objtool: Handle different entry size of rodata
  ...

1 files changed, 155 insertions, 53 deletions

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 387d56a7f5fb..5f761f420b8c 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -6,6 +6,10 @@
 #include <subcmd/parse-options.h>
 #include <string.h>
 #include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/sendfile.h>
 #include <objtool/builtin.h>
 #include <objtool/objtool.h>
 
@@ -14,6 +18,8 @@
 		"error: objtool: " format "\n",		\
 		##__VA_ARGS__)
 
+const char *objname;
+
 struct opts opts;
 
 static const char * const check_usage[] = {
@@ -71,7 +77,7 @@ static const struct option check_options[] = {
 	OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
 	OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
 	OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
-	OPT_BOOLEAN('o', "orc", &opts.orc, "generate ORC metadata"),
+	OPT_BOOLEAN(0,   "orc", &opts.orc, "generate ORC metadata"),
 	OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
 	OPT_BOOLEAN(0,   "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
 	OPT_BOOLEAN(0,   "unret", &opts.unret, "validate entry unret placement"),
@@ -84,16 +90,17 @@ static const struct option check_options[] = {
 	OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
 
 	OPT_GROUP("Options:"),
-	OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
-	OPT_BOOLEAN(0, "backup", &opts.backup, "create .orig files before modification"),
-	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"),
-	OPT_BOOLEAN(0, "mnop", &opts.mnop, "nop out mcount call sites"),
-	OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
-	OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
-	OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
+	OPT_BOOLEAN(0,   "backtrace", &opts.backtrace, "unwind on 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"),
+	OPT_BOOLEAN(0,   "mnop", &opts.mnop, "nop out mcount call sites"),
+	OPT_BOOLEAN(0,   "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
+	OPT_STRING('o',  "output", &opts.output, "file", "output file name"),
+	OPT_BOOLEAN(0,   "sec-address", &opts.sec_address, "print section addresses in warnings"),
+	OPT_BOOLEAN(0,   "stats", &opts.stats, "print statistics"),
 	OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
+	OPT_BOOLEAN(0,   "Werror", &opts.werror, "return error on warnings"),
 
 	OPT_END(),
 };
@@ -131,6 +138,26 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[])
 
 static bool opts_valid(void)
 {
+	if (opts.mnop && !opts.mcount) {
+		ERROR("--mnop requires --mcount");
+		return false;
+	}
+
+	if (opts.noinstr && !opts.link) {
+		ERROR("--noinstr requires --link");
+		return false;
+	}
+
+	if (opts.ibt && !opts.link) {
+		ERROR("--ibt requires --link");
+		return false;
+	}
+
+	if (opts.unret && !opts.link) {
+		ERROR("--unret requires --link");
+		return false;
+	}
+
 	if (opts.hack_jump_label	||
 	    opts.hack_noinstr		||
 	    opts.ibt			||
@@ -151,11 +178,6 @@ static bool opts_valid(void)
 		return true;
 	}
 
-	if (opts.unret && !opts.rethunk) {
-		ERROR("--unret requires --rethunk");
-		return false;
-	}
-
 	if (opts.dump_orc)
 		return true;
 
@@ -163,76 +185,156 @@ static bool opts_valid(void)
 	return false;
 }
 
-static bool mnop_opts_valid(void)
+static int copy_file(const char *src, const char *dst)
 {
-	if (opts.mnop && !opts.mcount) {
-		ERROR("--mnop requires --mcount");
-		return false;
+	size_t to_copy, copied;
+	int dst_fd, src_fd;
+	struct stat stat;
+	off_t offset = 0;
+
+	src_fd = open(src, O_RDONLY);
+	if (src_fd == -1) {
+		ERROR("can't open '%s' for reading", src);
+		return 1;
 	}
 
-	return true;
-}
-
-static bool link_opts_valid(struct objtool_file *file)
-{
-	if (opts.link)
-		return true;
+	dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0400);
+	if (dst_fd == -1) {
+		ERROR("can't open '%s' for writing", dst);
+		return 1;
+	}
 
-	if (has_multiple_files(file->elf)) {
-		ERROR("Linked object detected, forcing --link");
-		opts.link = true;
-		return true;
+	if (fstat(src_fd, &stat) == -1) {
+		perror("fstat");
+		return 1;
 	}
 
-	if (opts.noinstr) {
-		ERROR("--noinstr requires --link");
-		return false;
+	if (fchmod(dst_fd, stat.st_mode) == -1) {
+		perror("fchmod");
+		return 1;
 	}
 
-	if (opts.ibt) {
-		ERROR("--ibt requires --link");
-		return false;
+	for (to_copy = stat.st_size; to_copy > 0; to_copy -= copied) {
+		copied = sendfile(dst_fd, src_fd, &offset, to_copy);
+		if (copied == -1) {
+			perror("sendfile");
+			return 1;
+		}
 	}
 
-	if (opts.unret) {
-		ERROR("--unret requires --link");
-		return false;
+	close(dst_fd);
+	close(src_fd);
+	return 0;
+}
+
+static char **save_argv(int argc, const char **argv)
+{
+	char **orig_argv;
+
+	orig_argv = calloc(argc, sizeof(char *));
+	if (!orig_argv) {
+		perror("calloc");
+		return NULL;
 	}
 
-	return true;
+	for (int i = 0; i < argc; i++) {
+		orig_argv[i] = strdup(argv[i]);
+		if (!orig_argv[i]) {
+			perror("strdup");
+			return NULL;
+		}
+	};
+
+	return orig_argv;
 }
 
+#define ORIG_SUFFIX ".orig"
+
 int objtool_run(int argc, const char **argv)
 {
-	const char *objname;
 	struct objtool_file *file;
-	int ret;
+	char *backup = NULL;
+	char **orig_argv;
+	int ret = 0;
 
-	argc = cmd_parse_options(argc, argv, check_usage);
-	objname = argv[0];
+	orig_argv = save_argv(argc, argv);
+	if (!orig_argv)
+		return 1;
+
+	cmd_parse_options(argc, argv, check_usage);
 
 	if (!opts_valid())
 		return 1;
 
+	objname = argv[0];
+
 	if (opts.dump_orc)
 		return orc_dump(objname);
 
+	if (!opts.dryrun && opts.output) {
+		/* copy original .o file to output file */
+		if (copy_file(objname, opts.output))
+			return 1;
+
+		/* from here on, work directly on the output file */
+		objname = opts.output;
+	}
+
 	file = objtool_open_read(objname);
 	if (!file)
-		return 1;
+		goto err;
 
-	if (!mnop_opts_valid())
-		return 1;
-
-	if (!link_opts_valid(file))
-		return 1;
+	if (!opts.link && has_multiple_files(file->elf)) {
+		ERROR("Linked object requires --link");
+		goto err;
+	}
 
 	ret = check(file);
 	if (ret)
-		return ret;
+		goto err;
 
-	if (file->elf->changed)
-		return elf_write(file->elf);
+	if (!opts.dryrun && file->elf->changed && elf_write(file->elf))
+		goto err;
 
 	return 0;
+
+err:
+	if (opts.dryrun)
+		goto err_msg;
+
+	if (opts.output) {
+		unlink(opts.output);
+		goto err_msg;
+	}
+
+	/*
+	 * Make a backup before kbuild deletes the file so the error
+	 * can be recreated without recompiling or relinking.
+	 */
+	backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
+	if (!backup) {
+		perror("malloc");
+		return 1;
+	}
+
+	strcpy(backup, objname);
+	strcat(backup, ORIG_SUFFIX);
+	if (copy_file(objname, backup))
+		return 1;
+
+err_msg:
+	fprintf(stderr, "%s", orig_argv[0]);
+
+	for (int i = 1; i < argc; i++) {
+		char *arg = orig_argv[i];
+
+		if (backup && !strcmp(arg, objname))
+			fprintf(stderr, " %s -o %s", backup, objname);
+		else
+			fprintf(stderr, " %s", arg);
+	}
+
+	fprintf(stderr, "\n");
+
+	return 1;
 }