Commit 5a406031 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Peter Zijlstra
Browse files

objtool: Add --output option 



Add option to allow writing the changed binary to a separate file rather
than changing it in place.

Libelf makes this suprisingly hard, so take the easy way out and just
copy the file before editing it.

Also steal the -o short option from --orc.  Nobody will notice ;-)

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/0da308d42d82b3bbed16a31a72d6bde52afcd6bd.1741975349.git.jpoimboe@kernel.org
parent fdf5ff29

tools/objtool/builtin-check.c

+81 −17
Original line number Diff line number Diff line
@@ -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"),
@@ -91,6 +97,7 @@ static const struct option check_options[] = { 
	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"),
@@ -178,24 +185,75 @@ static bool opts_valid(void) 
	return false;

}



static int copy_file(const char *src, const char *dst)

{

	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;

	}



	dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC);

	if (dst_fd == -1) {

		ERROR("can't open '%s' for writing", dst);

		return 1;

	}



	if (fstat(src_fd, &stat) == -1) {

		perror("fstat");

		return 1;

	}



	if (fchmod(dst_fd, stat.st_mode) == -1) {

		perror("fchmod");

		return 1;

	}



	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;

		}

	}



	close(dst_fd);

	close(src_fd);

	return 0;

}



int objtool_run(int argc, const char **argv)

{

	const char *objname;

	struct objtool_file *file;

	int ret;



	argc = cmd_parse_options(argc, argv, check_usage);

	objname = argv[0];

	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 (!opts.link && has_multiple_files(file->elf)) {

		ERROR("Linked object requires --link");
@@ -204,10 +262,16 @@ int objtool_run(int argc, const char **argv) 


	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.output)

		unlink(opts.output);



	return 1;

}

tools/objtool/elf.c

+0 −3
Original line number Diff line number Diff line
@@ -1302,9 +1302,6 @@ int elf_write(struct elf *elf) 
	struct section *sec;

	Elf_Scn *s;



	if (opts.dryrun)

		return 0;



	/* Update changed relocation sections and section headers: */

	list_for_each_entry(sec, &elf->sections, list) {

		if (sec->truncate)

tools/objtool/include/objtool/builtin.h

+1 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ struct opts { 
	bool mnop;

	bool module;

	bool no_unreachable;

	const char *output;

	bool sec_address;

	bool stats;

	bool verbose;

tools/objtool/objtool.c

+5 −10
Original line number Diff line number Diff line
@@ -18,7 +18,6 @@ 


bool help;



const char *objname;

static struct objtool_file file;



static bool objtool_create_backup(const char *_objname)
@@ -79,18 +78,14 @@ static bool objtool_create_backup(const char *_objname) 
	return true;

}



struct objtool_file *objtool_open_read(const char *_objname)

struct objtool_file *objtool_open_read(const char *filename)

{

	if (objname) {

		if (strcmp(objname, _objname)) {

	if (file.elf) {

		WARN("won't handle more than one file at a time");

		return NULL;

	}

		return &file;

	}

	objname = _objname;



	file.elf = elf_open_read(objname, O_RDWR);

	file.elf = elf_open_read(filename, O_RDWR);

	if (!file.elf)

		return NULL;

tools/objtool/orc_dump.c

+2 −5
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ 
#include <objtool/warn.h>

#include <objtool/endianness.h>



int orc_dump(const char *_objname)

int orc_dump(const char *filename)

{

	int fd, nr_entries, i, *orc_ip = NULL, orc_size = 0;

	struct orc_entry *orc = NULL;
@@ -26,12 +26,9 @@ int orc_dump(const char *_objname) 
	Elf_Data *data, *symtab = NULL, *rela_orc_ip = NULL;

	struct elf dummy_elf = {};





	objname = _objname;



	elf_version(EV_CURRENT);



	fd = open(objname, O_RDONLY);

	fd = open(filename, O_RDONLY);

	if (fd == -1) {

		perror("open");

		return -1;