Commit 8ad15c69 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

objtool: Add --backup 



Teach objtool to write backups files, such that it becomes easier to
see what objtool did to the object file.

Backup files will be ${name}.orig.

Suggested-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YD4obT3aoXPWl7Ax@hirez.programming.kicks-ass.net
parent 36d92e43

tools/objtool/builtin-check.c

+3 −1
Original line number Diff line number Diff line
@@ -18,7 +18,8 @@ 
#include <objtool/builtin.h>

#include <objtool/objtool.h>



bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux, mcount, noinstr;

bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,

     validate_dup, vmlinux, mcount, noinstr, backup;



static const char * const check_usage[] = {

	"objtool check [<options>] file.o",
@@ -37,6 +38,7 @@ const struct option check_options[] = { 
	OPT_BOOLEAN('n', "noinstr", &noinstr, "noinstr validation for vmlinux.o"),

	OPT_BOOLEAN('l', "vmlinux", &vmlinux, "vmlinux.o validation"),

	OPT_BOOLEAN('M', "mcount", &mcount, "generate __mcount_loc"),

	OPT_BOOLEAN('B', "backup", &backup, "create .orig files before modification"),

	OPT_END(),

};

tools/objtool/include/objtool/builtin.h

+2 −1
Original line number Diff line number Diff line
@@ -8,7 +8,8 @@ 
#include <subcmd/parse-options.h>



extern const struct option check_options[];

extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux, mcount, noinstr;

extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,

            validate_dup, vmlinux, mcount, noinstr, backup;



extern int cmd_check(int argc, const char **argv);

extern int cmd_orc(int argc, const char **argv);

tools/objtool/objtool.c

+64 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <stdbool.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

#include <subcmd/exec-cmd.h>

#include <subcmd/pager.h>

#include <linux/kernel.h>
@@ -44,6 +45,64 @@ bool help; 
const char *objname;

static struct objtool_file file;



static bool objtool_create_backup(const char *_objname)

{

	int len = strlen(_objname);

	char *buf, *base, *name = malloc(len+6);

	int s, d, l, t;



	if (!name) {

		perror("failed backup name malloc");

		return false;

	}



	strcpy(name, _objname);

	strcpy(name + len, ".orig");



	d = open(name, O_CREAT|O_WRONLY|O_TRUNC, 0644);

	if (d < 0) {

		perror("failed to create backup file");

		return false;

	}



	s = open(_objname, O_RDONLY);

	if (s < 0) {

		perror("failed to open orig file");

		return false;

	}



	buf = malloc(4096);

	if (!buf) {

		perror("failed backup data malloc");

		return false;

	}



	while ((l = read(s, buf, 4096)) > 0) {

		base = buf;

		do {

			t = write(d, base, l);

			if (t < 0) {

				perror("failed backup write");

				return false;

			}

			base += t;

			l -= t;

		} while (l);

	}



	if (l < 0) {

		perror("failed backup read");

		return false;

	}



	free(name);

	free(buf);

	close(d);

	close(s);



	return true;

}



struct objtool_file *objtool_open_read(const char *_objname)

{

	if (objname) {
@@ -59,6 +118,11 @@ struct objtool_file *objtool_open_read(const char *_objname) 
	if (!file.elf)

		return NULL;



	if (backup && !objtool_create_backup(objname)) {

		WARN("can't create backup file");

		return NULL;

	}



	INIT_LIST_HEAD(&file.insn_list);

	hash_init(file.insn_hash);

	INIT_LIST_HEAD(&file.static_call_list);