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objtool: Add --backup

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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: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YD4obT3aoXPWl7Ax@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2021-02-26 10:59:59 +01:00 committed by Ingo Molnar
parent 36d92e43d0
commit 8ad15c6900
3 changed files with 69 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
tools/objtool/builtin-check.c
View File

@ -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(),
};

3
tools/objtool/include/objtool/builtin.h
View File

@ -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);

64
tools/objtool/objtool.c
View File

@ -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);