Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
objtool: Print headers for alternatives
When using the --disas option, objtool doesn't currently disassemble
any alternative. Print an header for each alternative. This identifies
places where alternatives are present but alternative code is still
not disassembled at the moment.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-20-alexandre.chartre@oracle.com
authored by
Alexandre Chartre
and committed by
Peter Zijlstra
87343e66
7ad7a4a7
+182
-6
+182
-6
tools/objtool/disas.c
+182
-6
tools/objtool/disas.c
···
29
29
struct disassemble_info info;
30
30
};
31
31
32
+
/*
33
+
* Maximum number of alternatives
34
+
*/
35
+
#define DISAS_ALT_MAX 5
36
+
37
+
/*
38
+
* Maximum number of instructions per alternative
39
+
*/
40
+
#define DISAS_ALT_INSN_MAX 50
41
+
42
+
/*
43
+
* Information to disassemble an alternative
44
+
*/
45
+
struct disas_alt {
46
+
struct instruction *orig_insn; /* original instruction */
47
+
struct alternative *alt; /* alternative or NULL if default code */
48
+
char *name; /* name for this alternative */
49
+
int width; /* formatting width */
50
+
};
51
+
52
+
/*
53
+
* Wrapper around asprintf() to allocate and format a string.
54
+
* Return the allocated string or NULL on error.
55
+
*/
56
+
static char *strfmt(const char *fmt, ...)
57
+
{
58
+
va_list ap;
59
+
char *str;
60
+
int rv;
61
+
62
+
va_start(ap, fmt);
63
+
rv = vasprintf(&str, fmt, ap);
64
+
va_end(ap);
65
+
66
+
return rv == -1 ? NULL : str;
67
+
}
68
+
32
69
static int sprint_name(char *str, const char *name, unsigned long offset)
33
70
{
34
71
int len;
···
351
314
#define DISAS_INSN_OFFSET_SPACE 10
352
315
#define DISAS_INSN_SPACE 60
353
316
317
+
#define DISAS_PRINSN(dctx, insn, depth) \
318
+
disas_print_insn(stdout, dctx, insn, depth, "\n")
319
+
354
320
/*
355
321
* Print a message in the instruction flow. If insn is not NULL then
356
322
* the instruction address is printed in addition of the message,
···
392
352
n += vfprintf(stream, format, ap);
393
353
394
354
return n;
355
+
}
356
+
357
+
static int disas_print(FILE *stream, struct section *sec, unsigned long offset,
358
+
int depth, const char *format, ...)
359
+
{
360
+
va_list args;
361
+
int len;
362
+
363
+
va_start(args, format);
364
+
len = disas_vprint(stream, sec, offset, depth, format, args);
365
+
va_end(args);
366
+
367
+
return len;
395
368
}
396
369
397
370
/*
···
577
524
}
578
525
579
526
/*
527
+
* Initialize an alternative. The default alternative should be initialized
528
+
* with alt=NULL.
529
+
*/
530
+
static int disas_alt_init(struct disas_alt *dalt,
531
+
struct instruction *orig_insn,
532
+
struct alternative *alt)
533
+
{
534
+
dalt->orig_insn = orig_insn;
535
+
dalt->alt = alt;
536
+
dalt->name = alt ? disas_alt_name(alt) : strdup("DEFAULT");
537
+
if (!dalt->name)
538
+
return -1;
539
+
dalt->width = strlen(dalt->name);
540
+
541
+
return 0;
542
+
}
543
+
544
+
/*
545
+
* Print all alternatives one above the other.
546
+
*/
547
+
static void disas_alt_print_compact(char *alt_name, struct disas_alt *dalts,
548
+
int alt_count)
549
+
{
550
+
struct instruction *orig_insn;
551
+
int len;
552
+
int i;
553
+
554
+
orig_insn = dalts[0].orig_insn;
555
+
556
+
len = disas_print(stdout, orig_insn->sec, orig_insn->offset, 0, NULL);
557
+
printf("%s\n", alt_name);
558
+
559
+
for (i = 0; i < alt_count; i++)
560
+
printf("%*s= %s\n", len, "", dalts[i].name);
561
+
}
562
+
563
+
/*
564
+
* Disassemble an alternative.
565
+
*
566
+
* Return the last instruction in the default alternative so that
567
+
* disassembly can continue with the next instruction. Return NULL
568
+
* on error.
569
+
*/
570
+
static void *disas_alt(struct disas_context *dctx,
571
+
struct instruction *orig_insn)
572
+
{
573
+
struct disas_alt dalts[DISAS_ALT_MAX] = { 0 };
574
+
struct alternative *alt;
575
+
int alt_count = 0;
576
+
char *alt_name;
577
+
int err;
578
+
int i;
579
+
580
+
alt_name = strfmt("<%s.%lx>", disas_alt_type_name(orig_insn),
581
+
orig_insn->offset);
582
+
if (!alt_name) {
583
+
WARN("Failed to define name for alternative at instruction 0x%lx",
584
+
orig_insn->offset);
585
+
goto done;
586
+
}
587
+
588
+
/*
589
+
* Initialize the default alternative.
590
+
*/
591
+
err = disas_alt_init(&dalts[0], orig_insn, NULL);
592
+
if (err) {
593
+
WARN("%s: failed to initialize default alternative", alt_name);
594
+
goto done;
595
+
}
596
+
597
+
/*
598
+
* Initialize all other alternatives.
599
+
*/
600
+
i = 1;
601
+
for (alt = orig_insn->alts; alt; alt = alt->next) {
602
+
if (i >= DISAS_ALT_MAX) {
603
+
WARN("%s has more alternatives than supported", alt_name);
604
+
break;
605
+
}
606
+
err = disas_alt_init(&dalts[i], orig_insn, alt);
607
+
if (err) {
608
+
WARN("%s: failed to disassemble alternative", alt_name);
609
+
goto done;
610
+
}
611
+
612
+
i++;
613
+
}
614
+
alt_count = i;
615
+
616
+
/*
617
+
* Print default and non-default alternatives.
618
+
*
619
+
* At the moment, this just prints an header for each alternative.
620
+
*/
621
+
disas_alt_print_compact(alt_name, dalts, alt_count);
622
+
623
+
done:
624
+
for (i = 0; i < alt_count; i++)
625
+
free(dalts[i].name);
626
+
627
+
free(alt_name);
628
+
629
+
/*
630
+
* Currently we are not disassembling any alternative but just
631
+
* printing alternative names. Return NULL to have disas_func()
632
+
* resume the disassembly with the default alternative.
633
+
*/
634
+
return NULL;
635
+
}
636
+
637
+
/*
580
638
* Disassemble a function.
581
639
*/
582
640
static void disas_func(struct disas_context *dctx, struct symbol *func)
583
641
{
642
+
struct instruction *insn_start;
584
643
struct instruction *insn;
585
-
size_t addr;
586
644
587
645
printf("%s:\n", func->name);
588
646
sym_for_each_insn(dctx->file, func, insn) {
589
-
addr = insn->offset;
590
-
disas_insn(dctx, insn);
591
-
printf(" %6lx: %s+0x%-6lx %s\n",
592
-
addr, func->name, addr - func->offset,
593
-
disas_result(dctx));
647
+
if (insn->alts) {
648
+
insn_start = insn;
649
+
insn = disas_alt(dctx, insn);
650
+
if (insn)
651
+
continue;
652
+
/*
653
+
* There was an error with disassembling
654
+
* the alternative. Resume disassembling
655
+
* at the current instruction, this will
656
+
* disassemble the default alternative
657
+
* only and continue with the code after
658
+
* the alternative.
659
+
*/
660
+
insn = insn_start;
661
+
}
662
+
663
+
DISAS_PRINSN(dctx, insn, 0);
594
664
}
595
665
printf("\n");
596
666
}