Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'objtool-urgent-2025-04-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc objtool fixes from Ingo Molnar:
- Remove the recently introduced ANNOTATE_IGNORE_ALTERNATIVE noise from
clac()/stac() code to make .s files more readable
- Fix INSN_SYSCALL / INSN_SYSRET semantics
- Fix various false-positive warnings
* tag 'objtool-urgent-2025-04-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix false-positive "ignoring unreachables" warning
objtool: Remove ANNOTATE_IGNORE_ALTERNATIVE from CLAC/STAC
objtool, xen: Fix INSN_SYSCALL / INSN_SYSRET semantics
objtool: Stop UNRET validation on UD2
objtool: Split INSN_CONTEXT_SWITCH into INSN_SYSCALL and INSN_SYSRET
objtool: Fix INSN_CONTEXT_SWITCH handling in validate_unret()
+72
-26
+6
-6
arch/x86/include/asm/smap.h
+6
-6
arch/x86/include/asm/smap.h
···
16
16
#ifdef __ASSEMBLER__
17
17
18
18
#define ASM_CLAC \
19
-
ALTERNATIVE __stringify(ANNOTATE_IGNORE_ALTERNATIVE), "clac", X86_FEATURE_SMAP
19
+
ALTERNATIVE "", "clac", X86_FEATURE_SMAP
20
20
21
21
#define ASM_STAC \
22
-
ALTERNATIVE __stringify(ANNOTATE_IGNORE_ALTERNATIVE), "stac", X86_FEATURE_SMAP
22
+
ALTERNATIVE "", "stac", X86_FEATURE_SMAP
23
23
24
24
#else /* __ASSEMBLER__ */
25
25
26
26
static __always_inline void clac(void)
27
27
{
28
28
/* Note: a barrier is implicit in alternative() */
29
-
alternative(ANNOTATE_IGNORE_ALTERNATIVE "", "clac", X86_FEATURE_SMAP);
29
+
alternative("", "clac", X86_FEATURE_SMAP);
30
30
}
31
31
32
32
static __always_inline void stac(void)
33
33
{
34
34
/* Note: a barrier is implicit in alternative() */
35
-
alternative(ANNOTATE_IGNORE_ALTERNATIVE "", "stac", X86_FEATURE_SMAP);
35
+
alternative("", "stac", X86_FEATURE_SMAP);
36
36
}
37
37
38
38
static __always_inline unsigned long smap_save(void)
···
59
59
60
60
/* These macros can be used in asm() statements */
61
61
#define ASM_CLAC \
62
-
ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "", "clac", X86_FEATURE_SMAP)
62
+
ALTERNATIVE("", "clac", X86_FEATURE_SMAP)
63
63
#define ASM_STAC \
64
-
ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "", "stac", X86_FEATURE_SMAP)
64
+
ALTERNATIVE("", "stac", X86_FEATURE_SMAP)
65
65
66
66
#define ASM_CLAC_UNSAFE \
67
67
ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "clac", X86_FEATURE_SMAP)
+1
-3
arch/x86/xen/xen-asm.S
+1
-3
arch/x86/xen/xen-asm.S
+11
-7
tools/objtool/arch/x86/decode.c
+11
-7
tools/objtool/arch/x86/decode.c
···
522
522
case INAT_PFX_REPNE:
523
523
if (modrm == 0xca)
524
524
/* eretu/erets */
525
-
insn->type = INSN_CONTEXT_SWITCH;
525
+
insn->type = INSN_SYSRET;
526
526
break;
527
527
default:
528
528
if (modrm == 0xca)
···
535
535
536
536
insn->type = INSN_JUMP_CONDITIONAL;
537
537
538
-
} else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 ||
539
-
op2 == 0x35) {
538
+
} else if (op2 == 0x05 || op2 == 0x34) {
540
539
541
-
/* sysenter, sysret */
542
-
insn->type = INSN_CONTEXT_SWITCH;
540
+
/* syscall, sysenter */
541
+
insn->type = INSN_SYSCALL;
542
+
543
+
} else if (op2 == 0x07 || op2 == 0x35) {
544
+
545
+
/* sysret, sysexit */
546
+
insn->type = INSN_SYSRET;
543
547
544
548
} else if (op2 == 0x0b || op2 == 0xb9) {
545
549
···
680
676
681
677
case 0xca: /* retf */
682
678
case 0xcb: /* retf */
683
-
insn->type = INSN_CONTEXT_SWITCH;
679
+
insn->type = INSN_SYSRET;
684
680
break;
685
681
686
682
case 0xe0: /* loopne */
···
725
721
} else if (modrm_reg == 5) {
726
722
727
723
/* jmpf */
728
-
insn->type = INSN_CONTEXT_SWITCH;
724
+
insn->type = INSN_SYSRET;
729
725
730
726
} else if (modrm_reg == 6) {
731
727
+1
-1
tools/objtool/arch/x86/special.c
+1
-1
tools/objtool/arch/x86/special.c
···
126
126
* indicates a rare GCC quirk/bug which can leave dead
127
127
* code behind.
128
128
*/
129
-
if (reloc_type(text_reloc) == R_X86_64_PC32) {
129
+
if (!file->ignore_unreachables && reloc_type(text_reloc) == R_X86_64_PC32) {
130
130
WARN_INSN(insn, "ignoring unreachables due to jump table quirk");
131
131
file->ignore_unreachables = true;
132
132
}
+51
-8
tools/objtool/check.c
+51
-8
tools/objtool/check.c
···
3505
3505
return next_insn_same_sec(file, alt_group->orig_group->last_insn);
3506
3506
}
3507
3507
3508
+
static bool skip_alt_group(struct instruction *insn)
3509
+
{
3510
+
struct instruction *alt_insn = insn->alts ? insn->alts->insn : NULL;
3511
+
3512
+
/* ANNOTATE_IGNORE_ALTERNATIVE */
3513
+
if (insn->alt_group && insn->alt_group->ignore)
3514
+
return true;
3515
+
3516
+
/*
3517
+
* For NOP patched with CLAC/STAC, only follow the latter to avoid
3518
+
* impossible code paths combining patched CLAC with unpatched STAC
3519
+
* or vice versa.
3520
+
*
3521
+
* ANNOTATE_IGNORE_ALTERNATIVE could have been used here, but Linus
3522
+
* requested not to do that to avoid hurting .s file readability
3523
+
* around CLAC/STAC alternative sites.
3524
+
*/
3525
+
3526
+
if (!alt_insn)
3527
+
return false;
3528
+
3529
+
/* Don't override ASM_{CLAC,STAC}_UNSAFE */
3530
+
if (alt_insn->alt_group && alt_insn->alt_group->ignore)
3531
+
return false;
3532
+
3533
+
return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
3534
+
}
3535
+
3508
3536
/*
3509
3537
* Follow the branch starting at the given instruction, and recursively follow
3510
3538
* any other branches (jumps). Meanwhile, track the frame pointer state at
···
3653
3625
}
3654
3626
}
3655
3627
3656
-
if (insn->alt_group && insn->alt_group->ignore)
3628
+
if (skip_alt_group(insn))
3657
3629
return 0;
3658
3630
3659
3631
if (handle_insn_ops(insn, next_insn, &state))
···
3712
3684
3713
3685
break;
3714
3686
3715
-
case INSN_CONTEXT_SWITCH:
3716
-
if (func) {
3717
-
if (!next_insn || !next_insn->hint) {
3718
-
WARN_INSN(insn, "unsupported instruction in callable function");
3719
-
return 1;
3720
-
}
3721
-
break;
3687
+
case INSN_SYSCALL:
3688
+
if (func && (!next_insn || !next_insn->hint)) {
3689
+
WARN_INSN(insn, "unsupported instruction in callable function");
3690
+
return 1;
3722
3691
}
3692
+
3693
+
break;
3694
+
3695
+
case INSN_SYSRET:
3696
+
if (func && (!next_insn || !next_insn->hint)) {
3697
+
WARN_INSN(insn, "unsupported instruction in callable function");
3698
+
return 1;
3699
+
}
3700
+
3723
3701
return 0;
3724
3702
3725
3703
case INSN_STAC:
···
3920
3886
WARN_INSN(insn, "RET before UNTRAIN");
3921
3887
return 1;
3922
3888
3889
+
case INSN_SYSCALL:
3890
+
break;
3891
+
3892
+
case INSN_SYSRET:
3893
+
return 0;
3894
+
3923
3895
case INSN_NOP:
3924
3896
if (insn->retpoline_safe)
3925
3897
return 0;
···
3934
3894
default:
3935
3895
break;
3936
3896
}
3897
+
3898
+
if (insn->dead_end)
3899
+
return 0;
3937
3900
3938
3901
if (!next) {
3939
3902
WARN_INSN(insn, "teh end!");