Skip to contentSkip to conversation

b7b8b4ccda: CFI_failure_at_do_one_initcall

linus:master kernel test robot 2 participants 2 messages Aug 20 Rust

lore
Share & tools
lore

kernel test robot

author build bot
#0 lore raw

Hello,

kernel test robot noticed "CFI_failure_at_do_one_initcall" on:

commit: b7b8b4ccdad45a59aafa5cfc32a51fe1ee5cb680 ("rust: extract bitfield! macro from register!") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

[test still failed on linus/master 8d3ae59288f1e7d58d76558a6ee96d533bc5019]

in testcase: rcutorture
with following parameters:

    runtime: 300s
    test: cpuhotplug
    torture_type: tasks-tracing

config: x86_64-randconfig-015-20260715
compiler: clang-22
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G

(please refer to attached dmesg/kmsg for entire log/backtrace)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-lkp/[email protected]

[   16.811904][    T1] CFI failure at do_one_initcall+0x12e/0x478 (target: _RINvCsdamrQDJyPhn_8pin_init6zeroedNtNvNvNvCsdPKRummocL6_25doctests_kernel_generated33rust_doctest_kernel_bitfield_rs_04main43__doctest_main_rust_kernel_bitfield_rs_118_05FlagsEBE_+0x0/0x4; expected type: 0x6fbb3035)
[   16.820524][    T1] WARNING: at do_one_initcall+0x12e/0x478, CPU#0: swapper/0/1
[   16.823875][    T1] Modules linked in:
[   16.825674][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.1.0-rc4-00055-gb7b8b4ccdad4 #1 PREEMPT  79da7d58e576708b28b47c0dd4cca3fe34a229fd
[   16.831720][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   16.836267][    T1] RIP: 0010:do_one_initcall+0x12e/0x478
[   16.838287][    T1] Code: d2 31 c9 e8 74 04 49 00 45 84 f6 75 0c 48 8d 3d 90 03 a1 0c 67 48 0f b9 3a 4c 8b 5c 24 08 41 ba cb cf 44 90 45 03 53 fc 74 02 <0f> 0b 2e e8 42 96 f8 06 41 89 c6 0f 1f 44 00 00 41 81 e5 ff ff ff
[   16.843506][    T1] RSP: 0018:ffffc9000001fb80 EFLAGS: 00010a13
[   16.845121][    T1] RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
[   16.847279][    T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[   16.849427][    T1] RBP: ffffc9000001fe70 R08: 0000000000000000 R09: 0000000b8a3be5a2
[   16.851619][    T1] R10: 000000006c292bb6 R11: ffffffff81407458 R12: ffffffff8f899850
[   16.853771][    T1] R13: 0000000080000000 R14: 0000000000000001 R15: 1ffffffff1edab41
[   16.855915][    T1] FS:  0000000000000000(0000) GS:0000000000000000(0000) knlGS:0000000000000000
[   16.858307][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   16.860091][    T1] CR2: 00007fd1104620ac CR3: 000000000ba86000 CR4: 00000000000406b0
[   16.862236][    T1] Call Trace:
[   16.863144][    T1]  <TASK>
[   16.863961][    T1]  ? __cfi__RINvCsdamrQDJyPhn_8pin_init6zeroedNtNvNvNvCsdPKRummocL6_25doctests_kernel_generated33rust_doctest_kernel_bitfield_rs_04main43__doctest_main_rust_kernel_bitfield_rs_118_05FlagsEBE_+0x8/0x8
[   16.869044][    T1]  ? stack_depot_save_flags+0x40f/0xab8
[   16.870574][    T1]  ? irqentry_exit+0x1b8/0x638
[   16.871878][    T1]  ? trace_irq_disable+0x25/0x100
[   16.873243][    T1]  ? __cfi_ignore_unknown_bootoption+0x8/0x8
[   16.874861][    T1]  ? strlen+0x32/0x78
[   16.875952][    T1]  ? parameq+0x1a/0xf8
[   16.877070][    T1]  ? __cfi_ignore_unknown_bootoption+0x8/0x8
[   16.878666][    T1]  ? parse_args+0x17e/0x538
[   16.879902][    T1]  do_initcall_level+0x10e/0x1c0
[   16.881314][    T1]  do_initcalls+0x59/0xc0
[   16.882501][    T1]  kernel_init_freeable+0x11e/0x1c0
[   16.883889][    T1]  ? __cfi_kernel_init+0x8/0x8
[   16.885175][    T1]  kernel_init+0x16/0x138
[   16.886357][    T1]  ret_from_fork+0x266/0x5f8
[   16.887598][    T1]  ? __cfi_kernel_init+0x8/0x8
[   16.888884][    T1]  ret_from_fork_asm+0x11/0x20
[   16.890220][    T1]  </TASK>
[   16.891058][    T1] irq event stamp: 306141
[   16.892233][    T1] hardirqs last  enabled at (306157): [<ffffffff81749821>] __console_unlock+0x61/0xc0
[   16.894765][    T1] hardirqs last disabled at (306170): [<ffffffff81749806>] __console_unlock+0x46/0xc0
[   16.897303][    T1] softirqs last  enabled at (305714): [<ffffffff81618b94>] handle_softirqs+0x614/0x780
[   16.899859][    T1] softirqs last disabled at (305705): [<ffffffff81618ec5>] __irq_exit_rcu+0x45/0x140
[   16.902401][    T1] ---[ end trace 0000000000000000 ]---

The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260820/[email protected]

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

reviewer
#1 lore raw

(Cc Clang/LLVM folks)

Quoted 23 lines · kernel test robot

Hello,

kernel test robot noticed "CFI_failure_at_do_one_initcall" on:

commit: b7b8b4ccdad45a59aafa5cfc32a51fe1ee5cb680 ("rust: extract bitfield! macro from register!") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

[test still failed on linus/master 8d3ae59288f1e7d58d76558a6ee96d533bc5019]

in testcase: rcutorture
with following parameters:

    runtime: 300s
    test: cpuhotplug
    torture_type: tasks-tracing

config: x86_64-randconfig-015-20260715
compiler: clang-22
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G

Quoted 5 lines

(please refer to attached dmesg/kmsg for entire log/backtrace)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-lkp/[email protected]

The issue looks like that LLVM is trying to merge functions by creating alias with different KCFI types.

See this minimized example: https://godbolt.org/z/PhhcGh4W5

Note that a and b have different !kcfi_types annotation, but they're merged regardless.

This causes the merge of __module_firmware_test_init with Flags::zeroed which ABI-wise are compatible as they all return just an integer, but have different KCFI signature.

I think we need to disable function merging pass when KCFI is enabled, until this has been fixed by LLVM. Clang disables this pass by default. We can also workaround the issue by disable the test that generates __module_firmware_test_init (perhaps we should do this regardless, it's strange that a module is produced from doc tests!)

So that commit is just a trigger and isn't buggy itself; it only introduces a new function which happens to be mergeable with the empty __module_firmware_test_init.

Best,
Gary

Quoted 54 lines

[   16.811904][    T1] CFI failure at do_one_initcall+0x12e/0x478 (target: _RINvCsdamrQDJyPhn_8pin_init6zeroedNtNvNvNvCsdPKRummocL6_25doctests_kernel_generated33rust_doctest_kernel_bitfield_rs_04main43__doctest_main_rust_kernel_bitfield_rs_118_05FlagsEBE_+0x0/0x4; expected type: 0x6fbb3035)
[   16.820524][    T1] WARNING: at do_one_initcall+0x12e/0x478, CPU#0: swapper/0/1
[   16.823875][    T1] Modules linked in:
[   16.825674][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.1.0-rc4-00055-gb7b8b4ccdad4 #1 PREEMPT  79da7d58e576708b28b47c0dd4cca3fe34a229fd
[   16.831720][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   16.836267][    T1] RIP: 0010:do_one_initcall+0x12e/0x478
[   16.838287][    T1] Code: d2 31 c9 e8 74 04 49 00 45 84 f6 75 0c 48 8d 3d 90 03 a1 0c 67 48 0f b9 3a 4c 8b 5c 24 08 41 ba cb cf 44 90 45 03 53 fc 74 02 <0f> 0b 2e e8 42 96 f8 06 41 89 c6 0f 1f 44 00 00 41 81 e5 ff ff ff
[   16.843506][    T1] RSP: 0018:ffffc9000001fb80 EFLAGS: 00010a13
[   16.845121][    T1] RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
[   16.847279][    T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[   16.849427][    T1] RBP: ffffc9000001fe70 R08: 0000000000000000 R09: 0000000b8a3be5a2
[   16.851619][    T1] R10: 000000006c292bb6 R11: ffffffff81407458 R12: ffffffff8f899850
[   16.853771][    T1] R13: 0000000080000000 R14: 0000000000000001 R15: 1ffffffff1edab41
[   16.855915][    T1] FS:  0000000000000000(0000) GS:0000000000000000(0000) knlGS:0000000000000000
[   16.858307][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   16.860091][    T1] CR2: 00007fd1104620ac CR3: 000000000ba86000 CR4: 00000000000406b0
[   16.862236][    T1] Call Trace:
[   16.863144][    T1]  <TASK>
[   16.863961][    T1]  ? __cfi__RINvCsdamrQDJyPhn_8pin_init6zeroedNtNvNvNvCsdPKRummocL6_25doctests_kernel_generated33rust_doctest_kernel_bitfield_rs_04main43__doctest_main_rust_kernel_bitfield_rs_118_05FlagsEBE_+0x8/0x8
[   16.869044][    T1]  ? stack_depot_save_flags+0x40f/0xab8
[   16.870574][    T1]  ? irqentry_exit+0x1b8/0x638
[   16.871878][    T1]  ? trace_irq_disable+0x25/0x100
[   16.873243][    T1]  ? __cfi_ignore_unknown_bootoption+0x8/0x8
[   16.874861][    T1]  ? strlen+0x32/0x78
[   16.875952][    T1]  ? parameq+0x1a/0xf8
[   16.877070][    T1]  ? __cfi_ignore_unknown_bootoption+0x8/0x8
[   16.878666][    T1]  ? parse_args+0x17e/0x538
[   16.879902][    T1]  do_initcall_level+0x10e/0x1c0
[   16.881314][    T1]  do_initcalls+0x59/0xc0
[   16.882501][    T1]  kernel_init_freeable+0x11e/0x1c0
[   16.883889][    T1]  ? __cfi_kernel_init+0x8/0x8
[   16.885175][    T1]  kernel_init+0x16/0x138
[   16.886357][    T1]  ret_from_fork+0x266/0x5f8
[   16.887598][    T1]  ? __cfi_kernel_init+0x8/0x8
[   16.888884][    T1]  ret_from_fork_asm+0x11/0x20
[   16.890220][    T1]  </TASK>
[   16.891058][    T1] irq event stamp: 306141
[   16.892233][    T1] hardirqs last  enabled at (306157): [<ffffffff81749821>] __console_unlock+0x61/0xc0
[   16.894765][    T1] hardirqs last disabled at (306170): [<ffffffff81749806>] __console_unlock+0x46/0xc0
[   16.897303][    T1] softirqs last  enabled at (305714): [<ffffffff81618b94>] handle_softirqs+0x614/0x780
[   16.899859][    T1] softirqs last disabled at (305705): [<ffffffff81618ec5>] __irq_exit_rcu+0x45/0x140
[   16.902401][    T1] ---[ end trace 0000000000000000 ]---

The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260820/[email protected]

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki