next: Rpi4: Unexpected kernel BRK exception at EL1

Wed Jun 21 06:38:57 PDT 2023

On Wed, 21 Jun 2023 at 18:27, Mark Rutland <mark.rutland at arm.com> wrote:
>
> On Wed, Jun 21, 2023 at 06:06:51PM +0530, Naresh Kamboju wrote:
> > Following boot warnings and crashes noticed on arm64 Rpi4 device running
> > Linux next-20230621 kernel.
> >
> > Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>
> >
> > boot log:
> >
> > [   22.331748] Kernel text patching generated an invalid instruction
> > at 0xffff8000835d6580!
> > [   22.340579] Unexpected kernel BRK exception at EL1
> > [   22.346141] Internal error: BRK handler: 00000000f2000100 [#1] PREEMPT SMP
>
> This indicates execution of AARCH64_BREAK_FAULT.

I see kernel panic with kselftest merge configs on Juno-r2 and Rpi4.

>
> That could be from dodgy arguments to aarch64_insn_gen_*(), or elsewhere, and
> given this is in the networking code I suspect this'll be related to BPF.
>
> Looking at next-20230621 I see commit:
>
>   49703aa2adfaff28 ("bpf, arm64: use bpf_jit_binary_pack_alloc")
>
> ... which changed the way BPF allocates memory, and has code that pads memory
> with a bunch of AARCH64_BREAK_FAULT, so it looks like that *might* be related.
>
> Are you able to bisect this?

I have not started bisection on this issue yet.
Let me give it a try.

>
> In the mean time, I've Cc'd the relevant BPF people to give them a heads-up.

Thanks.

Extra information from boot failures.
This is always reproducible on Juno-r2 and Rpi4 devices.

Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>

Boot crash log:
[    3.605232] Kernel text patching generated an invalid instruction
at bpf_prog_99a0cd861b84ee07___loader.prog+0x0/0x728!
[    3.616052] Unexpected kernel BRK exception at EL1
[    3.620849] Internal error: BRK handler: 00000000f2000100 [#1] PREEMPT SMP
[    3.627736] Modules linked in:
[    3.630796] CPU: 1 PID: 1 Comm: swapper/0 Not tainted
6.4.0-rc7-next-20230621 #1
[    3.638140] hub 1-1:1.0: USB hub found
[    3.638206] Hardware name: ARM Juno development board (r2) (DT)
[    3.638210] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    3.642431] hub 1-1:1.0: 4 ports detected
[    3.647879] pc : bpf_prog_99a0cd861b84ee07___loader.prog+0x0/0x728
[    3.647891] lr : kern_sys_bpf+0x130/0x218
[    3.669061] sp : ffff80008391bc10
[    3.672376] x29: ffff80008391bc10 x28: ffff8000826e70d8 x27: ffff800082450110
[    3.679533] x26: ffff8000820ed948 x25: ffff800082427b10 x24: 0000000000000289
[    3.686687] x23: ffff000800acfa00 x22: ffff8000837f8000 x21: ffff000823dbc240
[    3.693841] x20: ffff8000839b1000 x19: ffff80008391bca8 x18: 000000001d03406d
[    3.700995] x17: ffff800080464204 x16: ffff8000804640b4 x15: ffff8000803f8af0
[    3.708149] x14: ffff8000803f88f8 x13: ffff800081717720 x12: ffff8000824514b4
[    3.715302] x11: ffff800080015788 x10: ffff800082470304 x9 : ffff8000800f3338
[    3.722456] x8 : ffff80008391bcf8 x7 : 0000000000000000 x6 : 0000000000000001
[    3.729609] x5 : 0000000000000001 x4 : ffff8000831f0000 x3 : ffff8008fc63d000
[    3.736763] x2 : ffff800083b6d88c x1 : ffff8000839b1048 x0 : ffff000823dbc240
[    3.743917] Call trace:
[    3.746362]  bpf_prog_99a0cd861b84ee07___loader.prog+0x0/0x728
[    3.752210]  bpf_load_and_run.constprop.0+0x120/0x1d8
[    3.757270]  load+0xf4/0x278
[    3.760159]  do_one_initcall+0x50/0x2f0
[    3.764001]  kernel_init_freeable+0x224/0x438
[    3.768368]  kernel_init+0x30/0x200
[    3.771862]  ret_from_fork+0x10/0x20
[    3.775447] Code: d4202000 00000780 d4202000 d4202000 (910003c9)
[    3.781550] ---[ end trace 0000000000000000 ]---
[    3.786172] note: swapper/0[1] exited with irqs disabled
[    3.791526] note: swapper/0[1] exited with preempt_count 1
[    3.797043] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b
[    3.804711] SMP: stopping secondary CPUs
[    3.808843] Kernel Offset: disabled
[    3.812331] CPU features: 0x40000106,1e010000,0000421b
[    3.817476] Memory Limit: none
[    3.820536] ---[ end Kernel panic - not syncing: Attempted to kill
init! exitcode=0x0000000b ]---

Links:
https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230621/testrun/17701148/suite/log-parser-test/tests/
https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230621/testrun/17701148/suite/log-parser-test/test/check-kernel-panic/log
https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230621/testrun/17701148/suite/log-parser-test/test/check-kernel-panic/details/

metadata:
  git_ref: master
  git_repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next
  git_sha: 15e71592dbae49a674429c618a10401d7f992ac3
  git_describe: next-20230621
  kernel_version: 6.4.0-rc7
  kernel-config:
    https://storage.tuxsuite.com/public/linaro/lkft/builds/2RVAA4lj35ia3YDkqaoV6ztyqdW/config
  artifact-location:
    https://storage.tuxsuite.com/public/linaro/lkft/builds/2RVAA4lj35ia3YDkqaoV6ztyqdW/
  toolchain: gcc-11
  build_name: gcc-11-lkftconfig-kselftest

--
Linaro LKFT
https://lkft.linaro.org