Re: hw_breakpoint unit test failures with various architectures/platforms in qemu

[Huacai Chen]

Hi, Marco,

On Tue, Mar 5, 2024 at 4:34 AM Marco Elver <elver@xxxxxxxxxx> wrote:
>
> On Mon, 4 Mar 2024 at 19:12, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> >
> > Hi,
> >
> > I see a number of failures and tracebacks when running the hw_breakpoint
> > unit tests on various architectures in qemu. Some examples are below.
> >
> > Is this a potential problem with the unit tests, with the hardware,
> > or with the qemu emulation of that hardware ?
>
> The test is testing the accounting logic (allocating/deallocating HW
> breakpoints), not actually using the breakpoints. That requires that
> the architecture reports the correct number of HW breakpoints
> available. It looks like it's not doing that.
>
> > In other words, is it worthwhile to look into this further, or would
> > it make more sense to just disable those tests if they fail on a
> > given hardware/platform ?
>
> It's an arch bug:
> https://lore.kernel.org/lkml/Ytl9L0Zn1PVuL1cB@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
>
> Back then we decided to leave the test as-is, given it's reporting an
> actual issue. However, since then nothing has changed and the test
> continues to exist as a reminder the arch code needs fixing. I suspect
> none of us have the time to get to that soon, so we can either leave
> things as is, or skip the test on all the broken architectures.
>
> No idea what's going on with loongarch.
LoongArch's problem comes from QEMU, I have tested on real machine.

[    7.222500] KTAP version 1
[    7.226067] 1..1
[    7.228795]     KTAP version 1
[    7.232737]     # Subtest: hw_breakpoint
[    7.237512]     # module: hw_breakpoint_test
[    7.237520]     1..9
[    7.442899]     ok 1 test_one_cpu
[    7.443912]     ok 2 test_many_cpus
[    7.451298]     ok 3 test_one_task_on_all_cpus
[    7.456486]     ok 4 test_two_tasks_on_all_cpus
[    7.462291]     ok 5 test_one_task_on_one_cpu
[    7.468293]     ok 6 test_one_task_mixed
[    7.474405]     ok 7 test_two_tasks_on_one_cpu
[    7.479884]     ok 8 test_two_tasks_on_one_all_cpus
[    7.485699]     ok 9 test_task_on_all_and_one_cpu
[    7.491488] # hw_breakpoint: pass:9 fail:0 skip:0 total:9
[    7.496985] # Totals: pass:9 fail:0 skip:0 total:9
[    7.503179] ok 1 hw_breakpoint

Huacai

>
> Thanks,
> -- Marco
>
> > Thanks,
> > Guenter
> >
> > ---
> > arm:smdkc210:
> >
> > [    9.515572]     ok 2 test_many_cpus
> > [    9.519425] ########### searching unregister_test_bp
> > [    9.519989] ------------[ cut here ]------------
> > [    9.520995] ########### searching test_one_task_on_all_cpus
> > [    9.521318] WARNING: CPU: 1 PID: 63 at kernel/events/hw_breakpoint_test.c:49 test_one_task_on_all_cpus+0x90/0x1c4
> > [    9.521921] Modules linked in:
> > [    9.522532] CPU: 1 PID: 63 Comm: kunit_try_catch Tainted: G                 N 6.8.0-rc7-00028-g624465c9abd6 #1
> > [    9.523102] Hardware name: Samsung Exynos (Flattened Device Tree)
> > [    9.523610]  unwind_backtrace from show_stack+0x10/0x14
> > [    9.523936]  show_stack from dump_stack_lvl+0x68/0x90
> > [    9.524191]  dump_stack_lvl from __warn+0xbc/0x21c
> > [    9.524429]  __warn from warn_slowpath_fmt+0x1a8/0x1b0
> > [    9.524674]  warn_slowpath_fmt from test_one_task_on_all_cpus+0x90/0x1c4
> > [    9.524971]  test_one_task_on_all_cpus from kunit_try_run_case+0x58/0x18c
> > [    9.525273]  kunit_try_run_case from kunit_generic_run_threadfn_adapter+0x14/0x20
> > [    9.525593]  kunit_generic_run_threadfn_adapter from kthread+0x118/0x124
> > [    9.525889]  kthread from ret_from_fork+0x14/0x28
> > [    9.526200] Exception stack(0xf0ad5fb0 to 0xf0ad5ff8)
> > [    9.526663] 5fa0:                                     00000000 00000000 00000000 00000000
> > [    9.527112] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > [    9.527449] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > [    9.527876] irq event stamp: 113
> > [    9.528088] hardirqs last  enabled at (121): [<c01adfb4>] console_unlock+0x114/0x130
> > [    9.529049] hardirqs last disabled at (140): [<c01adfa0>] console_unlock+0x100/0x130
> > [    9.529501] softirqs last  enabled at (138): [<c010168c>] __do_softirq+0x340/0x520
> > [    9.529892] softirqs last disabled at (129): [<c012f23c>] irq_exit+0x190/0x1c0
> > [    9.530227] ---[ end trace 0000000000000000 ]---
> > [    9.531752]     # test_one_task_on_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    9.531752]     Expected IS_ERR(bp) to be false, but is true
> > [    9.537757]     not ok 3 test_one_task_on_all_cpus
> >
> > ---
> > arm:raspi2b (and others):
> >
> > [   14.718608]     # Subtest: hw_breakpoint
> > [   14.719351]     # module: hw_breakpoint_test
> > [   14.722275]     1..9
> > [   14.737927]     # test_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.737927]     Expected IS_ERR(bp) to be false, but is true
> > [   14.745960]     not ok 1 test_one_cpu
> > [   14.750052]     # test_many_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.750052]     Expected IS_ERR(bp) to be false, but is true
> > [   14.791453]     not ok 2 test_many_cpus
> > [   14.805964]     # test_one_task_on_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.805964]     Expected IS_ERR(bp) to be false, but is true
> > [   14.822662]     not ok 3 test_one_task_on_all_cpus
> > [   14.836897]     # test_two_tasks_on_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.836897]     Expected IS_ERR(bp) to be false, but is true
> > [   14.869770]     not ok 4 test_two_tasks_on_all_cpus
> > [   14.913412]     # test_one_task_on_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.913412]     Expected IS_ERR(bp) to be false, but is true
> > [   14.929852]     not ok 5 test_one_task_on_one_cpu
> > [   14.939676]     # test_one_task_mixed: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.939676]     Expected IS_ERR(bp) to be false, but is true
> > [   14.953670]     not ok 6 test_one_task_mixed
> > [   14.964403]     # test_two_tasks_on_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   14.964403]     Expected IS_ERR(bp) to be false, but is true
> > [   14.997262]     not ok 7 test_two_tasks_on_one_cpu
> > [   15.012825]     # test_two_tasks_on_one_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   15.012825]     Expected IS_ERR(bp) to be false, but is true
> > [   15.045472]     not ok 8 test_two_tasks_on_one_all_cpus
> > [   15.070033]     # test_task_on_all_and_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [   15.070033]     Expected IS_ERR(bp) to be false, but is true
> > [   15.077092]     not ok 9 test_task_on_all_and_one_cpu
> >
> > ---
> > arm64:virt:
> >
> > [    7.753199]     ok 2 test_many_cpus
> > [    7.766356]     # test_one_task_on_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.766356]     Expected IS_ERR(bp) to be false, but is true
> > [    7.775897]     not ok 3 test_one_task_on_all_cpus
> > [    7.786604]     # test_two_tasks_on_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.786604]     Expected IS_ERR(bp) to be false, but is true
> > [    7.793878]     not ok 4 test_two_tasks_on_all_cpus
> > [    7.799954]     # test_one_task_on_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.799954]     Expected IS_ERR(bp) to be false, but is true
> > [    7.811446]     not ok 5 test_one_task_on_one_cpu
> > [    7.823706]     # test_one_task_mixed: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.823706]     Expected IS_ERR(bp) to be false, but is true
> > [    7.838892]     not ok 6 test_one_task_mixed
> > [    7.843594]     # test_two_tasks_on_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.843594]     Expected IS_ERR(bp) to be false, but is true
> > [    7.862087]     not ok 7 test_two_tasks_on_one_cpu
> > [    7.869706]     # test_two_tasks_on_one_all_cpus: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.869706]     Expected IS_ERR(bp) to be false, but is true
> > [    7.874499]     not ok 8 test_two_tasks_on_one_all_cpus
> > [    7.878321]     # test_task_on_all_and_one_cpu: ASSERTION FAILED at kernel/events/hw_breakpoint_test.c:70
> > [    7.878321]     Expected IS_ERR(bp) to be false, but is true
> > [    7.894138]     not ok 9 test_task_on_all_and_one_cpu
> > [    7.894501] # hw_breakpoint: pass:2 fail:7 skip:0 total:9
> > [    7.894911] # Totals: pass:2 fail:7 skip:0 total:9
> >
> > ---
> > loongarch:
> >
> > [    7.327439]     ok 2 test_many_cpus
> > [    7.330144] ------------[ cut here ]------------
> > [    7.330849] WARNING: CPU: 1 PID: 87 at kernel/events/hw_breakpoint_test.c:49 test_one_task_on_all_cpus+0x204/0x210
>