Hi Lijiang & Kazu,

On Wed, Jun 12, 2024 at 1:03 PM lijiang <lijiang@redhat.com> wrote:
>
> On Wed, Jun 12, 2024 at 12:29 PM HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab@nec.com> wrote:
>>
>>
>> On 2024/06/12 12:42, Lianbo Jiang wrote:
>> > The commit 48764a14bc58 may cause a regression issue when the CONFIG_X86_FRED
>> > is not enabled, this is because the SIZE(fred_frame) will call the
>> > SIZE_verify() to determine if the fred_frame is valid, otherwise it will
>> > emit an error:
>> >
>> >    crash> bt 1
>> >
>> >    bt: invalid structure size: fred_frame
>> >          FILE: x86_64.c  LINE: 4089  FUNCTION: x86_64_low_budget_back_trace_cmd()
>> >
>> >    [/home/k-hagio/bin/crash] error trace: 588df3 => 5cbc72 => 5eb3e1 => 5eb366
>> >    PID: 1        TASK: ffff9f94c024b980  CPU: 2    COMMAND: "systemd"
>> >       #0 [ffffade44001bca8] __schedule at ffffffffb948ebbb
>> >       #1 [ffffade44001bd10] schedule at ffffffffb948f04d
>> >       #2 [ffffade44001bd20] schedule_hrtimeout_range_clock at ffffffffb9494fef
>> >       #3 [ffffade44001bda8] ep_poll at ffffffffb8c91be8
>> >       #4 [ffffade44001be48] do_epoll_wait at ffffffffb8c91d11
>> >       #5 [ffffade44001be80] __x64_sys_epoll_wait at ffffffffb8c92590
>> >       #6 [ffffade44001bed0] do_syscall_64 at ffffffffb947f459
>> >       #7 [ffffade44001bf50] entry_SYSCALL_64_after_hwframe at ffffffffb96000ea
>> >
>> >        5eb366: SIZE_verify.part.42+70
>> >        5eb3e1: SIZE_verify+49
>> >        5cbc72: x86_64_low_budget_back_trace_cmd+3010
>> >        588df3: back_trace+1523
>> >
>> >    bt: invalid structure size: fred_frame
>> >          FILE: x86_64.c  LINE: 4089  FUNCTION: x86_64_low_budget_back_trace_cmd()
>> >
>> > Let's replace the SIZE(fred_frame) with the VALID_SIZE(fred_frame) to
>> > fix it.
>> >
>> > Fixes: 48764a14bc58 ("x86_64: fix for adding top_of_kernel_stack_padding for kernel stack")
>> > Reported-by: Kazuhito Hagio <k-hagio-ab@nec.com>
>> > Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
>> > ---
>> >   x86_64.c | 4 ++--
>> >   1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/x86_64.c b/x86_64.c
>> > index 6777c93e6b47..469d26b05e24 100644
>> > --- a/x86_64.c
>> > +++ b/x86_64.c
>> > @@ -4086,7 +4086,7 @@ in_exception_stack:
>> >
>> >           if (!irq_eframe && !is_kernel_thread(bt->tc->task) &&
>> >               (GET_STACKBASE(bt->tc->task) == bt->stackbase)) {
>> > -             long stack_padding_size = SIZE(fred_frame) > 0 ? (2*8) : 0;
>> > +             long stack_padding_size = VALID_SIZE(fred_frame) ? (2*8) : 0;
>> >               user_mode_eframe = bt->stacktop - SIZE(pt_regs);
>> >               if (last_process_stack_eframe < user_mode_eframe)
>> >                       x86_64_exception_frame(EFRAME_PRINT, 0, bt->stackbuf +
>> > @@ -4408,7 +4408,7 @@ in_exception_stack:
>> >
>> >           if (!irq_eframe && !is_kernel_thread(bt->tc->task) &&
>> >               (GET_STACKBASE(bt->tc->task) == bt->stackbase)) {
>> > -             long stack_padding_size = SIZE(fred_frame) > 0 ? (2*8) : 0;
>> > +             long stack_padding_size = VALID_SIZE(fred_frame) ? (2*8) : 0;
>> >               user_mode_eframe = bt->stacktop - SIZE(pt_regs);
>> >               if (last_process_stack_eframe < user_mode_eframe)
>> >                       x86_64_exception_frame(EFRAME_PRINT, 0, bt->stackbuf +
>>
>> Thanks, tested ok with kernels configured without CONFIG_X86_FRED=y.
>>
>
> Thank you for helping with the test, Kazu.
>

Thanks for reporting and fixing the code. LGTM, so ack.

Thanks,
Tao Liu

> Lianbo
>
>>
>> Thanks,
>> Kazu