On Wed, Sep 11, 2024 at 2:36 PM Tao Liu <ltao@xxxxxxxxxx> wrote:
Hi lianbo,
On Wed, Sep 11, 2024 at 2:26 PM lijiang <lijiang@xxxxxxxxxx> wrote:
>
> Hi, Tao
>
> Thank you for the update.
>
> The following patch is a regression issue, so I tend to discuss it as a separate patch.
> [PATCH v7 01/15] Fix the regression of cpumask_t for xen hyper
Can you also post v2 for this one? I have two comments about it:
[1] is it possible to not introduce the code related to hyper to a common module such as tools.c?
[2] for IA64 arch, I saw the machdep->get_irq_affinity = generic_get_irq_affinity is registered (see the ia64_init())
>
> In addition, I found another issue in my tests(on ppc64le), the gdb bt can display the back trace for the panic task, but when I switch to another task, the gdb bt can not display the back trace:
>
> crash> gdb bt
> #0 0xc0000000002bde04 in crash_setup_regs (newregs=0xc00000003264b858, oldregs=0x0) at ./arch/powerpc/include/asm/kexec.h:133
> #1 0xc0000000002be4f8 in __crash_kexec (regs=0x0) at kernel/crash_core.c:122
> #2 0xc00000000016c254 in panic (fmt=0xc0000000015eef20 "sysrq triggered crash\n") at kernel/panic.c:373
> #3 0xc000000000a708b8 in sysrq_handle_crash (key=<optimized out>) at drivers/tty/sysrq.c:154
> #4 0xc000000000a713d4 in __handle_sysrq (key=key@entry=99 'c', check_mask=check_mask@entry=false) at drivers/tty/sysrq.c:612
> #5 0xc000000000a71e94 in write_sysrq_trigger (file=<optimized out>, buf=<optimized out>, count=2, ppos=<optimized out>) at drivers/tty/sysrq.c:1181
> #6 0xc00000000073260c in pde_write (pde=0xc00000000af9cc00, file=<optimized out>, buf=<optimized out>, count=<optimized out>, ppos=<optimized out>) at fs/proc/inode.c:334
> #7 proc_reg_write (file=<optimized out>, buf=<optimized out>, count=<optimized out>, ppos=<optimized out>) at fs/proc/inode.c:346
> #8 0xc00000000063c0e0 in vfs_write (file=0xc0000000092d2900, buf=0x10012536f60 <error: Cannot access memory at address 0x10012536f60>, count=2, pos=0xc00000003264bd30) at fs/read_write.c:588
> #9 vfs_write (file=0xc0000000092d2900, buf=0x10012536f60 <error: Cannot access memory at address 0x10012536f60>, count=<optimized out>, pos=0xc00000003264bd30) at fs/read_write.c:570
> #10 0xc00000000063c690 in ksys_write (fd=<optimized out>, buf=0x10012536f60 <error: Cannot access memory at address 0x10012536f60>, count=2) at fs/read_write.c:643
> #11 0xc000000000031a28 in system_call_exception (regs=0xc00000003264be80, r0=<optimized out>) at arch/powerpc/kernel/syscall.c:153
> #12 0xc00000000000d05c in system_call_vectored_common () at arch/powerpc/kernel/interrupt_64.S:198
>
> crash> ps
> PID PPID CPU TASK ST %MEM VSZ RSS COMM
> 0 0 0 c000000002bda980 RU 0.0 0 0 [swapper/0]
> > 0 0 1 c000000003864c80 RU 0.0 0 0 [swapper/1]
> ...
> 8017 923 0 c000000043a20000 IN 0.2 22528 16256 sshd-session
> 8025 8017 6 c000000032271880 IN 0.1 22784 11840 sshd-session
> > 8026 8025 0 c000000043a26600 RU 0.1 9664 6208 bash
> ...
> 11645 2 3 c000000032264c80 ID 0.0 0 0 [kworker/u32:2]
> 11738 6188 2 c00000003811b180 IN 0.1 43520 9408 pickup
> 12326 2 0 c00000003226b280 ID 0.0 0 0 [kworker/0:1]
> 13112 6089 2 c00000000c809900 IN 0.0 7232 3456 sleep
>
> Let's take the "pickup" task as an example:
>
> crash> set 11738
> PID: 11738
> COMMAND: "pickup"
> TASK: c00000003811b180 [THREAD_INFO: c00000003811b180]
> CPU: 2
> STATE: TASK_INTERRUPTIBLE
>
> crash> gdb bt
> #0 0xc0000000a7f876a0 in ?? ()
> gdb: gdb request failed: bt
> crash> set gdb on
> gdb: on
> gdb> bt
> #0 0xc0000000a7f876a0 in ?? ()
> gdb>
There is a bug for ppc64 crash of newer version kernel. The code for
determining the address of pt_regs from stack is outdated, see the
following code from crash:
ppc64.c:get_ppc64_frame()
readmem(sp+STACK_FRAME_OVERHEAD, KVADDR, ®s, sizeof(struct
ppc64_pt_regs), "PPC64 pt_regs", FAULT_ON_ERROR);
The pt_regs is expected to be placed at sp+STACK_FRAME_OVERHEAD, aka sp+112.
However since kernel >= v6.2, the value is no longer appropriate:
linux kernel:arch/powerpc/kernel/process.c:copy_thread():
kregs = (struct pt_regs *)(sp + STACK_SWITCH_FRAME_REGS);
p->thread.ksp = sp;
linux kernel:arch/powerpc/include/asm/ptrace.h:
#ifdef CONFIG_PPC64_ELF_ABI_V2
#define STACK_FRAME_MIN_SIZE 32
STACK_SWITCH_FRAME_REGS (STACK_FRAME_MIN_SIZE + 16)
Good findings, Tao.
If we apply the change to crash, i.e:
readmem(sp+0x30, KVADDR, ®s, sizeof(struct ppc64_pt_regs), "PPC64
pt_regs", FAULT_ON_ERROR);
The stack unwinding can work as expected, you can have a test locally
to see if the above change works for you.
So this bug isn't related to the gdb stack unwinding support to me,
just a bug relating to a newer version of kernel.
Agree. For the [PATCH V7 02/15] -[PATCH V7 15/15]: Ack.
And I will put them in the merging queue, once the current issue gets resolved, we can merge them together. Otherwise it may not work on ppc64 arch.
I think we can post an individual patch to deal with this issue. Since
there are plenty of places in crash which use the old
STACK_FRAME_OVERHEAD value, maybe they all need to be updated.
Please go ahead.
Thanks
Lianbo
Thanks,
Tao Liu
>
> Anyway, I did the same test on x86 64 and aarch64, it can work well as expected. Can you help to double check on ppc64 architecture?
>
> X86 64:
> crash> set 14599
> PID: 14599
> COMMAND: "pickup"
> TASK: ffff8f57a0d7c180 [THREAD_INFO: ffff8f57a0d7c180]
> CPU: 41
> STATE: TASK_INTERRUPTIBLE
> crash> gdb bt
> #0 0xffffffff8b3efe29 in context_switch (rq=0xffff8f6f1f835900, prev=0xffff8f57a0d7c180, next=0xffff8f5786720000, rf=0xffff9df22fea7b80) at kernel/sched/core.c:5208
> #1 __schedule (sched_mode=sched_mode@entry=0) at kernel/sched/core.c:6549
> #2 0xffffffff8b3f0217 in __schedule_loop (sched_mode=<optimized out>) at kernel/sched/core.c:6626
> #3 schedule () at kernel/sched/core.c:6641
> #4 0xffffffff8b3f6eef in schedule_hrtimeout_range_clock (expires=expires@entry=0xffff9df22fea7cb0, delta=<optimized out>, delta@entry=99999999, mode=mode@entry=HRTIMER_MODE_ABS, clock_id=clock_id@entry=1) at kernel/time/hrtimer.c:2293
> #5 0xffffffff8b3f7003 in schedule_hrtimeout_range (expires=expires@entry=0xffff9df22fea7cb0, delta=delta@entry=99999999, mode=mode@entry=HRTIMER_MODE_ABS) at kernel/time/hrtimer.c:2340
> #6 0xffffffff8aae301c in ep_poll (ep=0xffff8f5790d15d40, events=events@entry=0x7ffea91b6b90, maxevents=maxevents@entry=100, timeout=timeout@entry=0xffff9df22fea7d58) at fs/eventpoll.c:2062
> #7 0xffffffff8aae3138 in do_epoll_wait (epfd=epfd@entry=8, events=events@entry=0x7ffea91b6b90, maxevents=maxevents@entry=100, to=0xffff9df22fea7d58) at fs/eventpoll.c:2464
> #8 0xffffffff8aae44a1 in __do_sys_epoll_wait (epfd=<optimized out>, events=0x7ffea91b6b90, maxevents=<optimized out>, timeout=<optimized out>) at fs/eventpoll.c:2476
> #9 __se_sys_epoll_wait (epfd=<optimized out>, events=<optimized out>, maxevents=<optimized out>, timeout=<optimized out>) at fs/eventpoll.c:2471
> #10 __x64_sys_epoll_wait (regs=<optimized out>) at fs/eventpoll.c:2471
> #11 0xffffffff8b3e293d in do_syscall_x64 (regs=0xffff9df22fea7f48, nr=232) at arch/x86/entry/common.c:52
> #12 do_syscall_64 (regs=0xffff9df22fea7f48, nr=232) at arch/x86/entry/common.c:83
> #13 0xffffffff8b40012f in entry_SYSCALL_64 () at arch/x86/entry/entry_64.S:121
> crash>
>
>
> aarch64:
> crash> set 9338
> PID: 9338
> COMMAND: "pickup"
> TASK: ffff0000c7b05400 [THREAD_INFO: ffff0000c7b05400]
> CPU: 3
> STATE: TASK_INTERRUPTIBLE
> crash> gdb bt
> #0 __switch_to (prev=<unavailable>, prev@entry=0xffff0000c7b05400, next=next@entry=<unavailable>) at arch/arm64/kernel/process.c:555
> #1 0xffffafc5b5ebd744 in context_switch (rq=0xffff00077bbd0ec0, prev=0xffff0000c7b05400, next=<unavailable>, rf=0xffff80008ac63a60) at kernel/sched/core.c:5208
> #2 __schedule (sched_mode=sched_mode@entry=0) at kernel/sched/core.c:6549
> #3 0xffffafc5b5ebdc2c in __schedule_loop (sched_mode=<optimized out>) at kernel/sched/core.c:6626
> #4 schedule () at kernel/sched/core.c:6641
> #5 0xffffafc5b5ec6030 in schedule_hrtimeout_range_clock (expires=expires@entry=0xffff80008ac63be8, delta=delta@entry=99999999, mode=mode@entry=HRTIMER_MODE_ABS, clock_id=clock_id@entry=1) at kernel/time/hrtimer.c:2293
> #6 0xffffafc5b5ec618c in schedule_hrtimeout_range (expires=expires@entry=0xffff80008ac63be8, delta=delta@entry=99999999, mode=mode@entry=HRTIMER_MODE_ABS) at kernel/time/hrtimer.c:2340
> #7 0xffffafc5b545d33c in ep_poll (ep=<unavailable>, events=events@entry=0xffffde5c3f68, maxevents=maxevents@entry=100, timeout=timeout@entry=0xffff80008ac63ce0) at fs/eventpoll.c:2062
> #8 0xffffafc5b545d4e4 in do_epoll_wait (epfd=epfd@entry=8, events=events@entry=0xffffde5c3f68, maxevents=maxevents@entry=100, to=to@entry=0xffff80008ac63ce0) at fs/eventpoll.c:2464
> #9 0xffffafc5b545d534 in do_epoll_pwait (epfd=epfd@entry=8, events=events@entry=0xffffde5c3f68, maxevents=maxevents@entry=100, to=to@entry=0xffff80008ac63ce0, sigsetsize=<optimized out>, sigmask=<optimized out>) at fs/eventpoll.c:2498
> #10 0xffffafc5b545e7c8 in do_epoll_pwait (epfd=8, events=0xffffde5c3f68, maxevents=100, to=0xffff80008ac63ce0, sigmask=<optimized out>, sigsetsize=<optimized out>) at fs/eventpoll.c:2495
> #11 __do_sys_epoll_pwait (epfd=8, events=0xffffde5c3f68, maxevents=100, timeout=<optimized out>, sigmask=<optimized out>, sigsetsize=<optimized out>) at fs/eventpoll.c:2511
> #12 __se_sys_epoll_pwait (epfd=8, events=281474412330856, maxevents=100, timeout=<optimized out>, sigmask=<optimized out>, sigsetsize=<optimized out>) at fs/eventpoll.c:2505
> #13 __arm64_sys_epoll_pwait (regs=<optimized out>) at fs/eventpoll.c:2505
> #14 0xffffafc5b4fa99bc in __invoke_syscall (regs=0xffff80008ac63eb0, syscall_fn=<optimized out>) at arch/arm64/kernel/syscall.c:35
> #15 invoke_syscall (regs=regs@entry=0xffff80008ac63eb0, scno=<optimized out>, sc_nr=sc_nr@entry=463, syscall_table=<optimized out>) at arch/arm64/kernel/syscall.c:49
> #16 0xffffafc5b4fa9ac8 in el0_svc_common (sc_nr=463, syscall_table=<optimized out>, regs=0xffff80008ac63eb0, scno=<optimized out>) at arch/arm64/kernel/syscall.c:132
> #17 do_el0_svc (regs=regs@entry=0xffff80008ac63eb0) at arch/arm64/kernel/syscall.c:151
> #18 0xffffafc5b5eb6fa4 in el0_svc (regs=0xffff80008ac63eb0) at arch/arm64/kernel/entry-common.c:712
> #19 0xffffafc5b5eb74c0 in el0t_64_sync_handler (regs=<optimized out>) at arch/arm64/kernel/entry-common.c:730
> #20 0xffffafc5b4f91634 in el0t_64_sync () at arch/arm64/kernel/entry.S:598
> crash>
>
> BTW: other changes are fine to me.
>
> Thanks
> Lianbo
>
> On Wed, Sep 4, 2024 at 3:54 PM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Date: Wed, 4 Sep 2024 19:49:25 +1200
>> From: Tao Liu <ltao@xxxxxxxxxx>
>> Subject: [PATCH v7 00/15] gdb stack unwinding support
>> for crash utility
>> To: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>> Cc: Tao Liu <ltao@xxxxxxxxxx>
>> Message-ID: <20240904074940.21331-1-ltao@xxxxxxxxxx>
>> Content-Type: text/plain; charset=UTF-8
>>
>> This patchset is a rebase/merged version of the following 3 patchsets:
>>
>> 1): [PATCH v10 0/5] Improve stack unwind on ppc64 [1]
>> 2): [PATCH 0/5] x86_64 gdb stack unwinding support [2]
>> 3): Clean up on top of one-thread-v2 [3]
>>
>> A complete description of gdb stack unwinding support for crash can be
>> found in [1].
>>
>> This patchset can be divided into the following 3 parts:
>>
>> 1) part1: preparations before stack unwinding support, some
>> bugs/regressions found when drafting this patchset.
>> 2) part2: common part for all CPU archs, mainly dealing with
>> crash_target.c/gdb_interface.c files, in order to
>> support different archs.
>> 3) part3: arch specific, for each ppc64/x86_64/arm64/vmware
>> stack unwinding support.
>>
>> === part 3
>> arm64: Add gdb stack unwinding support
>> vmware_guestdump: Various format versions support
>> x86_64: Add gdb stack unwinding support
>> ppc64: correct gdb passthroughs by implementing machdep->get_current_task_reg
>>
>> === part 2
>> Conditionally output gdb stack unwinding stop reasons
>> Stop stack unwinding at non-kernel address
>> Print task pid/command instead of CPU index
>> Rename get_cpu_reg to get_current_task_reg
>> Let crash change gdb context
>> Leave only one gdb thread for crash
>> Remove 'frame' from prohibited commands list
>>
>> === part 1
>> Fix gdb_interface: restore gdb's output streams at end of gdb_interface
>> x86_64: Fix invalid input "=>" for bt command
>> Fix cpumask_t recursive dependence issue
>> Fix the regression of cpumask_t for xen hyper
>> ===
>>
>> v7 -> v6:
>> 1) Reorganise the patchset, re-divided them into 3 part against the
>> previous 2 parts.
>> 2) Re-dealed with the cpumask_t part, which solved the comment No.4
>> pointed out by lianbo in [4].
>> 3) Add conditional output for the failing message of gdb stack unwinding.
>> see [PATCH 11/15] Conditionally output gdb stack unwinding stop reasons
>> 4) Redraft the commit messages, updated some outdated info.
>> 5) Merged "Let crash change gdb context" and "set_context(): check if
>> context is already current" into one.
>>
>> [4]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg01067.html
>>
>> v6 -> v5:
>> 1) Refactor patch 4 & 9, which changed the function signature of struct
>> get_cpu_reg/get_current_task_reg, and let each patch compile with no
>> error when added on.
>> 2) Rebased the patchset on top of latest upstream:
>> ("79b93ecb2e72ec Fix a "Bus error" issue caused by 'crash --osrelease' or
>> crash loading")
>>
>> v5 -> v4:
>> 1) Plenty of code refactoring based on Lianbo's comments on v4.
>> 2) Removed the magic number when dealing with regs bitmap, see [6].
>> 3) Rebased the patchset on top of latest upstream:
>> ("1c6da3eaff8207 arm64: Fix bt command show wrong stacktrace on ramdump source")
>>
>> v4 -> v3:
>> Fixed the author issue in [PATCH v3 06/16] Fix gdb_interface: restore gdb's
>> output streams at end of gdb_interface.
>>
>> v3 -> v2:
>> 1) Updated CC list as pointed out in [4]
>> 2) Compiling issues as in [5]
>>
>> v2 -> v1:
>> 1) Added the patch: x86_64: Fix invalid input "=>" for bt command,
>> thanks for Kazu's testing.
>> 2) Modify the patch: x86_64: Add gdb stack unwinding support, added the
>> pcp_save, spp_save and sp, for restoring the value in match of the original
>> code logic.
>>
>> [1]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00469.html
>> [2]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00488.html
>> [3]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00554.html
>> [4]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00681.html
>> [5]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00715.html
>> [6]: https://www.mail-archive.com/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/msg00819.html
>>
>> Aditya Gupta (3):
>> Fix gdb_interface: restore gdb's output streams at end of
>> gdb_interface
>> Remove 'frame' from prohibited commands list
>> ppc64: correct gdb passthroughs by implementing
>> machdep->get_current_task_reg
>>
>> Alexey Makhalov (1):
>> vmware_guestdump: Various format versions support
>>
>> Tao Liu (11):
>> Fix the regression of cpumask_t for xen hyper
>> Fix cpumask_t recursive dependence issue
>> x86_64: Fix invalid input "=>" for bt command
>> Leave only one gdb thread for crash
>> Let crash change gdb context
>> Rename get_cpu_reg to get_current_task_reg
>> Print task pid/command instead of CPU index
>> Stop stack unwinding at non-kernel address
>> Conditionally output gdb stack unwinding stop reasons
>> x86_64: Add gdb stack unwinding support
>> arm64: Add gdb stack unwinding support
>>
>> arm64.c | 120 +++++++++++++++--
>> crash_target.c | 71 ++++++----
>> defs.h | 194 ++++++++++++++++++++++++++-
>> gdb-10.2.patch | 96 ++++++++++++++
>> gdb_interface.c | 39 ++----
>> kernel.c | 63 +++++++--
>> ppc64.c | 174 +++++++++++++++++++++++-
>> symbols.c | 15 +++
>> task.c | 34 +++--
>> tools.c | 16 ++-
>> unwind_x86_64.h | 4 -
>> vmware_guestdump.c | 321 +++++++++++++++++++++++++++++++-------------
>> x86_64.c | 323 ++++++++++++++++++++++++++++++++++++++++-----
>> 13 files changed, 1247 insertions(+), 223 deletions(-)
>>
>> --
>> 2.40.1
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