8:34 a.m.
Hi lianbo,
On Wed, Sep 11, 2024 at 2:26 PM lijiang <lijiang(a)redhat.com> 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
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)
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.
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.
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(a)lists.crash-utility.osci.io> wrote:
>
> Date: Wed, 4 Sep 2024 19:49:25 +1200
> From: Tao Liu <ltao(a)redhat.com>
> Subject: [Crash-utility] [PATCH v7 00/15] gdb stack unwinding support
> for crash utility
> To: devel(a)lists.crash-utility.osci.io
> Cc: Tao Liu <ltao(a)redhat.com>
> Message-ID: <20240904074940.21331-1-ltao(a)redhat.com>
> 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@lists.crash-utility.osci.io/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@lists.crash-utility.osci.io/msg00469.html
> [2]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg00488.html
> [3]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg00554.html
> [4]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg00681.html
> [5]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg00715.html
> [6]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/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