12:04 a.m.
Dave,
When I ran "bt" against a process running in a user mode, I got
an odd backtrace result:
===8<===
crash> ps
...
1324 1223 2 ffff80002018be80 RU 0.0 960 468 dhry
1325 2 1 ffff800021089900 IN 0.0 0 0 [kworker/u16:0]
crash> bt 1324
PID: 1324 TASK: ffff80002018be80 CPU: 2 COMMAND: "dhry"
ffff800022f6ae08: ffff00000812ae44 (crash_save_cpu on IRQ stack)
#0 [ffff800022f6ae10] crash_save_cpu at ffff00000812ae44
#1 [ffff800022f6ae60] handle_IPI at ffff00000808e718
#2 [ffff800022f6b020] gic_handle_irq at ffff0000080815f8
#3 [ffff800022f6b050] el0_irq_naked at ffff000008084c4c
pt_regs: ffff800022f6af60
PC: ffffffffffffffff [unknown or invalid address]
LR: ffff800020107ed0 [unknown or invalid address]
SP: 0000000000000000 PSTATE: 004016a4
X29: ffff000008084c4c X28: ffff800022f6b080 X27: ffff000008e60c54
X26: ffff800020107ed0 X25: 0000000000001fff X24: 0000000000000003
X23: ffff0000080815f8 X22: ffff800022f6b040 X21: 0000000000000000
X20: ffff000008bce000 X19: ffff00000808e758 X18: ffff800022f6b010
X17: ffff00000808a820 X16: ffff800022f6aff0 X15: 0000000000000000
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000402138
X11: ffff000008675850 X10: ffff800022f6afe0 X9: 0000000000000000
X8: ffff800022f6afc0 X7: 0000000000000000 X6: 0000000000000000
X5: 0000000000000000 X4: 0000000000000001 X3: 0000000000000000
X2: 0000000000493000 X1: 0000000000498000 X0: ffffffffffffffff
ORIG_X0: 0000000020000000 SYSCALLNO: 4021f0
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff800020107ed0 fp: 0 (?)
pt_regs: ffff800020107ed0
PC: 00000000004016a4 LR: 00000000004016a4 SP: 0000ffffc10c40a0
X29: 0000ffffc10c40a0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000402138 X24: 00000000004021f0
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004001a0
X20: 0000000000000000 X19: 0000000000000000 X18: 0000000000000000
X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000493000
X14: 0000000000498000 X13: ffffffffffffffff X12: 0000000000000005
X11: 000000000000001e X10: 0101010101010101 X9: fffffffff59a9190
X8: 7f7f7f7f7f7f7f7f X7: 1f535226301f2b4c X6: 00000003001d1000
X5: 00101d0003000000 X4: 0000000000000000 X3: 4952545320454d4f
X2: 0000000010c35b40 X1: 0000000000000011 X0: 0000000010c35b40
ORIG_X0: 0000000000498700 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
===>8===
* PC, LR and SP look wrong.
I don't know how those pt_regs values were derived.
* The message, "WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
ffff800020107ed0 fp: 0 (?)" should be refined.
Apparently, in this case, the process is running in a user mode,
and so there is no normal kernel stack.
Thanks,
-Takahiro AKASHI
9:52 a.m.
----- Original Message -----
Dave,
When I ran "bt" against a process running in a user mode, I got
an odd backtrace result:
===8<===
crash> ps
...
> 1324 1223 2 ffff80002018be80 RU 0.0 960 468 dhry
1325 2 1 ffff800021089900 IN 0.0 0 0
[kworker/u16:0]
crash> bt 1324
PID: 1324 TASK: ffff80002018be80 CPU: 2 COMMAND: "dhry"
ffff800022f6ae08: ffff00000812ae44 (crash_save_cpu on IRQ stack)
#0 [ffff800022f6ae10] crash_save_cpu at ffff00000812ae44
#1 [ffff800022f6ae60] handle_IPI at ffff00000808e718
#2 [ffff800022f6b020] gic_handle_irq at ffff0000080815f8
#3 [ffff800022f6b050] el0_irq_naked at ffff000008084c4c
pt_regs: ffff800022f6af60
PC: ffffffffffffffff [unknown or invalid address]
LR: ffff800020107ed0 [unknown or invalid address]
SP: 0000000000000000 PSTATE: 004016a4
X29: ffff000008084c4c X28: ffff800022f6b080 X27: ffff000008e60c54
X26: ffff800020107ed0 X25: 0000000000001fff X24: 0000000000000003
X23: ffff0000080815f8 X22: ffff800022f6b040 X21: 0000000000000000
X20: ffff000008bce000 X19: ffff00000808e758 X18: ffff800022f6b010
X17: ffff00000808a820 X16: ffff800022f6aff0 X15: 0000000000000000
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000402138
X11: ffff000008675850 X10: ffff800022f6afe0 X9: 0000000000000000
X8: ffff800022f6afc0 X7: 0000000000000000 X6: 0000000000000000
X5: 0000000000000000 X4: 0000000000000001 X3: 0000000000000000
X2: 0000000000493000 X1: 0000000000498000 X0: ffffffffffffffff
ORIG_X0: 0000000020000000 SYSCALLNO: 4021f0
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff800020107ed0 fp:
0 (?)
pt_regs: ffff800020107ed0
PC: 00000000004016a4 LR: 00000000004016a4 SP: 0000ffffc10c40a0
X29: 0000ffffc10c40a0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000402138 X24: 00000000004021f0
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004001a0
X20: 0000000000000000 X19: 0000000000000000 X18: 0000000000000000
X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000493000
X14: 0000000000498000 X13: ffffffffffffffff X12: 0000000000000005
X11: 000000000000001e X10: 0101010101010101 X9: fffffffff59a9190
X8: 7f7f7f7f7f7f7f7f X7: 1f535226301f2b4c X6: 00000003001d1000
X5: 00101d0003000000 X4: 0000000000000000 X3: 4952545320454d4f
X2: 0000000010c35b40 X1: 0000000000000011 X0: 0000000010c35b40
ORIG_X0: 0000000000498700 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
===>8===
* PC, LR and SP look wrong.
I don't know how those pt_regs values were derived.
* The message, "WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
ffff800020107ed0 fp: 0 (?)" should be refined.
Apparently, in this case, the process is running in a user mode,
and so there is no normal kernel stack.
Support for IRQ stacks was only recently put in place in crash-7.1.5,
and obviously backtraces for a crash-while-in-user-space task is not working
correctly. Unfortunately the only test kdump I have on hand only has IRQ
stack transitions from kernel space. I tried to create a kdump from a system
running user-space commands on our 4.5.0-based kernel, but as luck would
have it, kdump fails to work. (it never even reaches the secondary kernel
for some reason, even though the kdump facility says it's functional)
Obviously there's a problem in arm64_unwind_frame() trying to make the transition,
and it returns FALSE because of the NULL fp and therefore INSTACK(frame->fp, bt))
fails. The function is trying to emulate the kernel's unwind_frame() function,
which also would return -EINVAL because of the fp. But I'm not sure whether that
fp value has been set correctly because of the first, seemingly bogus, exception
frame that it's showing.
As you have seen, kernel space exceptions look like this, where the fp, sp and pc
values are legitimate, so it prints "-- <IRQ stack> --", and transitions
to the
exception frame on the process stack:
crash> set debug 1
debug: 1
crash> bt
PID: 0 TASK: fffffe035b0aae00 CPU: 3 COMMAND: "swapper/3"
fffffe03fe183d58: fffffe0000137ee4 (crash_save_cpu on IRQ stack)
#0 [fffffe03fe183d60] crash_save_cpu at fffffe0000137ee4
#1 [fffffe03fe183dc0] handle_IPI at fffffe000008e8d4
#2 [fffffe03fe183f80] gic_handle_irq at fffffe00000824c8
#3 [fffffe03fe183fd0] el1_irq at fffffe0000083520
bt: arm64_unwind_frame: switch stacks: fp: fffffe035b0f3f30 sp: fffffe035b0f3e10 pc:
fffffe000008611c
--- <IRQ stack> ---
pt_regs: fffffe035b0f3e10
PC: fffffe000008611c [arch_cpu_idle+60]
LR: fffffe0000086118 [arch_cpu_idle+56]
SP: fffffe035b0f3f30 PSTATE: 60000145
X29: fffffe035b0f3f30 X28: 0000000000000000 X27: fffffe0000084170
X26: fffffe0000bf13dc X25: fffffe0000cf4000 X24: fffffe035b0f0000
X23: 0000000000000001 X22: fffffe0000b94c48 X21: 0000000000000003
X20: fffffe0000cf6000 X19: fffffe0000cf6028 X18: 000002aabb090050
X17: 000003ff9131a228 X16: fffffe000026dba4 X15: 00000000000000bf
X14: 004894597490a924 X13: 0000000000000000 X12: 0000000000000010
X11: 0000000000000067 X10: 0000000000000ab0 X9: fffffe035b0f0000
X8: fffffe035b0ab910 X7: 0000000000007b17 X6: 000000000001c690
X5: 0000001515d0302c X4: 0100000000000000 X3: fffffe03fe184c8c
X2: fffffe03fe184c80 X1: 0000000000000000 X0: fffffe035b0f0000
ORIG_X0: fffffe035b0f0000 SYSCALLNO: fffffe0000b94c48
#4 [fffffe035b0f3e10] arch_cpu_idle at fffffe000008611c
#5 [fffffe035b0f3f40] default_idle_call at fffffe00000f81cc
#6 [fffffe035b0f3f70] cpu_startup_entry at fffffe00000f8320
#7 [fffffe035b0f3f80] secondary_start_kernel at fffffe000008e338
crash>
In your sample, it certainly doesn't appear that the first exception frame found
on the IRQ stack is legitimate, and probably should not pass the test in
arm64_is_kernel_exception_frame(), but it does:
crash> bt 1324
PID: 1324 TASK: ffff80002018be80 CPU: 2 COMMAND: "dhry"
ffff800022f6ae08: ffff00000812ae44 (crash_save_cpu on IRQ stack)
#0 [ffff800022f6ae10] crash_save_cpu at ffff00000812ae44
#1 [ffff800022f6ae60] handle_IPI at ffff00000808e718
#2 [ffff800022f6b020] gic_handle_irq at ffff0000080815f8
#3 [ffff800022f6b050] el0_irq_naked at ffff000008084c4c
pt_regs: ffff800022f6af60
PC: ffffffffffffffff [unknown or invalid address]
LR: ffff800020107ed0 [unknown or invalid address]
SP: 0000000000000000 PSTATE: 004016a4
X29: ffff000008084c4c X28: ffff800022f6b080 X27: ffff000008e60c54
X26: ffff800020107ed0 X25: 0000000000001fff X24: 0000000000000003
X23: ffff0000080815f8 X22: ffff800022f6b040 X21: 0000000000000000
X20: ffff000008bce000 X19: ffff00000808e758 X18: ffff800022f6b010
X17: ffff00000808a820 X16: ffff800022f6aff0 X15: 0000000000000000
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000402138
X11: ffff000008675850 X10: ffff800022f6afe0 X9: 0000000000000000
X8: ffff800022f6afc0 X7: 0000000000000000 X6: 0000000000000000
X5: 0000000000000000 X4: 0000000000000001 X3: 0000000000000000
X2: 0000000000493000 X1: 0000000000498000 X0: ffffffffffffffff
ORIG_X0: 0000000020000000 SYSCALLNO: 4021f0
Maybe that is the cause of the bogus "fp"? Anyway, since the orig_sp is
from a fixed location at the top of the IRQ stack, It then manages to make its
way back to the "dhry" process stack, where this exception frame
"looks" legitimate:
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
ffff800020107ed0 fp: 0 (?)
pt_regs: ffff800020107ed0
PC: 00000000004016a4 LR: 00000000004016a4 SP: 0000ffffc10c40a0
X29: 0000ffffc10c40a0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000402138 X24: 00000000004021f0
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004001a0
X20: 0000000000000000 X19: 0000000000000000 X18: 0000000000000000
X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000493000
X14: 0000000000498000 X13: ffffffffffffffff X12: 0000000000000005
X11: 000000000000001e X10: 0101010101010101 X9: fffffffff59a9190
X8: 7f7f7f7f7f7f7f7f X7: 1f535226301f2b4c X6: 00000003001d1000
X5: 00101d0003000000 X4: 0000000000000000 X3: 4952545320454d4f
X2: 0000000010c35b40 X1: 0000000000000011 X0: 0000000010c35b40
ORIG_X0: 0000000000498700 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
But I'm not sure what happens when an arm64 IRQ exception occurs when
the task is running in user space. Does it lay an exception frame down on the
process stack and then make the transition? (and therefore the user-space frame
above is legitimate?) Or does the user-space frame get laid down directly on the
IRQ stack? Unfortunately I don't know enough about arm64 exception handling.
In any case, the bt should display "-- <IRQ stack> ...", and them dump
the user-to-kernel-space exception frame, wherever it lies, i.e., either on the
normal process stack or (maybe?) on the IRQ stack.
Anyway, can you make the vmlinux/vmcore pair available for me to download? You can
send the details to me offline.
Thanks,
Dave
7:22 a.m.
On Thu, Jun 02, 2016 at 10:52:28AM -0400, Dave Anderson wrote:
----- Original Message -----
> Dave,
>
> When I ran "bt" against a process running in a user mode, I got
> an odd backtrace result:
> ===8<===
> crash> ps
> ...
> > 1324 1223 2 ffff80002018be80 RU 0.0 960 468 dhry
> 1325 2 1 ffff800021089900 IN 0.0 0 0
> [kworker/u16:0]
> crash> bt 1324
> PID: 1324 TASK: ffff80002018be80 CPU: 2 COMMAND: "dhry"
> ffff800022f6ae08: ffff00000812ae44 (crash_save_cpu on IRQ stack)
> #0 [ffff800022f6ae10] crash_save_cpu at ffff00000812ae44
> #1 [ffff800022f6ae60] handle_IPI at ffff00000808e718
> #2 [ffff800022f6b020] gic_handle_irq at ffff0000080815f8
> #3 [ffff800022f6b050] el0_irq_naked at ffff000008084c4c
> pt_regs: ffff800022f6af60
> PC: ffffffffffffffff [unknown or invalid address]
> LR: ffff800020107ed0 [unknown or invalid address]
> SP: 0000000000000000 PSTATE: 004016a4
> X29: ffff000008084c4c X28: ffff800022f6b080 X27: ffff000008e60c54
> X26: ffff800020107ed0 X25: 0000000000001fff X24: 0000000000000003
> X23: ffff0000080815f8 X22: ffff800022f6b040 X21: 0000000000000000
> X20: ffff000008bce000 X19: ffff00000808e758 X18: ffff800022f6b010
> X17: ffff00000808a820 X16: ffff800022f6aff0 X15: 0000000000000000
> X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000402138
> X11: ffff000008675850 X10: ffff800022f6afe0 X9: 0000000000000000
> X8: ffff800022f6afc0 X7: 0000000000000000 X6: 0000000000000000
> X5: 0000000000000000 X4: 0000000000000001 X3: 0000000000000000
> X2: 0000000000493000 X1: 0000000000498000 X0: ffffffffffffffff
> ORIG_X0: 0000000020000000 SYSCALLNO: 4021f0
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff800020107ed0 fp:
> 0 (?)
> pt_regs: ffff800020107ed0
> PC: 00000000004016a4 LR: 00000000004016a4 SP: 0000ffffc10c40a0
> X29: 0000ffffc10c40a0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000402138 X24: 00000000004021f0
> X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004001a0
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000000000000000
> X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000493000
> X14: 0000000000498000 X13: ffffffffffffffff X12: 0000000000000005
> X11: 000000000000001e X10: 0101010101010101 X9: fffffffff59a9190
> X8: 7f7f7f7f7f7f7f7f X7: 1f535226301f2b4c X6: 00000003001d1000
> X5: 00101d0003000000 X4: 0000000000000000 X3: 4952545320454d4f
> X2: 0000000010c35b40 X1: 0000000000000011 X0: 0000000010c35b40
> ORIG_X0: 0000000000498700 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
> ===>8===
>
> * PC, LR and SP look wrong.
> I don't know how those pt_regs values were derived.
> * The message, "WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
> ffff800020107ed0 fp: 0 (?)" should be refined.
> Apparently, in this case, the process is running in a user mode,
> and so there is no normal kernel stack.
Support for IRQ stacks was only recently put in place in crash-7.1.5,
and obviously backtraces for a crash-while-in-user-space task is not working
correctly. Unfortunately the only test kdump I have on hand only has IRQ
stack transitions from kernel space. I tried to create a kdump from a system
running user-space commands on our 4.5.0-based kernel, but as luck would
have it, kdump fails to work. (it never even reaches the secondary kernel
for some reason, even though the kdump facility says it's functional)
Obviously there's a problem in arm64_unwind_frame() trying to make the transition,
and it returns FALSE because of the NULL fp and therefore INSTACK(frame->fp, bt))
fails. The function is trying to emulate the kernel's unwind_frame() function,
which also would return -EINVAL because of the fp. But I'm not sure whether that
fp value has been set correctly because of the first, seemingly bogus, exception
frame that it's showing.
As you have seen, kernel space exceptions look like this, where the fp, sp and pc
values are legitimate, so it prints "-- <IRQ stack> --", and transitions
to the
exception frame on the process stack:
crash> set debug 1
debug: 1
crash> bt
PID: 0 TASK: fffffe035b0aae00 CPU: 3 COMMAND: "swapper/3"
fffffe03fe183d58: fffffe0000137ee4 (crash_save_cpu on IRQ stack)
#0 [fffffe03fe183d60] crash_save_cpu at fffffe0000137ee4
#1 [fffffe03fe183dc0] handle_IPI at fffffe000008e8d4
#2 [fffffe03fe183f80] gic_handle_irq at fffffe00000824c8
#3 [fffffe03fe183fd0] el1_irq at fffffe0000083520
bt: arm64_unwind_frame: switch stacks: fp: fffffe035b0f3f30 sp: fffffe035b0f3e10 pc:
fffffe000008611c
--- <IRQ stack> ---
pt_regs: fffffe035b0f3e10
PC: fffffe000008611c [arch_cpu_idle+60]
LR: fffffe0000086118 [arch_cpu_idle+56]
SP: fffffe035b0f3f30 PSTATE: 60000145
X29: fffffe035b0f3f30 X28: 0000000000000000 X27: fffffe0000084170
X26: fffffe0000bf13dc X25: fffffe0000cf4000 X24: fffffe035b0f0000
X23: 0000000000000001 X22: fffffe0000b94c48 X21: 0000000000000003
X20: fffffe0000cf6000 X19: fffffe0000cf6028 X18: 000002aabb090050
X17: 000003ff9131a228 X16: fffffe000026dba4 X15: 00000000000000bf
X14: 004894597490a924 X13: 0000000000000000 X12: 0000000000000010
X11: 0000000000000067 X10: 0000000000000ab0 X9: fffffe035b0f0000
X8: fffffe035b0ab910 X7: 0000000000007b17 X6: 000000000001c690
X5: 0000001515d0302c X4: 0100000000000000 X3: fffffe03fe184c8c
X2: fffffe03fe184c80 X1: 0000000000000000 X0: fffffe035b0f0000
ORIG_X0: fffffe035b0f0000 SYSCALLNO: fffffe0000b94c48
#4 [fffffe035b0f3e10] arch_cpu_idle at fffffe000008611c
#5 [fffffe035b0f3f40] default_idle_call at fffffe00000f81cc
#6 [fffffe035b0f3f70] cpu_startup_entry at fffffe00000f8320
#7 [fffffe035b0f3f80] secondary_start_kernel at fffffe000008e338
crash>
In your sample, it certainly doesn't appear that the first exception frame found
on the IRQ stack is legitimate, and probably should not pass the test in
arm64_is_kernel_exception_frame(), but it does:
> crash> bt 1324
> PID: 1324 TASK: ffff80002018be80 CPU: 2 COMMAND: "dhry"
> ffff800022f6ae08: ffff00000812ae44 (crash_save_cpu on IRQ stack)
> #0 [ffff800022f6ae10] crash_save_cpu at ffff00000812ae44
> #1 [ffff800022f6ae60] handle_IPI at ffff00000808e718
> #2 [ffff800022f6b020] gic_handle_irq at ffff0000080815f8
> #3 [ffff800022f6b050] el0_irq_naked at ffff000008084c4c
> pt_regs: ffff800022f6af60
> PC: ffffffffffffffff [unknown or invalid address]
> LR: ffff800020107ed0 [unknown or invalid address]
> SP: 0000000000000000 PSTATE: 004016a4
> X29: ffff000008084c4c X28: ffff800022f6b080 X27: ffff000008e60c54
> X26: ffff800020107ed0 X25: 0000000000001fff X24: 0000000000000003
> X23: ffff0000080815f8 X22: ffff800022f6b040 X21: 0000000000000000
> X20: ffff000008bce000 X19: ffff00000808e758 X18: ffff800022f6b010
> X17: ffff00000808a820 X16: ffff800022f6aff0 X15: 0000000000000000
> X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000402138
> X11: ffff000008675850 X10: ffff800022f6afe0 X9: 0000000000000000
> X8: ffff800022f6afc0 X7: 0000000000000000 X6: 0000000000000000
> X5: 0000000000000000 X4: 0000000000000001 X3: 0000000000000000
> X2: 0000000000493000 X1: 0000000000498000 X0: ffffffffffffffff
> ORIG_X0: 0000000020000000 SYSCALLNO: 4021f0
Maybe that is the cause of the bogus "fp"? Anyway, since the orig_sp is
from a fixed location at the top of the IRQ stack, It then manages to make its
way back to the "dhry" process stack, where this exception frame
"looks" legitimate:
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff800020107ed0 fp: 0 (?)
> pt_regs: ffff800020107ed0
> PC: 00000000004016a4 LR: 00000000004016a4 SP: 0000ffffc10c40a0
> X29: 0000ffffc10c40a0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000402138 X24: 00000000004021f0
> X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004001a0
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000000000000000
> X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000493000
> X14: 0000000000498000 X13: ffffffffffffffff X12: 0000000000000005
> X11: 000000000000001e X10: 0101010101010101 X9: fffffffff59a9190
> X8: 7f7f7f7f7f7f7f7f X7: 1f535226301f2b4c X6: 00000003001d1000
> X5: 00101d0003000000 X4: 0000000000000000 X3: 4952545320454d4f
> X2: 0000000010c35b40 X1: 0000000000000011 X0: 0000000010c35b40
> ORIG_X0: 0000000000498700 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
But I'm not sure what happens when an arm64 IRQ exception occurs when
the task is running in user space. Does it lay an exception frame down on the
process stack and then make the transition? (and therefore the user-space frame
above is legitimate?) Or does the user-space frame get laid down directly on the
IRQ stack? Unfortunately I don't know enough about arm64 exception handling.
Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help you.
but I don't have enough time to explain in details this week.
In any case, the bt should display "-- <IRQ stack>
...", and them dump
the user-to-kernel-space exception frame, wherever it lies, i.e., either on the
normal process stack or (maybe?) on the IRQ stack.
Anyway, can you make the vmlinux/vmcore pair available for me to download? You can
send the details to me offline.
I sent you a message which contains the link to those binaries.
Thanks,
-Takahiro AKASHI
Thanks,
Dave
--
Crash-utility mailing list
Crash-utility(a)redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
--
Thanks,
-Takahiro AKASHI
10:48 a.m.
----- Original Message -----
> But I'm not sure what happens when an arm64 IRQ exception
occurs when
> the task is running in user space. Does it lay an exception frame down on the
> process stack and then make the transition? (and therefore the user-space frame
> above is legitimate?) Or does the user-space frame get laid down directly on the
> IRQ stack? Unfortunately I don't know enough about arm64 exception
> handling.
Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help you.
but I don't have enough time to explain in details this week.
That's good news, your help will be greatly appreciated.
> In any case, the bt should display "-- <IRQ stack>
...", and then dump
> the user-to-kernel-space exception frame, wherever it lies, i.e., either on the
> normal process stack or (maybe?) on the IRQ stack.
>
> Anyway, can you make the vmlinux/vmcore pair available for me to download?
> You can send the details to me offline.
I sent you a message which contains the link to those binaries.
Got them -- thanks!
Also, I was finally able to generate a vmcore on a RHEL7 4.5.0-based kernel,
where the crash occurred on cpu 1, and other 7 cpus were running in user space.
I do see the same problem w/respect to the IRQ-stack-to-user-space transition.
However, I do not have the "phantom" exception frame dumps on the IRQ
stacks that your dumpfile displays on the 7 non-crashing cpus, regardless
whether they came from kernel or user space.
Here is the output:
crash> sys
KERNEL: ../vmlinux
DUMPFILE: ../vmcore [PARTIAL DUMP]
CPUS: 8 [OFFLINE: 7]
DATE: Thu Jun 2 15:09:34 2016
UPTIME: 05:06:18
LOAD AVERAGE: 7.56, 3.49, 1.38
TASKS: 202
NODENAME: apm-mustang-ev3-07.khw.lab.eng.bos.redhat.com
RELEASE: 4.5.0-0.38.el7.aarch64
VERSION: #1 SMP Thu May 19 15:37:24 EDT 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PANIC: "sysrq: SysRq : Trigger a crash"
crash> bt -a
PID: 2546 TASK: ffff8003d5ab9600 CPU: 0 COMMAND: "spin"
#0 [ffff8003ffe33d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe33dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe33f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe33fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b73ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffff911b0c94 SP: 0000fffffee69ca0
X29: 0000fffffee69ca0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000fffffee69bb0
X17: 0000000000420000 X16: 0000ffff911b0ba4 X15: 00000000001815e7
X14: 0000ffff9136ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: da16a3a21e08b5bc X4: 0000000000000000 X3: 00000000004005b0
X2: 0000fffffee69df8 X1: 0000fffffee69de8 X0: 0000000000000001
ORIG_X0: 0000ffff91310000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2513 TASK: ffff8003d925d000 CPU: 1 COMMAND: "bash"
#0 [ffff8003dbf238d0] crash_kexec at ffff8000001486cc
#1 [ffff8003dbf23a20] die at ffff80000009731c
#2 [ffff8003dbf23a50] __do_kernel_fault at ffff8000000a7210
#3 [ffff8003dbf23a90] do_page_fault at ffff80000077b244
#4 [ffff8003dbf23ac0] do_mem_abort at ffff8000000902e8
#5 [ffff8003dbf23b30] el1_da at ffff800000091368
PC: ffff8000004970e4 [sysrq_handle_crash+36]
LR: ffff800000497c5c [__handle_sysrq+296]
SP: ffff8003dbf23cf0 PSTATE: 60000145
X29: ffff8003dbf23cf0 X28: ffff8003dbf20000 X27: ffff800000792000
X26: 0000000000000040 X25: 000000000000011e X24: 0000000000000007
X23: 0000000000000000 X22: ffff800000ce4000 X21: 0000000000000063
X20: ffff800000c50000 X19: ffff800000ce4888 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: ffff800000237848 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: ffff800000c50000
X11: 0000000000000000 X10: 00000000000001d3 X9: 00000000000001d4
X8: ffff80000121ce10 X7: 0000000000008d88 X6: ffff8000012140b8
X5: 0000000000000000 X4: 0000000000000000 X3: 0000000000000000
X2: ffff8003ffe76448 X1: 0000000000000000 X0: 0000000000000001
ORIG_X0: 00000000000001d3 SYSCALLNO: 0
#6 [ffff8003dbf23d00] __handle_sysrq at ffff800000497c5c
#7 [ffff8003dbf23d10] write_sysrq_trigger at ffff8000004980d4
#8 [ffff8003dbf23d50] proc_reg_write at ffff80000029b934
#9 [ffff8003dbf23d70] __vfs_write at ffff800000235fd0
#10 [ffff8003dbf23db0] vfs_write at ffff800000236d54
#11 [ffff8003dbf23e40] sys_write at ffff80000023789c
#12 [ffff8003dbf23e90] __sys_trace_return at ffff800000091a8c
PC: 0000ffff7d7dbda8 LR: 0000ffff7d7835d4 SP: 0000fffff90fe1b0
X29: 0000fffff90fe1b0 X28: 0000000000000000 X27: 00000000004fb000
X26: 00000000004bb420 X25: 0000000000000001 X24: 00000000004f8000
X23: 0000000000000000 X22: 0000000000000002 X21: 0000ffff7d881168
X20: 0000ffff76e30000 X19: 0000000000000002 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: 0000000000000000 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000000001
X11: 000000001c1fc6a0 X10: 00000000004fd000 X9: 0000fffff90fe130
X8: 0000000000000040 X7: 0000000000000001 X6: 0000ffff7d759a98
X5: 0000000000000001 X4: 00000000fbad2a84 X3: 0000000000000000
X2: 0000000000000002 X1: 0000ffff76e30000 X0: 0000000000000001
ORIG_X0: 0000000000000001 SYSCALLNO: 40 PSTATE: 20000000
PID: 2545 TASK: ffff8003d5901d00 CPU: 2 COMMAND: "spin"
#0 [ffff8003ffe93d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe93dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe93f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe93fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4f3ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb50f0c94 SP: 0000ffffe48b4910
X29: 0000ffffe48b4910 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe48b4820
X17: 0000000000420000 X16: 0000ffffb50f0ba4 X15: 00000000001815e7
X14: 0000ffffb52affb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: 46c7b691c219cb7a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe48b4a68 X1: 0000ffffe48b4a58 X0: 0000000000000001
ORIG_X0: 0000ffffb5250000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2541 TASK: ffff8003d917b300 CPU: 3 COMMAND: "usex"
#0 [ffff8003ffec3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffec3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffec3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffec3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbecbed0 fp: 0 (?)
PC: 00000000004361e0 LR: 0000000000435be0 SP: 0000ffffcee64ac0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000062a44 X18: 0000ffffcee64980
X17: 0000ffff8c891b9c X16: 00000000004602b8 X15: 002c4612d8986fa7
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000b5585 X10: 000000005750846e X9: 00000000001ecba2
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 0000000000000032 X3: 0000000000000007
X2: 0000000000000007 X1: 0000000000000005 X0: 00000000004b21cc
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 80000000
PID: 2544 TASK: ffff8003d9176a80 CPU: 4 COMMAND: "usex"
#0 [ffff8003ffef3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffef3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffef3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffef3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbea7ed0 fp: 0 (?)
PC: 0000000000435e38 LR: 0000000000435c94 SP: 0000ffffcee64af0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000041b82 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0034caab9974abe0
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d83c1 X10: 000000005750846e X9: 00000000001eccc0
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 0000000000000042 X1: 000000000000002a X0: 0000ffffcee64b84
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
PID: 2547 TASK: ffff8003d5906580 CPU: 5 COMMAND: "spin"
#0 [ffff8003fff23d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff23dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff23f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff23fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4efed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb33d0c94 SP: 0000ffffe5813a70
X29: 0000ffffe5813a70 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe5813980
X17: 0000000000420000 X16: 0000ffffb33d0ba4 X15: 00000000001815e7
X14: 0000ffffb358ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: f72609a0900e9af5 X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe5813bc8 X1: 0000ffffe5813bb8 X0: 0000000000000001
ORIG_X0: 0000ffffb3530000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2542 TASK: ffff8003d9178780 CPU: 6 COMMAND: "usex"
#0 [ffff8003fff53d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff53dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff53f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff53fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbebbed0 fp: 0 (?)
PC: 0000000000435e10 LR: 0000000000435ddc SP: 0000ffffcee64ad0
X29: 0000ffffcee64ad0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000054c83 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0033b1eeb687fcdc
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d3be2 X10: 000000005750846e X9: 00000000001ecc9a
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 000000003693b600 X1: 000000003693b5f0 X0: 0000000000000006
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 80000000
PID: 2548 TASK: ffff8003d5ab4d80 CPU: 7 COMMAND: "spin"
#0 [ffff8003fff83d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff83dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff83f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff83fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b63ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffae060c94 SP: 0000ffffcf219e20
X29: 0000ffffcf219e20 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffcf219d30
X17: 0000000000420000 X16: 0000ffffae060ba4 X15: 00000000001815e7
X14: 0000ffffae21ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: aa704cb48aa4536a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffcf219f78 X1: 0000ffffcf219f68 X0: 0000000000000001
ORIG_X0: 0000ffffae1c0000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
crash>
Given that the link at the top of each of the IRQ stacks back to the
kernel-entry-from-user-space exception frames look to be legitimate, perhaps
the "fp: 0" could be used as a key to recognizing the IRQ-while-in-user-space
scenario? And also it doesn't appear that the phantom exception frames
that are dumped in your vmcore are mistakenly generating the fp of 0.
Thanks,
Dave
11:10 a.m.
Hello Takahiro,
I went ahead and checked in a fix for the user-space backtrace issue here:
https://github.com/crash-utility/crash/commit/2d53b97a476e71bfd5e2054d64a...
Fix for the ARM64 "bt" command in Linux 4.5 and later kernels which
use per-cpu IRQ stacks. Without the patch, if an active non-crashing
task was running in user space when it received the shutdown IPI from
the crashing task, the "-- <IRQ stack> ---" transition marker from
the IRQ stack to the process stack is not displayed, and a message
indicating "bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
<address> fp: 0 (?)" gets displayed.
(anderson(a)redhat.com)
The "phantom" exception frames in your 4.7 kernel vmcore are seen because
your kernel doesn't have CONFIG_FUNCTION_GRAPH_TRACER configured, and
therefore __in_irqentry_text() is a no-op:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static inline int __in_irqentry_text(unsigned long ptr)
{
extern char __irqentry_text_start[];
extern char __irqentry_text_end[];
return ptr >= (unsigned long)&__irqentry_text_start &&
ptr < (unsigned long)&__irqentry_text_end;
}
#else
static inline int __in_irqentry_text(unsigned long ptr)
{
return 0;
}
#endif
static inline int in_exception_text(unsigned long ptr)
{
extern char __exception_text_start[];
extern char __exception_text_end[];
int in;
in = ptr >= (unsigned long)&__exception_text_start &&
ptr < (unsigned long)&__exception_text_end;
return in ? : __in_irqentry_text(ptr);
}
In my Linux 4.5 kernel, CONFIG_FUNCTION_GRAPH_TRACER is configured,
and as a result, "gic_handle_irq" is outside of the range from
__exception_text_start to __exception_text_end:
crash> sym -l
... [ cut ] ...
ffff800000090000 (T) __exception_text_start
ffff800000090000 (T) _stext
ffff800000090000 (T) do_undefinstr
ffff8000000901d8 (T) do_debug_exception
ffff800000090294 (T) do_mem_abort
ffff800000090348 (T) do_sp_pc_abort
ffff800000090428 (T) __exception_text_end
ffff800000090428 (T) __irqentry_text_start
ffff800000090428 (t) gic_handle_irq
ffff8000000904e0 (t) gic_handle_irq
ffff800000090670 (T) __entry_text_start
ffff800000090670 (T) __irqentry_text_end
...
In your Linux 4.7 kernel, gic_handle_irq is located within
the range, and as a result, the phantom exception frame gets
dumped:
crash> sym -l
... [ cut ] ...
ffff000008081000 (T) __exception_text_start
ffff000008081000 (T) _stext
ffff000008081000 (T) do_undefinstr
ffff000008081000 (t) efi_header_end
ffff000008081248 (T) do_mem_abort
ffff0000080812e8 (T) do_sp_pc_abort
ffff0000080813c0 (T) do_debug_exception
ffff000008081460 (t) sun4i_handle_irq
ffff0000080814d0 (t) gic_handle_irq
ffff000008081580 (t) gic_handle_irq
ffff0000080816e0 (T) __exception_text_end
...
The crash utility's in_exception_frame() function is based upon an older
kernel's version before _irqentry_text_start and __irqentry_text_end existed.
So two things need to be fixed in the crash utility:
(1) the __irqentry_text_start and __irqentry_text_end range must
be checked by in_exception_text() if they exist, and
(2) this IRQ stack kludge that was added to the kernel's dump_backtrace()
function needs to be handled the same way in the crash utility:
if (in_exception_text(where)) {
/*
* If we switched to the irq_stack before calling this
* exception handler, then the pt_regs will be on the
* task stack. The easiest way to tell is if the large
* pt_regs would overlap with the end of the irq_stack.
*/
if (stack < irq_stack_ptr &&
(stack + sizeof(struct pt_regs)) > irq_stack_ptr)
stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
dump_mem("", "Exception stack", stack,
stack + sizeof(struct pt_regs), false);
}
I'm working on a patch for the above as we speak.
Thanks,
Dave
----- Original Message -----
----- Original Message -----
> > But I'm not sure what happens when an arm64 IRQ exception occurs when
> > the task is running in user space. Does it lay an exception frame down
> > on the
> > process stack and then make the transition? (and therefore the
> > user-space frame
> > above is legitimate?) Or does the user-space frame get laid down
> > directly on the
> > IRQ stack? Unfortunately I don't know enough about arm64 exception
> > handling.
>
> Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help
> you.
> but I don't have enough time to explain in details this week.
That's good news, your help will be greatly appreciated.
> > In any case, the bt should display "-- <IRQ stack> ...", and
then dump
> > the user-to-kernel-space exception frame, wherever it lies, i.e., either
> > on the
> > normal process stack or (maybe?) on the IRQ stack.
> >
> > Anyway, can you make the vmlinux/vmcore pair available for me to
> > download?
> > You can send the details to me offline.
>
> I sent you a message which contains the link to those binaries.
Got them -- thanks!
Also, I was finally able to generate a vmcore on a RHEL7 4.5.0-based kernel,
where the crash occurred on cpu 1, and other 7 cpus were running in user
space.
I do see the same problem w/respect to the IRQ-stack-to-user-space
transition.
However, I do not have the "phantom" exception frame dumps on the IRQ
stacks that your dumpfile displays on the 7 non-crashing cpus, regardless
whether they came from kernel or user space.
Here is the output:
crash> sys
KERNEL: ../vmlinux
DUMPFILE: ../vmcore [PARTIAL DUMP]
CPUS: 8 [OFFLINE: 7]
DATE: Thu Jun 2 15:09:34 2016
UPTIME: 05:06:18
LOAD AVERAGE: 7.56, 3.49, 1.38
TASKS: 202
NODENAME: apm-mustang-ev3-07.khw.lab.eng.bos.redhat.com
RELEASE: 4.5.0-0.38.el7.aarch64
VERSION: #1 SMP Thu May 19 15:37:24 EDT 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PANIC: "sysrq: SysRq : Trigger a crash"
crash> bt -a
PID: 2546 TASK: ffff8003d5ab9600 CPU: 0 COMMAND: "spin"
#0 [ffff8003ffe33d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe33dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe33f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe33fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b73ed0
fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffff911b0c94 SP: 0000fffffee69ca0
X29: 0000fffffee69ca0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000fffffee69bb0
X17: 0000000000420000 X16: 0000ffff911b0ba4 X15: 00000000001815e7
X14: 0000ffff9136ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: da16a3a21e08b5bc X4: 0000000000000000 X3: 00000000004005b0
X2: 0000fffffee69df8 X1: 0000fffffee69de8 X0: 0000000000000001
ORIG_X0: 0000ffff91310000 SYSCALLNO: ffffffffffffffff PSTATE:
60000000
PID: 2513 TASK: ffff8003d925d000 CPU: 1 COMMAND: "bash"
#0 [ffff8003dbf238d0] crash_kexec at ffff8000001486cc
#1 [ffff8003dbf23a20] die at ffff80000009731c
#2 [ffff8003dbf23a50] __do_kernel_fault at ffff8000000a7210
#3 [ffff8003dbf23a90] do_page_fault at ffff80000077b244
#4 [ffff8003dbf23ac0] do_mem_abort at ffff8000000902e8
#5 [ffff8003dbf23b30] el1_da at ffff800000091368
PC: ffff8000004970e4 [sysrq_handle_crash+36]
LR: ffff800000497c5c [__handle_sysrq+296]
SP: ffff8003dbf23cf0 PSTATE: 60000145
X29: ffff8003dbf23cf0 X28: ffff8003dbf20000 X27: ffff800000792000
X26: 0000000000000040 X25: 000000000000011e X24: 0000000000000007
X23: 0000000000000000 X22: ffff800000ce4000 X21: 0000000000000063
X20: ffff800000c50000 X19: ffff800000ce4888 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: ffff800000237848 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: ffff800000c50000
X11: 0000000000000000 X10: 00000000000001d3 X9: 00000000000001d4
X8: ffff80000121ce10 X7: 0000000000008d88 X6: ffff8000012140b8
X5: 0000000000000000 X4: 0000000000000000 X3: 0000000000000000
X2: ffff8003ffe76448 X1: 0000000000000000 X0: 0000000000000001
ORIG_X0: 00000000000001d3 SYSCALLNO: 0
#6 [ffff8003dbf23d00] __handle_sysrq at ffff800000497c5c
#7 [ffff8003dbf23d10] write_sysrq_trigger at ffff8000004980d4
#8 [ffff8003dbf23d50] proc_reg_write at ffff80000029b934
#9 [ffff8003dbf23d70] __vfs_write at ffff800000235fd0
#10 [ffff8003dbf23db0] vfs_write at ffff800000236d54
#11 [ffff8003dbf23e40] sys_write at ffff80000023789c
#12 [ffff8003dbf23e90] __sys_trace_return at ffff800000091a8c
PC: 0000ffff7d7dbda8 LR: 0000ffff7d7835d4 SP: 0000fffff90fe1b0
X29: 0000fffff90fe1b0 X28: 0000000000000000 X27: 00000000004fb000
X26: 00000000004bb420 X25: 0000000000000001 X24: 00000000004f8000
X23: 0000000000000000 X22: 0000000000000002 X21: 0000ffff7d881168
X20: 0000ffff76e30000 X19: 0000000000000002 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: 0000000000000000 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000000001
X11: 000000001c1fc6a0 X10: 00000000004fd000 X9: 0000fffff90fe130
X8: 0000000000000040 X7: 0000000000000001 X6: 0000ffff7d759a98
X5: 0000000000000001 X4: 00000000fbad2a84 X3: 0000000000000000
X2: 0000000000000002 X1: 0000ffff76e30000 X0: 0000000000000001
ORIG_X0: 0000000000000001 SYSCALLNO: 40 PSTATE: 20000000
PID: 2545 TASK: ffff8003d5901d00 CPU: 2 COMMAND: "spin"
#0 [ffff8003ffe93d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe93dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe93f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe93fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4f3ed0
fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb50f0c94 SP: 0000ffffe48b4910
X29: 0000ffffe48b4910 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe48b4820
X17: 0000000000420000 X16: 0000ffffb50f0ba4 X15: 00000000001815e7
X14: 0000ffffb52affb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: 46c7b691c219cb7a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe48b4a68 X1: 0000ffffe48b4a58 X0: 0000000000000001
ORIG_X0: 0000ffffb5250000 SYSCALLNO: ffffffffffffffff PSTATE:
60000000
PID: 2541 TASK: ffff8003d917b300 CPU: 3 COMMAND: "usex"
#0 [ffff8003ffec3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffec3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffec3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffec3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbecbed0
fp: 0 (?)
PC: 00000000004361e0 LR: 0000000000435be0 SP: 0000ffffcee64ac0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000062a44 X18: 0000ffffcee64980
X17: 0000ffff8c891b9c X16: 00000000004602b8 X15: 002c4612d8986fa7
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000b5585 X10: 000000005750846e X9: 00000000001ecba2
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 0000000000000032 X3: 0000000000000007
X2: 0000000000000007 X1: 0000000000000005 X0: 00000000004b21cc
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
80000000
PID: 2544 TASK: ffff8003d9176a80 CPU: 4 COMMAND: "usex"
#0 [ffff8003ffef3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffef3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffef3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffef3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbea7ed0
fp: 0 (?)
PC: 0000000000435e38 LR: 0000000000435c94 SP: 0000ffffcee64af0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000041b82 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0034caab9974abe0
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d83c1 X10: 000000005750846e X9: 00000000001eccc0
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 0000000000000042 X1: 000000000000002a X0: 0000ffffcee64b84
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
20000000
PID: 2547 TASK: ffff8003d5906580 CPU: 5 COMMAND: "spin"
#0 [ffff8003fff23d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff23dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff23f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff23fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4efed0
fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb33d0c94 SP: 0000ffffe5813a70
X29: 0000ffffe5813a70 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe5813980
X17: 0000000000420000 X16: 0000ffffb33d0ba4 X15: 00000000001815e7
X14: 0000ffffb358ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: f72609a0900e9af5 X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe5813bc8 X1: 0000ffffe5813bb8 X0: 0000000000000001
ORIG_X0: 0000ffffb3530000 SYSCALLNO: ffffffffffffffff PSTATE:
60000000
PID: 2542 TASK: ffff8003d9178780 CPU: 6 COMMAND: "usex"
#0 [ffff8003fff53d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff53dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff53f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff53fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbebbed0
fp: 0 (?)
PC: 0000000000435e10 LR: 0000000000435ddc SP: 0000ffffcee64ad0
X29: 0000ffffcee64ad0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000054c83 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0033b1eeb687fcdc
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d3be2 X10: 000000005750846e X9: 00000000001ecc9a
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 000000003693b600 X1: 000000003693b5f0 X0: 0000000000000006
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
80000000
PID: 2548 TASK: ffff8003d5ab4d80 CPU: 7 COMMAND: "spin"
#0 [ffff8003fff83d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff83dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff83f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff83fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b63ed0
fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffae060c94 SP: 0000ffffcf219e20
X29: 0000ffffcf219e20 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffcf219d30
X17: 0000000000420000 X16: 0000ffffae060ba4 X15: 00000000001815e7
X14: 0000ffffae21ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: aa704cb48aa4536a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffcf219f78 X1: 0000ffffcf219f68 X0: 0000000000000001
ORIG_X0: 0000ffffae1c0000 SYSCALLNO: ffffffffffffffff PSTATE:
60000000
crash>
Given that the link at the top of each of the IRQ stacks back to the
kernel-entry-from-user-space exception frames look to be legitimate, perhaps
the "fp: 0" could be used as a key to recognizing the IRQ-while-in-user-space
scenario? And also it doesn't appear that the phantom exception frames
that are dumped in your vmcore are mistakenly generating the fp of 0.
Thanks,
Dave
2:01 p.m.
And a fix for the phantom exception frame issue has been checked in:
https://github.com/crash-utility/crash/commit/14b3eadfd8cfafa19115c06aa4e...
Fix for the ARM64 "bt" command in Linux 4.5 and later kernels which
are not configured with CONFIG_FUNCTION_GRAPH_TRACER. Without the
patch, backtraces that originate from a per-cpu IRQ stack will dump
an invalid exception frame before transitioning to the process stack.
(anderson(a)redhat.com)
Dave
----- Original Message -----
Hello Takahiro,
I went ahead and checked in a fix for the user-space backtrace issue here:
https://github.com/crash-utility/crash/commit/2d53b97a476e71bfd5e2054d64a...
Fix for the ARM64 "bt" command in Linux 4.5 and later kernels which
use per-cpu IRQ stacks. Without the patch, if an active non-crashing
task was running in user space when it received the shutdown IPI from
the crashing task, the "-- <IRQ stack> ---" transition marker from
the IRQ stack to the process stack is not displayed, and a message
indicating "bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
<address> fp: 0 (?)" gets displayed.
(anderson(a)redhat.com)
The "phantom" exception frames in your 4.7 kernel vmcore are seen because
your kernel doesn't have CONFIG_FUNCTION_GRAPH_TRACER configured, and
therefore __in_irqentry_text() is a no-op:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static inline int __in_irqentry_text(unsigned long ptr)
{
extern char __irqentry_text_start[];
extern char __irqentry_text_end[];
return ptr >= (unsigned long)&__irqentry_text_start &&
ptr < (unsigned long)&__irqentry_text_end;
}
#else
static inline int __in_irqentry_text(unsigned long ptr)
{
return 0;
}
#endif
static inline int in_exception_text(unsigned long ptr)
{
extern char __exception_text_start[];
extern char __exception_text_end[];
int in;
in = ptr >= (unsigned long)&__exception_text_start &&
ptr < (unsigned long)&__exception_text_end;
return in ? : __in_irqentry_text(ptr);
}
In my Linux 4.5 kernel, CONFIG_FUNCTION_GRAPH_TRACER is configured,
and as a result, "gic_handle_irq" is outside of the range from
__exception_text_start to __exception_text_end:
crash> sym -l
... [ cut ] ...
ffff800000090000 (T) __exception_text_start
ffff800000090000 (T) _stext
ffff800000090000 (T) do_undefinstr
ffff8000000901d8 (T) do_debug_exception
ffff800000090294 (T) do_mem_abort
ffff800000090348 (T) do_sp_pc_abort
ffff800000090428 (T) __exception_text_end
ffff800000090428 (T) __irqentry_text_start
ffff800000090428 (t) gic_handle_irq
ffff8000000904e0 (t) gic_handle_irq
ffff800000090670 (T) __entry_text_start
ffff800000090670 (T) __irqentry_text_end
...
In your Linux 4.7 kernel, gic_handle_irq is located within
the range, and as a result, the phantom exception frame gets
dumped:
crash> sym -l
... [ cut ] ...
ffff000008081000 (T) __exception_text_start
ffff000008081000 (T) _stext
ffff000008081000 (T) do_undefinstr
ffff000008081000 (t) efi_header_end
ffff000008081248 (T) do_mem_abort
ffff0000080812e8 (T) do_sp_pc_abort
ffff0000080813c0 (T) do_debug_exception
ffff000008081460 (t) sun4i_handle_irq
ffff0000080814d0 (t) gic_handle_irq
ffff000008081580 (t) gic_handle_irq
ffff0000080816e0 (T) __exception_text_end
...
The crash utility's in_exception_frame() function is based upon an older
kernel's version before _irqentry_text_start and __irqentry_text_end existed.
So two things need to be fixed in the crash utility:
(1) the __irqentry_text_start and __irqentry_text_end range must
be checked by in_exception_text() if they exist, and
(2) this IRQ stack kludge that was added to the kernel's dump_backtrace()
function needs to be handled the same way in the crash utility:
if (in_exception_text(where)) {
/*
* If we switched to the irq_stack before calling
this
* exception handler, then the pt_regs will be on the
* task stack. The easiest way to tell is if the
large
* pt_regs would overlap with the end of the
irq_stack.
*/
if (stack < irq_stack_ptr &&
(stack + sizeof(struct pt_regs)) > irq_stack_ptr)
stack =
IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
dump_mem("", "Exception stack", stack,
stack + sizeof(struct pt_regs), false);
}
I'm working on a patch for the above as we speak.
Thanks,
Dave
----- Original Message -----
>
>
>
> ----- Original Message -----
>
> > > But I'm not sure what happens when an arm64 IRQ exception occurs when
> > > the task is running in user space. Does it lay an exception frame down
> > > on the
> > > process stack and then make the transition? (and therefore the
> > > user-space frame
> > > above is legitimate?) Or does the user-space frame get laid down
> > > directly on the
> > > IRQ stack? Unfortunately I don't know enough about arm64 exception
> > > handling.
> >
> > Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help
> > you.
> > but I don't have enough time to explain in details this week.
>
> That's good news, your help will be greatly appreciated.
>
> > > In any case, the bt should display "-- <IRQ stack> ...",
and then dump
> > > the user-to-kernel-space exception frame, wherever it lies, i.e.,
> > > either
> > > on the
> > > normal process stack or (maybe?) on the IRQ stack.
> > >
> > > Anyway, can you make the vmlinux/vmcore pair available for me to
> > > download?
> > > You can send the details to me offline.
> >
> > I sent you a message which contains the link to those binaries.
>
> Got them -- thanks!
>
> Also, I was finally able to generate a vmcore on a RHEL7 4.5.0-based
> kernel,
> where the crash occurred on cpu 1, and other 7 cpus were running in user
> space.
> I do see the same problem w/respect to the IRQ-stack-to-user-space
> transition.
>
> However, I do not have the "phantom" exception frame dumps on the IRQ
> stacks that your dumpfile displays on the 7 non-crashing cpus, regardless
> whether they came from kernel or user space.
>
> Here is the output:
>
> crash> sys
> KERNEL: ../vmlinux
> DUMPFILE: ../vmcore [PARTIAL DUMP]
> CPUS: 8 [OFFLINE: 7]
> DATE: Thu Jun 2 15:09:34 2016
> UPTIME: 05:06:18
> LOAD AVERAGE: 7.56, 3.49, 1.38
> TASKS: 202
> NODENAME: apm-mustang-ev3-07.khw.lab.eng.bos.redhat.com
> RELEASE: 4.5.0-0.38.el7.aarch64
> VERSION: #1 SMP Thu May 19 15:37:24 EDT 2016
> MACHINE: aarch64 (unknown Mhz)
> MEMORY: 16 GB
> PANIC: "sysrq: SysRq : Trigger a crash"
> crash> bt -a
> PID: 2546 TASK: ffff8003d5ab9600 CPU: 0 COMMAND: "spin"
> #0 [ffff8003ffe33d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003ffe33dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003ffe33f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003ffe33fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b73ed0
> fp: 0 (?)
> PC: 00000000004005b0 LR: 0000ffff911b0c94 SP: 0000fffffee69ca0
> X29: 0000fffffee69ca0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000fffffee69bb0
> X17: 0000000000420000 X16: 0000ffff911b0ba4 X15: 00000000001815e7
> X14: 0000ffff9136ffb8 X13: 000000000000000f X12: 0000000000000090
> X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> X5: da16a3a21e08b5bc X4: 0000000000000000 X3: 00000000004005b0
> X2: 0000fffffee69df8 X1: 0000fffffee69de8 X0: 0000000000000001
> ORIG_X0: 0000ffff91310000 SYSCALLNO: ffffffffffffffff PSTATE:
> 60000000
>
> PID: 2513 TASK: ffff8003d925d000 CPU: 1 COMMAND: "bash"
> #0 [ffff8003dbf238d0] crash_kexec at ffff8000001486cc
> #1 [ffff8003dbf23a20] die at ffff80000009731c
> #2 [ffff8003dbf23a50] __do_kernel_fault at ffff8000000a7210
> #3 [ffff8003dbf23a90] do_page_fault at ffff80000077b244
> #4 [ffff8003dbf23ac0] do_mem_abort at ffff8000000902e8
> #5 [ffff8003dbf23b30] el1_da at ffff800000091368
> PC: ffff8000004970e4 [sysrq_handle_crash+36]
> LR: ffff800000497c5c [__handle_sysrq+296]
> SP: ffff8003dbf23cf0 PSTATE: 60000145
> X29: ffff8003dbf23cf0 X28: ffff8003dbf20000 X27: ffff800000792000
> X26: 0000000000000040 X25: 000000000000011e X24: 0000000000000007
> X23: 0000000000000000 X22: ffff800000ce4000 X21: 0000000000000063
> X20: ffff800000c50000 X19: ffff800000ce4888 X18: 0000000000000000
> X17: 0000ffff7d780e20 X16: ffff800000237848 X15: 00192ea0bab15d05
> X14: 0000000000000000 X13: 0000000000000000 X12: ffff800000c50000
> X11: 0000000000000000 X10: 00000000000001d3 X9: 00000000000001d4
> X8: ffff80000121ce10 X7: 0000000000008d88 X6: ffff8000012140b8
> X5: 0000000000000000 X4: 0000000000000000 X3: 0000000000000000
> X2: ffff8003ffe76448 X1: 0000000000000000 X0: 0000000000000001
> ORIG_X0: 00000000000001d3 SYSCALLNO: 0
> #6 [ffff8003dbf23d00] __handle_sysrq at ffff800000497c5c
> #7 [ffff8003dbf23d10] write_sysrq_trigger at ffff8000004980d4
> #8 [ffff8003dbf23d50] proc_reg_write at ffff80000029b934
> #9 [ffff8003dbf23d70] __vfs_write at ffff800000235fd0
> #10 [ffff8003dbf23db0] vfs_write at ffff800000236d54
> #11 [ffff8003dbf23e40] sys_write at ffff80000023789c
> #12 [ffff8003dbf23e90] __sys_trace_return at ffff800000091a8c
> PC: 0000ffff7d7dbda8 LR: 0000ffff7d7835d4 SP: 0000fffff90fe1b0
> X29: 0000fffff90fe1b0 X28: 0000000000000000 X27: 00000000004fb000
> X26: 00000000004bb420 X25: 0000000000000001 X24: 00000000004f8000
> X23: 0000000000000000 X22: 0000000000000002 X21: 0000ffff7d881168
> X20: 0000ffff76e30000 X19: 0000000000000002 X18: 0000000000000000
> X17: 0000ffff7d780e20 X16: 0000000000000000 X15: 00192ea0bab15d05
> X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000000001
> X11: 000000001c1fc6a0 X10: 00000000004fd000 X9: 0000fffff90fe130
> X8: 0000000000000040 X7: 0000000000000001 X6: 0000ffff7d759a98
> X5: 0000000000000001 X4: 00000000fbad2a84 X3: 0000000000000000
> X2: 0000000000000002 X1: 0000ffff76e30000 X0: 0000000000000001
> ORIG_X0: 0000000000000001 SYSCALLNO: 40 PSTATE: 20000000
>
> PID: 2545 TASK: ffff8003d5901d00 CPU: 2 COMMAND: "spin"
> #0 [ffff8003ffe93d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003ffe93dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003ffe93f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003ffe93fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4f3ed0
> fp: 0 (?)
> PC: 00000000004005b0 LR: 0000ffffb50f0c94 SP: 0000ffffe48b4910
> X29: 0000ffffe48b4910 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe48b4820
> X17: 0000000000420000 X16: 0000ffffb50f0ba4 X15: 00000000001815e7
> X14: 0000ffffb52affb8 X13: 000000000000000f X12: 0000000000000090
> X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> X5: 46c7b691c219cb7a X4: 0000000000000000 X3: 00000000004005b0
> X2: 0000ffffe48b4a68 X1: 0000ffffe48b4a58 X0: 0000000000000001
> ORIG_X0: 0000ffffb5250000 SYSCALLNO: ffffffffffffffff PSTATE:
> 60000000
>
> PID: 2541 TASK: ffff8003d917b300 CPU: 3 COMMAND: "usex"
> #0 [ffff8003ffec3d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003ffec3dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003ffec3f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003ffec3fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbecbed0
> fp: 0 (?)
> PC: 00000000004361e0 LR: 0000000000435be0 SP: 0000ffffcee64ac0
> X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> X20: 0000ffff8c790000 X19: 0000000000062a44 X18: 0000ffffcee64980
> X17: 0000ffff8c891b9c X16: 00000000004602b8 X15: 002c4612d8986fa7
> X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> X11: 00000000000b5585 X10: 000000005750846e X9: 00000000001ecba2
> X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> X5: 0000ffff8c894768 X4: 0000000000000032 X3: 0000000000000007
> X2: 0000000000000007 X1: 0000000000000005 X0: 00000000004b21cc
> ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> 80000000
>
> PID: 2544 TASK: ffff8003d9176a80 CPU: 4 COMMAND: "usex"
> #0 [ffff8003ffef3d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003ffef3dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003ffef3f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003ffef3fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbea7ed0
> fp: 0 (?)
> PC: 0000000000435e38 LR: 0000000000435c94 SP: 0000ffffcee64af0
> X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> X20: 0000ffff8c790000 X19: 0000000000041b82 X18: 0000ffffcee64980
> X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0034caab9974abe0
> X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> X11: 00000000000d83c1 X10: 000000005750846e X9: 00000000001eccc0
> X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
> X2: 0000000000000042 X1: 000000000000002a X0: 0000ffffcee64b84
> ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> 20000000
>
> PID: 2547 TASK: ffff8003d5906580 CPU: 5 COMMAND: "spin"
> #0 [ffff8003fff23d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003fff23dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003fff23f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003fff23fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4efed0
> fp: 0 (?)
> PC: 00000000004005b0 LR: 0000ffffb33d0c94 SP: 0000ffffe5813a70
> X29: 0000ffffe5813a70 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe5813980
> X17: 0000000000420000 X16: 0000ffffb33d0ba4 X15: 00000000001815e7
> X14: 0000ffffb358ffb8 X13: 000000000000000f X12: 0000000000000090
> X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> X5: f72609a0900e9af5 X4: 0000000000000000 X3: 00000000004005b0
> X2: 0000ffffe5813bc8 X1: 0000ffffe5813bb8 X0: 0000000000000001
> ORIG_X0: 0000ffffb3530000 SYSCALLNO: ffffffffffffffff PSTATE:
> 60000000
>
> PID: 2542 TASK: ffff8003d9178780 CPU: 6 COMMAND: "usex"
> #0 [ffff8003fff53d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003fff53dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003fff53f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003fff53fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbebbed0
> fp: 0 (?)
> PC: 0000000000435e10 LR: 0000000000435ddc SP: 0000ffffcee64ad0
> X29: 0000ffffcee64ad0 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> X20: 0000ffff8c790000 X19: 0000000000054c83 X18: 0000ffffcee64980
> X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0033b1eeb687fcdc
> X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> X11: 00000000000d3be2 X10: 000000005750846e X9: 00000000001ecc9a
> X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
> X2: 000000003693b600 X1: 000000003693b5f0 X0: 0000000000000006
> ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> 80000000
>
> PID: 2548 TASK: ffff8003d5ab4d80 CPU: 7 COMMAND: "spin"
> #0 [ffff8003fff83d60] crash_save_cpu at ffff800000148444
> #1 [ffff8003fff83dc0] handle_IPI at ffff80000009c8d0
> #2 [ffff8003fff83f80] gic_handle_irq at ffff8000000904c8
> #3 [ffff8003fff83fd0] el0_irq_naked at ffff80000009180c
> bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b63ed0
> fp: 0 (?)
> PC: 00000000004005b0 LR: 0000ffffae060c94 SP: 0000ffffcf219e20
> X29: 0000ffffcf219e20 X28: 0000000000000000 X27: 0000000000000000
> X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffcf219d30
> X17: 0000000000420000 X16: 0000ffffae060ba4 X15: 00000000001815e7
> X14: 0000ffffae21ffb8 X13: 000000000000000f X12: 0000000000000090
> X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> X5: aa704cb48aa4536a X4: 0000000000000000 X3: 00000000004005b0
> X2: 0000ffffcf219f78 X1: 0000ffffcf219f68 X0: 0000000000000001
> ORIG_X0: 0000ffffae1c0000 SYSCALLNO: ffffffffffffffff PSTATE:
> 60000000
> crash>
>
> Given that the link at the top of each of the IRQ stacks back to the
> kernel-entry-from-user-space exception frames look to be legitimate,
> perhaps
> the "fp: 0" could be used as a key to recognizing the
> IRQ-while-in-user-space
> scenario? And also it doesn't appear that the phantom exception frames
> that are dumped in your vmcore are mistakenly generating the fp of 0.
>
> Thanks,
> Dave
>
>
9:25 p.m.
On Tue, Jun 07, 2016 at 03:01:49PM -0400, Dave Anderson wrote:
And a fix for the phantom exception frame issue has been checked in:
https://github.com/crash-utility/crash/commit/14b3eadfd8cfafa19115c06aa4e...
Fix for the ARM64 "bt" command in Linux 4.5 and later kernels which
are not configured with CONFIG_FUNCTION_GRAPH_TRACER. Without the
patch, backtraces that originate from a per-cpu IRQ stack will dump
an invalid exception frame before transitioning to the process stack.
(anderson(a)redhat.com)
OK, thanks.
But those two patches contain trailing white-spaces at the end of
some lines :)
I also have some concerns on "bt -f" output.
I will send out a separate patch about this issue.
Thanks,
-Takahiro AKASHI
Dave
----- Original Message -----
>
>
> Hello Takahiro,
>
> I went ahead and checked in a fix for the user-space backtrace issue here:
>
>
https://github.com/crash-utility/crash/commit/2d53b97a476e71bfd5e2054d64a...
>
> Fix for the ARM64 "bt" command in Linux 4.5 and later kernels which
> use per-cpu IRQ stacks. Without the patch, if an active non-crashing
> task was running in user space when it received the shutdown IPI from
> the crashing task, the "-- <IRQ stack> ---" transition marker
from
> the IRQ stack to the process stack is not displayed, and a message
> indicating "bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp:
> <address> fp: 0 (?)" gets displayed.
> (anderson(a)redhat.com)
>
>
> The "phantom" exception frames in your 4.7 kernel vmcore are seen because
> your kernel doesn't have CONFIG_FUNCTION_GRAPH_TRACER configured, and
> therefore __in_irqentry_text() is a no-op:
>
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> static inline int __in_irqentry_text(unsigned long ptr)
> {
> extern char __irqentry_text_start[];
> extern char __irqentry_text_end[];
>
> return ptr >= (unsigned long)&__irqentry_text_start &&
> ptr < (unsigned long)&__irqentry_text_end;
> }
> #else
> static inline int __in_irqentry_text(unsigned long ptr)
> {
> return 0;
> }
> #endif
>
> static inline int in_exception_text(unsigned long ptr)
> {
> extern char __exception_text_start[];
> extern char __exception_text_end[];
> int in;
>
> in = ptr >= (unsigned long)&__exception_text_start &&
> ptr < (unsigned long)&__exception_text_end;
>
> return in ? : __in_irqentry_text(ptr);
> }
>
> In my Linux 4.5 kernel, CONFIG_FUNCTION_GRAPH_TRACER is configured,
> and as a result, "gic_handle_irq" is outside of the range from
> __exception_text_start to __exception_text_end:
>
> crash> sym -l
> ... [ cut ] ...
> ffff800000090000 (T) __exception_text_start
> ffff800000090000 (T) _stext
> ffff800000090000 (T) do_undefinstr
> ffff8000000901d8 (T) do_debug_exception
> ffff800000090294 (T) do_mem_abort
> ffff800000090348 (T) do_sp_pc_abort
> ffff800000090428 (T) __exception_text_end
> ffff800000090428 (T) __irqentry_text_start
> ffff800000090428 (t) gic_handle_irq
> ffff8000000904e0 (t) gic_handle_irq
> ffff800000090670 (T) __entry_text_start
> ffff800000090670 (T) __irqentry_text_end
> ...
>
> In your Linux 4.7 kernel, gic_handle_irq is located within
> the range, and as a result, the phantom exception frame gets
> dumped:
>
> crash> sym -l
> ... [ cut ] ...
> ffff000008081000 (T) __exception_text_start
> ffff000008081000 (T) _stext
> ffff000008081000 (T) do_undefinstr
> ffff000008081000 (t) efi_header_end
> ffff000008081248 (T) do_mem_abort
> ffff0000080812e8 (T) do_sp_pc_abort
> ffff0000080813c0 (T) do_debug_exception
> ffff000008081460 (t) sun4i_handle_irq
> ffff0000080814d0 (t) gic_handle_irq
> ffff000008081580 (t) gic_handle_irq
> ffff0000080816e0 (T) __exception_text_end
> ...
>
> The crash utility's in_exception_frame() function is based upon an older
> kernel's version before _irqentry_text_start and __irqentry_text_end existed.
>
> So two things need to be fixed in the crash utility:
>
> (1) the __irqentry_text_start and __irqentry_text_end range must
> be checked by in_exception_text() if they exist, and
> (2) this IRQ stack kludge that was added to the kernel's dump_backtrace()
> function needs to be handled the same way in the crash utility:
>
> if (in_exception_text(where)) {
> /*
> * If we switched to the irq_stack before calling
> this
> * exception handler, then the pt_regs will be on the
> * task stack. The easiest way to tell is if the
> large
> * pt_regs would overlap with the end of the
> irq_stack.
> */
> if (stack < irq_stack_ptr &&
> (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
> stack =
> IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
>
> dump_mem("", "Exception stack", stack,
> stack + sizeof(struct pt_regs), false);
> }
>
> I'm working on a patch for the above as we speak.
>
> Thanks,
> Dave
>
>
> ----- Original Message -----
> >
> >
> >
> > ----- Original Message -----
> >
> > > > But I'm not sure what happens when an arm64 IRQ exception occurs
when
> > > > the task is running in user space. Does it lay an exception frame
down
> > > > on the
> > > > process stack and then make the transition? (and therefore the
> > > > user-space frame
> > > > above is legitimate?) Or does the user-space frame get laid down
> > > > directly on the
> > > > IRQ stack? Unfortunately I don't know enough about arm64
exception
> > > > handling.
> > >
> > > Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help
> > > you.
> > > but I don't have enough time to explain in details this week.
> >
> > That's good news, your help will be greatly appreciated.
> >
> > > > In any case, the bt should display "-- <IRQ stack>
...", and then dump
> > > > the user-to-kernel-space exception frame, wherever it lies, i.e.,
> > > > either
> > > > on the
> > > > normal process stack or (maybe?) on the IRQ stack.
> > > >
> > > > Anyway, can you make the vmlinux/vmcore pair available for me to
> > > > download?
> > > > You can send the details to me offline.
> > >
> > > I sent you a message which contains the link to those binaries.
> >
> > Got them -- thanks!
> >
> > Also, I was finally able to generate a vmcore on a RHEL7 4.5.0-based
> > kernel,
> > where the crash occurred on cpu 1, and other 7 cpus were running in user
> > space.
> > I do see the same problem w/respect to the IRQ-stack-to-user-space
> > transition.
> >
> > However, I do not have the "phantom" exception frame dumps on the
IRQ
> > stacks that your dumpfile displays on the 7 non-crashing cpus, regardless
> > whether they came from kernel or user space.
> >
> > Here is the output:
> >
> > crash> sys
> > KERNEL: ../vmlinux
> > DUMPFILE: ../vmcore [PARTIAL DUMP]
> > CPUS: 8 [OFFLINE: 7]
> > DATE: Thu Jun 2 15:09:34 2016
> > UPTIME: 05:06:18
> > LOAD AVERAGE: 7.56, 3.49, 1.38
> > TASKS: 202
> > NODENAME: apm-mustang-ev3-07.khw.lab.eng.bos.redhat.com
> > RELEASE: 4.5.0-0.38.el7.aarch64
> > VERSION: #1 SMP Thu May 19 15:37:24 EDT 2016
> > MACHINE: aarch64 (unknown Mhz)
> > MEMORY: 16 GB
> > PANIC: "sysrq: SysRq : Trigger a crash"
> > crash> bt -a
> > PID: 2546 TASK: ffff8003d5ab9600 CPU: 0 COMMAND: "spin"
> > #0 [ffff8003ffe33d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003ffe33dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003ffe33f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003ffe33fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b73ed0
> > fp: 0 (?)
> > PC: 00000000004005b0 LR: 0000ffff911b0c94 SP: 0000fffffee69ca0
> > X29: 0000fffffee69ca0 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> > X20: 0000000000000000 X19: 0000000000000000 X18: 0000fffffee69bb0
> > X17: 0000000000420000 X16: 0000ffff911b0ba4 X15: 00000000001815e7
> > X14: 0000ffff9136ffb8 X13: 000000000000000f X12: 0000000000000090
> > X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> > X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> > X5: da16a3a21e08b5bc X4: 0000000000000000 X3: 00000000004005b0
> > X2: 0000fffffee69df8 X1: 0000fffffee69de8 X0: 0000000000000001
> > ORIG_X0: 0000ffff91310000 SYSCALLNO: ffffffffffffffff PSTATE:
> > 60000000
> >
> > PID: 2513 TASK: ffff8003d925d000 CPU: 1 COMMAND: "bash"
> > #0 [ffff8003dbf238d0] crash_kexec at ffff8000001486cc
> > #1 [ffff8003dbf23a20] die at ffff80000009731c
> > #2 [ffff8003dbf23a50] __do_kernel_fault at ffff8000000a7210
> > #3 [ffff8003dbf23a90] do_page_fault at ffff80000077b244
> > #4 [ffff8003dbf23ac0] do_mem_abort at ffff8000000902e8
> > #5 [ffff8003dbf23b30] el1_da at ffff800000091368
> > PC: ffff8000004970e4 [sysrq_handle_crash+36]
> > LR: ffff800000497c5c [__handle_sysrq+296]
> > SP: ffff8003dbf23cf0 PSTATE: 60000145
> > X29: ffff8003dbf23cf0 X28: ffff8003dbf20000 X27: ffff800000792000
> > X26: 0000000000000040 X25: 000000000000011e X24: 0000000000000007
> > X23: 0000000000000000 X22: ffff800000ce4000 X21: 0000000000000063
> > X20: ffff800000c50000 X19: ffff800000ce4888 X18: 0000000000000000
> > X17: 0000ffff7d780e20 X16: ffff800000237848 X15: 00192ea0bab15d05
> > X14: 0000000000000000 X13: 0000000000000000 X12: ffff800000c50000
> > X11: 0000000000000000 X10: 00000000000001d3 X9: 00000000000001d4
> > X8: ffff80000121ce10 X7: 0000000000008d88 X6: ffff8000012140b8
> > X5: 0000000000000000 X4: 0000000000000000 X3: 0000000000000000
> > X2: ffff8003ffe76448 X1: 0000000000000000 X0: 0000000000000001
> > ORIG_X0: 00000000000001d3 SYSCALLNO: 0
> > #6 [ffff8003dbf23d00] __handle_sysrq at ffff800000497c5c
> > #7 [ffff8003dbf23d10] write_sysrq_trigger at ffff8000004980d4
> > #8 [ffff8003dbf23d50] proc_reg_write at ffff80000029b934
> > #9 [ffff8003dbf23d70] __vfs_write at ffff800000235fd0
> > #10 [ffff8003dbf23db0] vfs_write at ffff800000236d54
> > #11 [ffff8003dbf23e40] sys_write at ffff80000023789c
> > #12 [ffff8003dbf23e90] __sys_trace_return at ffff800000091a8c
> > PC: 0000ffff7d7dbda8 LR: 0000ffff7d7835d4 SP: 0000fffff90fe1b0
> > X29: 0000fffff90fe1b0 X28: 0000000000000000 X27: 00000000004fb000
> > X26: 00000000004bb420 X25: 0000000000000001 X24: 00000000004f8000
> > X23: 0000000000000000 X22: 0000000000000002 X21: 0000ffff7d881168
> > X20: 0000ffff76e30000 X19: 0000000000000002 X18: 0000000000000000
> > X17: 0000ffff7d780e20 X16: 0000000000000000 X15: 00192ea0bab15d05
> > X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000000001
> > X11: 000000001c1fc6a0 X10: 00000000004fd000 X9: 0000fffff90fe130
> > X8: 0000000000000040 X7: 0000000000000001 X6: 0000ffff7d759a98
> > X5: 0000000000000001 X4: 00000000fbad2a84 X3: 0000000000000000
> > X2: 0000000000000002 X1: 0000ffff76e30000 X0: 0000000000000001
> > ORIG_X0: 0000000000000001 SYSCALLNO: 40 PSTATE: 20000000
> >
> > PID: 2545 TASK: ffff8003d5901d00 CPU: 2 COMMAND: "spin"
> > #0 [ffff8003ffe93d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003ffe93dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003ffe93f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003ffe93fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4f3ed0
> > fp: 0 (?)
> > PC: 00000000004005b0 LR: 0000ffffb50f0c94 SP: 0000ffffe48b4910
> > X29: 0000ffffe48b4910 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> > X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe48b4820
> > X17: 0000000000420000 X16: 0000ffffb50f0ba4 X15: 00000000001815e7
> > X14: 0000ffffb52affb8 X13: 000000000000000f X12: 0000000000000090
> > X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> > X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> > X5: 46c7b691c219cb7a X4: 0000000000000000 X3: 00000000004005b0
> > X2: 0000ffffe48b4a68 X1: 0000ffffe48b4a58 X0: 0000000000000001
> > ORIG_X0: 0000ffffb5250000 SYSCALLNO: ffffffffffffffff PSTATE:
> > 60000000
> >
> > PID: 2541 TASK: ffff8003d917b300 CPU: 3 COMMAND: "usex"
> > #0 [ffff8003ffec3d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003ffec3dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003ffec3f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003ffec3fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbecbed0
> > fp: 0 (?)
> > PC: 00000000004361e0 LR: 0000000000435be0 SP: 0000ffffcee64ac0
> > X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> > X20: 0000ffff8c790000 X19: 0000000000062a44 X18: 0000ffffcee64980
> > X17: 0000ffff8c891b9c X16: 00000000004602b8 X15: 002c4612d8986fa7
> > X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> > X11: 00000000000b5585 X10: 000000005750846e X9: 00000000001ecba2
> > X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> > X5: 0000ffff8c894768 X4: 0000000000000032 X3: 0000000000000007
> > X2: 0000000000000007 X1: 0000000000000005 X0: 00000000004b21cc
> > ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> > 80000000
> >
> > PID: 2544 TASK: ffff8003d9176a80 CPU: 4 COMMAND: "usex"
> > #0 [ffff8003ffef3d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003ffef3dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003ffef3f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003ffef3fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbea7ed0
> > fp: 0 (?)
> > PC: 0000000000435e38 LR: 0000000000435c94 SP: 0000ffffcee64af0
> > X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> > X20: 0000ffff8c790000 X19: 0000000000041b82 X18: 0000ffffcee64980
> > X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0034caab9974abe0
> > X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> > X11: 00000000000d83c1 X10: 000000005750846e X9: 00000000001eccc0
> > X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> > X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
> > X2: 0000000000000042 X1: 000000000000002a X0: 0000ffffcee64b84
> > ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> > 20000000
> >
> > PID: 2547 TASK: ffff8003d5906580 CPU: 5 COMMAND: "spin"
> > #0 [ffff8003fff23d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003fff23dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003fff23f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003fff23fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4efed0
> > fp: 0 (?)
> > PC: 00000000004005b0 LR: 0000ffffb33d0c94 SP: 0000ffffe5813a70
> > X29: 0000ffffe5813a70 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> > X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe5813980
> > X17: 0000000000420000 X16: 0000ffffb33d0ba4 X15: 00000000001815e7
> > X14: 0000ffffb358ffb8 X13: 000000000000000f X12: 0000000000000090
> > X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> > X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> > X5: f72609a0900e9af5 X4: 0000000000000000 X3: 00000000004005b0
> > X2: 0000ffffe5813bc8 X1: 0000ffffe5813bb8 X0: 0000000000000001
> > ORIG_X0: 0000ffffb3530000 SYSCALLNO: ffffffffffffffff PSTATE:
> > 60000000
> >
> > PID: 2542 TASK: ffff8003d9178780 CPU: 6 COMMAND: "usex"
> > #0 [ffff8003fff53d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003fff53dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003fff53f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003fff53fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbebbed0
> > fp: 0 (?)
> > PC: 0000000000435e10 LR: 0000000000435ddc SP: 0000ffffcee64ad0
> > X29: 0000ffffcee64ad0 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
> > X20: 0000ffff8c790000 X19: 0000000000054c83 X18: 0000ffffcee64980
> > X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0033b1eeb687fcdc
> > X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
> > X11: 00000000000d3be2 X10: 000000005750846e X9: 00000000001ecc9a
> > X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
> > X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
> > X2: 000000003693b600 X1: 000000003693b5f0 X0: 0000000000000006
> > ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE:
> > 80000000
> >
> > PID: 2548 TASK: ffff8003d5ab4d80 CPU: 7 COMMAND: "spin"
> > #0 [ffff8003fff83d60] crash_save_cpu at ffff800000148444
> > #1 [ffff8003fff83dc0] handle_IPI at ffff80000009c8d0
> > #2 [ffff8003fff83f80] gic_handle_irq at ffff8000000904c8
> > #3 [ffff8003fff83fd0] el0_irq_naked at ffff80000009180c
> > bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b63ed0
> > fp: 0 (?)
> > PC: 00000000004005b0 LR: 0000ffffae060c94 SP: 0000ffffcf219e20
> > X29: 0000ffffcf219e20 X28: 0000000000000000 X27: 0000000000000000
> > X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
> > X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
> > X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffcf219d30
> > X17: 0000000000420000 X16: 0000ffffae060ba4 X15: 00000000001815e7
> > X14: 0000ffffae21ffb8 X13: 000000000000000f X12: 0000000000000090
> > X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
> > X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
> > X5: aa704cb48aa4536a X4: 0000000000000000 X3: 00000000004005b0
> > X2: 0000ffffcf219f78 X1: 0000ffffcf219f68 X0: 0000000000000001
> > ORIG_X0: 0000ffffae1c0000 SYSCALLNO: ffffffffffffffff PSTATE:
> > 60000000
> > crash>
> >
> > Given that the link at the top of each of the IRQ stacks back to the
> > kernel-entry-from-user-space exception frames look to be legitimate,
> > perhaps
> > the "fp: 0" could be used as a key to recognizing the
> > IRQ-while-in-user-space
> > scenario? And also it doesn't appear that the phantom exception frames
> > that are dumped in your vmcore are mistakenly generating the fp of 0.
> >
> > Thanks,
> > Dave
> >
> >
>
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AKASHI Takahiro -
Dave Anderson