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
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