where a user space task with "resume_userspace" or "entry_INT80_32"
at the top of the stack, or which was interrupted by the crash NMI
while handling a timer interrupt. Without the patch, the backtrace
would be proceeded with the error message "bt: cannot resolve stack
trace", and then dump the text symbols found on the stack and all
possible exception frames.
(anderson@redhat.com)
with retpoline gcc support. Without the patch, backtraces may fail
with the error message "bt: cannot resolve stack trace", followed by
the text symbols found on the stack and possible exception frames.
(anderson@redhat.com)
the "bt" command on Linux 4.2 and later 32-bit X86 kernels. Without
the patch, the first "bt" command that is executed will be preceded
by "bt: WARNING: "system_call" symbol does not exist", followed by
"bt: WARNING: neither "ret_from_sys_call" nor "syscall_badsys"
symbols exist".
(anderson@redhat.com)
Without the patch, the backtrace displays the "cannot resolve stack
trace" warning, dumps the backtrace, and then the text symbols:
crash> bt
PID: 0 TASK: f0962180 CPU: 6 COMMAND: "swapper/6"
bt: cannot resolve stack trace:
#0 [f095ff1c] __schedule at c0b6ef8d
#1 [f095ff58] schedule at c0b6f4a9
#2 [f095ff64] schedule_preempt_disabled at c0b6f728
#3 [f095ff6c] cpu_startup_entry at c04b0310
#4 [f095ff94] start_secondary at c04468c0
bt: text symbols on stack:
[f095ff1c] __schedule at c0b6ef8d
[f095ff58] schedule at c0b6f4ae
[f095ff64] schedule_preempt_disabled at c0b6f72d
[f095ff6c] cpu_startup_entry at c04b0315
[f095ff94] start_secondary at c04468c5
crash>
The backtrace shown is actually correct.
(anderson@redhat.com)
Dave Anderson