<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/67665>67665</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [lldb]freebsd kernel unwinding unaware of trap frames
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          emaste
      </td>
    </tr>
</table>

<pre>
    While testing #67106 I experimented with a kernel module that generates a fault (using #ud2). The module loading from #67106 works correctly, but unwinding is not aware of the FreeBSD trap frame, and we report an incorrect address (frame 6):

```
(lldb) bt
* thread #1, name = '(pid 1860) sysctl (crashed)'
  * frame #0: 0xffffffff80b42bbe kernel`doadump + 46
    frame #1: 0xffffffff80b42947 kernel`kern_reboot + 1495
    frame #2: 0xffffffff80b42e1f kernel`vpanic + 415
    frame #3: 0xffffffff80b42c73 kernel`panic + 67
    frame #4: 0xffffffff8100b81c kernel`trap_fatal + 1036
    frame #5: 0xffffffff80fe2378 kernel`calltrap + 8
    frame #6: 0xfffffe013627cbc4
    frame #7: 0xffffffff80b54590 kernel`sysctl_root_handler_locked + 144
    frame #8: 0xffffffff80b539c1 kernel`sysctl_root + 577
    frame #9: 0xffffffff80b54046 kernel`userland_sysctl + 374
    frame #10: 0xffffffff80b53e8c kernel`sys___sysctl + 92
    frame #11: 0xffffffff8100c0d9 kernel`amd64_syscall + 265
    frame #12: 0xffffffff80fe2c8b kernel`fast_syscall_common + 248
```

gdb, by contrast, is able to parse the trap frame, and the address in frame 7 below is correct (although gdb wasn't able to load the module debug data):
```
(kgdb) bt
#0 __curthread () at /usr/src/sys/amd64/include/pcpu_aux.h:57
#1  doadump (textdump=<optimized out>) at /usr/src/sys/kern/kern_shutdown.c:405
#2 0xffffffff80b42947 in kern_reboot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:526
#3  0xffffffff80b42e1f in vpanic (fmt=0xffffffff81134c30 "%s", ap=ap@entry=0xfffffe013627ca70) at /usr/src/sys/kern/kern_shutdown.c:970
#4  0xffffffff80b42c73 in panic (fmt=<unavailable>) at /usr/src/sys/kern/kern_shutdown.c:894
#5 0xffffffff8100b81c in trap_fatal (frame=0xfffffe013627cb00, eva=0) at /usr/src/sys/amd64/amd64/trap.c:952
#6  <signal handler called>
#7 0xffffffff8262f27d in ?? ()
#8  0x0000000100000000 in ?? ()
#9 0xffffffff82631270 in ?? ()
#10 0xfffffe013627cc20 in ?? ()
#11 0xffffffff80b54590 in sysctl_root_handler_locked (oid=0xfffffe013627ccc0, arg1=0x0, arg2=0, req=0xfffffe013627ccc0, tracker=0xffffffff8262f27d) at /usr/src/sys/kern/kern_sysctl.c:185
Backtrace stopped: frame did not save the PC
```


</pre>
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