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x86_64: Fix "bt" command not printing stack trace enough
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On recent x86_64 kernels, the check of caller function (BT_CHECK_CALLER)
does not work correctly due to inappropriate direct_call_targets.  As a
result, the correct frame is ignored and the remaining frames will be
truncated.

Skip the caller check if ORC unwinder is available, as the check is not
necessary with it.

Without the patch:
  crash> bt 493113
  PID: 493113   TASK: ff2e34ecbd3ca2c0  CPU: 27   COMMAND: "sriov_fec_daemo"
   #0 [ff77abc4e81cfb08] __schedule at ffffffff81b239cb
   crash-utility#1 [ff77abc4e81cfb70] schedule at ffffffff81b23e2d
   crash-utility#2 [ff77abc4e81cfb88] schedule_timeout at ffffffff81b2c9e8
      RIP: 000000000047cdbb  RSP: 000000c0000975a8  RFLAGS: 00000216
      ...

With the patch:
  crash> bt 493113
  PID: 493113   TASK: ff2e34ecbd3ca2c0  CPU: 27   COMMAND: "sriov_fec_daemo"
   #0 [ff77abc4e81cfb08] __schedule at ffffffff81b239cb
   crash-utility#1 [ff77abc4e81cfb70] schedule at ffffffff81b23e2d
   crash-utility#2 [ff77abc4e81cfb88] schedule_timeout at ffffffff81b2c9e8
   crash-utility#3 [ff77abc4e81cfbf0] __wait_for_common at ffffffff81b24abb
   crash-utility#4 [ff77abc4e81cfc68] vfio_unregister_group_dev at ffffffffc10e76ae [vfio]
   crash-utility#5 [ff77abc4e81cfca8] vfio_pci_core_unregister_device at ffffffffc11bb599 [vfio_pci_core]
   crash-utility#6 [ff77abc4e81cfcc0] vfio_pci_remove at ffffffffc103e045 [vfio_pci]
   crash-utility#7 [ff77abc4e81cfcd0] pci_device_remove at ffffffff815d7513
   ...

Reported-by: Crystal Wood <[email protected]>
Signed-off-by: Kazuhito Hagio <[email protected]>
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@k-hagio @liutgnu
k-hagio authored and liutgnu committed Dec 1, 2024
1 parent 253e347 commit 96031c4
Showing 1 changed file with 7 additions and 0 deletions.
7 changes: 7 additions & 0 deletions x86_64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3342,6 +3342,13 @@ x86_64_print_stack_entry(struct bt_info *bt, FILE *ofp, int level,

bt->call_target = name;

/*
* The caller check below does not work correctly for some kernels,
* so skip it if ORC unwinder is available.
*/
if (machdep->flags & ORC)
return result;

if (is_direct_call_target(bt)) {
if (CRASHDEBUG(2))
fprintf(ofp, "< enable BT_CHECK_CALLER for %s >\n",
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