x86_64: Fix for "bt" command incorrectly printing "bogus exception fr…

…ame" warning

The "bogus exception frame" warning was observed again on a specific
vmcore, and the remaining frame was truncated on x86_64 machine, when
executing the "bt" command as below:

  crash> bt 0 -c 8
  PID: 0        TASK: ffff9948c08f5640  CPU: 8    COMMAND: "swapper/8"
   #0 [fffffe1788788e58] crash_nmi_callback at ffffffff972672bb
   #1 [fffffe1788788e68] nmi_handle at ffffffff9722eb8e
   #2 [fffffe1788788eb0] default_do_nmi at ffffffff97e51cd0
   #3 [fffffe1788788ed0] exc_nmi at ffffffff97e51ee1
   #4 [fffffe1788788ef0] end_repeat_nmi at ffffffff980015f9
      [exception RIP: __update_load_avg_se+13]
      RIP: ffffffff9736b16d  RSP: ffffbec3c08acc78  RFLAGS: 00000046
      RAX: 0000000000000000  RBX: ffff994c2f2b1a40  RCX: ffffbec3c08acdc0
      RDX: ffff9948e4fe1d80  RSI: ffff994c2f2b1a40  RDI: 0000001d7ad7d55d
      RBP: ffffbec3c08acc88   R8: 0000001d921fca6f   R9: ffff994c2f2b1328
      R10: 00000000fffd0010  R11: ffffffff98e060c0  R12: 0000001d7ad7d55d
      R13: 0000000000000005  R14: ffff994c2f2b19c0  R15: 0000000000000001
      ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  --- <NMI exception stack> ---
   #5 [ffffbec3c08acc78] __update_load_avg_se at ffffffff9736b16d
   #6 [ffffbec3c08acce0] enqueue_entity at ffffffff9735c9ab
   #7 [ffffbec3c08acd28] enqueue_task_fair at ffffffff9735cef8
  ...
  #18 [ffffbec3c08acf90] blk_complete_reqs at ffffffff977978d0
  #19 [ffffbec3c08acfa0] __do_softirq at ffffffff97e66f7a
  #20 [ffffbec3c08acff0] do_softirq at ffffffff9730f6ef
  --- <IRQ stack> ---
  #21 [ffffbec3c022ff18] do_idle at ffffffff97368288
      [exception RIP: unknown or invalid address]
      RIP: 0000000000000000  RSP: 0000000000000000  RFLAGS: 00000000
      RAX: 0000000000000000  RBX: 000000089726a2d0  RCX: 0000000000000000
      RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000000000000
      RBP: ffffffff9726a3dd   R8: 0000000000000000   R9: 0000000000000000
      R10: ffffffff9720015a  R11: e48885e126bc1600  R12: 0000000000000000
      R13: ffffffff973684a9  R14: 0000000000000094  R15: 0000000040000000
      ORIG_RAX: 0000000000000000  CS: 0000  SS: 0000
  bt: WARNING: possibly bogus exception frame
  crash>

Actually there is no exception frame, when called from do_softirq().
With the patch:

  crash> bt 0 -c 8
  ...
  #18 [ffffbec3c08acf90] blk_complete_reqs at ffffffff977978d0
  #19 [ffffbec3c08acfa0] __do_softirq at ffffffff97e66f7a
  #20 [ffffbec3c08acff0] do_softirq at ffffffff9730f6ef
  --- <IRQ stack> ---
  #21 [ffffbec3c022ff28] cpu_startup_entry at ffffffff973684a9
  #22 [ffffbec3c022ff38] start_secondary at ffffffff9726a3dd
  #23 [ffffbec3c022ff50] secondary_startup_64_no_verify at ffffffff9720015a
  crash>

Reported-by: Jie Li <[email protected]>
Signed-off-by: Lianbo Jiang <[email protected]>

x86_64.c

@@ -3841,11 +3841,12 @@ x86_64_low_budget_back_trace_cmd(struct bt_info *bt_in)
 		up -= 1;
                 bt->instptr = *up;
 		/*
-		 *  No exception frame when coming from do_softirq_own_stack
-		 *  or call_softirq.
+		 *  No exception frame when coming from do_softirq,
+		 *  do_softirq_own_stack or call_softirq.
 		 */
 		if ((sp = value_search(bt->instptr, &offset)) && 
-		    (STREQ(sp->name, "do_softirq_own_stack") || STREQ(sp->name, "call_softirq")))
+		    (STREQ(sp->name, "do_softirq") || STREQ(sp->name, "do_softirq_own_stack") ||
+		     STREQ(sp->name, "call_softirq")))
 			irq_eframe = 0;
                 bt->frameptr = 0;
                 done = FALSE;