Currently, the "bt" command may print a bogus exception frame
and the rest frame will be truncated on x86 64 when using the
"virsh send-key <kvm guest> KEY_LEFTALT KEY_SYSRQ KEY_C" command
to trigger a panic from the KVM host. For example:
crash> bt
PID: 0 TASK: ffff9e7a47e32f00 CPU: 3 COMMAND: "swapper/3"
#0 [ffffba7900118bb8] machine_kexec at ffffffff87e5c2c7
#1 [ffffba7900118c08] __crash_kexec at ffffffff87f9500d
#2 [ffffba7900118cd0] panic at ffffffff87edfff9
#3 [ffffba7900118d50] sysrq_handle_crash at ffffffff883ce2c1
#4 [ffffba7900118d58] __handle_sysrq.cold.15 at ffffffff883ceb56
#5 [ffffba7900118d88] sysrq_filter at ffffffff883ce9a2
#6 [ffffba7900118dc0] input_to_handler at ffffffff884fb0bf
#7 [ffffba7900118df8] input_pass_values at ffffffff884fc1b7
#8 [ffffba7900118e20] input_handle_event at ffffffff884fe278
#9 [ffffba7900118e50] input_event at ffffffff884fe74b
#10 [ffffba7900118e88] atkbd_interrupt at ffffffff88504e2f
#11 [ffffba7900118ee0] serio_interrupt at ffffffff884f7516
#12 [ffffba7900118f10] i8042_interrupt at ffffffff884f8b04
#13 [ffffba7900118f50] __handle_irq_event_percpu at ffffffff87f51430
#14 [ffffba7900118f90] handle_irq_event_percpu at ffffffff87f51590
#15 [ffffba7900118fb8] handle_irq_event at ffffffff87f51616
#16 [ffffba7900118fd8] handle_edge_irq at ffffffff87f559f2
#17 [ffffba7900118ff0] asm_call_on_stack at ffffffff88800fa2
--- <IRQ stack> ---
#18 [ffffba790008bda0] asm_call_on_stack at ffffffff88800fa2
RIP: ffffffffffffffff RSP: 0000000000000124 RFLAGS: 00000003
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffffffff88800c1e RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R8: 0000000000000000 R9: 0000000000000000
R10: 0000000000000000 R11: ffffffff88760555 R12: ffffba790008be08
R13: ffffffff87f18002 R14: ffff9e7a47e32f00 R15: ffff9e7bb6198e00
ORIG_RAX: 0000000000000000 CS: 0003 SS: 0000
bt: WARNING: possibly bogus exception frame
crash>
Kernel commit fa5e5c409213 ("x86/entry: Use idtentry for interrupts")
change causes the current issue, crash needs to adjust the value of
irq eframe.
Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
---
x86_64.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/x86_64.c b/x86_64.c
index 7a5d6f050c89..6504d16fb17e 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -4647,10 +4647,15 @@ x86_64_exception_frame(ulong flags, ulong kvaddr, char *local,
r14 = ULONG(pt_regs_buf + ms->pto.r14);
r15 = ULONG(pt_regs_buf + ms->pto.r15);
- verified = x86_64_eframe_verify(bt,
- kvaddr ? kvaddr : (local - bt->stackbuf) + bt->stackbase,
- cs, ss, rip, rsp, rflags);
-
+ /*
+ * Do not verify when the flags is not set to EFRAME_VERIFY.
+ */
+ if (symbol_search("asm_common_interrupt") && !(flags & EFRAME_VERIFY))
+ verified = TRUE;
+ else
+ verified = x86_64_eframe_verify(bt,
+ kvaddr ? kvaddr : (local - bt->stackbuf) + bt->stackbase,
+ cs, ss, rip, rsp, rflags);
/*
* If it's print-if-verified request, don't print bogus eframes.
*/
@@ -6577,6 +6582,8 @@ x86_64_irq_eframe_link(ulong stkref, struct bt_info *bt, FILE *ofp)
return stkref;
irq_eframe = stkref - machdep->machspec->irq_eframe_link;
+ if (symbol_search("asm_common_interrupt"))
+ irq_eframe -= 80;
if (x86_64_exception_frame(EFRAME_VERIFY, irq_eframe, 0, bt, ofp))
return irq_eframe;
--
2.37.1
--
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