Re: [Crash-utility] [PATCH] Fix for "bt" command prints a bogus warning

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(a)redhat.com&gt; --- 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;