On 2023/02/13 12:12, Lianbo Jiang wrote:
> Currently, the "bt" command may print a bogus exception frame
> and the remaining 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>
>
> The following related kernel commits cause the current issue, crash
> needs to adjust the value of irq eframe.
>
> Related kernel commits:
> [1] v5.8: 931b94145981 ("x86/entry: Provide helpers for executing on the irqstack")
> [2] v5.8: fa5e5c409213 ("x86/entry: Use idtentry for interrupts")
> [3] v5.12: 52d743f3b712 ("x86/softirq: Remove indirection in do_softirq_own_stack()")
>
> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
> ---
> x86_64.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/x86_64.c b/x86_64.c
> index 7a5d6f050c89..5b671bd97775 100644
> --- a/x86_64.c
> +++ b/x86_64.c
> @@ -3938,6 +3938,11 @@ in_exception_stack:
> if (irq_eframe) {
> bt->flags |= BT_EXCEPTION_FRAME;
> i = (irq_eframe - bt->stackbase)/sizeof(ulong);
> + if (symbol_exists("asm_common_interrupt")) {
> + i -= 1;
> + up = (ulong *)(&bt->stackbuf[i*sizeof(ulong)]);
> + bt->instptr = *up;
> + }
> x86_64_print_stack_entry(bt, ofp, level, i, bt->instptr);
> bt->flags &= ~(ulonglong)BT_EXCEPTION_FRAME;
> cs = x86_64_exception_frame(EFRAME_PRINT|EFRAME_CS, 0,
> @@ -6521,6 +6526,14 @@ x86_64_irq_eframe_link_init(void)
> else
> return;
>
> + if (symbol_exists("asm_common_interrupt")) {
> + if (symbol_exists("asm_call_on_stack"))
> + machdep->machspec->irq_eframe_link = -64;
> + else
> + machdep->machspec->irq_eframe_link = -32;
> + return;
> + }
> +
> if (THIS_KERNEL_VERSION < LINUX(2,6,9))
> return;
>
Thanks for the v2, applied.
https://github.com/crash-utility/crash/commit/92de7c34b1f910abff4d77522f74454ea0263a90
Thanks,
Kazu
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