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From 92de7c34b1f910abff4d77522f74454ea0263a90 Mon Sep 17 00:00:00 2001
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From: Lianbo Jiang <lijiang@redhat.com>
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Date: Mon, 13 Feb 2023 11:12:12 +0800
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Subject: [PATCH] Fix for "bt" command printing "bogus exception frame" warning
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Currently, the "bt" command may print a bogus exception frame
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and the remaining frame will be truncated on x86_64 when using the
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"virsh send-key <kvm guest> KEY_LEFTALT KEY_SYSRQ KEY_C" command
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to trigger a panic from the KVM host. For example:
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crash> bt
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PID: 0 TASK: ffff9e7a47e32f00 CPU: 3 COMMAND: "swapper/3"
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#0 [ffffba7900118bb8] machine_kexec at ffffffff87e5c2c7
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#1 [ffffba7900118c08] __crash_kexec at ffffffff87f9500d
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#2 [ffffba7900118cd0] panic at ffffffff87edfff9
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#3 [ffffba7900118d50] sysrq_handle_crash at ffffffff883ce2c1
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...
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#16 [ffffba7900118fd8] handle_edge_irq at ffffffff87f559f2
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#17 [ffffba7900118ff0] asm_call_on_stack at ffffffff88800fa2
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--- <IRQ stack> ---
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#18 [ffffba790008bda0] asm_call_on_stack at ffffffff88800fa2
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RIP: ffffffffffffffff RSP: 0000000000000124 RFLAGS: 00000003
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RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
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RDX: ffffffff88800c1e RSI: 0000000000000000 RDI: 0000000000000000
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RBP: 0000000000000001 R8: 0000000000000000 R9: 0000000000000000
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R10: 0000000000000000 R11: ffffffff88760555 R12: ffffba790008be08
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R13: ffffffff87f18002 R14: ffff9e7a47e32f00 R15: ffff9e7bb6198e00
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ORIG_RAX: 0000000000000000 CS: 0003 SS: 0000
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bt: WARNING: possibly bogus exception frame
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crash>
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The following related kernel commits cause the current issue, crash
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needs to adjust the value of irq_eframe_link.
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Related kernel commits:
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[1] v5.8: 931b94145981 ("x86/entry: Provide helpers for executing on the irqstack")
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[2] v5.8: fa5e5c409213 ("x86/entry: Use idtentry for interrupts")
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[3] v5.12: 52d743f3b712 ("x86/softirq: Remove indirection in do_softirq_own_stack()")
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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---
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x86_64.c | 13 +++++++++++++
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1 file changed, 13 insertions(+)
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diff --git a/x86_64.c b/x86_64.c
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index 7a5d6f050c89..5b671bd97775 100644
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--- a/x86_64.c
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+++ b/x86_64.c
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@@ -3938,6 +3938,11 @@ in_exception_stack:
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if (irq_eframe) {
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bt->flags |= BT_EXCEPTION_FRAME;
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i = (irq_eframe - bt->stackbase)/sizeof(ulong);
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+ if (symbol_exists("asm_common_interrupt")) {
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+ i -= 1;
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+ up = (ulong *)(&bt->stackbuf[i*sizeof(ulong)]);
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+ bt->instptr = *up;
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+ }
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x86_64_print_stack_entry(bt, ofp, level, i, bt->instptr);
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bt->flags &= ~(ulonglong)BT_EXCEPTION_FRAME;
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cs = x86_64_exception_frame(EFRAME_PRINT|EFRAME_CS, 0,
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@@ -6521,6 +6526,14 @@ x86_64_irq_eframe_link_init(void)
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else
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return;
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+ if (symbol_exists("asm_common_interrupt")) {
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+ if (symbol_exists("asm_call_on_stack"))
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+ machdep->machspec->irq_eframe_link = -64;
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+ else
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+ machdep->machspec->irq_eframe_link = -32;
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+ return;
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+ }
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+
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if (THIS_KERNEL_VERSION < LINUX(2,6,9))
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return;
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--
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2.37.1
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