commit ddace9720fe7582cd2c92000f75f1f261daa53fd

Author: Dave Anderson <anderson@redhat.com>

Date:   Fri Feb 9 16:26:27 2018 -0500

    Fix for the ARM64 "bt" command in kernels that contain commit

    30d88c0e3ace625a92eead9ca0ad94093a8f59fe, titled "arm64: entry:

    Apply BP hardening for suspicious interrupts from EL0".  Without

    the patch, there may be invalid kernel kernel exception frames

    displayed on an active task's kernel stack, often below a stackframe

    of the "do_el0_ia_bp_hardening" function; the address translation

    of the PC and LR values in the the bogus exception frame will

    display "[unknown or invalid address]".

    (anderson@redhat.com)

--- crash-7.2.0/arm64.c.orig

+++ crash-7.2.0/arm64.c

@@ -2411,8 +2411,10 @@ arm64_back_trace_cmd(struct bt_info *bt)

 		if (arm64_in_exception_text(bt->instptr) && INSTACK(stackframe.fp, bt)) {

 			if (!(bt->flags & BT_IRQSTACK) ||

-			    (((stackframe.sp + SIZE(pt_regs)) < bt->stacktop)))

-				exception_frame = stackframe.fp - KERN_EFRAME_OFFSET;

+			    ((stackframe.sp + SIZE(pt_regs)) < bt->stacktop)) {

+				if (arm64_is_kernel_exception_frame(bt, stackframe.fp - KERN_EFRAME_OFFSET))

+					exception_frame = stackframe.fp - KERN_EFRAME_OFFSET;

+			}

 		}

 		if ((bt->flags & BT_IRQSTACK) &&