+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Kernel Stacks
+=============
+
Kernel stacks on x86-64 bit
----------------------------
+===========================
Most of the text from Keith Owens, hacked by AK
stack size allocated to an IST assumes no nesting for the same code.
If that assumption is ever broken then the stacks will become corrupt.
-The currently assigned IST stacks are :-
+The currently assigned IST stacks are:
* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE).
Printing backtraces on x86
---------------------------
+==========================
The question about the '?' preceding function names in an x86 stacktrace
keeps popping up, here's an indepth explanation. It helps if the reader
Adapted from Ingo's mail, Message-ID: <20150521101614.GA10889@gmail.com>:
We always scan the full kernel stack for return addresses stored on
-the kernel stack(s) [*], from stack top to stack bottom, and print out
+the kernel stack(s) [1]_, from stack top to stack bottom, and print out
anything that 'looks like' a kernel text address.
If it fits into the frame pointer chain, we print it without a question
we still print out the real call chain as well - just with more question
marks than ideal.
-[*] For things like IRQ and IST stacks, we also scan those stacks, in
- the right order, and try to cross from one stack into another
- reconstructing the call chain. This works most of the time.
+.. [1] For things like IRQ and IST stacks, we also scan those stacks, in
+ the right order, and try to cross from one stack into another
+ reconstructing the call chain. This works most of the time.