x86/dumpstack: Fix interrupt and exception stack boundary checks
authorJosh Poimboeuf <jpoimboe@redhat.com>
Tue, 11 Jul 2017 15:33:41 +0000 (10:33 -0500)
committerIngo Molnar <mingo@kernel.org>
Tue, 18 Jul 2017 08:56:23 +0000 (10:56 +0200)
commit5a3cf86978a1ac433407704ec280919751aa2699
tree5254ac3df5f4bd281ef6aa9a7b606e4d18b1eb80
parentb0529becebde629ff6abf2afdca6def6824f4fa9
x86/dumpstack: Fix interrupt and exception stack boundary checks

On x86_64, the double fault exception stack is located immediately after
the interrupt stack in memory.  This causes confusion in the unwinder
when it tries to unwind through an empty interrupt stack, where the
stack pointer points to the address bordering the two stacks.  The
unwinder incorrectly thinks it's running on the double fault stack.

Fix this kind of stack border confusion by never considering the
beginning address of an exception or interrupt stack to be part of the
stack.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Fixes: 5fe599e02e41 ("x86/dumpstack: Add support for unwinding empty IRQ stacks")
Link: http://lkml.kernel.org/r/bcc142160a5104de5c354c21c394c93a0173943f.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/dumpstack_32.c
arch/x86/kernel/dumpstack_64.c