x86/entry/traps: Clear DR6 early in do_debug() and improve the comment
authorAndy Lutomirski <luto@kernel.org>
Thu, 10 Mar 2016 03:00:29 +0000 (19:00 -0800)
committerIngo Molnar <mingo@kernel.org>
Thu, 10 Mar 2016 08:48:13 +0000 (09:48 +0100)
commit8bb5643686d2898bec181c407651cf84e77d413f
treefffaba109deef6957634a64d7830c2214b9d652d
parent81edd9f69a6fd214fdbe66b43de6aa1610c84c63
x86/entry/traps: Clear DR6 early in do_debug() and improve the comment

Leaving any bits set in DR6 on return from a debug exception is
asking for trouble.  Prevent it by writing zero right away and
clarify the comment.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3857676e1be8fb27db4b89bbb1e2052b7f435ff4.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/traps.c