x86: prevent unconditional writes to DebugCtl MSR
commit5b0e508415a83989fe704b4718a1a214bc333ca7
authorJan Beulich <jbeulich@novell.com>
Mon, 10 Mar 2008 13:11:17 +0000 (10 13:11 +0000)
committerIngo Molnar <mingo@elte.hu>
Thu, 17 Apr 2008 15:40:58 +0000 (17 17:40 +0200)
treebf73f1e6b944c190441413cedfb49b05e04ffe6b
parentf694010185c429629ad5a65245da08103e611852
x86: prevent unconditional writes to DebugCtl MSR

Otherwise, enabling (or better, subsequent disabling) of single
stepping would cause a kernel oops on CPUs not having this MSR.

The patch could have been added a conditional to the MSR write in
user_disable_single_step(), but centralizing the updates seems safer
and (looking forward) better manageable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/kprobes.c
arch/x86/kernel/process_32.c
arch/x86/kernel/process_64.c
arch/x86/kernel/step.c
include/asm-x86/processor.h