From 5b0e508415a83989fe704b4718a1a214bc333ca7 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 10 Mar 2008 13:11:17 +0000 Subject: 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 Cc: Markus Metzger Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/kprobes.c') diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 34a591283f5..1e3de7db9ad 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -410,13 +410,13 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, static void __kprobes clear_btf(void) { if (test_thread_flag(TIF_DEBUGCTLMSR)) - wrmsrl(MSR_IA32_DEBUGCTLMSR, 0); + update_debugctlmsr(0); } static void __kprobes restore_btf(void) { if (test_thread_flag(TIF_DEBUGCTLMSR)) - wrmsrl(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr); + update_debugctlmsr(current->thread.debugctlmsr); } static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) -- cgit v1.2.3