From f7da04c9e363e479258135ac825734d78aecd2b0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 8 Jul 2013 16:01:06 -0700 Subject: [PATCH] ptrace/x86: flush_ptrace_hw_breakpoint() shoule clear the virtual debug registers flush_ptrace_hw_breakpoint() destroys the counters set by ptrace, but "leaks" ->debugreg6 and ->ptrace_dr7. The problem is minor, but still it doesn't look right and flush_thread() did this until commit 66cb59172959 ("hw-breakpoints: use the new wrapper routines to access debug registers in process/thread code"). Now that PTRACE_DETACH does flush_ too this makes even more sense. Signed-off-by: Oleg Nesterov Cc: Benjamin Herrenschmidt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jan Kratochvil Cc: Michael Neuling Cc: Paul Mackerras Cc: Paul Mundt Cc: Will Deacon Cc: Prasad Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/kernel/hw_breakpoint.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 02f07634d265..f66ff162dce8 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -393,6 +393,9 @@ void flush_ptrace_hw_breakpoint(struct task_struct *tsk) unregister_hw_breakpoint(t->ptrace_bps[i]); t->ptrace_bps[i] = NULL; } + + t->debugreg6 = 0; + t->ptrace_dr7 = 0; } void hw_breakpoint_restore(void) -- 2.20.1