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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 66cb591729 ("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 <oleg@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2013-07-08 16:01:06 -07:00 committed by Linus Torvalds
parent fab840fc2d
commit f7da04c9e3
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kernel/hw_breakpoint.c
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@ -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)