ptrace/x86: ptrace_write_dr7() should create bp if !disabled
Commit 24f1e32c ("hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events") introduced the minor regression. Before this commit PTRACE_POKEUSER DR7, enableDR0 PTRACE_POKEUSER DR0, address was perfectly valid, now PTRACE_POKEUSER(DR7) fails if DR0 was not previously initialized by PTRACE_POKEUSER(DR0). Change ptrace_write_dr7() to do ptrace_register_breakpoint(addr => 0) if !bp && !disabled. This fixes watchpoint-zeroaddr from ptrace-tests, see https://bugzilla.redhat.com/show_bug.cgi?id=660204. Signed-off-by: NOleg Nesterov <oleg@redhat.com> Reported-by: NJan Kratochvil <jan.kratochvil@redhat.com> Acked-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@kernel.org> 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: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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