Re: [PATCH 4/6] ptrace/x86: ptrace_write_dr7() should create bp if!disabled

[Frederic Weisbecker]

On Thu, Apr 18, 2013 at 08:44:19PM +0200, Oleg Nesterov wrote:
> 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.
> 
> Reported-by: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
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