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Date: Fri, 7 Dec 2018 17:34:10 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: "Dmitry V. Levin" <ldv@altlinux.org>
Subject: Re: [PATCH v4] powerpc/ptrace: replace ptrace_report_syscall() with
 a tracehook call
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Cc: Eugene Syromyatnikov <esyr@redhat.com>, linux-kernel@vger.kernel.org,
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On 12/07, Dmitry V. Levin wrote:
>
> On Fri, Dec 07, 2018 at 10:12:49PM +1100, Michael Ellerman wrote:
>
> > > Sorry, this patch does not work, please ignore it.
> >
> > Hmm OK. Why exactly?
>
> Unfortunately, I have no idea why it doesn't work.
> All I can say is it breaks strace because the kernel no longer sends
> syscall entry stops.

May be because TIF_SYSCALL_EMU/etc is a bit number, not a mask? IOW, rather
than

	whatever & TIF_XXX

you should do

	whatever & _TIF_XXX

intstead?

Oleg.