linux-kernel - Re: [PATCH] powerpc/bpf: Enable bpf_probe

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Date:   Thu, 28 May 2020 11:13:52 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Brendan Gregg <brendan.d.gregg@...il.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH] powerpc/bpf: Enable bpf_probe_read{, str}() on powerpc
 again

On Thu 2020-05-28 11:03:43, Michael Ellerman wrote:
> Petr Mladek <pmladek@...e.com> writes:
> > The commit 0ebeea8ca8a4d1d453a ("bpf: Restrict bpf_probe_read{, str}() only
> > to archs where they work") caused that bpf_probe_read{, str}() functions
> > were not longer available on architectures where the same logical address
> > might have different content in kernel and user memory mapping. These
> > architectures should use probe_read_{user,kernel}_str helpers.
> >
> > For backward compatibility, the problematic functions are still available
> > on architectures where the user and kernel address spaces are not
> > overlapping. This is defined CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
> >
> > At the moment, these backward compatible functions are enabled only
> > on x86_64, arm, and arm64. Let's do it also on powerpc that has
> > the non overlapping address space as well.
> >
> > Signed-off-by: Petr Mladek <pmladek@...e.com>
> 
> This seems like it should have a Fixes: tag and go into v5.7?

Good point:

Fixes: commit 0ebeea8ca8a4d1d4 ("bpf: Restrict bpf_probe_read{, str}() only to archs where they work")

And yes, it should ideally go into v5.7 either directly or via stable.

Should I resend the patch with Fixes and
Cc: stable@...r.kernel.org #v45.7 lines, please?

Best Regards,
Petr