From: Michael Ellerman <mpe@ellerman.id.au>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Thadeu Lima de Souza Cascardo <cascardo@redhat.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
netdev@vger.kernel.org, Matt Evans <matt@ozlabs.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@fb.com>,
Denis Kirjanov <kda@linux-powerpc.org>,
Paul Mackerras <paulus@samba.org>,
"David S. Miller" <davem@davemloft.net>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Subject: Re: [PATCH] ppc: Fix BPF JIT for ABIv2
Date: Tue, 21 Jun 2016 21:15:48 +1000 [thread overview]
Message-ID: <1466507748.18876.3.camel@ellerman.id.au> (raw)
In-Reply-To: <20160621085807.GE8886@naverao1-tp.localdomain>
On Tue, 2016-06-21 at 14:28 +0530, Naveen N. Rao wrote:
> On 2016/06/20 03:56PM, Thadeu Lima de Souza Cascardo wrote:
> > On Sun, Jun 19, 2016 at 11:19:14PM +0530, Naveen N. Rao wrote:
> > > On 2016/06/17 10:00AM, Thadeu Lima de Souza Cascardo wrote:
> > > >
> > > > Hi, Michael and Naveen.
> > > >
> > > > I noticed independently that there is a problem with BPF JIT and ABIv2, and
> > > > worked out the patch below before I noticed Naveen's patchset and the latest
> > > > changes in ppc tree for a better way to check for ABI versions.
> > > >
> > > > However, since the issue described below affect mainline and stable kernels,
> > > > would you consider applying it before merging your two patchsets, so that we can
> > > > more easily backport the fix?
> > >
> > > Hi Cascardo,
> > > Given that this has been broken on ABIv2 since forever, I didn't bother
> > > fixing it. But, I can see why this would be a good thing to have for
> > > -stable and existing distros. However, while your patch below may fix
> > > the crash you're seeing on ppc64le, it is not sufficient -- you'll need
> > > changes in bpf_jit_asm.S as well.
> >
> > Hi, Naveen.
> >
> > Any tips on how to exercise possible issues there? Or what changes you think
> > would be sufficient?
>
> The calling convention is different with ABIv2 and so we'll need changes
> in bpf_slow_path_common() and sk_negative_common().
How big would those changes be? Do we know?
How come no one reported this was broken previously? This is the first I've
heard of it being broken.
> However, rather than enabling classic JIT for ppc64le, are we better off
> just disabling it?
>
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -128,7 +128,7 @@ config PPC
> select IRQ_FORCED_THREADING
> select HAVE_RCU_TABLE_FREE if SMP
> select HAVE_SYSCALL_TRACEPOINTS
> - select HAVE_CBPF_JIT
> + select HAVE_CBPF_JIT if CPU_BIG_ENDIAN
> select HAVE_ARCH_JUMP_LABEL
> select ARCH_HAVE_NMI_SAFE_CMPXCHG
> select ARCH_HAS_GCOV_PROFILE_ALL
>
>
> Michael,
> Let me know your thoughts on whether you intend to take this patch or
> Cascardo's patch for -stable before the eBPF patches. I can redo my
> patches accordingly.
This patch sounds like the best option at the moment for something we can
backport. Unless the changes to fix it are minimal.
cheers
next prev parent reply other threads:[~2016-06-21 11:39 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 13:32 [PATCH 0/6] eBPF JIT for PPC64 Naveen N. Rao
2016-06-07 13:32 ` [PATCH 1/6] ppc: bpf/jit: Fix/enhance 32-bit Load Immediate implementation Naveen N. Rao
2016-06-07 13:32 ` [PATCH 2/6] ppc: bpf/jit: Optimize 64-bit Immediate loads Naveen N. Rao
2016-06-07 13:32 ` [PATCH 3/6] ppc: bpf/jit: Introduce rotate immediate instructions Naveen N. Rao
2016-06-07 13:32 ` [PATCH 4/6] ppc: bpf/jit: A few cleanups Naveen N. Rao
2016-06-07 13:32 ` [PATCH 5/6] ppc: bpf/jit: Isolate classic BPF JIT specifics into a separate header Naveen N. Rao
2016-06-07 13:32 ` [PATCH 6/6] ppc: ebpf/jit: Implement JIT compiler for extended BPF Naveen N. Rao
2016-06-07 22:56 ` Alexei Starovoitov
2016-06-08 17:17 ` Naveen N. Rao
2016-06-09 3:19 ` Nilay Vaish
2016-06-09 6:07 ` Naveen N. Rao
2016-06-17 12:53 ` [6/6] " Michael Ellerman
2016-06-17 13:00 ` [PATCH] ppc: Fix BPF JIT for ABIv2 Thadeu Lima de Souza Cascardo
2016-06-19 17:49 ` Naveen N. Rao
2016-06-20 18:56 ` Thadeu Lima de Souza Cascardo
2016-06-21 8:58 ` Naveen N. Rao
2016-06-21 11:15 ` Michael Ellerman [this message]
2016-06-21 14:47 ` Thadeu Lima de Souza Cascardo
2016-06-21 15:45 ` Alexei Starovoitov
2016-06-22 4:06 ` Michael Ellerman
2016-06-22 7:12 ` Naveen N. Rao
2016-06-22 14:57 ` Naveen N. Rao
2016-06-22 5:20 ` Michael Ellerman
2016-06-22 5:18 ` Michael Ellerman
2016-06-19 17:36 ` [6/6] ppc: ebpf/jit: Implement JIT compiler for extended BPF Naveen N. Rao
2016-06-20 23:38 ` Michael Ellerman
2016-06-21 6:58 ` Naveen N. Rao
2016-06-21 11:04 ` Michael Ellerman
2016-06-22 7:06 ` Naveen N. Rao
2016-06-22 10:37 ` [PATCH 6/6] " Michael Ellerman
2016-06-22 12:32 ` Naveen N. Rao
2016-06-11 5:47 ` [PATCH 0/6] eBPF JIT for PPC64 David Miller
2016-06-13 5:40 ` Naveen N. Rao
2016-06-18 4:57 ` mpe
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