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Date: Mon, 20 Jun 2016 15:56:21 -0300 From: Thadeu Lima de Souza Cascardo <cascardo@...hat.com> To: "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> Cc: Michael Ellerman <mpe@...erman.id.au>, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org, Matt Evans <matt@...abs.org>, Daniel Borkmann <daniel@...earbox.net>, Alexei Starovoitov <ast@...com>, Denis Kirjanov <kda@...ux-powerpc.org>, Paul Mackerras <paulus@...ba.org>, "David S. Miller" <davem@...emloft.net>, Ananth N Mavinakayanahalli <ananth@...ibm.com> Subject: Re: [PATCH] ppc: Fix BPF JIT for ABIv2 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: > > On Fri, Jun 17, 2016 at 10:53:21PM +1000, Michael Ellerman wrote: > > > On Tue, 2016-07-06 at 13:32:23 UTC, "Naveen N. Rao" wrote: > > > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > > > > new file mode 100644 > > > > index 0000000..954ff53 > > > > --- /dev/null > > > > +++ b/arch/powerpc/net/bpf_jit_comp64.c > > > > @@ -0,0 +1,956 @@ > > > ... > > > > + > > > > +static void bpf_jit_fill_ill_insns(void *area, unsigned int size) > > > > +{ > > > > + int *p = area; > > > > + > > > > + /* Fill whole space with trap instructions */ > > > > + while (p < (int *)((char *)area + size)) > > > > + *p++ = BREAKPOINT_INSTRUCTION; > > > > +} > > > > > > This breaks the build for some configs, presumably you're missing a header: > > > > > > arch/powerpc/net/bpf_jit_comp64.c:30:10: error: 'BREAKPOINT_INSTRUCTION' undeclared (first use in this function) > > > > > > http://kisskb.ellerman.id.au/kisskb/buildresult/12720611/ > > > > > > cheers > > > > 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? I will see what I can find by myself, but would appreciate any help. Regards. Cascardo. > > Regards, > Naveen >
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