From: Michael Ellerman <mpe@ellerman.id.au>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
netdev@vger.kernel.org
Cc: Matt Evans <matt@ozlabs.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@fb.com>,
Denis Kirjanov <kda@linux-powerpc.org>,
Thadeu Lima de Souza Cascardo <cascardo@redhat.com>,
Paul Mackerras <paulus@samba.org>,
"David S. Miller" <davem@davemloft.net>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Subject: Re: [PATCHv2, 2/7] ppc: bpf/jit: Fix/enhance 32-bit Load Immediate implementation
Date: Tue, 28 Jun 2016 22:10:12 +1000 (AEST) [thread overview]
Message-ID: <3rf4Pc1S8mz9sXy@ozlabs.org> (raw)
In-Reply-To: <d584015e9fb33ed526d693c5ab3c228d385f3c74.1466612260.git.naveen.n.rao@linux.vnet.ibm.com>
On Wed, 2016-22-06 at 16:25:02 UTC, "Naveen N. Rao" wrote:
> The existing LI32() macro can sometimes result in a sign-extended 32-bit
> load that does not clear the top 32-bits properly. As an example,
> loading 0x7fffffff results in the register containing
> 0xffffffff7fffffff. While this does not impact classic BPF JIT
> implementation (since that only uses the lower word for all operations),
> we would like to share this macro between classic BPF JIT and extended
> BPF JIT, wherein the entire 64-bit value in the register matters. Fix
> this by first doing a shifted LI followed by ORI.
>
> An additional optimization is with loading values between -32768 to -1,
> where we now only need a single LI.
>
> The new implementation now generates the same or less number of
> instructions.
>
> Acked-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Series applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/aaf2f7e09932a08c1287d8e4c6
cheers
next prev parent reply other threads:[~2016-06-28 12:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-22 16:25 [PATCHv2 0/7] eBPF JIT for PPC64 Naveen N. Rao
2016-06-22 16:25 ` [PATCHv2 1/7] ppc bpf/jit: Disable classic BPF JIT on ppc64le Naveen N. Rao
2016-06-22 16:50 ` Thadeu Lima de Souza Cascardo
2016-06-23 9:26 ` [PATCHv2,1/7] " Michael Ellerman
2016-06-22 16:25 ` [PATCHv2 2/7] ppc: bpf/jit: Fix/enhance 32-bit Load Immediate implementation Naveen N. Rao
2016-06-28 12:10 ` Michael Ellerman [this message]
2016-06-22 16:25 ` [PATCHv2 3/7] ppc: bpf/jit: Optimize 64-bit Immediate loads Naveen N. Rao
2016-06-22 16:25 ` [PATCHv2 4/7] ppc: bpf/jit: Introduce rotate immediate instructions Naveen N. Rao
2016-06-22 16:25 ` [PATCHv2 5/7] ppc: bpf/jit: A few cleanups Naveen N. Rao
2016-06-22 16:25 ` [PATCHv2 6/7] ppc: bpf/jit: Isolate classic BPF JIT specifics into a separate header Naveen N. Rao
2016-06-22 16:25 ` [PATCHv2 7/7] ppc: ebpf/jit: Implement JIT compiler for extended BPF Naveen N. Rao
2016-06-30 9:06 ` [PATCHv2 0/7] eBPF JIT for PPC64 Andreas Ziegler
2016-06-30 9:34 ` Denis Kirjanov
2016-06-30 10:32 ` Naveen N. Rao
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