MIPS: eBPF: Initial eBPF support for MIPS32 architecture.

Currently MIPS32 supports a JIT for classic BPF only, not extended BPF.
This patch adds JIT support for extended BPF on MIPS32, so code is
actually JIT'ed instead of being only interpreted. Instructions with
64-bit operands are not supported at this point.
We can delete classic BPF because the kernel will translate classic BPF
programs into extended BPF and JIT them, eliminating the need for
classic BPF.

Signed-off-by: Hassan Naveed <hnaveed@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: kafai@fb.com
Cc: songliubraving@fb.com
Cc: yhs@fb.com
Cc: netdev@vger.kernel.org
Cc: bpf@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: open list:MIPS <linux-mips@linux-mips.org>
Cc: open list <linux-kernel@vger.kernel.org>

arch/mips/Kconfig

@@ -44,8 +44,7 @@ config MIPS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
-	select HAVE_CBPF_JIT if (!64BIT && !CPU_MICROMIPS)
-	select HAVE_EBPF_JIT if (64BIT && !CPU_MICROMIPS)
+	select HAVE_EBPF_JIT if (!CPU_MICROMIPS)
 	select HAVE_CONTEXT_TRACKING
 	select HAVE_COPY_THREAD_TLS
 	select HAVE_C_RECORDMCOUNT

arch/mips/net/Makefile

@@ -1,4 +1,3 @@
 # MIPS networking code
 
-obj-$(CONFIG_MIPS_CBPF_JIT) += bpf_jit.o bpf_jit_asm.o
 obj-$(CONFIG_MIPS_EBPF_JIT) += ebpf_jit.o