MIPS: Add support for eBPF JIT.

Since the eBPF machine has 64-bit registers, we only support this in
64-bit kernels.  As of the writing of this commit log test-bpf is showing:

  test_bpf: Summary: 316 PASSED, 0 FAILED, [308/308 JIT'ed]

All current test cases are successfully compiled.

Many examples in samples/bpf are usable, specifically tracex5 which
uses tail calls works.
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16369/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -33,7 +33,8 @@ 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 !CPU_MICROMIPS
+	select HAVE_CBPF_JIT if (!64BIT && !CPU_MICROMIPS)
+	select HAVE_EBPF_JIT if (64BIT && !CPU_MICROMIPS)
 	select HAVE_CC_STACKPROTECTOR
 	select HAVE_CONTEXT_TRACKING
 	select HAVE_COPY_THREAD_TLS
@@ -1178,6 +1179,15 @@ config SYS_SUPPORTS_RELOCATABLE
 	 The platform must provide plat_get_fdt() if it selects CONFIG_USE_OF
 	 to allow access to command line and entropy sources.
 
+config MIPS_CBPF_JIT
+	def_bool y
+	depends on BPF_JIT && HAVE_CBPF_JIT
+
+config MIPS_EBPF_JIT
+	def_bool y
+	depends on BPF_JIT && HAVE_EBPF_JIT
+
+
 #
 # Endianness selection.  Sufficiently obscure so many users don't know what to
 # answer,so we try hard to limit the available choices.  Also the use of a

arch/mips/net/Makefile

 # MIPS networking code
 
-obj-$(CONFIG_BPF_JIT) += bpf_jit.o bpf_jit_asm.o
+obj-$(CONFIG_MIPS_CBPF_JIT) += bpf_jit.o bpf_jit_asm.o
+obj-$(CONFIG_MIPS_EBPF_JIT) += ebpf_jit.o