Add conformance test for callx instruction (#195)

Signed-off-by: Dave Thaler <dthaler1968@gmail.com>

include/bpf_conformance.h

@@ -23,6 +23,7 @@ typedef enum class _bpf_conformance_test_cpu_version
     v2 = 2,
     v3 = 3,
     v4 = 4,
+    vnext = 100,
     unknown = -1,
 } bpf_conformance_test_cpu_version_t;
 

src/bpf_assembler.cc

@@ -309,8 +309,15 @@ typedef class _bpf_assembler
             auto target = operands[1];
             // Mode determines if this is a helper function, a local call, or a call to a runtime function.
             if (mode == "helper") {
-                inst.imm = _decode_imm32(target);
-                inst.src = 0;
+                if (target.starts_with('%')) {
+                    inst.opcode |= EBPF_SRC_REG;
+                    inst.imm = 0;
+                    inst.src = _decode_register(target);
+                } else {
+                    inst.opcode |= EBPF_SRC_IMM;
+                    inst.imm = _decode_imm32(target);
+                    inst.src = 0;
+                }
             } else if (mode == "local") {
                 inst.imm = _decode_jump_target(target);
                 inst.src = 1;

src/bpf_conformance.cc

@@ -213,7 +213,7 @@ bpf_conformance_options(
             instructions_used.insert(bpf_conformance_instruction_t(required_cpu_version, inst));
         }
 
-        // If the caller requires this as a XDP program, then add the prolog instructions.
+        // If the caller requires this as an XDP program, then add the prolog instructions.
         if (options.xdp_prolog && input_memory.size() > 0) {
             auto prolog_instructions = _generate_xdp_prolog(input_memory.size());
             byte_code.insert(byte_code.begin(), prolog_instructions.begin(), prolog_instructions.end());

src/opcode_names.h

@@ -291,6 +291,7 @@ static const std::set<bpf_conformance_instruction_t, InstCmp> instructions_from_
     {bpf_conformance_test_cpu_version_t::v3, 0x85, 0x01},
     {bpf_conformance_test_cpu_version_t::v3, 0x85, 0x02},
     {bpf_conformance_test_cpu_version_t::v1, 0x87},
+    {bpf_conformance_test_cpu_version_t::vnext, 0x8d, 0x00},
     {bpf_conformance_test_cpu_version_t::v1, 0x94, 0x00, 0x00, 0x00},
     {bpf_conformance_test_cpu_version_t::v4, 0x94, 0x00, 0x00, 0x01},
     {bpf_conformance_test_cpu_version_t::v1, 0x95},

src/runner.cc

@@ -123,6 +123,8 @@ main(int argc, char** argv)
                 cpu_version = bpf_conformance_test_cpu_version_t::v3;
             } else if (cpu_version_string == "v4") {
                 cpu_version = bpf_conformance_test_cpu_version_t::v4;
+            } else if (cpu_version_string == "vnext") {
+                cpu_version = bpf_conformance_test_cpu_version_t::vnext;
             } else {
                 std::cout << "Invalid CPU version" << std::endl;
                 return 1;

tests/callx.data

@@ -0,0 +1,12 @@
+# Copyright (c) Big Switch Networks, Inc
+# SPDX-License-Identifier: Apache-2.0
+-- asm
+mov %r1, -1
+mov %r2, 5
+call %r2
+mov %r0, 2
+exit
+-- result
+0x2
+-- no register offset
+call instruction