add haveV4ISA probe

This commit introduces the haveV4ISA probe and HaveV4ISA API to check
in the running kernel if instructions of the v4 ISA are supported.
The upstream commit used as reference is 1f9a1ea821ff ("bpf: Support new sign-extension load insns").
The probes tests the new long jump given by `BPF_JMP32 | BPF_JA`.

Signed-off-by: Simone Magnani <[email protected]>

features/misc.go

@@ -93,3 +93,25 @@ var haveV3ISA = internal.NewFeatureTest("v3 ISA", func() error {
 		},
 	})
 }, "5.1")
+
+// HaveV4ISA probes the running kernel if instructions of the v4 ISA are supported.
+//
+// Upstream commit 1f9a1ea821ff ("bpf: Support new sign-extension load insns").
+//
+// See the package documentation for the meaning of the error return value.
+func HaveV4ISA() error {
+	return haveV4ISA()
+}
+
+var haveV4ISA = internal.NewFeatureTest("v4 ISA", func() error {
+	return probeProgram(&ebpf.ProgramSpec{
+		Type: ebpf.SocketFilter,
+		Instructions: asm.Instructions{
+			asm.Mov.Imm(asm.R0, 0),
+			asm.JEq.Imm(asm.R0, 1, "error"),
+			asm.LongJump("exit"),
+			asm.Mov.Imm(asm.R0, 1).WithSymbol("error"),
+			asm.Return().WithSymbol("exit"),
+		},
+	})
+}, "6.6")

features/misc_test.go

@@ -21,3 +21,7 @@ func TestHaveV2ISA(t *testing.T) {
 func TestHaveV3ISA(t *testing.T) {
 	testutils.CheckFeatureTest(t, HaveV3ISA)
 }
+
+func TestHaveV4ISA(t *testing.T) {
+	testutils.CheckFeatureTest(t, HaveV4ISA)
+}