prog: add concept of "special pointers"

Currently we only generate either valid user-space pointers or NULL.
Extend NULL to a set of special pointers that we will use in programs.
All targets now contain 3 special values:
 - NULL
 - 0xfffffffffffffff (invalid kernel pointer)
 - 0x999999999999999 (non-canonical address)
Each target can add additional special pointers on top of this.

Also generate NULL/special pointers for non-opt ptr's.
This restriction was always too restrictive. We may want to generate
them with very low probability, but we do want to generate them.

Also change pointers to NULL/special during mutation
(but still not in the opposite direction).

1 files changed, 24 insertions, 0 deletions

diff --git a/prog/encodingexec_test.go b/prog/encodingexec_test.go
index 94064c317..5a0e35750 100644
--- a/prog/encodingexec_test.go
+++ b/prog/encodingexec_test.go
@@ -403,6 +403,30 @@ func TestSerializeForExec(t *testing.T) {
 			},
 			nil,
 		},
+		{
+			"test$excessive_fields1(0x0)",
+			[]uint64{
+				callID("test$excessive_fields1"), ExecNoCopyout, 1, execArgConst, ptrSize, 0x0,
+				execInstrEOF,
+			},
+			nil,
+		},
+		{
+			"test$excessive_fields1(0xffffffffffffffff)",
+			[]uint64{
+				callID("test$excessive_fields1"), ExecNoCopyout, 1, execArgConst, ptrSize, 0xffffffffffffffff,
+				execInstrEOF,
+			},
+			nil,
+		},
+		{
+			"test$excessive_fields1(0xfffffffffffffffe)",
+			[]uint64{
+				callID("test$excessive_fields1"), ExecNoCopyout, 1, execArgConst, ptrSize, 0x9999999999999999,
+				execInstrEOF,
+			},
+			nil,
+		},
 	}
 
 	buf := make([]byte, ExecBufferSize)