Add initial nistec project files

p256_asm_test.go

@@ -0,0 +1,53 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (amd64 || arm64 || ppc64le || s390x) && !purego && linux
+
+package nistec
+
+import (
+	"syscall"
+	"testing"
+	"unsafe"
+)
+
+// Lightly adapted from the bytes test package. Allocate a pair of T one at the start of a page, another at the
+// end. Any access beyond or before the page boundary should cause a fault. This is linux specific.
+func dangerousObjs[T any](t *testing.T) (start *T, end *T) {
+	pagesize := syscall.Getpagesize()
+	b, err := syscall.Mmap(0, 0, 3*pagesize, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANONYMOUS|syscall.MAP_PRIVATE)
+	if err != nil {
+		t.Fatalf("mmap failed %s", err)
+	}
+	err = syscall.Mprotect(b[:pagesize], syscall.PROT_NONE)
+	if err != nil {
+		t.Fatalf("mprotect low failed %s\n", err)
+	}
+	err = syscall.Mprotect(b[2*pagesize:], syscall.PROT_NONE)
+	if err != nil {
+		t.Fatalf("mprotect high failed %s\n", err)
+	}
+	b = b[pagesize : 2*pagesize]
+	end = (*T)(unsafe.Pointer(&b[len(b)-(int)(unsafe.Sizeof(*end))]))
+	start = (*T)(unsafe.Pointer(&b[0]))
+	return start, end
+}
+
+func TestP256SelectAffinePageBoundary(t *testing.T) {
+	var out p256AffinePoint
+	begintp, endtp := dangerousObjs[p256AffineTable](t)
+	for i := 0; i < 31; i++ {
+		p256SelectAffine(&out, begintp, i)
+		p256SelectAffine(&out, endtp, i)
+	}
+}
+
+func TestP256SelectPageBoundary(t *testing.T) {
+	var out P256Point
+	begintp, endtp := dangerousObjs[p256Table](t)
+	for i := 0; i < 15; i++ {
+		p256Select(&out, begintp, i)
+		p256Select(&out, endtp, i)
+	}
+}