Add a test for stack pivots that trigger page faults.

"Regress is always open for commits" @deraadt

1 files changed, 60 insertions, 0 deletions

diff --git a/regress/sys/kern/stackpivot/pagefault/stackpivot.c b/regress/sys/kern/stackpivot/pagefault/stackpivot.c
new file mode 100644
index 00000000000..0d31e43f840
--- /dev/null
+++ b/regress/sys/kern/stackpivot/pagefault/stackpivot.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2018 Todd Mortimer <mortimer@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include "../pivot.h"
+
+static size_t *realstack;
+static char *scan;
+static size_t scansize = UINT16_MAX;
+
+/* scan some memory crossing a page boundary */
+size_t dowork() {
+    size_t b = 0;
+    size_t i;
+    for (i = 0; i < scansize; ++i)
+        b += *scan++;
+    return b;
+}
+
+void doexit() {
+    exit(0);
+}
+
+void unpivot() {
+    pivot(realstack);
+}
+
+int main() {
+
+    /* allocate some memory to scan */
+    scan = malloc(scansize);
+
+    /* set up a rop chain on the real stack for syscalls */
+    size_t stack[10];
+    stack[0] = (size_t)doexit;
+    realstack = stack;
+
+    /* set up a basic alt stack on the heap that does some work */
+    size_t *newstack = calloc(10, sizeof(size_t));
+    newstack[0] = (size_t)dowork;
+    newstack[1] = (size_t)unpivot;
+    pivot(newstack);
+    return 0;
+}