From 7c3a119d6deefb15aa1bdbe72a2a2d047e767030 Mon Sep 17 00:00:00 2001
From: Dmitry Borisov <di.sean@protonmail.com>
Date: Sat, 19 Apr 2025 11:22:29 +0600
Subject: [PATCH] [KMTESTS:HAL] Add a test for string I/O intrinsic functions

CORE-20078
---
 modules/rostests/kmtests/CMakeLists.txt       |   3 +-
 modules/rostests/kmtests/hal/HalPortIo.c      | 145 ++++++++++++++++++
 .../rostests/kmtests/kmtest_drv/testlist.c    |   6 +
 3 files changed, 153 insertions(+), 1 deletion(-)
 create mode 100644 modules/rostests/kmtests/hal/HalPortIo.c

diff --git a/modules/rostests/kmtests/CMakeLists.txt b/modules/rostests/kmtests/CMakeLists.txt
index 63d8bd469f7..6b5a9ea6fe6 100644
--- a/modules/rostests/kmtests/CMakeLists.txt
+++ b/modules/rostests/kmtests/CMakeLists.txt
@@ -124,7 +124,8 @@ if(ARCH STREQUAL "i386" OR ARCH STREQUAL "amd64")
     add_asm_files(KMTEST_DRV_ASM
         kmtest_drv/vm_detect.S)
     list(APPEND KMTEST_DRV_SOURCE
-        ${KMTEST_DRV_ASM})
+        ${KMTEST_DRV_ASM}
+        hal/HalPortIo.c)
 endif()
 
 add_library(kmtest_drv MODULE ${KMTEST_DRV_SOURCE})
diff --git a/modules/rostests/kmtests/hal/HalPortIo.c b/modules/rostests/kmtests/hal/HalPortIo.c
new file mode 100644
index 00000000000..ecaed0dfff9
--- /dev/null
+++ b/modules/rostests/kmtests/hal/HalPortIo.c
@@ -0,0 +1,145 @@
+/*
+ * PROJECT:     ReactOS Kernel-Mode Tests
+ * LICENSE:     LGPL-2.1-or-later (https://spdx.org/licenses/LGPL-2.1-or-later)
+ * PURPOSE:     Tests for string I/O intrinsic functions
+ * COPYRIGHT:   Copyright 2025 Dmitry Borisov <di.sean@protonmail.com>
+ */
+
+/* INCLUDES *******************************************************************/
+
+#include <kmt_test.h>
+
+#define NDEBUG
+#include <debug.h>
+
+/* GLOBALS ********************************************************************/
+
+/* Compile with the highest optimization level to trigger a bug (See CORE-20078) */
+#ifdef _MSC_VER
+#pragma optimize("gst", on)
+#pragma auto_inline(on)
+#else
+#pragma GCC optimize("O3")
+#endif
+
+/* Used to isolate the effects of intrinsics from each other */
+typedef struct _TEST_CONTEXT
+{
+    PVOID OldBuffer;
+    UCHAR Pad[78];
+    USHORT Port;
+    ULONG Size;
+    PVOID Buffer;
+} TEST_CONTEXT, *PTEST_CONTEXT;
+
+/* TEST FUNCTIONS *************************************************************/
+
+static
+/*
+ * Isolate the effects of intrinsics from each other
+ * and hide the TEST_CONTEXT initialization from the optimizer.
+ */
+DECLSPEC_NOINLINE
+VOID
+TestWriteStringUshort(
+    _In_ PTEST_CONTEXT Context)
+{
+    __outwordstring(Context->Port, Context->Buffer, Context->Size / sizeof(USHORT));
+
+    /*
+     * The 'rep outsw' instruction increments or decrements the address in ESI by Size * 2.
+     * Test for CORE-20078: the ESI value should be preserved across calls.
+     */
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+DECLSPEC_NOINLINE
+VOID
+TestWriteStringUlong(
+    _In_ PTEST_CONTEXT Context)
+{
+    __outdwordstring(Context->Port, Context->Buffer, Context->Size / sizeof(ULONG));
+
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+DECLSPEC_NOINLINE
+VOID
+TestWriteStringUchar(
+    _In_ PTEST_CONTEXT Context)
+{
+    __inbytestring(Context->Port, Context->Buffer, Context->Size);
+
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+DECLSPEC_NOINLINE
+VOID
+TestReadStringUshort(
+    _In_ PTEST_CONTEXT Context)
+{
+    __inwordstring(Context->Port, Context->Buffer, Context->Size / sizeof(USHORT));
+
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+DECLSPEC_NOINLINE
+VOID
+TestReadStringUlong(
+    _In_ PTEST_CONTEXT Context)
+{
+    __outdwordstring(Context->Port, Context->Buffer, Context->Size / sizeof(ULONG));
+
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+DECLSPEC_NOINLINE
+VOID
+TestReadStringUchar(
+    _In_ PTEST_CONTEXT Context)
+{
+    __inbytestring(Context->Port, Context->Buffer, Context->Size);
+
+    ok_eq_pointer(Context->Buffer, Context->OldBuffer);
+}
+
+static
+VOID
+TestStringIo(VOID)
+{
+    TEST_CONTEXT Context;
+    UCHAR Buffer[20];
+
+    /* End of the x86 I/O range */
+    Context.Port = 0xFFFF - sizeof(ULONG);
+
+    Context.Buffer = Buffer;
+    Context.OldBuffer = Buffer;
+    Context.Size = sizeof(Buffer);
+
+    TestReadStringUchar(&Context);
+    TestReadStringUshort(&Context);
+    TestReadStringUlong(&Context);
+
+    /*
+     * Check whether the driver is running inside a virtual machine
+     * as it's not safe to write to I/O ports
+     * without having the port resources assigned.
+     */
+    if (!skip(KmtIsVirtualMachine, "Please run those tests in a supported virtual machine\n"))
+    {
+        TestWriteStringUchar(&Context);
+        TestWriteStringUshort(&Context);
+        TestWriteStringUlong(&Context);
+    }
+}
+
+START_TEST(HalPortIo)
+{
+    TestStringIo();
+}
diff --git a/modules/rostests/kmtests/kmtest_drv/testlist.c b/modules/rostests/kmtests/kmtest_drv/testlist.c
index b863bcf7b04..25db57346b7 100644
--- a/modules/rostests/kmtests/kmtest_drv/testlist.c
+++ b/modules/rostests/kmtests/kmtest_drv/testlist.c
@@ -26,6 +26,9 @@ KMT_TESTFUNC Test_FsRtlLegal;
 KMT_TESTFUNC Test_FsRtlMcb;
 KMT_TESTFUNC Test_FsRtlRemoveDotsFromPath;
 KMT_TESTFUNC Test_FsRtlTunnel;
+#if defined(_M_IX86) || defined(_M_AMD64)
+KMT_TESTFUNC Test_HalPortIo;
+#endif
 KMT_TESTFUNC Test_HalSystemInfo;
 KMT_TESTFUNC Test_IoCreateFile;
 KMT_TESTFUNC Test_IoDeviceInterface;
@@ -110,6 +113,9 @@ const KMT_TEST TestList[] =
     { "FsRtlMcb",                           Test_FsRtlMcb },
     { "FsRtlRemoveDotsFromPath",            Test_FsRtlRemoveDotsFromPath },
     { "FsRtlTunnel",                        Test_FsRtlTunnel },
+#if defined(_M_IX86) || defined(_M_AMD64)
+    { "HalPortIo",                          Test_HalPortIo },
+#endif
     { "HalSystemInfo",                      Test_HalSystemInfo },
     { "IoCreateFile",                       Test_IoCreateFile },
     { "IoDeviceInterface",                  Test_IoDeviceInterface },