1 files changed, 150 insertions, 0 deletions
diff --git a/test/tx/regression/threadx_thread_misaligned_stack_test.c b/test/tx/regression/threadx_thread_misaligned_stack_test.c
new file mode 100644
index 00000000..63d64775
--- /dev/null
+++ b/test/tx/regression/threadx_thread_misaligned_stack_test.c
@@ -0,0 +1,150 @@
+/***************************************************************************
+ * Copyright (c) 2026 Eclipse ThreadX contributors
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the MIT License which is available at
+ * https://opensource.org/licenses/MIT.
+ *
+ * AI Disclosure: This file was largely AI-generated by Claude Code (Opus 5).
+ * The AI-generated portions may be considered public domain (CC0-1.0)
+ * and not subject to the project's licence. The human contributor has
+ * reviewed and verified that the code is correct.
+ *
+ * SPDX-License-Identifier: MIT and CC0-1.0
+ **************************************************************************/
+
+/* This test creates a thread whose stack does not begin on a ULONG boundary.
+
+   tx_thread_create rounds the starting address up to the next ULONG and then
+   takes a ULONG off the size, so that the rounding cannot push the end of the
+   stack past the memory the caller supplied:
+
+       if (new_stack_start != updated_stack_start)
+       {
+           stack_size =  stack_size - (sizeof(ULONG));
+       }
+
+   Every other test in the suite hands tx_thread_create an aligned stack, so
+   that subtraction was never executed -- the only uncovered line in
+   tx_thread_create.c across all five build configurations. A misaligned stack
+   is legitimate: the API takes a VOID * and the alignment fix-up exists
+   precisely to accept one.
+
+   The thread is then run to completion rather than merely created, because the
+   point of the adjustment is that the resulting stack is still usable and still
+   inside the caller's buffer.  */
+
+#include   <stdio.h>
+#include   "tx_api.h"
+
+
+void  test_control_return(UINT status);
+
+
+static TX_THREAD       thread_0;
+static TX_THREAD       thread_1;
+
+/* Thread 1's stack is carved out of this by hand so that its start can be put
+   deliberately off a ULONG boundary. The extra ULONG is what the misaligned
+   start is offset into, so that the stack still ends inside the array after
+   tx_thread_create has rounded the start up.  */
+
+static UCHAR           misaligned_area[TEST_STACK_SIZE_PRINTF + sizeof(ULONG)];
+
+static ULONG           thread_1_counter =  0;
+
+
+static void    thread_0_entry(ULONG thread_input);
+static void    thread_1_entry(ULONG thread_input);
+
+
+/* Define what the initial system looks like.  */
+
+#ifdef CTEST
+void test_application_define(void *first_unused_memory)
+#else
+void    threadx_thread_misaligned_stack_application_define(void *first_unused_memory)
+#endif
+{
+
+UINT    status;
+CHAR    *pointer;
+CHAR    *misaligned_stack;
+
+
+    /* Setup a pointer.  */
+    pointer =  (CHAR *) first_unused_memory;
+
+    status =  tx_thread_create(&thread_0, "thread 0", thread_0_entry, 0,
+            pointer, TEST_STACK_SIZE_PRINTF,
+            16, 16, TX_NO_TIME_SLICE, TX_AUTO_START);
+    pointer =  pointer + TEST_STACK_SIZE_PRINTF;
+
+    if (status != TX_SUCCESS)
+    {
+
+        printf("Running Thread Misaligned Stack Test................................ ERROR #1\n");
+        test_control_return(1);
+    }
+
+    /* Push the start one byte past a ULONG boundary. The array itself is
+       aligned, so adding one is enough to guarantee the fix-up runs whatever
+       the alignment of the array turned out to be.  */
+    misaligned_stack =  ((CHAR *) misaligned_area) + 1;
+
+    status =  tx_thread_create(&thread_1, "thread 1", thread_1_entry, 0,
+            misaligned_stack, TEST_STACK_SIZE_PRINTF,
+            15, 15, TX_NO_TIME_SLICE, TX_AUTO_START);
+
+    if (status != TX_SUCCESS)
+    {
+
+        printf("Running Thread Misaligned Stack Test................................ ERROR #2\n");
+        test_control_return(1);
+    }
+}
+
+
+static void    thread_0_entry(ULONG thread_input)
+{
+
+    /* Thread 1 is the higher priority of the two, so this thread first gets the
+       processor while thread 1 is sleeping. Sleep past that, so the check below
+       is made against a thread that has actually finished.  */
+    tx_thread_sleep(5);
+
+    /* Both increments must have happened: one before thread 1 slept and one
+       after it woke, which is the half that needed the stack to survive a
+       context switch.  */
+    if (thread_1_counter != ((ULONG) 2))
+    {
+
+        printf("Running Thread Misaligned Stack Test................................ ERROR #3\n");
+        test_control_return(1);
+    }
+
+    /* The thread that ran on the misaligned stack must have run to completion,
+       which is what says the adjusted stack was usable.  */
+    if (thread_1.tx_thread_state != TX_COMPLETED)
+    {
+
+        printf("Running Thread Misaligned Stack Test................................ ERROR #4\n");
+        test_control_return(1);
+    }
+
+    printf("Running Thread Misaligned Stack Test................................ SUCCESS!\n");
+    test_control_return(0);
+}
+
+
+static void    thread_1_entry(ULONG thread_input)
+{
+
+    /* Use the stack either side of a context switch rather than returning
+       straight away.  */
+    thread_1_counter++;
+
+    tx_thread_sleep(1);
+
+    thread_1_counter++;
+}