Covered the trace entry update paths and the misaligned stack adjustment (#666)

Against the merged coverage report -- every build configuration instrumented and
unioned -- eighteen lines of common/src were uncovered. Seventeen of them were
one missing scenario rather than eighteen separate gaps.

tx_block_allocate, tx_byte_allocate, tx_thread_system_suspend and
tx_thread_system_resume each carry blocks under TX_ENABLE_EVENT_TRACE that go
back and patch a trace entry once the call has done its work, all of the shape:

    if (entry_ptr != TX_NULL)
    {
        if (time_stamp == entry_ptr -> tx_trace_buffer_entry_time_stamp)

entry_ptr comes from _tx_trace_buffer_current_ptr, which stays TX_NULL until
tx_trace_enable is called at run time. Building with TX_ENABLE_EVENT_TRACE is
not enough, and exactly one test in the suite enables tracing --
threadx_trace_basic_test -- which tests the enable API itself and never calls
either allocator. So those blocks sat in the report's denominator and never in
its covered set.

threadx_trace_entry_update_test enables tracing and then drives both allocators
twice each, once on the path that succeeds immediately and once through a
suspension that a second thread satisfies, since each allocator carries one
update block on either side. It then sleeps so that the last runnable thread
suspends with nothing ready to take over: tx_thread_system_suspend lines 345 and
351 are on the branch that sets _tx_thread_execute_ptr to TX_NULL, and the two
allocator suspensions never reach it because the other thread was always ready.

The same test closes tx_trace_object_register's TX_NULL name break by creating a
semaphore with no name. A semaphore and not a thread deliberately: for
TX_TRACE_OBJECT_TYPE_THREAD the register function dereferences the pointer it is
given to read the thread's priority, so that type needs a real TX_THREAD behind
it. threadx_trace_basic_test makes the equivalent call only under
ifndef TX_ENABLE_EVENT_TRACE, against the no-op stub.

threadx_thread_misaligned_stack_test covers the remaining line,
tx_thread_create.c:136, where a stack that does not begin on a ULONG boundary
costs a ULONG of size so that rounding the start up cannot run past the end of
the caller's buffer. Every other test hands tx_thread_create an aligned stack.
That line is compiled only under TX_ENABLE_STACK_CHECKING, so it is absent from
three of the five configurations' reports rather than uncovered in them, and it
was verified under stack_checking_build.

Measured on the merged report, all 480 tests passing and 5 of 5 configurations
green: 4485 of 4503 covered before, 4502 of 4503 after, denominator unchanged.

One line remains, tx_thread_system_resume.c:529, and it is the report's last
flapping line rather than a standing gap -- two clean runs of the same tree gave
4503 of 4503 and 4502 of 4503. Reaching it by construction was tried twice and
failed both times, so it is left alone here. It needs the preempt disable flag
and the system state both clear, and tx_thread_resume raises the preempt disable
flag before calling _tx_thread_system_resume, as do the put and send paths;
creating a higher priority auto-start thread from thread context does not raise
it but does not reach the check either, which a probe showed is executed only
during initialisation, with the system state at TX_INITIALIZE_IN_PROGRESS.

Assisted-by: Claude Opus 5 <noreply@anthropic.com>

test/tx/cmake/regression/CMakeLists.txt

@@ -80,6 +80,7 @@ set(regression_test_cases
     ${SOURCE_DIR}/threadx_thread_create_preemption_threshold_test.c
     ${SOURCE_DIR}/threadx_thread_delayed_suspension_test.c
     ${SOURCE_DIR}/threadx_thread_information_test.c
+    ${SOURCE_DIR}/threadx_thread_misaligned_stack_test.c
     ${SOURCE_DIR}/threadx_thread_multi_level_preemption_threshold_test.c
     ${SOURCE_DIR}/threadx_thread_multiple_non_current_test.c
     ${SOURCE_DIR}/threadx_thread_multiple_sleep_test.c
@@ -109,6 +110,7 @@ set(regression_test_cases
     ${SOURCE_DIR}/threadx_timer_multiple_test.c
     ${SOURCE_DIR}/threadx_timer_simple_test.c
     ${SOURCE_DIR}/threadx_trace_basic_test.c
+    ${SOURCE_DIR}/threadx_trace_entry_update_test.c
     ${SOURCE_DIR}/threadx_initialize_kernel_setup_test.c)
 
 add_custom_command(

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++;
+}