ARC: test failure in tests/kernel/threads/thread_apis

[andrewboie]

Seen on nsim_sem_mpu_stack_guard and nsim_em_mpu_stack_guard

starting test - test_k_thread_foreach
TEST: Newly added thread found
TEST: tid: 0x80000204, prio: 0

    Assertion failed at /home/apboie/projects/zephyr3/zephyr/tests/kernel/threads/thread_apis/src/test_kthread_for_each.c:90: test_k_thread_foreach: ((tcount > count) && thread_flag && stack_flag is false)
thread_callback() not getting called
FAIL - test_k_thread_foreach

[vonhust]

@andrewboie @ruuddw this is caused by
if ((char *)thread->stack_info.start == K_THREAD_STACK_BUFFER(tstack)) {

one of issues caused by the mismatch in stack_info. It's not a critical issue. I plan to clear them in 1.15
When MPU_STACK_GUARD is enabled. The layout of thread's stack area will be

User stack layout
user stack defind in K_THREAD_STACK_DEFINE
stack guard
fixed size privilege stack

and

Kernel stack layout
stack guard
stack defind in K_THREAD_STACK_DEFINE
fixed size privilege stack (which can be merged with the up part)

for user thread stack_info.start == K_THREAD_STACK_BUFFER(tstack)
for kernel thread stack_info.start == K_THREAD_STACK_BUFFER(tstack) + STACK_GUARD_SIZE

When MPU_STACK_GUARD is not enabled, it's no proble,

So as the arch will set stack_info according to the type of thread, it's dynamic, should not rely on
static info like K_THREAD_STACK_BUFFER.

If in 1.15, other archs like ARM plan to refer arc's stack allocation mechnism , there will be similar issues.

[andrewboie]

the problem is that the test is trying to do too much. PR sent.