SCHED_CONTEXT_0014: Use sel4utils thread directly

start_helper would do unnecessary complicated thread startup code
which may contain FPU instructions with some compilers and configs.

Normally this would be harmless (though it would thwart the test's
intention), but if the task runs out of budget before it finishes
the FPU instruction, it will be put on the release queue and make
no forward progress (unclear why).

This is only a problem for tasks with budget equal to MIN_BUDGET,
any time lost because of syscalls or traps will cause the task to
hang.

Signed-off-by: Indan Zupancic <indan@nul.nu>

Author: Indanz

apps/sel4test-tests/src/tests/schedcontext.c

@@ -732,8 +732,10 @@ test_revoke_sched_context_on_call_chain(env_t env)
 DEFINE_TEST(SCHED_CONTEXT_0013, "Test revoking a scheduling context on a call chain",
             test_revoke_sched_context_on_call_chain, config_set(CONFIG_KERNEL_MCS) &&config_set(CONFIG_HAVE_TIMER))
 
-void sched_context_0014_helper_fn(_Atomic seL4_Word *counter)
+void sched_context_0014_helper_fn(void *arg0, void *arg1, void *ipc_buf)
 {
+    _Atomic seL4_Word *counter = arg0;
+
     while (1) {
         (*counter)++;
     }
@@ -742,24 +744,32 @@ void sched_context_0014_helper_fn(_Atomic seL4_Word *counter)
 /* Try to recreate race situation of issue 633 */
 int test_smp_delete_sched_context(env_t env)
 {
-    seL4_Error error;
-    helper_thread_t helper;
     _Atomic seL4_Word counter = 0;
     seL4_Word prev_counter = counter;
+    seL4_Error error;
+    sel4utils_thread_t thread;
+    sel4utils_thread_config_t config = thread_config_new(&env->simple);
+    sched_params_t *p = &config.sched_params;
+    seL4_Word core = CONFIG_MAX_NUM_NODES - 1;
+
+    config.no_ipc_buffer = true;
+    config.custom_stack_size = true;
+    config.stack_size = BIT(seL4_PageBits);
 
-    create_helper_thread(env, &helper);
-    set_helper_priority(env, &helper, env->priority - 1);
     /* Run it on another core and time it such that it runs out of budget during the SC free */
-    error = api_sched_ctrl_configure(simple_get_sched_ctrl(&env->simple, CONFIG_MAX_NUM_NODES - 1),
-                                     helper.thread.sched_context.cptr, MIN_BUDGET_US, 10 * US_IN_MS, 0, 0);
-    test_eq(error, seL4_NoError);
+    *p = sched_params_periodic(*p, &env->simple, core, 10 * US_IN_MS, MIN_BUDGET_US, 0, 0);
 
-    start_helper(env, &helper, (helper_fn_t)sched_context_0014_helper_fn, (seL4_Word)&counter, 0, 0, 0);
+    error = sel4utils_configure_thread_config(&env->vka, &env->vspace, &env->vspace, config, &thread);
+    assert(error == 0);
+
+    /* Don't use start_helper, we want to run the helper function directly: */
+    error = sel4utils_start_thread(&thread, sched_context_0014_helper_fn, &counter, NULL, 1);
+    test_eq(error, seL4_NoError);
 
     /* Wait till helper runs */
     while (counter == prev_counter);
 
-    vka_free_object(&env->vka, &helper.thread.sched_context);
+    vka_free_object(&env->vka, &thread.sched_context);
 
     return sel4test_get_result();
 }