Calling non-secure callable from FreeRTOS Thread causing HardFault on STM32H573

[NickO]

I've been struggling with this problem for several hours.

• Using bare metal, I can invoke a non-secure callable from the non-secure application.
• When I added FreeRTOS + CMSIS RTOS v2 wrapper, and try to do the same from a thread context, I get a hard fault when I try to invoke the non-secure callable (see below)

I would assume this is related to the thread stack. 

I am using the following:

• Cube MX 6.16
• Cube IDE Version: 2.0.0 Build: 26820_20251114_1348 (UTC)

In the secure project is secure_nsc.c, I define my API:

    CMSE_NS_ENTRY void ToggleBackLight(void)
    {
    	HAL_GPIO_TogglePin(BACKLIGHT_GPIO_Port, BACKLIGHT_Pin);
    }

 In the non-secure project, I invoke this from a thread as follows:

/* Private application code --------------------------------------------------*/
/* USER CODE BEGIN Application */
typedef void (*SecureFunc_t)(void) __attribute__((cmse_nonsecure_call));
void doBlinkyThread(void *argument)
{
  /* USER CODE BEGIN defaultTask */
  SecureFunc_t secure_func = (SecureFunc_t)ToggleBackLight; // from veneer table
  /* Infinite loop */
  for(;;)
  {
	  secure_func();
	  osDelay(500);
  }
  /* USER CODE END defaultTask */
}
/* USER CODE END Application */

 Notes:

I've used Cube MX to generate the thread-initialisation code, as shown below:

/* Definitions for blinkyThread */
osThreadId_t blinkyThreadHandle;
uint32_t MyBufferTask02[ 256 ];
osStaticThreadDef_t MycontrolBlocTask02;
const osThreadAttr_t blinkyThread_attributes = {
  .name = "blinkyThread",
  .stack_mem = &MyBufferTask02[0],
  .stack_size = sizeof(MyBufferTask02),
  .cb_mem = &MycontrolBlocTask02,
  .cb_size = sizeof(MycontrolBlocTask02),
  .priority = (osPriority_t) osPriorityRealtime7,
};

...

  /* creation of blinkyThread */
  blinkyThreadHandle = osThreadNew(doBlinkyThread, NULL, &blinkyThread_attributes);

I note that there is nothing in the attribute structure to make this TrustZone (see below). I tried setting .tz_module=1 (as suggested in another forum post), but this did not solve it.

typedef struct {
  const char                   *name;   ///< name of the thread
  uint32_t                 attr_bits;   ///< attribute bits
  void                      *cb_mem;    ///< memory for control block
  uint32_t                   cb_size;   ///< size of provided memory for control block
  void                   *stack_mem;    ///< memory for stack
  uint32_t                stack_size;   ///< size of stack
  osPriority_t              priority;   ///< initial thread priority (default: osPriorityNormal)
  TZ_ModuleId_t            tz_module;   ///< TrustZone module identifier
  uint32_t                  reserved;   ///< reserved (must be 0)
} osThreadAttr_t;

I also noted a warning:

warning: 'cmse_nonsecure_call' attribute ignored without '-mcmse' option [-Wattributes]

So, in addition to the above, I added this parameter to the compiler (on both sides), and the warning went away, but I still get the hard fault.

When I find myself having to mess with MX generated code and settings, it suggests I've missed something in Cube MX?