mcu/nrf5340: Trust zone RAM clean update
RAM_SIZE was always taken from bps.h.
With trust zone in place it may be that the bootloader
had limited RAM assigned in linker scripts.
This may happen when MCU_BOOT_MEASURED_STARTUP is used.
This change clears only RAM that bootloader used.
If nothing special was done to linker scripts RAM size
will be the same as it used to be.
Signed-off-by: Jerzy Kasenberg <jerzy.kasenberg@codecoup.pl>
diff --git a/hw/mcu/nordic/nrf5340/src/hal_system_start.c b/hw/mcu/nordic/nrf5340/src/hal_system_start.c
index ecb3cf1..c744a5b 100644
--- a/hw/mcu/nordic/nrf5340/src/hal_system_start.c
+++ b/hw/mcu/nordic/nrf5340/src/hal_system_start.c
@@ -68,6 +68,8 @@
static const unsigned int periph_gpios[] = { UNMANGLE_MYNEWT_VAL(MYNEWT_VAL(MCU_GPIO_PERIPH)) };
#endif
+extern uint8_t __StackTop[];
+
void
hal_system_start(void *img_start)
{
@@ -142,13 +144,12 @@
* Normal loop here is inlined by GCC to call to memset hence asm version of
* memset that does not use stack (that just get erased).
*/
- asm volatile(" add %1, %1, %0 \n"
- " mov r0, #0 \n"
+ asm volatile(" mov r0, #0 \n"
"1: stmia %0!, {r0} \n"
" cmp %0, %1 \n"
" blt 1b \n"
:
- : "r" (&_ram_start), "r" (RAM_SIZE)
+ : "r" (&_ram_start), "r" (&__StackTop)
: "r0");
/* Application startup code expects interrupts to be enabled */
__enable_irq();
