[nrf noup] platform: nordic_nrf: Use aliased default IRQ handlers

Currently we are generating dozens of default IRQ Handlers that each
just spin. In sum, 256 bytes of IRQ handlers that do nothing.

In this patch we save these bytes by using the alias attribute.

Now there is only one default IRQ handler placed in flash and all the
default IRQ handlers alias to it.

I tried to place the duplicated default_tfm_IRQHandler in the common
startup.c, but it did not work. I am not certain, but I think this is
due to a problem with the way we link in TF-M.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>

platform/ext/target/nordic_nrf/common/core/startup.h

@@ -24,10 +24,7 @@ typedef void(*VECTOR_TABLE_Type)(void);
 void __PROGRAM_START(void) __NO_RETURN;
 
 #define DEFAULT_IRQ_HANDLER(handler_name)  \
-void __WEAK handler_name(void) __NO_RETURN; \
-void handler_name(void) { \
-    while(1); \
-}
+__NO_RETURN void __attribute__((weak, alias("default_tfm_IRQHandler"))) handler_name(void);
 
 __NO_RETURN void Reset_Handler(void);
 

platform/ext/target/nordic_nrf/common/nrf5340/gcc/startup_nrf5340.c

@@ -25,6 +25,10 @@
 #include "hw_init.h"
 #include "startup.h"
 
+__NO_RETURN __attribute__((naked)) void default_tfm_IRQHandler(void) {
+    while(1);
+}
+
 DEFAULT_IRQ_HANDLER(NMI_Handler)
 DEFAULT_IRQ_HANDLER(HardFault_Handler)
 DEFAULT_IRQ_HANDLER(MemManage_Handler)

platform/ext/target/nordic_nrf/common/nrf91/gcc/startup_nrf91.c

@@ -25,6 +25,10 @@
 #include "hw_init.h"
 #include "startup.h"
 
+__NO_RETURN __attribute__((naked)) void default_tfm_IRQHandler(void) {
+    while(1);
+}
+
 DEFAULT_IRQ_HANDLER(NMI_Handler)
 DEFAULT_IRQ_HANDLER(HardFault_Handler)
 DEFAULT_IRQ_HANDLER(MemManage_Handler)