[M2351] Make exported NSC symbols consistent across toolchains

This idea comes from TFM.

Author: ccli8

targets/TARGET_NUVOTON/TARGET_M2351/device/TOOLCHAIN_GCC_ARM/M2351.ld

@@ -216,8 +216,8 @@ SECTIONS
        __sgstubs_end = .;    
     } > NSC_FLASH
 
-    __nu_tz_nsc_start = NU_TZ_NSC_START;
-    __nu_tz_nsc_size = NU_TZ_NSC_SIZE;
+    Load$$LR$$LR_IROM_NSC$$Base = NU_TZ_NSC_START;
+    Load$$LR$$LR_IROM_NSC$$Length = NU_TZ_NSC_SIZE;
 
     /* By IDAU, 0~0x4000 is secure. NSC can only locate in 0x4000~0x10000000. */
     ASSERT(__sgstubs_start >= 0x4000, "By IDAU, 0~0x4000 is secure. NSC can only locate in 0x4000~0x10000000.")

targets/TARGET_NUVOTON/TARGET_M2351/device/TOOLCHAIN_IAR/M2351.icf

@@ -92,8 +92,8 @@ if (isdefinedsymbol(DOMAIN_NS)) {
     if (! isdefinedsymbol(NU_TZ_NSC_START)) {
         define symbol NU_TZ_NSC_START               = MBED_APP_START + MBED_APP_SIZE - 0x2000 - NU_TZ_NSC_SIZE;
     }
-    define exported symbol __NU_TZ_NSC_start__      = NU_TZ_NSC_START;
-    define exported symbol __NU_TZ_NSC_size__       = NU_TZ_NSC_SIZE;
+    define exported symbol Load$$LR$$LR_IROM_NSC$$Base      = NU_TZ_NSC_START;
+    define exported symbol Load$$LR$$LR_IROM_NSC$$Length    = NU_TZ_NSC_SIZE;
 
     /*-Specials-*/
     define symbol __ICFEDIT_intvec_start__          = MBED_APP_START;

targets/TARGET_NUVOTON/TARGET_M2351/device/partition_M2351.h

@@ -24,32 +24,14 @@
 #define NU_TZ_SECURE_FLASH_SIZE     NU_ROM_SIZE_S
 #define NU_TZ_SECURE_SRAM_SIZE      NU_RAM_SIZE_S
 
-#if defined(__CC_ARM) || (defined(__ARMCC_VERSION) && (__ARMCC_VERSION >= 6010050))
-
+/* We make exported symbols consistent across toolchains. This helps for porting e.g. TFM.
+ * Because Keil scatter file doesn't support custom exported symbols, other toolchains's
+ * linker files must export the same symbol names as region names in Keil scatter file. */
 extern int Load$$LR$$LR_IROM_NSC$$Base;
 extern int Load$$LR$$LR_IROM_NSC$$Length;
-
 #define NU_TZ_NSC_REGION_START  ((uint32_t) &Load$$LR$$LR_IROM_NSC$$Base)
 #define NU_TZ_NSC_REGION_SIZE   ((uint32_t) &Load$$LR$$LR_IROM_NSC$$Length)
 
-#elif defined(__ICCARM__)
-
-extern int __NU_TZ_NSC_start__;
-extern int __NU_TZ_NSC_size__;
-
-#define NU_TZ_NSC_REGION_START  ((uint32_t) &__NU_TZ_NSC_start__)
-#define NU_TZ_NSC_REGION_SIZE   ((uint32_t) &__NU_TZ_NSC_size__)
-
-#elif defined(__GNUC__)
-
-extern int __nu_tz_nsc_start;
-extern int __nu_tz_nsc_size;
-
-#define NU_TZ_NSC_REGION_START  ((uint32_t) &__nu_tz_nsc_start)
-#define NU_TZ_NSC_REGION_SIZE   ((uint32_t) &__nu_tz_nsc_size)
-
-#endif
-
 /* Check relevant macros have been defined */
 #if (! defined(NU_TZ_SECURE_FLASH_SIZE))
 #error("NU_TZ_SECURE_FLASH_SIZE not defined")