RISC-V: change pointer and stack types

portPOINTER_SIZE_TYPE is used in FreeRTOS to store both pointer and
integer values. Using a plain integer type for this purpose is unsafe on
architectures that distinguish between pointers and integers, where an
integer type (e.g. uint64_t) may not be able to represent all pointer
values.

The standard intptr_t type is explicitly defined to safely hold either a
pointer or an integer. This commit changes portPOINTER_SIZE_TYPE to
intptr_t, similar to the existing POSIX port, improving portability of
the RISC-V port.

Similarly, portSTACK_TYPE is used to store word-sized values on the
stack that may represent either integers or pointers, and is often cast
to pointer types. Changing it to uintptr_t makes this usage explicit and
correct, improving portability, intent, and safety for capability-based
extensions such as CHERI-RISC-V.

Signed-off-by: Hesham Almatary <Hesham.Almatary@cl.cam.ac.uk>

Author: heshamelmatary

portable/GCC/RISC-V/portmacro.h

@@ -48,20 +48,20 @@
 
 /* Type definitions. */
 #if __riscv_xlen == 64
-    #define portSTACK_TYPE           uint64_t
     #define portBASE_TYPE            int64_t
     #define portUBASE_TYPE           uint64_t
     #define portMAX_DELAY            ( TickType_t ) 0xffffffffffffffffUL
-    #define portPOINTER_SIZE_TYPE    uint64_t
 #elif __riscv_xlen == 32
-    #define portSTACK_TYPE           uint32_t
     #define portBASE_TYPE            int32_t
     #define portUBASE_TYPE           uint32_t
     #define portMAX_DELAY            ( TickType_t ) 0xffffffffUL
 #else /* if __riscv_xlen == 64 */
     #error "Assembler did not define __riscv_xlen"
 #endif /* if __riscv_xlen == 64 */
 
+#define portPOINTER_SIZE_TYPE    intptr_t
+#define portSTACK_TYPE           uintptr_t
+
 typedef portSTACK_TYPE   StackType_t;
 typedef portBASE_TYPE    BaseType_t;
 typedef portUBASE_TYPE   UBaseType_t;