[Patch, AArch64] Fix pointer assignment to param_block_t variables

[Yufeng Zhang <Yufeng dot Zhang at arm dot com>]

Hi,

In the AArch64 libgloss backend, param_block_t is the base type for the 
Angle API block parameter and is defined as "long long".  Pointers are 
assigned to variables of this type via explicit casting, i.e. 
(param_block_t), which is OK when the pointer is 64-bit size but wrong 
when we have 32-bit pointers.

This patch replace the incorrect casting with a cpp macro which casts a 
pointer properly.

OK to go upstream?

Thanks,
Yufeng


libgloss/

        * aarch64/syscalls.c (POINTER_TO_PARAM_BLOCK_T): New macro.
        (initialise_monitor_handles): Replace the casting
        with the cpp macro POINTER_TO_PARAM_BLOCK_T.
        (_swiread): Likewise.
        (_swiwrite): Likewise.
        (_swiopen): Likewise.
        (_unlink): Likewise.
        (_system): Likewise.
        (_rename): Likewise.

diff --git a/libgloss/aarch64/syscalls.c b/libgloss/aarch64/syscalls.c
index 35567ad..058cef5 100644
--- a/libgloss/aarch64/syscalls.c
+++ b/libgloss/aarch64/syscalls.c
@@ -42,6 +42,10 @@
 #include <sys/wait.h>
 #include "svc.h"
 
+/* Safe casting in both LP64 and ILP32.  */
+#define POINTER_TO_PARAM_BLOCK_T(PTR)		\
+  (param_block_t)(unsigned long) (PTR)
+
 /* Forward prototypes.  */
 int _system _PARAMS ((const char *));
 int _rename _PARAMS ((const char *, const char *));
@@ -179,17 +183,17 @@ initialise_monitor_handles (void)
 
   param_block_t block[3];
 
-  block[0] = (param_block_t) ":tt";
+  block[0] = POINTER_TO_PARAM_BLOCK_T (":tt");
   block[2] = 3;			/* length of filename */
   block[1] = 0;			/* mode "r" */
   monitor_stdin = do_AngelSVC (AngelSVC_Reason_Open, block);
 
-  block[0] = (param_block_t) ":tt";
+  block[0] = POINTER_TO_PARAM_BLOCK_T (":tt");
   block[2] = 3;			/* length of filename */
   block[1] = 4;			/* mode "w" */
   monitor_stdout = do_AngelSVC (AngelSVC_Reason_Open, block);
 
-  block[0] = (param_block_t) ":tt";
+  block[0] = POINTER_TO_PARAM_BLOCK_T (":tt");
   block[2] = 3;			/* length of filename */
   block[1] = 8;			/* mode "a" */
   monitor_stderr = do_AngelSVC (AngelSVC_Reason_Open, block);
@@ -245,7 +249,7 @@ _swiread (int fh, char *ptr, int len)
   param_block_t block[3];
 
   block[0] = fh;
-  block[1] = (param_block_t) ptr;
+  block[1] = POINTER_TO_PARAM_BLOCK_T (ptr);
   block[2] = len;
 
   return checkerror (do_AngelSVC (AngelSVC_Reason_Read, block));
@@ -353,7 +357,7 @@ _swiwrite (int fh, char *ptr, int len)
   param_block_t block[3];
 
   block[0] = fh;
-  block[1] = (param_block_t) ptr;
+  block[1] = POINTER_TO_PARAM_BLOCK_T (ptr);
   block[2] = len;
 
   return checkerror (do_AngelSVC (AngelSVC_Reason_Write, block));
@@ -445,7 +449,7 @@ _swiopen (const char *path, int flags)
       aflags |= 8;
     }
 
-  block[0] = (param_block_t) path;
+  block[0] = POINTER_TO_PARAM_BLOCK_T (path);
   block[2] = strlen (path);
   block[1] = aflags;
 
@@ -621,7 +625,7 @@ _unlink (const char *path)
 {
   int res;
   param_block_t block[2];
-  block[0] = (param_block_t) path;
+  block[0] = POINTER_TO_PARAM_BLOCK_T (path);
   block[1] = strlen (path);
   res = do_AngelSVC (AngelSVC_Reason_Remove, block);
   if (res == -1)
@@ -714,7 +718,7 @@ _system (const char *s)
      meaning to its return value.  Try to do something reasonable....  */
   if (!s)
     return 1;			/* maybe there is a shell available? we can hope. :-P */
-  block[0] = (param_block_t) s;
+  block[0] = POINTER_TO_PARAM_BLOCK_T (s);
   block[1] = strlen (s);
   e = checkerror (do_AngelSVC (AngelSVC_Reason_System, block));
   if ((e >= 0) && (e < 256))
@@ -734,9 +738,9 @@ int
 _rename (const char *oldpath, const char *newpath)
 {
   param_block_t block[4];
-  block[0] = (param_block_t) oldpath;
+  block[0] = POINTER_TO_PARAM_BLOCK_T (oldpath);
   block[1] = strlen (oldpath);
-  block[2] = (param_block_t) newpath;
+  block[2] = POINTER_TO_PARAM_BLOCK_T (newpath);
   block[3] = strlen (newpath);
   return checkerror (do_AngelSVC (AngelSVC_Reason_Rename, block)) ? -1 : 0;
 }