mips32: Fix a problem with gdb invoker.

This patch fixes the endian issue with gdb invoker on mips32
big endian. Now we are using pointer to long long and
we don't need to sign extend registers. On mips32 o32 abi
we need to make extra stack space when we are calling
function.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13507 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/vgdb.c b/coregrind/vgdb.c
index 23936c9..c3bfcba 100644
--- a/coregrind/vgdb.c
+++ b/coregrind/vgdb.c
@@ -81,7 +81,7 @@
    specific code and/or some OS specific code. */
 #if defined(VGA_arm) || defined(VGA_x86) || defined(VGA_amd64) \
     || defined(VGA_ppc32) || defined(VGA_ppc64) || defined(VGA_s390x) \
-    || defined(VGP_mips32_linux) || defined(VGA_mips64)
+    || defined(VGA_mips32) || defined(VGA_mips64)
 #define PTRACEINVOKER
 #else
 I_die_here : (PTRACEINVOKER) architecture missing in vgdb.c
@@ -916,7 +916,8 @@
 #elif defined(VGA_s390x)
    sp = user_mod.regs.gprs[15];
 #elif defined(VGA_mips32)
-   sp = user_mod.regs[29*2];
+   long long *p = (long long *)user_mod.regs;
+   sp = p[29];
 #elif defined(VGA_mips64)
    sp = user_mod.regs[29];
 #else
@@ -993,17 +994,14 @@
       XERROR(0, "(fn32) s390x has no 32bits implementation");
 #elif defined(VGA_mips32)
       /* put check arg in register 4 */
-      user_mod.regs[4*2] = check;
-      user_mod.regs[4*2+1] = 0xffffffff; // sign extend $a0
-      /* This sign extension is needed when vgdb 32 bits runs
-         on a 64 bits OS. */
+      p[4] = check;
       /* put NULL return address in ra */
-      user_mod.regs[31*2] = bad_return;
-      user_mod.regs[31*2+1] = 0;
-      user_mod.regs[34*2] = shared32->invoke_gdbserver;
-      user_mod.regs[34*2+1] = 0;
-      user_mod.regs[25*2] = shared32->invoke_gdbserver;
-      user_mod.regs[25*2+1] = 0;
+      p[31] = bad_return;
+      p[34] = shared32->invoke_gdbserver;
+      p[25] = shared32->invoke_gdbserver;
+      /* make stack space for args */
+      p[29] = sp - 32;
+
 #elif defined(VGA_mips64)
       assert(0); // cannot vgdb a 32 bits executable with a 64 bits exe
 #else