[POWERPC] Define copy_siginfo_from_user32

Define the copy_siginfo_from_user32 entry point for powerpc, so
that generic CONFIG_COMPAT code can call it.  We already had the
code rolled into compat_sys_rt_sigqueueinfo, this just moves it
out into the canonical function that other arch's define.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/signal_32.c

@@ -621,6 +621,18 @@ int copy_siginfo_to_user32(struct compat_siginfo __user *d, siginfo_t *s)
 
 #define copy_siginfo_to_user	copy_siginfo_to_user32
 
+int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
+{
+	memset(to, 0, sizeof *to);
+
+	if (copy_from_user(to, from, 3*sizeof(int)) ||
+	    copy_from_user(to->_sifields._pad,
+			   from->_sifields._pad, SI_PAD_SIZE32))
+		return -EFAULT;
+
+	return 0;
+}
+
 /*
  * Note: it is necessary to treat pid and sig as unsigned ints, with the
  * corresponding cast to a signed int to insure that the proper conversion
@@ -634,9 +646,10 @@ long compat_sys_rt_sigqueueinfo(u32 pid, u32 sig, compat_siginfo_t __user *uinfo
 	int ret;
 	mm_segment_t old_fs = get_fs();
 
-	if (copy_from_user (&info, uinfo, 3*sizeof(int)) ||
-	    copy_from_user (info._sifields._pad, uinfo->_sifields._pad, SI_PAD_SIZE32))
-		return -EFAULT;
+	ret = copy_siginfo_from_user32(&info, uinfo);
+	if (unlikely(ret))
+		return ret;
+
 	set_fs (KERNEL_DS);
 	/* The __user pointer cast is valid becasuse of the set_fs() */
 	ret = sys_rt_sigqueueinfo((int)pid, (int)sig, (siginfo_t __user *) &info);