Hexagon: Add user access functions

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/hexagon/mm/copy_from_user.S

@@ -0,0 +1,114 @@
+/*
+ * User memory copy functions for kernel
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/*
+ * The right way to do this involves valignb
+ * The easy way to do this is only speed up src/dest similar alignment.
+ */
+
+/*
+ * Copy to/from user are the same, except that for packets with a load and
+ * a store, I don't know how to tell which kind of exception we got.
+ * Therefore, we duplicate the function, and handle faulting addresses
+ * differently for each function
+ */
+
+/*
+ * copy from user: loads can fault
+ */
+#define src_sav r13
+#define dst_sav r12
+#define src_dst_sav r13:12
+#define d_dbuf r15:14
+#define w_dbuf r15
+
+#define dst r0
+#define src r1
+#define bytes r2
+#define loopcount r5
+
+#define FUNCNAME __copy_from_user_hexagon
+#include "copy_user_template.S"
+
+	/* LOAD FAULTS from COPY_FROM_USER */
+
+	/* Alignment loop.  r2 has been updated. Return it. */
+	.falign
+1009:
+2009:
+4009:
+	{
+		r0 = r2
+		jumpr r31
+	}
+	/* Normal copy loops. Do epilog. Use src-src_sav to compute distance */
+	/* X - (A - B) == X + B - A */
+	.falign
+8089:
+	{
+		memd(dst) = d_dbuf
+		r2 += sub(src_sav,src)
+	}
+	{
+		r0 = r2
+		jumpr r31
+	}
+	.falign
+4089:
+	{
+		memw(dst) = w_dbuf
+		r2 += sub(src_sav,src)
+	}
+	{
+		r0 = r2
+		jumpr r31
+	}
+	.falign
+2089:
+	{
+		memh(dst) = w_dbuf
+		r2 += sub(src_sav,src)
+	}
+	{
+		r0 = r2
+		jumpr r31
+	}
+	.falign
+1089:
+	{
+		memb(dst) = w_dbuf
+		r2 += sub(src_sav,src)
+	}
+	{
+		r0 = r2
+		jumpr r31
+	}
+
+	/* COPY FROM USER: only loads can fail */
+
+	.section __ex_table,"a"
+	.long 1000b,1009b
+	.long 2000b,2009b
+	.long 4000b,4009b
+	.long 8080b,8089b
+	.long 4080b,4089b
+	.long 2080b,2089b
+	.long 1080b,1089b
+	.previous