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authorRichard Kuo <rkuo@codeaurora.org>2011-10-31 18:48:07 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-01 07:34:20 -0700
commit7567746e1c0d66ac0ef8a9d8816ca694462c7370 (patch)
tree5812837c9a8024091e253496cbdbbe888c0f7ab9 /arch/hexagon/include
parentdd472da380c3819740d740cfd70b7f8e700e834b (diff)
downloadlinux-linaro-stable-7567746e1c0d66ac0ef8a9d8816ca694462c7370.tar.gz
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>
Diffstat (limited to 'arch/hexagon/include')
-rw-r--r--arch/hexagon/include/asm/uaccess.h116
1 files changed, 116 insertions, 0 deletions
diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
new file mode 100644
index 000000000000..7e706eadbf0a
--- /dev/null
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -0,0 +1,116 @@
+/*
+ * User memory access support for Hexagon
+ *
+ * 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.
+ */
+
+#ifndef _ASM_UACCESS_H
+#define _ASM_UACCESS_H
+/*
+ * User space memory access functions
+ */
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/segment.h>
+#include <asm/sections.h>
+
+/*
+ * access_ok: - Checks if a user space pointer is valid
+ * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
+ * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
+ * to write to a block, it is always safe to read from it.
+ * @addr: User space pointer to start of block to check
+ * @size: Size of block to check
+ *
+ * Context: User context only. This function may sleep.
+ *
+ * Checks if a pointer to a block of memory in user space is valid.
+ *
+ * Returns true (nonzero) if the memory block *may* be valid, false (zero)
+ * if it is definitely invalid.
+ *
+ * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
+ * simple MSB-based tests used by MIPS won't work. Some further
+ * optimization is probably possible here, but for now, keep it
+ * reasonably simple and not *too* slow. After all, we've got the
+ * MMU for backup.
+ */
+#define VERIFY_READ 0
+#define VERIFY_WRITE 1
+
+#define __access_ok(addr, size) \
+ ((get_fs().seg == KERNEL_DS.seg) || \
+ (((unsigned long)addr < get_fs().seg) && \
+ (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
+
+/*
+ * When a kernel-mode page fault is taken, the faulting instruction
+ * address is checked against a table of exception_table_entries.
+ * Each entry is a tuple of the address of an instruction that may
+ * be authorized to fault, and the address at which execution should
+ * be resumed instead of the faulting instruction, so as to effect
+ * a workaround.
+ */
+
+/* Assembly somewhat optimized copy routines */
+unsigned long __copy_from_user_hexagon(void *to, const void __user *from,
+ unsigned long n);
+unsigned long __copy_to_user_hexagon(void __user *to, const void *from,
+ unsigned long n);
+
+#define __copy_from_user(to, from, n) __copy_from_user_hexagon(to, from, n)
+#define __copy_to_user(to, from, n) __copy_to_user_hexagon(to, from, n)
+
+/*
+ * XXX todo: some additonal performance gain is possible by
+ * implementing __copy_to/from_user_inatomic, which is much
+ * like __copy_to/from_user, but performs slightly less checking.
+ */
+
+__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
+#define __clear_user(a, s) __clear_user_hexagon((a), (s))
+
+#define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
+
+/* get around the ifndef in asm-generic/uaccess.h */
+#define __strnlen_user __strnlen_user
+
+extern long __strnlen_user(const char __user *src, long n);
+
+static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
+ long n);
+
+#include <asm-generic/uaccess.h>
+
+/* Todo: an actual accelerated version of this. */
+static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
+ long n)
+{
+ long res = __strnlen_user(src, n);
+
+ /* return from strnlen can't be zero -- that would be rubbish. */
+
+ if (res > n) {
+ copy_from_user(dst, src, n);
+ return n;
+ } else {
+ copy_from_user(dst, src, res);
+ return res-1;
+ }
+}
+
+#endif