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-rw-r--r--arch/metag/include/asm/uaccess.h40
1 files changed, 24 insertions, 16 deletions
diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h
index 469a2f1393d3..1e5f26d2dce8 100644
--- a/arch/metag/include/asm/uaccess.h
+++ b/arch/metag/include/asm/uaccess.h
@@ -28,24 +28,32 @@
#define segment_eq(a, b) ((a).seg == (b).seg)
-#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
-/*
- * Explicitly allow NULL pointers here. Parts of the kernel such
- * as readv/writev use access_ok to validate pointers, but want
- * to allow NULL pointers for various reasons. NULL pointers are
- * safe to allow through because the first page is not mappable on
- * Meta.
- *
- * We also wish to avoid letting user code access the system area
- * and the kernel half of the address space.
- */
-#define __user_bad(addr, size) (((addr) > 0 && (addr) < META_MEMORY_BASE) || \
- ((addr) > PAGE_OFFSET && \
- (addr) < LINCORE_BASE))
-
static inline int __access_ok(unsigned long addr, unsigned long size)
{
- return __kernel_ok || !__user_bad(addr, size);
+ /*
+ * Allow access to the user mapped memory area, but not the system area
+ * before it. The check extends to the top of the address space when
+ * kernel access is allowed (there's no real reason to user copy to the
+ * system area in any case).
+ */
+ if (likely(addr >= META_MEMORY_BASE && addr < get_fs().seg &&
+ size <= get_fs().seg - addr))
+ return true;
+ /*
+ * Explicitly allow NULL pointers here. Parts of the kernel such
+ * as readv/writev use access_ok to validate pointers, but want
+ * to allow NULL pointers for various reasons. NULL pointers are
+ * safe to allow through because the first page is not mappable on
+ * Meta.
+ */
+ if (!addr)
+ return true;
+ /* Allow access to core code memory area... */
+ if (addr >= LINCORE_CODE_BASE && addr <= LINCORE_CODE_LIMIT &&
+ size <= LINCORE_CODE_LIMIT + 1 - addr)
+ return true;
+ /* ... but no other areas. */
+ return false;
}
#define access_ok(type, addr, size) __access_ok((unsigned long)(addr), \