parisc: Call pagefault_disable/pagefault_enable in kmap_atomic/kunmap_atomic

Based on the generic implementation of kmap_atomic and kunmap_atomic,
we should call pagefault_disable and pagefault_enable in our PA8000
implementation.

The define for kmap_atomic_prot was also missing, and I updated
kmap_atomic_pfn to use the generic implementation because of the
change to kmap_atomic.

I believe that this change is needed to fix the fork copy-on-write
bug.

Signed-off-by: John David Anglin <[e-mail]>
Signed-off-by: Kyle McMartin <[e-mail]>

arch/parisc/include/asm/cacheflush.h

···
 #define _PARISC_CACHEFLUSH_H
 
 #include <linux/mm.h>
+#include <linux/uaccess.h>
 
 /* The usual comment is "Caches aren't brain-dead on the <architecture>".
  * Unfortunately, that doesn't apply to PA-RISC. */
···
 
 #define kunmap(page)			kunmap_parisc(page_address(page))
 
-#define kmap_atomic(page, idx)		page_address(page)
+static inline void *kmap_atomic(struct page *page, enum km_type idx)
+{
+	pagefault_disable();
+	return page_address(page);
+}
 
-#define kunmap_atomic(addr, idx)	kunmap_parisc(addr)
+static inline void kunmap_atomic(void *addr, enum km_type idx)
+{
+	kunmap_parisc(addr);
+	pagefault_enable();
+}
 
-#define kmap_atomic_pfn(pfn, idx)	page_address(pfn_to_page(pfn))
+#define kmap_atomic_prot(page, idx, prot)	kmap_atomic(page, idx)
+#define kmap_atomic_pfn(pfn, idx)	kmap_atomic(pfn_to_page(pfn), (idx))
 #define kmap_atomic_to_page(ptr)	virt_to_page(ptr)
 #endif