Implement proper support for memory map operations in the LinuxKPI,

like open, close and fault using the character device pager.

Some notes about the implementation:

1) Linux drivers set the vm_ops and vm_private_data fields during a
mmap() call to indicate that the driver wants to use the LinuxKPI VM
operations. Else these operations are not used.

2) The vm_private_data pointer is associated with a VM area structure
and inserted into an internal LinuxKPI list. If the vm_private_data
pointer already exists, the existing VM area structure is used instead
of the allocated one which gets freed.

3) The LinuxKPI's vm_private_data pointer is used as the callback
handle for the FreeBSD VM object. The VM subsystem in FreeBSD has a
similar list to identify equal handles and will only call the
character device pager's close function once.

4) All LinuxKPI VM operations are serialized through the mmap_sem
sempaphore, which is per procedure, which prevents simultaneous access
to the shared VM area structure when receiving page faults.

Obtained from:		kmacy @
MFC after:		1 week
Sponsored by:		Mellanox Technologies

2 files changed, 42 insertions, 6 deletions

diff --git a/sys/compat/linuxkpi/common/include/linux/mm.h b/sys/compat/linuxkpi/common/include/linux/mm.h
index f652e3be325e..67ac02daff76 100644
--- a/sys/compat/linuxkpi/common/include/linux/mm.h
+++ b/sys/compat/linuxkpi/common/include/linux/mm.h
@@ -38,6 +38,7 @@
 #include <linux/kernel.h>
 #include <linux/mm_types.h>
 #include <linux/pfn.h>
+#include <linux/list.h>
 
 #include <asm/pgtable.h>
 
@@ -89,12 +90,25 @@ CTASSERT((VM_PROT_ALL & -(1 << 8)) == 0);
 typedef int (*pte_fn_t)(pte_t *, pgtable_t, unsigned long addr, void *data);
 
 struct vm_area_struct {
-	vm_offset_t	vm_start;
-	vm_offset_t	vm_end;
-	vm_offset_t	vm_pgoff;
-	vm_paddr_t	vm_pfn;		/* PFN For mmap. */
-	vm_size_t	vm_len;		/* length for mmap. */
-	vm_memattr_t	vm_page_prot;
+	vm_offset_t vm_start;
+	vm_offset_t vm_end;
+	vm_offset_t vm_pgoff;
+	pgprot_t vm_page_prot;
+	unsigned long vm_flags;
+	struct mm_struct *vm_mm;
+	void   *vm_private_data;
+	const struct vm_operations_struct *vm_ops;
+	struct linux_file *vm_file;
+
+	/* internal operation */
+	vm_paddr_t vm_pfn;		/* PFN for memory map */
+	vm_size_t vm_len;		/* length for memory map */
+	vm_pindex_t vm_pfn_first;
+	int	vm_pfn_count;
+	int    *vm_pfn_pcount;
+	vm_object_t vm_obj;
+	vm_map_t vm_cached_map;
+	TAILQ_ENTRY(vm_area_struct) vm_entry;
 };
 
 struct vm_fault {
diff --git a/sys/compat/linuxkpi/common/include/linux/page.h b/sys/compat/linuxkpi/common/include/linux/page.h
index 7e84e0440451..a40308e44dee 100644
--- a/sys/compat/linuxkpi/common/include/linux/page.h
+++ b/sys/compat/linuxkpi/common/include/linux/page.h
@@ -47,6 +47,28 @@ typedef unsigned long pgprot_t;
 
 #define page	vm_page
 
+#define	LINUXKPI_PROT_VALID (1 << 4)
+#define	LINUXKPI_CACHE_MODE_SHIFT 3
+
+static inline pgprot_t
+cachemode2protval(vm_memattr_t attr)
+{
+	return ((attr | LINUXKPI_PROT_VALID) << LINUXKPI_CACHE_MODE_SHIFT);
+}
+
+static inline vm_memattr_t
+pgprot2cachemode(pgprot_t prot)
+{
+	int val;
+
+	val = prot >> LINUXKPI_CACHE_MODE_SHIFT;
+
+	if (val & LINUXKPI_PROT_VALID)
+		return (val & ~LINUXKPI_PROT_VALID);
+	else
+		return (VM_MEMATTR_DEFAULT);
+}
+
 #define	virt_to_page(x)		PHYS_TO_VM_PAGE(vtophys((x)))
 #define	page_to_pfn(pp)		(VM_PAGE_TO_PHYS((pp)) >> PAGE_SHIFT)
 #define	pfn_to_page(pfn)	(PHYS_TO_VM_PAGE((pfn) << PAGE_SHIFT))