Introduce a new pmap function, pmap_extract_and_hold(). This function

atomically extracts and holds the physical page that is associated with the
given pmap and virtual address.  Such a function is needed to make the
memory mapping optimizations used by, for example, pipes and raw disk I/O
MP-safe.

Reviewed by:	tegge

6 files changed, 118 insertions, 0 deletions

diff --git a/sys/alpha/alpha/pmap.c b/sys/alpha/alpha/pmap.c
index 223d824..a2f5a50 100644
--- a/sys/alpha/alpha/pmap.c
+++ b/sys/alpha/alpha/pmap.c
@@ -811,6 +811,29 @@ pmap_extract(pmap, va)
 		return 0;
 }
 
+/*
+ *	Routine:	pmap_extract_and_hold
+ *	Function:
+ *		Atomically extract and hold the physical page
+ *		with the given pmap and virtual address. 
+ */
+vm_page_t
+pmap_extract_and_hold(pmap_t pmap, vm_offset_t va)
+{
+	vm_paddr_t pa;
+	vm_page_t m;
+
+	m = NULL;
+	mtx_lock(&Giant);
+	if ((pa = pmap_extract(pmap, va)) != 0) {
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_lock_queues();
+		vm_page_hold(m);
+		vm_page_unlock_queues();
+	}
+	mtx_unlock(&Giant);
+	return (m);
+}
 
 /***************************************************
  * Low level mapping routines.....
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index e862c82..fed7dac 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -749,6 +749,30 @@ pmap_extract(pmap, va)
 
 }
 
+/*
+ *	Routine:	pmap_extract_and_hold
+ *	Function:
+ *		Atomically extract and hold the physical page
+ *		with the given pmap and virtual address. 
+ */
+vm_page_t
+pmap_extract_and_hold(pmap_t pmap, vm_offset_t va)
+{
+	vm_paddr_t pa;
+	vm_page_t m;
+
+	m = NULL;
+	mtx_lock(&Giant);
+	if ((pa = pmap_extract(pmap, va)) != 0) {
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_lock_queues();
+		vm_page_hold(m);
+		vm_page_unlock_queues();
+	}
+	mtx_unlock(&Giant);
+	return (m);
+}
+
 vm_paddr_t
 pmap_kextract(vm_offset_t va)
 {
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index 1f13890..924a14f 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -861,6 +861,30 @@ pmap_extract(pmap, va)
 
 }
 
+/*
+ *	Routine:	pmap_extract_and_hold
+ *	Function:
+ *		Atomically extract and hold the physical page
+ *		with the given pmap and virtual address. 
+ */
+vm_page_t
+pmap_extract_and_hold(pmap_t pmap, vm_offset_t va)
+{
+	vm_paddr_t pa;
+	vm_page_t m;
+
+	m = NULL;
+	mtx_lock(&Giant);
+	if ((pa = pmap_extract(pmap, va)) != 0) {
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_lock_queues();
+		vm_page_hold(m);
+		vm_page_unlock_queues();
+	}
+	mtx_unlock(&Giant);
+	return (m);
+}
+
 /***************************************************
  * Low level mapping routines.....
  ***************************************************/
diff --git a/sys/ia64/ia64/pmap.c b/sys/ia64/ia64/pmap.c
index 8b0a8c0..f5f5459 100644
--- a/sys/ia64/ia64/pmap.c
+++ b/sys/ia64/ia64/pmap.c
@@ -1102,6 +1102,30 @@ pmap_extract(pmap, va)
 	return pmap_pte_pa(pte);
 }
 
+/*
+ *	Routine:	pmap_extract_and_hold
+ *	Function:
+ *		Atomically extract and hold the physical page
+ *		with the given pmap and virtual address. 
+ */
+vm_page_t
+pmap_extract_and_hold(pmap_t pmap, vm_offset_t va)
+{
+	vm_paddr_t pa;
+	vm_page_t m;
+
+	m = NULL;
+	mtx_lock(&Giant);
+	if ((pa = pmap_extract(pmap, va)) != 0) {
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_lock_queues();
+		vm_page_hold(m);
+		vm_page_unlock_queues();
+	}
+	mtx_unlock(&Giant);
+	return (m);
+}
+
 /***************************************************
  * Low level mapping routines.....
  ***************************************************/
diff --git a/sys/sparc64/sparc64/pmap.c b/sys/sparc64/sparc64/pmap.c
index f4a391b..f532152 100644
--- a/sys/sparc64/sparc64/pmap.c
+++ b/sys/sparc64/sparc64/pmap.c
@@ -621,6 +621,28 @@ pmap_extract(pmap_t pm, vm_offset_t va)
 }
 
 /*
+ * Atomically extract and hold the physical page with the given
+ * pmap and virtual address pair.
+ */
+vm_page_t
+pmap_extract_and_hold(pmap_t pmap, vm_offset_t va)
+{
+	vm_paddr_t pa;
+	vm_page_t m;
+
+	m = NULL;
+	mtx_lock(&Giant);
+	if ((pa = pmap_extract(pmap, va)) != 0) {
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_lock_queues();
+		vm_page_hold(m);
+		vm_page_unlock_queues();
+	}
+	mtx_unlock(&Giant);
+	return (m);
+}
+
+/*
  * Extract the physical page address associated with the given kernel virtual
  * address.
  */
diff --git a/sys/vm/pmap.h b/sys/vm/pmap.h
index af809bb..29f20c2 100644
--- a/sys/vm/pmap.h
+++ b/sys/vm/pmap.h
@@ -106,6 +106,7 @@ void		 pmap_enter(pmap_t, vm_offset_t, vm_page_t, vm_prot_t,
 vm_page_t	 pmap_enter_quick(pmap_t pmap, vm_offset_t va, vm_page_t m,
 		    vm_page_t mpte);
 vm_paddr_t	 pmap_extract(pmap_t pmap, vm_offset_t va);
+vm_page_t	 pmap_extract_and_hold(pmap_t pmap, vm_offset_t va);
 void		 pmap_growkernel(vm_offset_t);
 void		 pmap_init(vm_paddr_t, vm_paddr_t);
 boolean_t	 pmap_is_modified(vm_page_t m);