Module Name: src
Committed By: christos
Date: Fri Jul 18 12:19:10 UTC 2014
Modified Files:
src/sys/uvm: uvm_map.c
Log Message:
Split out the minherit code into separate functions for readability (allows
us to indent them properly), and merge the new vm_map_entry creation into
a common function to avoid code duplication. No functional change.
To generate a diff of this commit:
cvs rdiff -u -r1.328 -r1.329 src/sys/uvm/uvm_map.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/uvm/uvm_map.c
diff -u src/sys/uvm/uvm_map.c:1.328 src/sys/uvm/uvm_map.c:1.329
--- src/sys/uvm/uvm_map.c:1.328 Wed Mar 5 00:35:55 2014
+++ src/sys/uvm/uvm_map.c Fri Jul 18 08:19:09 2014
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_map.c,v 1.328 2014/03/05 05:35:55 matt Exp $ */
+/* $NetBSD: uvm_map.c,v 1.329 2014/07/18 12:19:09 christos Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -66,7 +66,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.328 2014/03/05 05:35:55 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.329 2014/07/18 12:19:09 christos Exp $");
#include "opt_ddb.h"
#include "opt_uvmhist.h"
@@ -4183,6 +4183,168 @@ uvmspace_free(struct vmspace *vm)
pool_cache_put(&uvm_vmspace_cache, vm);
}
+static struct vm_map_entry *
+uvm_mapent_clone(struct vm_map *new_map, struct vm_map_entry *old_entry,
+ int flags)
+{
+ struct vm_map_entry *new_entry;
+
+ new_entry = uvm_mapent_alloc(new_map, 0);
+ /* old_entry -> new_entry */
+ uvm_mapent_copy(old_entry, new_entry);
+
+ /* new pmap has nothing wired in it */
+ new_entry->wired_count = 0;
+
+ /*
+ * gain reference to object backing the map (can't
+ * be a submap, already checked this case).
+ */
+
+ if (new_entry->aref.ar_amap)
+ uvm_map_reference_amap(new_entry, flags);
+
+ if (new_entry->object.uvm_obj &&
+ new_entry->object.uvm_obj->pgops->pgo_reference)
+ new_entry->object.uvm_obj->pgops->pgo_reference(
+ new_entry->object.uvm_obj);
+
+ /* insert entry at end of new_map's entry list */
+ uvm_map_entry_link(new_map, new_map->header.prev,
+ new_entry);
+
+ return new_entry;
+}
+
+/*
+ * share the mapping: this means we want the old and
+ * new entries to share amaps and backing objects.
+ */
+static void
+uvm_mapent_forkshared(struct vm_map *new_map, struct vm_map *old_map,
+ struct vm_map_entry *old_entry)
+{
+ /*
+ * if the old_entry needs a new amap (due to prev fork)
+ * then we need to allocate it now so that we have
+ * something we own to share with the new_entry. [in
+ * other words, we need to clear needs_copy]
+ */
+
+ if (UVM_ET_ISNEEDSCOPY(old_entry)) {
+ /* get our own amap, clears needs_copy */
+ amap_copy(old_map, old_entry, AMAP_COPY_NOCHUNK,
+ 0, 0);
+ /* XXXCDC: WAITOK??? */
+ }
+
+ uvm_mapent_clone(new_map, old_entry, AMAP_SHARED);
+}
+
+
+static void
+uvm_mapent_forkcopy(struct vm_map *new_map, struct vm_map *old_map,
+ struct vm_map_entry *old_entry)
+{
+ struct vm_map_entry *new_entry;
+
+ /*
+ * copy-on-write the mapping (using mmap's
+ * MAP_PRIVATE semantics)
+ *
+ * allocate new_entry, adjust reference counts.
+ * (note that new references are read-only).
+ */
+
+ new_entry = uvm_mapent_clone(new_map, old_entry, 0);
+
+ new_entry->etype |=
+ (UVM_ET_COPYONWRITE|UVM_ET_NEEDSCOPY);
+
+ /*
+ * the new entry will need an amap. it will either
+ * need to be copied from the old entry or created
+ * from scratch (if the old entry does not have an
+ * amap). can we defer this process until later
+ * (by setting "needs_copy") or do we need to copy
+ * the amap now?
+ *
+ * we must copy the amap now if any of the following
+ * conditions hold:
+ * 1. the old entry has an amap and that amap is
+ * being shared. this means that the old (parent)
+ * process is sharing the amap with another
+ * process. if we do not clear needs_copy here
+ * we will end up in a situation where both the
+ * parent and child process are refering to the
+ * same amap with "needs_copy" set. if the
+ * parent write-faults, the fault routine will
+ * clear "needs_copy" in the parent by allocating
+ * a new amap. this is wrong because the
+ * parent is supposed to be sharing the old amap
+ * and the new amap will break that.
+ *
+ * 2. if the old entry has an amap and a non-zero
+ * wire count then we are going to have to call
+ * amap_cow_now to avoid page faults in the
+ * parent process. since amap_cow_now requires
+ * "needs_copy" to be clear we might as well
+ * clear it here as well.
+ *
+ */
+
+ if (old_entry->aref.ar_amap != NULL) {
+ if ((amap_flags(old_entry->aref.ar_amap) & AMAP_SHARED) != 0 ||
+ VM_MAPENT_ISWIRED(old_entry)) {
+
+ amap_copy(new_map, new_entry,
+ AMAP_COPY_NOCHUNK, 0, 0);
+ /* XXXCDC: M_WAITOK ... ok? */
+ }
+ }
+
+ /*
+ * if the parent's entry is wired down, then the
+ * parent process does not want page faults on
+ * access to that memory. this means that we
+ * cannot do copy-on-write because we can't write
+ * protect the old entry. in this case we
+ * resolve all copy-on-write faults now, using
+ * amap_cow_now. note that we have already
+ * allocated any needed amap (above).
+ */
+
+ if (VM_MAPENT_ISWIRED(old_entry)) {
+
+ /*
+ * resolve all copy-on-write faults now
+ * (note that there is nothing to do if
+ * the old mapping does not have an amap).
+ */
+ if (old_entry->aref.ar_amap)
+ amap_cow_now(new_map, new_entry);
+
+ } else {
+ /*
+ * setup mappings to trigger copy-on-write faults
+ * we must write-protect the parent if it has
+ * an amap and it is not already "needs_copy"...
+ * if it is already "needs_copy" then the parent
+ * has already been write-protected by a previous
+ * fork operation.
+ */
+ if (old_entry->aref.ar_amap &&
+ !UVM_ET_ISNEEDSCOPY(old_entry)) {
+ if (old_entry->max_protection & VM_PROT_WRITE) {
+ pmap_protect(old_map->pmap,
+ old_entry->start, old_entry->end,
+ old_entry->protection & ~VM_PROT_WRITE);
+ }
+ old_entry->etype |= UVM_ET_NEEDSCOPY;
+ }
+ }
+}
+
/*
* F O R K - m a i n e n t r y p o i n t
*/
@@ -4200,7 +4362,6 @@ uvmspace_fork(struct vmspace *vm1)
struct vm_map *old_map = &vm1->vm_map;
struct vm_map *new_map;
struct vm_map_entry *old_entry;
- struct vm_map_entry *new_entry;
UVMHIST_FUNC("uvmspace_fork"); UVMHIST_CALLED(maphist);
vm_map_lock(old_map);
@@ -4230,7 +4391,6 @@ uvmspace_fork(struct vmspace *vm1)
switch (old_entry->inheritance) {
case MAP_INHERIT_NONE:
-
/*
* drop the mapping, modify size
*/
@@ -4238,171 +4398,17 @@ uvmspace_fork(struct vmspace *vm1)
break;
case MAP_INHERIT_SHARE:
-
- /*
- * share the mapping: this means we want the old and
- * new entries to share amaps and backing objects.
- */
- /*
- * if the old_entry needs a new amap (due to prev fork)
- * then we need to allocate it now so that we have
- * something we own to share with the new_entry. [in
- * other words, we need to clear needs_copy]
- */
-
- if (UVM_ET_ISNEEDSCOPY(old_entry)) {
- /* get our own amap, clears needs_copy */
- amap_copy(old_map, old_entry, AMAP_COPY_NOCHUNK,
- 0, 0);
- /* XXXCDC: WAITOK??? */
- }
-
- new_entry = uvm_mapent_alloc(new_map, 0);
- /* old_entry -> new_entry */
- uvm_mapent_copy(old_entry, new_entry);
-
- /* new pmap has nothing wired in it */
- new_entry->wired_count = 0;
-
- /*
- * gain reference to object backing the map (can't
- * be a submap, already checked this case).
- */
-
- if (new_entry->aref.ar_amap)
- uvm_map_reference_amap(new_entry, AMAP_SHARED);
-
- if (new_entry->object.uvm_obj &&
- new_entry->object.uvm_obj->pgops->pgo_reference)
- new_entry->object.uvm_obj->
- pgops->pgo_reference(
- new_entry->object.uvm_obj);
-
- /* insert entry at end of new_map's entry list */
- uvm_map_entry_link(new_map, new_map->header.prev,
- new_entry);
-
+ uvm_mapent_forkshared(new_map, old_map, old_entry);
break;
case MAP_INHERIT_COPY:
+ uvm_mapent_forkcopy(new_map, old_map, old_entry);
+ break;
- /*
- * copy-on-write the mapping (using mmap's
- * MAP_PRIVATE semantics)
- *
- * allocate new_entry, adjust reference counts.
- * (note that new references are read-only).
- */
-
- new_entry = uvm_mapent_alloc(new_map, 0);
- /* old_entry -> new_entry */
- uvm_mapent_copy(old_entry, new_entry);
-
- if (new_entry->aref.ar_amap)
- uvm_map_reference_amap(new_entry, 0);
-
- if (new_entry->object.uvm_obj &&
- new_entry->object.uvm_obj->pgops->pgo_reference)
- new_entry->object.uvm_obj->pgops->pgo_reference
- (new_entry->object.uvm_obj);
-
- /* new pmap has nothing wired in it */
- new_entry->wired_count = 0;
-
- new_entry->etype |=
- (UVM_ET_COPYONWRITE|UVM_ET_NEEDSCOPY);
- uvm_map_entry_link(new_map, new_map->header.prev,
- new_entry);
-
- /*
- * the new entry will need an amap. it will either
- * need to be copied from the old entry or created
- * from scratch (if the old entry does not have an
- * amap). can we defer this process until later
- * (by setting "needs_copy") or do we need to copy
- * the amap now?
- *
- * we must copy the amap now if any of the following
- * conditions hold:
- * 1. the old entry has an amap and that amap is
- * being shared. this means that the old (parent)
- * process is sharing the amap with another
- * process. if we do not clear needs_copy here
- * we will end up in a situation where both the
- * parent and child process are refering to the
- * same amap with "needs_copy" set. if the
- * parent write-faults, the fault routine will
- * clear "needs_copy" in the parent by allocating
- * a new amap. this is wrong because the
- * parent is supposed to be sharing the old amap
- * and the new amap will break that.
- *
- * 2. if the old entry has an amap and a non-zero
- * wire count then we are going to have to call
- * amap_cow_now to avoid page faults in the
- * parent process. since amap_cow_now requires
- * "needs_copy" to be clear we might as well
- * clear it here as well.
- *
- */
-
- if (old_entry->aref.ar_amap != NULL) {
- if ((amap_flags(old_entry->aref.ar_amap) &
- AMAP_SHARED) != 0 ||
- VM_MAPENT_ISWIRED(old_entry)) {
-
- amap_copy(new_map, new_entry,
- AMAP_COPY_NOCHUNK, 0, 0);
- /* XXXCDC: M_WAITOK ... ok? */
- }
- }
-
- /*
- * if the parent's entry is wired down, then the
- * parent process does not want page faults on
- * access to that memory. this means that we
- * cannot do copy-on-write because we can't write
- * protect the old entry. in this case we
- * resolve all copy-on-write faults now, using
- * amap_cow_now. note that we have already
- * allocated any needed amap (above).
- */
-
- if (VM_MAPENT_ISWIRED(old_entry)) {
-
- /*
- * resolve all copy-on-write faults now
- * (note that there is nothing to do if
- * the old mapping does not have an amap).
- */
- if (old_entry->aref.ar_amap)
- amap_cow_now(new_map, new_entry);
-
- } else {
-
- /*
- * setup mappings to trigger copy-on-write faults
- * we must write-protect the parent if it has
- * an amap and it is not already "needs_copy"...
- * if it is already "needs_copy" then the parent
- * has already been write-protected by a previous
- * fork operation.
- */
-
- if (old_entry->aref.ar_amap &&
- !UVM_ET_ISNEEDSCOPY(old_entry)) {
- if (old_entry->max_protection & VM_PROT_WRITE) {
- pmap_protect(old_map->pmap,
- old_entry->start,
- old_entry->end,
- old_entry->protection &
- ~VM_PROT_WRITE);
- }
- old_entry->etype |= UVM_ET_NEEDSCOPY;
- }
- }
+ default:
+ KASSERT(0);
break;
- } /* end of switch statement */
+ }
old_entry = old_entry->next;
}
