1 files changed, 177 insertions, 11 deletions

diff --git a/kernel/vm/shadow.c b/kernel/vm/shadow.c
index 312b32e..91b1fce 100644
--- a/kernel/vm/shadow.c
+++ b/kernel/vm/shadow.c
@@ -41,7 +41,8 @@ static mobj_ops_t shadow_mobj_ops = {.get_pframe = shadow_get_pframe,
  */
 void shadow_init()
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_init");
+    // NOT_YET_IMPLEMENTED("VM: shadow_init");
+    shadow_allocator = slab_allocator_create("shadow", sizeof(mobj_shadow_t));
 }
 
 /*
@@ -60,8 +61,37 @@ void shadow_init()
  */
 mobj_t *shadow_create(mobj_t *shadowed)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_create");
-    return NULL;
+    // NOT_YET_IMPLEMENTED("VM: shadow_create");
+
+    // create a new shadow object
+    mobj_shadow_t *so = (mobj_shadow_t *)slab_obj_alloc(shadow_allocator);
+    if (!so)
+    {
+        return NULL;
+    }
+
+    // initialize the mobj_shadow_t
+    
+    // set the bottom_mobj based on the two cases
+    if (shadowed->mo_type == MOBJ_SHADOW)
+    {
+        so->bottom_mobj = MOBJ_TO_SO(so->shadowed)->bottom_mobj;
+    }
+    else
+    {
+        so->bottom_mobj = shadowed;
+    }
+    // init the other fields
+    so->shadowed = shadowed;
+    mobj_init(&so->mobj, MOBJ_SHADOW, &shadow_mobj_ops);
+    mobj_ref(so->shadowed);
+    mobj_ref(so->bottom_mobj);
+
+    // lock the shadow object
+    mobj_lock(&so->mobj);
+
+    // return the shadow object
+    return &so->mobj;
 }
 
 /*
@@ -80,7 +110,52 @@ mobj_t *shadow_create(mobj_t *shadowed)
  */
 void shadow_collapse(mobj_t *o)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_collapse");
+    // NOT_YET_IMPLEMENTED("VM: shadow_collapse");
+
+    // get the mobj_shadow_t and it's mobj
+    mobj_shadow_t *so = MOBJ_TO_SO(o);
+    mobj_t *iter = so->shadowed;
+    // iterate through the shadow chain
+    while (iter && so->shadowed->mo_type == MOBJ_SHADOW)
+    {
+        // check to see if the refcount is not 1. if so, continue to next shadowed object
+        if (so->shadowed->mo_refcount != 1)
+        {
+            iter = so->shadowed;
+            continue;
+        }
+        // else, go over the shadowed object's pframes
+
+        // iterate through the pframes
+        mobj_lock(&so->shadowed);
+        list_iterate(&so->shadowed->mo_pframes, pframe, pframe_t, pf_link)
+        {
+            // get the pframe from the shadow object
+            pframe_t *spf = NULL;
+
+            mobj_lock(iter); // lock before getting the pframe
+            mobj_find_pframe(o, pframe->pf_pagenum, &spf);
+            mobj_unlock(iter);
+
+            // check if the pframe is not in the shadow object when migrating
+            if (spf == NULL)
+            {
+                // if not, remove the pframe from the shadowed object 
+                // and insert it into out iterated shadow object
+                list_remove(&pframe->pf_link);
+                list_insert_tail(&iter->mo_pframes, &pframe->pf_link);
+            }
+            else
+            {
+                // if it is, release the pframe we found
+                pframe_release(&spf);
+            }
+        }
+
+        // put locked the shadowed object after iterating through it
+        mobj_put_locked(&so->shadowed);
+        // FIXME: this is probably wrong
+    }
 }
 
 /*
@@ -111,8 +186,47 @@ void shadow_collapse(mobj_t *o)
 static long shadow_get_pframe(mobj_t *o, size_t pagenum, long forwrite,
                               pframe_t **pfp)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_get_pframe");
-    return 0;
+    // NOT_YET_IMPLEMENTED("VM: shadow_get_pframe");
+
+    // if forwrite is set, use mobj_default_get_pframe
+    if (forwrite)
+    {
+        return mobj_default_get_pframe(o, pagenum, forwrite, pfp);
+    }
+
+    // else, check if the object already contains the desired frame
+    pframe_t *pf = NULL;
+    mobj_find_pframe(o, pagenum, &pf);
+    if (pf)
+    {
+        // if it does, return the pframe
+        *pfp = pf;
+        return 0;
+    }
+
+    // iterate through the shadow chain to find the nearest shadow mobj that has the frame
+    mobj_shadow_t *so = MOBJ_TO_SO(o);
+    mobj_t *iter = so->shadowed;
+    while (iter && iter->mo_type == MOBJ_SHADOW)
+    {
+        mobj_lock(iter);
+        mobj_find_pframe(o, pagenum, &pf);
+        mobj_unlock(iter);
+        if (pf)
+        {
+            *pfp = pf;
+            return 0;
+        }
+        // update the iterator
+        iter = MOBJ_TO_SO(iter)->shadowed;
+    }
+
+    // if no shadow objects have the page, call mobj_get_pframe() to get the page from the bottom object
+    // at this point, iter is the bottom object
+    mobj_lock(iter);
+    long ret = mobj_get_pframe(iter, pagenum, forwrite, pfp);
+    mobj_unlock(iter);
+    return ret;
 }
 
 /*
@@ -138,8 +252,47 @@ static long shadow_get_pframe(mobj_t *o, size_t pagenum, long forwrite,
  */
 static long shadow_fill_pframe(mobj_t *o, pframe_t *pf)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_fill_pframe");
-    return -1;
+    // NOT_YET_IMPLEMENTED("VM: shadow_fill_pframe");
+
+    // get the mobj_shadow_t
+    mobj_shadow_t *so = MOBJ_TO_SO(o);
+    // iterate over the shadow chain
+    mobj_t *iter = so->shadowed;
+    while (iter && iter->mo_type == MOBJ_SHADOW)
+    {
+        // get the pframe from the shadow object
+        pframe_t *spf = NULL;
+        mobj_lock(iter);
+        mobj_find_pframe(o, pf->pf_pagenum, &spf);
+        mobj_unlock(iter);
+
+        // if the pframe is found, copy the contents into pf 
+        // then release the pframe
+        if (spf)
+        {
+            memcpy(pf->pf_addr, spf->pf_addr, PAGE_SIZE);
+            pframe_release(&spf);
+            return 0;
+        }
+
+        // update the iterator
+        iter = MOBJ_TO_SO(iter)->shadowed;
+    }
+
+    // if none of the shadow objects have a copy of the frame, use mobj_get_pframe on the bottom object
+    pframe_t *spf = NULL;
+    mobj_lock(iter);
+    long ret = mobj_get_pframe(iter, pf->pf_pagenum, 0, &spf);
+    mobj_unlock(iter);
+    // check if the operation was sucessful, memcpy the contents into pf
+    // and release the pframe
+    if (ret == 0)
+    {
+        memcpy(pf->pf_addr, pf->pf_addr, PAGE_SIZE);
+        pframe_release(&spf);
+    }
+
+    return ret;
 }
 
 /*
@@ -153,8 +306,8 @@ static long shadow_fill_pframe(mobj_t *o, pframe_t *pf)
  */
 static long shadow_flush_pframe(mobj_t *o, pframe_t *pf)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_flush_pframe");
-    return -1;
+    // NOT_YET_IMPLEMENTED("VM: shadow_flush_pframe");
+    return 0;
 }
 
 /*
@@ -169,5 +322,18 @@ static long shadow_flush_pframe(mobj_t *o, pframe_t *pf)
  */
 static void shadow_destructor(mobj_t *o)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_destructor");
+    // NOT_YET_IMPLEMENTED("VM: shadow_destructor");
+
+    // get the mobj_shadow_t
+    mobj_shadow_t *so = MOBJ_TO_SO(o);
+
+    // call the default destructor
+    mobj_default_destructor(o);
+
+    // put the shadow and bottom_mobj
+    mobj_put(&so->shadowed);
+    mobj_put(&so->bottom_mobj);
+
+    // free the slab
+    slab_obj_free(shadow_allocator, so);
 }