fixes to work on dept machine

3 files changed, 98 insertions, 98 deletions

diff --git a/kernel/vm/pagefault.c b/kernel/vm/pagefault.c
index b289537..39e5776 100644
--- a/kernel/vm/pagefault.c
+++ b/kernel/vm/pagefault.c
@@ -49,80 +49,87 @@ void handle_pagefault(uintptr_t vaddr, uintptr_t cause)
 {
     dbg(DBG_VM, "vaddr = 0x%p (0x%p), cause = %lu\n", (void *)vaddr,
         PAGE_ALIGN_DOWN(vaddr), cause);
+
     // NOT_YET_IMPLEMENTED("VM: handle_pagefault");
 
-    // 1) Find the vmarea that contains vaddr, if it exists.
-    // check that the vaddr is valid
-    if (vaddr < USER_MEM_LOW || vaddr > USER_MEM_HIGH)
+    // Check that the vaddr is valid
+    if (vaddr < USER_MEM_LOW) 
     {
         do_exit(EFAULT);
     }
-    // lookup the vmarea for this addr
-    vmarea_t *vma = vmmap_lookup(curproc->p_vmmap, ADDR_TO_PN(vaddr));
-    if (vma == NULL)
+    if (vaddr > USER_MEM_HIGH) 
     {
         do_exit(EFAULT);
     }
 
-    // 2) Check the vmarea's protections (see the vmarea_t struct) against the 'cause'
-    // error out if the fault has cause write and we don't have write permission in the area
-    if ((cause & FAULT_WRITE) && !(vma->vma_prot & PROT_WRITE))
+    // Lookup the vmarea for this address
+    size_t pn = ADDR_TO_PN(vaddr);
+    vmarea_t* vma = vmmap_lookup(curproc->p_vmmap, pn);
+    if (!vma) 
     {
         do_exit(EFAULT);
     }
-    // error out if the fault has cause exec and we don't have exec permission in the area
-    if ((cause & FAULT_EXEC) && !(vma->vma_prot & PROT_EXEC))
+
+    // Error out if we don't have any permission in the area
+    if (vma->vma_prot == PROT_NONE) 
     {
         do_exit(EFAULT);
     }
-    // error out if we don't have read permission in the area
-    if (!(vma->vma_prot & PROT_READ))
+
+    // Check the vmarea's protections (see the vmarea_t struct) against the 'cause' of the pagefault
+    if ((cause & FAULT_WRITE) && !(vma->vma_prot & PROT_WRITE)) 
     {
         do_exit(EFAULT);
-    }
-    // error our if we don't have any permission in the area
-    if (vma->vma_prot == PROT_NONE)
+    } 
+    else if ((cause & FAULT_EXEC) && !(vma->vma_prot & PROT_EXEC)) 
+    {
+        do_exit(EFAULT);
+    } 
+    else if (!(vma->vma_prot & PROT_READ)) 
     {
         do_exit(EFAULT);
     }
 
-    // 3) Obtain the corresponding pframe from the vmarea's mobj.
-    pframe_t *pf;
+    // Obtain the corresponding pframe from the vmarea's mobj
+    long forwrite = 0;
+    if (cause & FAULT_WRITE) 
+    {
+        forwrite = 1;
+    }
+    pframe_t* pfp;
     mobj_lock(vma->vma_obj);
-    int ret = mobj_get_pframe(
+    long status = mobj_get_pframe(
         vma->vma_obj, 
-        vma->vma_off + ADDR_TO_PN(vaddr) - vma->vma_start, 
-        cause & FAULT_WRITE ? 1 : 0,
-        &pf
+        pn - vma->vma_start + vma->vma_off,
+        forwrite, 
+        &pfp
     );
     mobj_unlock(vma->vma_obj);
-    if (ret < 0)
+    if (status < 0) 
     {
         do_exit(EFAULT);
     }
 
-    // 4) Finally, set up a call to pt_map to insert a new mapping into the appropriate pagetable
-    uintptr_t paddr = pt_virt_to_phys(pf->pf_addr);
-    pframe_release(&pf);
-    int pdflags = PT_PRESENT | PT_WRITE | PT_USER;
-    int ptflags = PT_PRESENT | PT_USER;
-    if (cause & FAULT_WRITE)
+    // Set up a call to pt_map to insert a new mapping into the appropriate pagetable
+    uintptr_t paddr = pt_virt_to_phys((uintptr_t) pfp->pf_addr);
+    pframe_release(&pfp);
+    uint32_t ptflags = PT_PRESENT | PT_USER;
+    if (cause & FAULT_WRITE) 
     {
         ptflags |= PT_WRITE;
     }
-
-    int err = pt_map(
+    status = pt_map(
         curproc->p_pml4, 
-        paddr,
-        (uintptr_t) PAGE_ALIGN_DOWN(vaddr),
-        pdflags, 
+        paddr, 
+        (uintptr_t) PAGE_ALIGN_DOWN(vaddr), 
+        PT_PRESENT | PT_USER | PT_WRITE,
         ptflags
     );
-    if (err < 0)
+    if (status < 0) 
     {
         do_exit(EFAULT);
     }
 
-    // 5) Flush the TLB
-    tlb_flush((uintptr_t) PAGE_ALIGN_DOWN(vaddr));
+    // Flush the TLB
+    tlb_flush(vaddr);
 }
diff --git a/kernel/vm/shadow.c b/kernel/vm/shadow.c
index 06cf20d..4883160 100644
--- a/kernel/vm/shadow.c
+++ b/kernel/vm/shadow.c
@@ -43,6 +43,7 @@ void shadow_init()
 {
     // NOT_YET_IMPLEMENTED("VM: shadow_init");
     shadow_allocator = slab_allocator_create("shadow", sizeof(mobj_shadow_t));
+    KASSERT(shadow_allocator);
 }
 
 /*
@@ -55,7 +56,7 @@ void shadow_init()
  *  2) Set up the bottom object of the shadow chain, which could have two cases:
  *     a) Either shadowed is a shadow object, and you can use its bottom_mobj
  *     b) Or shadowed is not a shadow object, in which case it is the bottom 
- *        object of this chain.
+ *        object of this chain.shadow_create
  * 
  *  Make sure to manage the refcounts correctly.
  */
@@ -63,6 +64,11 @@ mobj_t *shadow_create(mobj_t *shadowed)
 {
     // NOT_YET_IMPLEMENTED("VM: shadow_create");
 
+    if (!shadowed)
+    {
+        return NULL;
+    }
+
     // create a new shadow object
     mobj_shadow_t *so = (mobj_shadow_t *)slab_obj_alloc(shadow_allocator);
     if (!so)
@@ -142,46 +148,41 @@ static long shadow_get_pframe(mobj_t *o, size_t pagenum, long forwrite,
                               pframe_t **pfp)
 {
     // NOT_YET_IMPLEMENTED("VM: shadow_get_pframe");
-
-    // if forwrite is set, use mobj_default_get_pframe
+    // return 0;
     if (forwrite)
     {
         return mobj_default_get_pframe(o, pagenum, forwrite, pfp);
     }
-
-    // else, check if the object already contains the desired frame
+    // check if o 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_shadow_t *shadow = MOBJ_TO_SO(o);
+    mobj_t *current = shadow->shadowed; 
+
+    while (current && current->mo_type == MOBJ_SHADOW)
     {
-        mobj_lock(iter);
-        mobj_find_pframe(iter, pagenum, &pf);
-        mobj_unlock(iter);
+        mobj_lock(current);
+        mobj_find_pframe(current, pagenum, &pf);
+        mobj_unlock(current);
+        
         if (pf)
         {
             *pfp = pf;
             return 0;
         }
-        // update the iterator
-        so = MOBJ_TO_SO(iter);
-        iter = so->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(so->bottom_mobj);
-    long ret = mobj_get_pframe(so->bottom_mobj, pagenum, forwrite, pfp);
-    mobj_unlock(so->bottom_mobj);
+        shadow = MOBJ_TO_SO(current);
+        current = shadow->shadowed;
+    }
+    mobj_lock(shadow->bottom_mobj);
+    long ret = mobj_get_pframe(shadow->bottom_mobj, pagenum, forwrite, pfp);
+    mobj_unlock(shadow->bottom_mobj);
     return ret;
 }
 
@@ -208,48 +209,39 @@ 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_IMPLEMENTEDshadow_fill_pframe");
+    // NOT_YET_IMPLEMENTED("VM: shadow_fill_pframe");
+    // return -1;
+    pframe_t *pf_shadow = NULL;
+    long ret = 0;
+
 
-    // 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)
+    mobj_t *shadowed = so->shadowed;
+    while (shadowed && shadowed->mo_type == MOBJ_SHADOW)
     {
-        // get the pframe from the shadow object
-        pframe_t *spf = NULL;
-        mobj_lock(iter);
-        mobj_find_pframe(iter, pf->pf_pagenum, &spf);
-        mobj_unlock(iter);
+        mobj_lock(shadowed);
+        mobj_find_pframe(shadowed, pf->pf_pagenum, &pf_shadow);
+        mobj_unlock(shadowed);
 
-        // if the pframe is found, copy the contents into pf 
-        // then release the pframe
-        if (spf)
+        if (pf_shadow)
         {
-            memcpy(pf->pf_addr, spf->pf_addr, PAGE_SIZE);
-            pframe_release(&spf);
+            memcpy(pf->pf_addr, pf_shadow->pf_addr, PAGE_SIZE);
+            pframe_release(&pf_shadow);
             return 0;
         }
 
-        // update the iterator
-        so = MOBJ_TO_SO(iter);
-        iter = so->shadowed;
+        so = MOBJ_TO_SO(shadowed);
+        shadowed = so->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(so->bottom_mobj);
-    long ret = mobj_get_pframe(so->bottom_mobj, pf->pf_pagenum, 0, &spf);
+    ret = mobj_get_pframe(so->bottom_mobj, pf->pf_pagenum, 0, &pf_shadow);
     mobj_unlock(so->bottom_mobj);
-    // check if the operation was sucessful, memcpy the contents into pf
-    // and release the pframe
-    if (ret >= 0)
-    {
-        memcpy(pf->pf_addr, spf->pf_addr, PAGE_SIZE);
-        pframe_release(&spf);
+    if (ret < 0) {
+        return ret;
     }
-
-    return ret;
+    memcpy(pf->pf_addr, pf_shadow->pf_addr, PAGE_SIZE);
+    pframe_release(&pf_shadow);
+    return 0;
 }
 
 /*
@@ -264,6 +256,7 @@ 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;
     return 0;
 }
 
@@ -280,17 +273,17 @@ static long shadow_flush_pframe(mobj_t *o, pframe_t *pf)
 static void shadow_destructor(mobj_t *o)
 {
     // NOT_YET_IMPLEMENTED("VM: shadow_destructor");
+    mobj_default_destructor(o);
 
-    // get the mobj_shadow_t
     mobj_shadow_t *so = MOBJ_TO_SO(o);
+    // dbg(DBG_PROC, "shadow_destructor: refcount bottom: %d\n", so->bottom_mobj->mo_refcount);
+    // dbg(DBG_PROC, "shadow_destructor: refcount: %d\n", so->shadowed->mo_refcount);
 
-    // call the default destructor
-    mobj_default_destructor(o);
-
-    // put the shadow and bottom_mobj
+    // put the shadow and bottom_mobj members of the shadow object
     mobj_put(&so->shadowed);
     mobj_put(&so->bottom_mobj);
 
-    // free the slab
     slab_obj_free(shadow_allocator, so);
-}
\ No newline at end of file
+
+    return;
+}
diff --git a/kernel/vm/vmmap.c b/kernel/vm/vmmap.c
index 8c1a455..5f8e575 100644
--- a/kernel/vm/vmmap.c
+++ b/kernel/vm/vmmap.c
@@ -169,7 +169,7 @@ void vmmap_insert(vmmap_t *map, vmarea_t *new_vma)
  */
 ssize_t vmmap_find_range(vmmap_t *map, size_t npages, int dir)
 {
-    // NOT_YET_IMPLEMENTED("VM: vmmap_find_range");
+    // : vmmap_find_range");
 
     // case 1: dir is VMMAP_DIR_LOHI
     if (dir == VMMAP_DIR_LOHI)
@@ -871,4 +871,4 @@ end:
         buf[osize - 1] = '\0';
     }
     return osize - size;
-}
+}
\ No newline at end of file