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Split vmas had no objects. Now fixed.

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When sys_munmap() splits a vma, the new vma had no copy of the objects
in the original vma. Now we fixed that using a vma_copy_links() function
which can also be used as part of fork().
This commit is contained in:
Bahadir Balban
2008-11-07 20:39:11 +02:00
parent 61751a896b
commit daffc1d084
4 changed files with 37 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
tasks/mm0/include/vm_area.h
View File

@@ -252,6 +252,7 @@ static inline void task_add_vma(struct tcb *task, struct vm_area *vma)
/* Main page fault entry point */
int page_fault_handler(struct tcb *faulty_task, fault_kdata_t *fkdata);
int vma_copy_links(struct vm_area *new_vma, struct vm_area *vma);
int vma_drop_merge_delete(struct vm_area *vma, struct vm_obj_link *link);
int vma_drop_merge_delete_all(struct vm_area *vma);

26
tasks/mm0/src/fault.c
View File

@@ -262,6 +262,32 @@ struct page *copy_to_new_page(struct page *orig)
}
/* Copy all mapped object link stack from vma to new vma */
int vma_copy_links(struct vm_area *new_vma, struct vm_area *vma)
{
struct vm_obj_link *vmo_link, *new_link;
/* Get the first object on the vma */
BUG_ON(list_empty(&vma->vm_obj_list));
vmo_link = list_entry(vma->vm_obj_list.next,
struct vm_obj_link, list);
do {
/* Create a new link */
new_link = vm_objlink_create();
/* Link object with new link */
vm_link_object(new_link, vmo_link->obj);
/* Add the new link to vma in object order */
list_add_tail(&new_link->list, &new_vma->vm_obj_list);
/* Continue traversing links, doing the same copying */
} while((vmo_link = vma_next_link(&vmo_link->list,
&vma->vm_obj_list)));
return 0;
}
/*
* Determine if an object is deletable.
*

9
tasks/mm0/src/munmap.c
View File

@@ -8,7 +8,7 @@
#include <l4/api/errno.h>
#include <l4/lib/math.h>
#include <l4lib/arch/syslib.h>
#include <vm_area.h>
/* This splits a vma, splitter region must be in the *middle* of original vma */
int vma_split(struct vm_area *vma, struct tcb *task,
@@ -33,6 +33,13 @@ int vma_split(struct vm_area *vma, struct tcb *task,
vma->pfn_end = pfn_start;
new->flags = vma->flags;
/*
* Copy the object links of original vma to new vma. A split like this
* increases the map count of mapped object(s) since now 2 vmas on the
* same task maps the same object(s).
*/
vma_copy_links(new, vma);
/* Add new one next to original vma */
list_add_tail(&new->list, &vma->list);

20
tasks/mm0/src/task.c
View File

@@ -129,7 +129,6 @@ int tcb_destroy(struct tcb *task)
int copy_vmas(struct tcb *to, struct tcb *from)
{
struct vm_area *vma, *new_vma;
struct vm_obj_link *vmo_link, *new_link;
list_for_each_entry(vma, &from->vm_area_head->list, list) {
@@ -137,23 +136,8 @@ int copy_vmas(struct tcb *to, struct tcb *from)
new_vma = vma_new(vma->pfn_start, vma->pfn_end - vma->pfn_start,
vma->flags, vma->file_offset);
/* Get the first object on the vma */
BUG_ON(list_empty(&vma->vm_obj_list));
vmo_link = list_entry(vma->vm_obj_list.next,
struct vm_obj_link, list);
do {
/* Create a new link */
new_link = vm_objlink_create();
/* Link object with new link */
vm_link_object(new_link, vmo_link->obj);
/* Add the new link to vma in object order */
list_add_tail(&new_link->list, &new_vma->vm_obj_list);
/* Continue traversing links, doing the same copying */
} while((vmo_link = vma_next_link(&vmo_link->list,
&vma->vm_obj_list)));
/* Copy all object links */
vma_copy_links(new_vma, vma);
/* All link copying is finished, now add the new vma to task */
task_add_vma(to, new_vma);