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Added copy-on-write shared memory but untested yet.

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For anonymous shm, mmap now adds a shm_file and devzero behind it
as two vm_objects. Faults are handled by copy_on_write(). Just as
shadows copy r/w pages from original files, it should copy r/w
pages from devzero into the shm_file in front.

shmat/shmget uses mmap to set-up their areas.

Untested yet so bugs expected.

	modified:   tasks/libl4/src/init.c
	modified:   tasks/mm0/include/shm.h
	modified:   tasks/mm0/include/vm_area.h
	modified:   tasks/mm0/src/fault.c
	modified:   tasks/mm0/src/mmap.c
	modified:   tasks/mm0/src/shm.c
This commit is contained in:
Bahadir Balban
2008-03-21 15:40:54 +00:00
parent 466138f125
commit b369ff6efe
6 changed files with 129 additions and 79 deletions
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24
tasks/mm0/src/fault.c
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@@ -302,7 +302,7 @@ int copy_on_write(struct fault_data *fault)
*
* vma->link0->link1
* | |
* V V
* v v
* shadow original
*/
list_add(&shadow_link->list, &vma->vm_obj_list);
@@ -313,7 +313,8 @@ int copy_on_write(struct fault_data *fault)
/* Shadow is the copier object */
copier_link = shadow_link;
} else {
dprintf("No shadows. Going to add to topmost r/w shadow object\n");
dprintf("No new shadows. Going to add to "
"topmost r/w shadow object\n");
/* No new shadows, the topmost r/w vmo is the copier object */
copier_link = vmo_link;
@@ -328,7 +329,7 @@ int copy_on_write(struct fault_data *fault)
/* Traverse the list of read-only vm objects and search for the page */
while (IS_ERR(page = vmo_link->obj->pager->ops.page_in(vmo_link->obj,
file_offset))) {
file_offset))) {
if (!(vmo_link = vma_next_link(&vmo_link->list,
&vma->vm_obj_list))) {
printf("%s:%s: Traversed all shadows and the original "
@@ -367,6 +368,10 @@ int copy_on_write(struct fault_data *fault)
page_align(fault->address), fault->task->tid);
vm_object_print(new_page->owner);
/* Shm faults don't have shadows so we're done here. */
if (vma->flags & VMA_SHARED)
return 0;
/*
* Finished handling the actual fault, now check for possible
* shadow collapses. Does the copier completely shadow the one
@@ -408,8 +413,8 @@ int __do_page_fault(struct fault_data *fault)
unsigned int vma_flags = fault->vma->flags;
unsigned int pte_flags = vm_prot_flags(fault->kdata->pte);
struct vm_area *vma = fault->vma;
unsigned long file_offset;
struct vm_obj_link *vmo_link;
unsigned long file_offset;
struct page *page;
/* Handle read */
@@ -449,8 +454,8 @@ int __do_page_fault(struct fault_data *fault)
/* Handle write */
if ((reason & VM_WRITE) && (pte_flags & VM_READ)) {
/* Copy-on-write */
if (vma_flags & VMA_PRIVATE)
/* Copy-on-write. For all private 'union' all anonymous vmas. */
if ((vma_flags & VMA_PRIVATE) || (vma_flags & VMA_ANONYMOUS))
copy_on_write(fault);
/* Regular files */
@@ -479,13 +484,6 @@ int __do_page_fault(struct fault_data *fault)
page_align(fault->address), fault->task->tid);
vm_object_print(vmo_link->obj);
}
/* FIXME: Just do fs files for now, anon shm objects later. */
/* Things to think about:
* - Is utcb a shm memory really? Then each task must map it in via
* shmget(). FS0 must map all user tasks' utcb via shmget() as well.
* For example to pass on pathnames etc.
*/
BUG_ON((vma_flags & VMA_SHARED) && (vma_flags & VMA_ANONYMOUS));
}
return 0;