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Reimplemented space handling by introducing an address_space structure.

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- Fixed potential concurrency bugs due to preemption being enabled.
- Introduced a new address space structure to better account for
  address spaces and page tables.
- Currently executes fine up to forking. Will investigate.
This commit is contained in:
Bahadir Balban
2009-05-08 23:35:19 +03:00
parent 2df8875a88
commit 7415546410
12 changed files with 403 additions and 81 deletions
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56
src/arch/arm/v5/mm.c
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@@ -419,9 +419,64 @@ int remove_mapping(unsigned long vaddr)
return remove_mapping_pgd(vaddr, TASK_PGD(current));
}
/*
* Copies userspace entries of one task to another. In order to do that,
* it allocates new pmds and copies the original values into new ones.
*/
int copy_user_tables(struct address_space *new, struct address_space *orig_space)
{
pgd_table_t *to = new->pgd, *from = orig_space->pgd;
pmd_table_t *pmd, *orig;
/* Allocate and copy all pmds that will be exclusive to new task. */
for (int i = 0; i < PGD_ENTRY_TOTAL; i++) {
/* Detect a pmd entry that is not a kernel pmd? */
if (!is_kern_pgdi(i) &&
((from->entry[i] & PGD_TYPE_MASK) == PGD_TYPE_COARSE)) {
/* Allocate new pmd */
if (!(pmd = alloc_pmd()))
goto out_error;
/* Find original pmd */
orig = (pmd_table_t *)
phys_to_virt((from->entry[i] &
PGD_COARSE_ALIGN_MASK));
/* Copy original to new */
memcpy(pmd, orig, sizeof(pmd_table_t));
/* Replace original pmd entry in pgd with new */
to->entry[i] = (pgd_t)virt_to_phys(pmd);
to->entry[i] |= PGD_TYPE_COARSE;
}
}
return 0;
out_error:
/* Find all non-kernel pmds we have just allocated and free them */
for (int i = 0; i < PGD_ENTRY_TOTAL; i++) {
/* Non-kernel pmd that has just been allocated. */
if (!is_kern_pgdi(i) &&
(to->entry[i] & PGD_TYPE_MASK) == PGD_TYPE_COARSE) {
/* Obtain the pmd handle */
pmd = (pmd_table_t *)
phys_to_virt((to->entry[i] &
PGD_COARSE_ALIGN_MASK));
/* Free pmd */
free_pmd(pmd);
}
}
return -ENOMEM;
}
/*
* Allocates and copies all levels of page tables from one task to another.
* Useful when forking.
*
* The copied page tables end up having shared pmds for kernel entries
* and private copies of same pmds for user entries.
*/
pgd_table_t *copy_page_tables(pgd_table_t *from)
{
@@ -432,6 +487,7 @@ pgd_table_t *copy_page_tables(pgd_table_t *from)
if (!(pgd = alloc_pgd()))
return PTR_ERR(-ENOMEM);
/* First copy whole pgd entries */
memcpy(pgd, from, sizeof(pgd_table_t));
/* Allocate and copy all pmds that will be exclusive to new task. */