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Towards implementing fork.

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Issue is that shadow object references from original objects are into
the links rather than the objects.
This commit is contained in:
Bahadir Balban
2008-08-19 18:03:23 +03:00
parent f436b44e81
commit 69db3a04c0
11 changed files with 258 additions and 93 deletions
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79
src/api/thread.c
View File

@@ -10,6 +10,7 @@
#include <l4/generic/tcb.h>
#include <l4/lib/idpool.h>
#include <l4/generic/pgalloc.h>
#include INC_ARCH(mm.h)
int sys_thread_switch(struct syscall_args *regs)
{
@@ -59,51 +60,47 @@ int thread_start(struct task_ids *ids)
return -EINVAL;
}
/*
* Creates a thread, with a new thread id, and depending on whether the space
* id exists, either adds it to an existing space or creates a new space.
*
* NOTE: Add: Depending on whether the thread id exists, it creates a new space
* copying the space of that thread id.
*
* For example:
* thread id = inval, space id = inval, -> new thread, new space.
* thread id = x, space id = inval, -> new thread, new space, copying space of x
* thread id = inval, space id = x, -> new thread, use space x.
* Creates a thread, with a new thread id, and depending on the flags,
* either creates a new space, uses the same space as another thread,
* or creates a new space copying the space of another thread. These
* are respectively used when creating a brand new task, creating a
* new thread in an existing address space, or forking a task.
*/
int thread_create(struct task_ids *ids)
int thread_create(struct task_ids *ids, unsigned int flags)
{
struct ktcb *task, *new = (struct ktcb *)zalloc_page();
flags &= THREAD_FLAGS_MASK;
/* Visit all tasks to see if space ids match. */
list_for_each_entry(task, &global_task_list, task_list) {
/* Space ids match, can use existing space */
if (task->spid == ids->spid) {
BUG(); /* This is untested yet. */
goto spc_found;
}
}
if (flags == THREAD_CREATE_NEWSPC) {
/* Allocate new pgd and copy all kernel areas */
new->pgd = alloc_pgd();
copy_pgd_kern_all(new->pgd);
/* No existing space with such id. Creating a new address space */
new->pgd = alloc_pgd();
/* Copies all bits that are fixed for all tasks. */
copy_pgd_kern_all(new->pgd);
/* Get new space id */
if (ids->spid == TASK_ID_INVALID)
ids->spid = id_new(space_id_pool);
else
/* New space id, or requested id if available */
if ((ids->spid = id_get(space_id_pool, ids->spid)) < 0)
ids->spid = id_new(space_id_pool);
spc_found:
/* Get a new thread id */
if (ids->tid == TASK_ID_INVALID)
} else {
/* Existing space will be used, find it from all tasks */
list_for_each_entry(task, &global_task_list, task_list) {
/* Space ids match, can use existing space */
if (task->spid == ids->spid) {
if (flags == THREAD_CREATE_SAMESPC)
new->pgd = task->pgd;
else
new->pgd = copy_page_tables(task->pgd);
goto out;
}
}
printk("Could not find given space, is ",
"SAMESPC/COPYSPC the right flag?\n");
BUG();
}
out:
/* New thread id, or requested id if available */
if ((ids->tid = id_get(thread_id_pool, ids->tid)) < 0)
ids->tid = id_new(thread_id_pool);
else
if ((ids->tid = id_get(thread_id_pool, ids->tid)) < 0)
ids->tid = id_new(thread_id_pool);
/* Set all ids */
set_task_ids(new, ids);
@@ -128,14 +125,14 @@ spc_found:
*/
int sys_thread_control(struct syscall_args *regs)
{
u32 *reg = (u32 *)regs;
unsigned int action = reg[0];
struct task_ids *ids = (struct task_ids *)reg[1];
int ret = 0;
u32 *reg = (u32 *)regs;
unsigned int flags = reg[0];
struct task_ids *ids = (struct task_ids *)reg[1];
switch (action) {
switch (flags & THREAD_ACTION_MASK) {
case THREAD_CREATE:
ret = thread_create(ids);
ret = thread_create(ids, flags);
break;
case THREAD_RUN:
ret = thread_start(ids);

36
src/arch/arm/v5/mm.c
View File

@@ -359,6 +359,42 @@ void remove_mapping(unsigned long vaddr)
remove_mapping_pgd(vaddr, current->pgd);
}
/*
* Allocates and copies all levels of page tables from one task to another.
* Useful when forking.
*/
pgd_table_t *copy_page_tables(pgd_table_t *from)
{
struct pmd_table_t *pmd, *orig;
struct pgd_table_t *pgd;
/* Allocate and copy pgd */
pgd = alloc_pgd();
memcpy(pgd, from, sizeof(struct pgd_table_t));
/* Allocate and copy all valid pmds */
for (int i = 0; i < PGD_ENTRY_TOTAL; i++) {
/* Detect a pmd entry in original pgd? */
if ((pgd->entry[i] & PGD_TYPE_MASK) == PGD_TYPE_COARSE) {
/* Allocate new pmd */
pmd = alloc_pmd();
/* Find original pmd */
orig = (pmd_table_t *)
phys_to_virt((pgd->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 */
pgd->entry[i] = (pgd_t)virt_to_phys(pmd);
pgd->entry[i] |= PGD_TYPE_COARSE;
}
}
BUG();
return pgd;
}
extern pmd_table_t *pmd_array;