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Added the first means to pass information between 2 tasks using the

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utcb as a shared page instead of the message registers.

Implemented the code that passes task information from mm0 to fs0
using the fs0 utcb. The code seems to work OK but:

There's an issue with anon pages that they end up on the same swapfile
and with same file offsets (e.g. utcb and stack at offset 0). Need to
fix this issue but otherwise this implementation seems to work.

TODO:
- Separate anon regions into separate vmfiles.
- Possibly map the stacks from virtual files so that they can be
  read from userspace in the future for debugging.
- Possibly utcb could be created as a shared memory object using shmget/shmat
  during startup.
This commit is contained in:
Bahadir Balban
2008-02-29 21:56:05 +00:00
parent 55117c600b
commit 4f346cea53
9 changed files with 166 additions and 19 deletions
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83
tasks/mm0/src/task.c
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@@ -9,9 +9,11 @@
#include <l4/lib/list.h>
#include <l4/api/thread.h>
#include <l4/api/kip.h>
#include <l4/api/errno.h>
#include INC_GLUE(memory.h)
#include <l4lib/arch/syscalls.h>
#include <l4lib/arch/syslib.h>
#include <l4lib/arch/utcb.h>
#include <l4lib/ipcdefs.h>
#include <lib/addr.h>
#include <task.h>
@@ -221,6 +223,61 @@ void init_pm(struct initdata *initdata)
start_boot_tasks(initdata, &tcb_head);
}
/*
* Makes the virtual to page translation for a given user task.
*/
struct page *task_virt_to_page(struct tcb *t, unsigned long virtual)
{
unsigned long vaddr_vma_offset;
unsigned long vaddr_file_offset;
struct vm_area *vma;
struct vm_file *vmfile;
struct page *page;
/* First find the vma that maps that virtual address */
if (!(vma = find_vma(virtual, &t->vm_area_list))) {
printf("%s: No VMA found for 0x%x on task: %d\n",
__FUNCTION__, virtual, t->tid);
return PTR_ERR(-EINVAL);
}
/* Find the pfn offset of virtual address in this vma */
BUG_ON(__pfn(virtual) < vma->pfn_start ||
__pfn(virtual) > vma->pfn_end);
vaddr_vma_offset = __pfn(virtual) - vma->pfn_start;
/* Find the file offset of virtual address in this file */
vmfile = vma->owner;
vaddr_file_offset = vma->f_offset + vaddr_vma_offset;
/*
* Find the page with the same file offset with that of the
* virtual address, that is, if the page is resident in memory.
*/
list_for_each_entry(page, &vmfile->page_cache_list, list)
if (vaddr_file_offset == page->f_offset) {
printf("%s: %s: Found page @ 0x%x, f_offset: 0x%x, with vma @ 0x%x, vmfile @ 0x%x\n", __TASKNAME__,
__FUNCTION__, (unsigned long)page, page->f_offset, vma, vma->owner);
return page;
}
/*
* The page is not found, meaning that it is not mapped in
* yet, e.g. via a page fault.
*/
return 0;
}
struct task_data {
unsigned long tid;
unsigned long utcb_address;
};
struct task_data_head {
unsigned long total;
struct task_data tdata[];
};
/*
* During its initialisation FS0 wants to learn how many boot tasks
* are running, and their tids, which includes itself. This function
@@ -228,8 +285,10 @@ void init_pm(struct initdata *initdata)
*/
void send_task_data(l4id_t requester)
{
struct tcb *t;
int li, err;
struct tcb *t, *vfs;
struct utcb *vfs_utcb;
struct task_data_head *tdata_head;
if (requester != VFS_TID) {
printf("%s: Task data requested by %d, which is not "
@@ -238,14 +297,26 @@ void send_task_data(l4id_t requester)
return;
}
/* First word is total number of tcbs */
write_mr(L4SYS_ARG0, tcb_head.total);
BUG_ON(!(vfs = find_task(requester)));
/* Write each tcb's tid */
/* Map in vfs's utcb. FIXME: Whatif it is already mapped? */
l4_map((void *)page_to_phys(task_virt_to_page(vfs, vfs->utcb_address)),
(void *)vfs->utcb_address, 1, MAP_USR_RW_FLAGS, self_tid());
/* Get a handle on vfs utcb */
vfs_utcb = (struct utcb *)vfs->utcb_address;
/* Write all requested task information to utcb's user buffer area */
tdata_head = (struct task_data_head *)vfs_utcb->buf;
/* First word is total number of tcbs */
tdata_head->total = tcb_head.total;
/* Write per-task data for all tasks */
li = 0;
list_for_each_entry(t, &tcb_head.list, list) {
BUG_ON(li >= MR_USABLE_TOTAL);
write_mr(L4SYS_ARG1 + li, t->tid);
tdata_head->tdata[li].tid = t->tid;
tdata_head->tdata[li].utcb_address = t->utcb_address;
li++;
}