Pagers can now share their own private capabilities with their
paged children, or their siblings with whom they have a common pager
ancestor.
Added flags CAP_SHARE_CHILD and CAP_SHARE_SIBLINGS for that.
Notion of pager hierarchy introduced using the existing but unused
pagerid field.
Thread creation now has two more flags TC_AS_PAGER and TC_SHARE_PAGER.
The former sets creator as pager, the latter sets creator's pager as pager.
Thread group capability sharing now correctly carries shared capabilities
to the thread group leader's tgr_cap_list list, and this list is checked
during capability checking.
Capabilities will be shared among collection of threads. A pager
will have a right to share its own capabilities with its space,
its thread group and its container.
Currently sharing is possible with only all of the caps. Next,
it will be support for cap splitting, granting, and partial sharing
and granting.
Added support for pagers that fault to suspend and become zombies
along with all the threads that they manage. Zombie killing is to
be done at a later time, from this special zombie queue.
The implementation works same as a suspension, with the added action
that the thread is moved to a queue in kernel container.
Issues:
- A page-faulting thread suspends if receives -1 from pager page fault ipc.
This is fine if pager is about to delete the thread, but it is not if
it is a buggy pager.
- Need to find a way to completely get rid of suspended pager.
- A method of deleting suspended tasks could remedy both cases above.
Any thread that touches a utcb inside the kernel now properly checks
whether the utcb is mapped on its owner, and whether the mapped physical
address matches that of the current thread's tables. If not the tables
are updated.
This way, even though page tables become incoherent on utcb address
change situations (such as fork() exit(), execve()) they get updated
as they are referenced.
Since mappings are added only conditionally, caches are flushed only
when an update is necessary.
test0 now successfully runs its beginning.
test0 SConscript has a dependency problem.
Issues to be investigated:
- vm_file and vnodes need to be merged fully in all functions.
- libposix shared page references need to be removed.
- Any references to VFS_TID, PAGER_TID need to be removed.
Changes:
It is now possible to use do_mmap() from within mm0.
- pager_new_virtual()/delete_virtual() return addresses that are
disjoint from find_unmapped_area() used by mmap() interface for
anonymous or not-fixed areas.
- find_unmapped_area() now uses task->map_start task->map_end instead
of task->start and task->end. task->start/end are still valid task
space addresses for mmap(), but finding a new address is limited to
map_start/map_end.
- We have both interfaces because mmap() is only useful for backed-files.
When the pager needs to access a user memory range for example, that is
not backed by a file and thus we need to use pager_new_virtual() instead
of mmap() for mapping.
It makes more sense to have a scheduler (or runqueue pair) per-cpu
rather than per-container. This provides more flexible global scheduling
policy that is also simpler due to all scheduling details being controlled
from a single point.
Also fixed a bug with configurator in that the containers
were not sorted properly and consequently an already filled
in container was getting overwritten by the new one.
modified: config/configuration.py
modified: configure.py
new file: generate_kernel_cinfo.py
deleted: src/generic/cinfo.c
Status:
- Capability initialization is a bit hacky with dummy current etc.
- All container caps belong to the pager
- Tasks refer to their pager's capabilities for mutex allocation - Hacky.
- Kernel container keeps quantitative caps and memory caps in separate lists - Hacky.
These will all evolve and get fixed.
Previously virt_to_phys/phys_to_virt macros were used such that they did a
blind offset translation for creating a pager internal virtual address for
user mappings.
This is now changed such that a properly bookkeeped virtual address pool is
used which will avoid any clashes on the virtual space.
Bahadir Balban