Commit Graph

6 Commits

Author SHA1 Message Date
Norman Feske
73ab30c22c Update copyright headers to 2013 2013-01-10 21:44:47 +01:00
Stefan Kalkowski
a5ea6765d1 Fiasco.OC: several capability ref-counter fixes.
This commit fixes several issues that were triggered e.g. by the
'noux_tool_chain' run-script (fix #208 in part). The following problems
are tackled:
* Don't reference count capability selectors within a task that are actually
  controlled by core (all beneath 0x200000), because it's undecideable which
  "version" of a capability selector we currently use, e.g. a thread gets
  destroyed and a new one gets created immediately some other thread might
  have a Native_capability pointing to the already destroyed thread's gate
  capability-slot, that is now a new valid one (the one of the new thread)
* In core we cannot invalidate and remove a capability from the so called
  Cap_map before each reference to it is destroyed, so don't do this in
  Cap_session_component::free, but only reference-decrement within there,
  the actual removal can only be done in Cap_map::remove. Because core also
  has to invalidate a capability to be removed in all protection-domains
  we have to implement a core specific Cap_map::remove method
* When a capability gets inserted into the Cap_map, and we detect an old
  invalid entry with the dame id in the tree, don't just overmap that
  invalid entry (as there exist remaining references to it), but just remove
  it from the tree and allocate an new entry.
* Use the Cap_session_component interface to free a Pager_object when it
  gets dissolved, as its also used for allocation
2012-09-03 10:59:54 +02:00
Stefan Kalkowski
54e08cfed5 Fiasco.OC: make capability ref-counter thread-safe
Introduce process global spin-lock for Cap_index's reference-counter
to avoid non-atomic increment/decrement of the counter. Here, we don't
use a static Spinlock object, because it's constructor wouldn't be
initialized before used for the first time.
2012-05-29 13:55:00 +02:00
Stefan Kalkowski
66fbea127b Fiasco.OC: fix bugs in cap_map insertion/removal
The following fixes partly solve the problems triggered by the noux stress
test introduced by nfeske in issue #208.
* The check whether a capability exists in the Cap_map, and its insertion,
  has to be done atomically
* While removing a capability it is looked up in the Cap_map via its id,
  check whether the found capability pointer is the same like the looked up,
  otherwise the wrong capability gets freed
* When a local capability is un- resp. marshalled, only the local pointer
  gets transfered, not the redundant capability id
* Introduce several assertions and warnings to facilitate debugging
2012-05-29 13:55:00 +02:00
Stefan Kalkowski
ca004658d9 Fiasco.OC: smart-pointer for kernel capabilities.
Implements Native_capability as smart-pointer type referencing Cap_index
objects. Whenever capabilities are copied, assigned, constructed, or destructed
the reference-counter of the Cap_index is incremented/decremented. When it
reaches zero the Cap_index is removed from the process-global cap_map and
gets freed. Fix for issue #32.
2012-05-09 20:50:57 +02:00
Stefan Kalkowski
d287b9d893 Fiasco.OC: introduce Cap_index (fixes #149, #112)
This commit introduces a Cap_index class for Fiasco.OC's capabilities.
A Cap_index is a combination of the global capability id, that is used by Genode
to correctly identify a kernel-object, and a corresponding entry in a
protection-domain's (kernel-)capability-space. The cap-indices are non-copyable,
unique objects, that are held in a Cap_map. The Cap_map is used to re-find
capabilities already present in the protection-domain, when a capability is
received via IPC. The retrieval of capabilities effectively fixes issue #112,
meaning the waste of capability-space entries.
Because Cap_index objects are non-copyable (their address indicates the position
in the capability-space of the pd), they are inappropriate to use as
Native_capability. Therefore, Native_capability is implemented as a reference
to Cap_index objects. This design seems to be a good pre-condition to implement
smart-pointers for entries in the capability-space, and thereby closing existing
leaks (please refer to issue #32).

Cap_index, Cap_map, and the allocator for Cap_index objects are designed in a way,
that it should be relatively easy to apply the same concept to NOVA also. By now,
these classes are located in the `base-foc` repository, but they intentionally
contain no Fiasco.OC specific elements.

The previously explained changes had extensive impact on the whole Fiasco.OC
platform implementation, due to various dependencies. The following things had to
be changed:

* The Thread object's startup and destruction routine is re-arranged, to
  enable another thread (that calls the Thread destructor) gaining the
  capability id of the thread's gate to remove it from the Cap_map, the
  thread's UTCB had to be made available to the caller, because there
  is the current location of that id. After having the UTCB available
  in the Thread object for that reason, the whole thread bootstrapping
  could be simplified.
* In the course of changing the Native_capability's semantic, a new Cap_mapping
  class was introduced in core, that facilitates the establishment and
  destruction of capability mappings between core and it's client's, especially
  mappings related to Platform_thread and Platform_task, that are relevant to
  task and thread creation and destruction. Thereby, the destruction of
  threads had to be reworked, which effectively removed a bug (issue #149)
  where some threads weren't destroyed properly.
* In the quick fix for issue #112, something similar to the Cap_map was
  introduced available in all processes. Moreover, some kind of a capability
  map already existed in core, to handle cap-session request properly. The
  introduction of the Cap_map unified both structures, so that the
  cap-session component code in core had to be reworked too.
* The platform initialization code had to be changed sligthly due to the
  changes in Native_capability
* The vcpu initialization in the L4Linux support library had to be adapted
  according to the already mentioned changes in the Thread object's bootstrap
  code.
2012-03-22 14:10:44 +01:00