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nova: fix pager cleanup handling 

The cleanup call must be performed already during the _dissolve function
shortly after the object at the cap_session is freed up. Otherwise there
is the chance that an in-flight IPC will find the to be dissolved function
again.

Bomb test triggered the case, that a already dissolved rpc_object was found
by a in-flight IPC. If the rpc_object was already freed up by alloc->destroy
the thread using this stale rpc_object pointer cause page-faults in core.

Fixes partly #549
This commit is contained in:
Alexander Boettcher 2012-12-04 09:49:01 +01:00 committed by Norman Feske
parent 28f7cf5dc2
commit edd30b56a2
2 changed files with 51 additions and 39 deletions
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9
base-nova/include/base/pager.h
View File

@ -186,6 +186,15 @@ namespace Genode {
*/
Thread_capability thread_cap() { return _thread_cap; } const
void thread_cap(Thread_capability cap) { _thread_cap = cap; }
/**
* Make sure nobody is in the handler anymore by doing an IPC to a
* local cap pointing to same serving thread (if not running in the
* context of the serving thread). When the call returns
* we know that nobody is handled by this object anymore, because
* all remotely available portals had been revoked beforehand.
*/
void cleanup_call();
};

81
base-nova/src/base/pager/pager.cc
View File

@ -79,8 +79,8 @@ void Pager_object::_exception_handler(addr_t portal_id)
Utcb *utcb = _check_handler(myself, obj);
addr_t fault_ip = utcb->ip;
if (obj->submit_exception_signal())
/* Somebody takes care don't die - just recall and block */
if (obj->submit_exception_signal())
/* somebody takes care don't die - just recall and block */
obj->client_recall();
else {
PWRN("unresolvable exception at ip 0x%lx, exception portal 0x%lx",
@ -126,13 +126,13 @@ void Pager_object::_recall_handler()
utcb->flags = obj->_state.thread.eflags | 0x100UL;
utcb->mtd = Nova::Mtd(Mtd::EFL).value();
} else
if (!obj->_state.singlestep && singlestep_state) {
utcb->flags = obj->_state.thread.eflags & ~0x100UL;
utcb->mtd = Nova::Mtd(Mtd::EFL).value();
} else
utcb->mtd = 0;
if (!obj->_state.singlestep && singlestep_state) {
utcb->flags = obj->_state.thread.eflags & ~0x100UL;
utcb->mtd = Nova::Mtd(Mtd::EFL).value();
} else
utcb->mtd = 0;
utcb->set_msg_word(0);
reply(myself->stack_top());
}
@ -200,6 +200,27 @@ uint8_t Pager_object::client_recall()
}
void Pager_object::cleanup_call()
{
/*
* Revoke all portals of Pager_object from others.
* The portals will be finally revoked during thread destruction.
*/
revoke(Obj_crd(exc_pt_sel(), NUM_INITIAL_PT_LOG2), false);
Utcb *utcb = (Utcb *)Thread_base::myself()->utcb();
if (reinterpret_cast<Utcb *>(this->utcb()) == utcb) return;
/* if pager is blocked wake him up */
wake_up();
utcb->set_msg_word(0);
if (uint8_t res = call(_pt_cleanup))
PERR("%8p - cleanup call to pager (%8p) failed res=%d",
utcb, this->utcb(), res);
}
Pager_object::Pager_object(unsigned long badge)
: Thread_base("pager", PF_HANDLER_STACK_SIZE), _badge(badge)
{
@ -290,40 +311,24 @@ Pager_object::Pager_object(unsigned long badge)
Pager_object::~Pager_object()
{
/*
* Revoke all portals of Pager_object from others.
* The portals will be finally revoked during thread destruction.
*/
revoke(Obj_crd(exc_pt_sel(), NUM_INITIAL_PT_LOG2), false);
/* revoke semaphore cap to signal valid state after recall */
addr_t sm_cap = _sm_state_notify;
addr_t sm_cap = _sm_state_notify;
_sm_state_notify = Native_thread::INVALID_INDEX;
/* wake up client blocked in a thread::pause call */
/* if pager is blocked wake him up */
sm_ctrl(sm_cap, SEMAPHORE_UP);
revoke(Obj_crd(sm_cap, 0));
/* if pager is blocked wake him up */
wake_up();
/*
* Make sure nobody is in the handler anymore by doing an IPC to a
* local cap pointing to same serving thread (if not running in the
* context of the serving thread). When the call returns
* we know that nobody is handled by this object anymore, because
* all remotely available portals had been revoked beforehand.
*/
Utcb *utcb = (Utcb *)Thread_base::myself()->utcb();
if (reinterpret_cast<Utcb *>(&_context->utcb) != utcb) {
utcb->set_msg_word(0);
if (uint8_t res = call(_pt_cleanup))
PERR("failure - cleanup call failed res=%d", res);
}
/* take care nobody is handled anymore by this object */
cleanup_call();
/* revoke portal used for the cleanup call */
revoke(Obj_crd(_pt_cleanup, 0));
Native_capability pager_obj = ::Object_pool<Pager_object>::Entry::cap();
cap_selector_allocator()->free(_pt_cleanup, 0);
cap_selector_allocator()->free(sm_cap, 0);
cap_selector_allocator()->free(pager_obj.local_name(), 0);
}
@ -346,17 +351,15 @@ Pager_capability Pager_entrypoint::manage(Pager_object *obj)
void Pager_entrypoint::dissolve(Pager_object *obj)
{
Native_capability pager_obj = obj->Object_pool<Pager_object>::Entry::cap();
/* cleanup at cap session */
_cap_session->free(obj->Object_pool<Pager_object>::Entry::cap());
_cap_session->free(pager_obj);
/* cleanup locally */
Native_capability pager_pt =
obj->Object_pool<Pager_object>::Entry::cap();
revoke(pager_pt.dst(), true);
cap_selector_allocator()->free(pager_pt.local_name(), 0);
revoke(pager_obj.dst(), true);
remove_locked(obj);
obj->cleanup_call();
}