From 22084dbfa58cad645b3692ca4e6135cb45cb7613 Mon Sep 17 00:00:00 2001
From: Norman Feske <norman.feske@genode-labs.com>
Date: Fri, 23 Mar 2012 17:22:49 +0100
Subject: [PATCH] Ignore suspicious wake-up messages on OKL4

---
 base-okl4/include/base/ipc_pager.h |  6 ++++++
 base-okl4/src/base/ipc/pager.cc    |  1 +
 base-okl4/src/base/pager/pager.cc  | 18 ++++++++++--------
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/base-okl4/include/base/ipc_pager.h b/base-okl4/include/base/ipc_pager.h
index f63a789253..8316b53ee1 100644
--- a/base-okl4/include/base/ipc_pager.h
+++ b/base-okl4/include/base/ipc_pager.h
@@ -77,6 +77,7 @@ namespace Genode {
 
 			Okl4::L4_MsgTag_t   _faulter_tag;   /* fault flags                    */
 			Okl4::L4_ThreadId_t _last;          /* faulted thread                 */
+			Okl4::L4_Word_t     _last_space;    /* space of faulted thread        */
 			Okl4::L4_Word_t     _fault_addr;    /* page-fault address             */
 			Okl4::L4_Word_t     _fault_ip;      /* instruction pointer of faulter */
 			Mapping             _reply_mapping; /* page-fault answer              */
@@ -148,6 +149,11 @@ namespace Genode {
 			 */
 			Native_thread_id last() const { return _last; }
 
+			/**
+			 * Return address space where the last page fault occurred
+			 */
+			unsigned long last_space() const { return _last_space; }
+
 			/**
 			 * Return badge for faulting thread
 			 *
diff --git a/base-okl4/src/base/ipc/pager.cc b/base-okl4/src/base/ipc/pager.cc
index 7d97d1ca8f..f78d2ba3f3 100644
--- a/base-okl4/src/base/ipc/pager.cc
+++ b/base-okl4/src/base/ipc/pager.cc
@@ -108,6 +108,7 @@ void Ipc_pager::wait_for_fault()
 		if (verbose_page_fault)
 			print_page_fault(L4_Label(_faulter_tag), _fault_addr, _fault_ip, _last.raw);
 	}
+	_last_space = L4_SenderSpace().raw;
 }
 
 
diff --git a/base-okl4/src/base/pager/pager.cc b/base-okl4/src/base/pager/pager.cc
index 79a0ea1457..51c1ef4c37 100644
--- a/base-okl4/src/base/pager/pager.cc
+++ b/base-okl4/src/base/pager/pager.cc
@@ -54,14 +54,16 @@ void Pager_activation_base::entry()
 
 		} else {
 
-			/* prevent threads outside of core to mess with our wake-up interface */
-//			enum { CORE_TASK_ID = 4 };
-//			if (pager.last() != CORE_TASK_ID) {
-
-#warning Check for messages from outside of core
-			if (0) {
-
-			} else {
+			/*
+			 * Prevent threads outside of core to mess with our wake-up
+			 * interface. This condition can trigger if a process gets
+			 * destroyed which triggered a page fault shortly before getting
+			 * killed. In this case, 'wait_for_fault()' returns (because of
+			 * the page fault delivery) but the pager-object lookup will fail
+			 * (because core removed the process already).
+			 */
+			enum { CORE_SPACE = 0 };
+			if (pager.last_space() == CORE_SPACE) {
 
 				/*
 				 * We got a request from one of cores region-manager sessions