From bcfcc1db9c0ea258447b46107b0976fa225d872b Mon Sep 17 00:00:00 2001
From: Alexander Boettcher <alexander.boettcher@genode-labs.com>
Date: Thu, 24 Aug 2017 11:53:19 +0200
Subject: [PATCH] sel4: handle unmap error more gracefully

Issue #2505
---
 repos/base-sel4/src/core/include/map_local.h | 3 +--
 repos/base-sel4/src/core/include/vm_space.h  | 9 ++++++---
 repos/base-sel4/src/core/platform_thread.cc  | 6 +++++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/repos/base-sel4/src/core/include/map_local.h b/repos/base-sel4/src/core/include/map_local.h
index f53d77212..8a59e58e5 100644
--- a/repos/base-sel4/src/core/include/map_local.h
+++ b/repos/base-sel4/src/core/include/map_local.h
@@ -56,8 +56,7 @@ namespace Genode {
 	                        Platform * platform = nullptr)
 	{
 		platform = platform ? platform : platform_specific();
-		platform->core_vm_space().unmap(virt_addr, num_pages);
-		return true;
+		return platform->core_vm_space().unmap(virt_addr, num_pages);
 	}
 }
 
diff --git a/repos/base-sel4/src/core/include/vm_space.h b/repos/base-sel4/src/core/include/vm_space.h
index 2bc034164..2849d98c6 100644
--- a/repos/base-sel4/src/core/include/vm_space.h
+++ b/repos/base-sel4/src/core/include/vm_space.h
@@ -388,11 +388,13 @@ class Genode::Vm_space
 			}
 		}
 
-		void unmap(addr_t virt, size_t num_pages)
+		bool unmap(addr_t virt, size_t num_pages)
 		{
+			bool unmap_success = true;
+
 			Lock::Guard guard(_lock);
 
-			for (size_t i = 0; i < num_pages; i++) {
+			for (size_t i = 0; unmap_success && i < num_pages; i++) {
 				off_t const offset = i << get_page_size_log2();
 
 				_page_table_registry.flush_page(virt + offset, [&] (Cap_sel const &idx, addr_t) {
@@ -401,7 +403,7 @@ class Genode::Vm_space
 					if (result != seL4_NoError) {
 						error("unmap ", Hex(virt + offset), " failed, idx=",
 						      idx, " result=", result);
-						return;
+						unmap_success = false;
 					}
 
 					_leaf_cnode(idx.value()).remove(_leaf_cnode_entry(idx.value()));
@@ -409,6 +411,7 @@ class Genode::Vm_space
 					_sel_alloc.free(idx.value());
 				});
 			}
+			return unmap_success;
 		}
 
 		void unsynchronized_alloc_page_tables(addr_t const start,
diff --git a/repos/base-sel4/src/core/platform_thread.cc b/repos/base-sel4/src/core/platform_thread.cc
index c9f7591f2..2ceb753f5 100644
--- a/repos/base-sel4/src/core/platform_thread.cc
+++ b/repos/base-sel4/src/core/platform_thread.cc
@@ -121,7 +121,11 @@ static void prepopulate_ipc_buffer(addr_t ipc_buffer_phys, Cap_sel ep_sel,
 	utcb.lock_sel = lock_sel.value();
 
 	/* unmap IPC buffer from core */
-	unmap_local((addr_t)virt_addr, 1);
+	if (!unmap_local((addr_t)virt_addr, 1)) {
+		Genode::error("could not unmap core virtual address ",
+		              virt_addr, " in ", __PRETTY_FUNCTION__);
+		return;
+	}
 
 	/* free core's virtual address space */
 	platform()->region_alloc()->free(virt_addr, page_rounded_size);