sel4/arm: make alignment faults visible

Fixes #2993

repos/base-sel4/src/core/include/ipc_pager.h

@@ -93,6 +93,7 @@ class Genode::Ipc_pager : public Native_capability
 		addr_t _fault_type = 0;    /* type of fault */
 		bool   _pf_write = false;  /* true on write fault            */
 		bool   _pf_exec  = false;  /* true on exec  fault            */
+		bool   _pf_align = false;  /* true on unaligned fault */
 
 		Mapping _reply_mapping { };
 
@@ -151,6 +152,16 @@ class Genode::Ipc_pager : public Native_capability
 		 * Return true if page fault was on non-executable memory
 		 */
 		bool exec_fault() const { return _pf_exec; }
+
+		/**
+		 * Return true if page fault was due to unaligned memory access
+		 */
+		bool align_fault() const { return _pf_align; }
+
+		/**
+		 * Install memory mapping after pager code executed.
+		 */
+		bool install_mapping();
 };
 
 #endif /* _CORE__INCLUDE__IPC_PAGER_H_ */

repos/base-sel4/src/core/include/vm_space.h

@@ -389,22 +389,30 @@ class Genode::Vm_space
 			_cap_sel_alloc.free(_vm_pad_cnode.sel());
 		}
 
-		void map(addr_t const from_phys, addr_t const to_virt,
+		bool map(addr_t const from_phys, addr_t const to_virt,
 		         size_t const num_pages, Cache_attribute const cacheability,
 		         bool const writable, bool const executable, bool flush_support)
 		{
 			Lock::Guard guard(_lock);
 
+			bool ok = true;
+
 			for (size_t i = 0; i < num_pages; i++) {
 				off_t const offset = i << get_page_size_log2();
 
-				if (!_map_frame(from_phys + offset, to_virt + offset,
-				                cacheability, writable, executable,
-				                flush_support))
-					warning("mapping failed ", Hex(from_phys + offset),
-					        " -> ", Hex(to_virt + offset), " ",
-					        !flush_support ? "core" : "");
+				if (_map_frame(from_phys + offset, to_virt + offset,
+				               cacheability, writable, executable,
+				               flush_support))
+					continue;
+
+				ok = false;
+
+				warning("mapping failed ", Hex(from_phys + offset),
+				        " -> ", Hex(to_virt + offset), " ",
+				        !flush_support ? "core" : "");
 			}
+
+			return ok;
 		}
 
 		bool unmap(addr_t const virt, size_t const num_pages,

repos/base-sel4/src/core/pager.cc

@@ -47,12 +47,14 @@ void Ipc_pager::wait_for_fault()
 	reply_and_wait_for_fault();
 }
 
+bool Ipc_pager::install_mapping()
+{
+	_badge = Genode::install_mapping(_reply_mapping, _badge);
+	return _badge;
+}
 
 void Ipc_pager::reply_and_wait_for_fault()
 {
-	if (_badge)
-		_badge = install_mapping(_reply_mapping, _badge);
-
 	seL4_Word badge = Rpc_obj_key::INVALID;
 
 	seL4_MessageInfo_t page_fault_msg_info;
@@ -76,6 +78,7 @@ void Ipc_pager::reply_and_wait_for_fault()
 	_pf_write   = fault_info.write;
 	_pf_exec    = fault_info.exec_fault();
 	_fault_type = seL4_MessageInfo_get_label(page_fault_msg_info);
+	_pf_align   = fault_info.align_fault();
 
 	_badge = badge;
 }
@@ -187,6 +190,23 @@ void Pager_entrypoint::entry()
 				        " ip=", Hex(_pager.fault_ip()),
 				        " pf-addr=", Hex(_pager.fault_addr()));
 				_pager.reply_save_caller(obj->reply_cap_sel());
+				return;
+			}
+
+			try {
+				/* install memory mappings */
+				if (_pager.install_mapping())
+					return;
+
+				/* on alignment fault don't reply and submit signal */
+				if (_pager.align_fault()) {
+					warning("alignment fault, addr=", Hex(_pager.fault_addr()),
+					        " ip=", Hex(_pager.fault_ip()));
+					throw 1;
+				}
+			} catch (...) {
+				reply_pending = false;
+				obj->submit_exception_signal();
 			}
 		});
 	}

repos/base-sel4/src/core/platform_pd.cc

@@ -160,10 +160,14 @@ bool Platform_pd::install_mapping(Mapping const &mapping,
 		_vm_space.alloc_page_tables(mapping.to_virt(),
 		                            mapping.num_pages() * get_page_size());
 
-		_vm_space.map(mapping.from_phys(), mapping.to_virt(),
-		              mapping.num_pages(), mapping.cacheability(),
-		              mapping.writeable(), mapping.executable(), FLUSHABLE);
-		return true;
+		if (_vm_space.map(mapping.from_phys(), mapping.to_virt(),
+		                  mapping.num_pages(), mapping.cacheability(),
+		                  mapping.writeable(), mapping.executable(), FLUSHABLE))
+			return true;
+
+		Genode::warning("mapping failure for thread '", thread_name,
+		                "' in pd '", _vm_space.pd_label(), "'");
+		return false;
 	} catch (...) {
 		char const * fault_name = "unknown";
 
@@ -185,11 +189,12 @@ bool Platform_pd::install_mapping(Mapping const &mapping,
 			break;
 		}
 
-		/* pager ep would die when we re-throw - let core survive */
 		Genode::error("unexpected exception during fault '", fault_name, "'",
 		              " - thread '", thread_name, "' in pd '",
 		              _vm_space.pd_label(),"' stopped");
-		return false;
+
+		/* catched by Pager_entrypoint::entry() in base-sel4/pager.cc */
+		throw;
 	}
 }
 

repos/base-sel4/src/core/spec/arm/fault_info.h

@@ -13,14 +13,16 @@
 
 struct Fault_info
 {
-	Genode::addr_t ip         = 0;
-	Genode::addr_t pf         = 0;
-	bool           data_abort = 0;
-	bool           write      = 0;
+	Genode::addr_t const ip;
+	Genode::addr_t const pf;
+	bool           data_abort;
+	bool const     write;
+	bool const     align;
 
 	enum {
 		IFSR_FAULT = 1,
 		IFSR_FAULT_PERMISSION = 0xf,
+		DFSR_ALIGN_FAULT = 1UL << 0,
 		DFSR_WRITE_FAULT = 1UL << 11
 	};
 
@@ -30,11 +32,13 @@ struct Fault_info
 		pf(seL4_GetMR(1)),
 		data_abort(seL4_GetMR(2) != IFSR_FAULT),
 		/* Instruction Fault Status Register (IFSR) resp. Data FSR (DFSR) */
-		write(data_abort && (seL4_GetMR(3) & DFSR_WRITE_FAULT))
+		write(data_abort && (seL4_GetMR(3) & DFSR_WRITE_FAULT)),
+		align(data_abort && (seL4_GetMR(3) == DFSR_ALIGN_FAULT))
 	{
 		if (!data_abort && seL4_GetMR(3) != IFSR_FAULT_PERMISSION)
 			data_abort = true;
 	}
 
 	bool exec_fault() const { return !data_abort; }
+	bool align_fault() const { return align; }
 };

repos/base-sel4/src/core/spec/x86/fault_info.h

@@ -37,4 +37,5 @@ struct Fault_info
 	{ }
 
 	bool exec_fault() const { return false; }
+	bool align_fault() const { return false; }
 };