plugin/checkpoint: add possibility to cache data

The checkpoint plugin is able to use dynamic values from within the
target to calculate its ranges. If the experiment injects faults within
those dynamic values, we will always get an digest error, even if it has
no influence on the outcome of the experiment or the integrity of the
data range.

Therefore, the plugin now provides a possiblity to cache those dynamic
values, before injecting them. This has to be done explicitly within the
experiment.

Change-Id: Ib2cbedd570ea9ab9c97efc152279e8eb79c573f4

src/plugins/checkpoint/Checkpoint.cc

@@ -53,10 +53,16 @@ address_t Checkpoint::resolve_address(const indirectable_address_t &addr) {
 		const address_t paddr = addr.first;
 		address_t value = 0;
 
-		MemoryManager& mm = simulator.getMemoryManager();
-
-		if(mm.isMapped(paddr) && mm.isMapped(paddr+1) && mm.isMapped(paddr+2) && mm.isMapped(paddr+3)) {
-			simulator.getMemoryManager().getBytes(paddr, 4, &value);
+		std::map<fail::address_t, fail::address_t>::iterator it = cached_stackpointer_variables.find(paddr);
+		if (it != cached_stackpointer_variables.end()) {
+			m_log << "Use Cached Value! " << std::hex << it->first << "=" << it->second << std::dec << endl;
+			value = it->second;
+		} else {
+			MemoryManager& mm = simulator.getMemoryManager();
+
+			if(mm.isMapped(paddr) && mm.isMapped(paddr+1) && mm.isMapped(paddr+2) && mm.isMapped(paddr+3)) {
+				simulator.getMemoryManager().getBytes(paddr, 4, &value);
+			}
 		}
 
 		// HACK/WORKAROUND for dOSEK, which uses bit 31 for parity!
@@ -68,6 +74,24 @@ address_t Checkpoint::resolve_address(const indirectable_address_t &addr) {
 	}
 }
 
+bool Checkpoint::in_range(fail::address_t addr)
+{
+	// iterate memory regions
+	std::vector<address_range>::const_iterator it = m_check_ranges.begin();
+	for( ; it != m_check_ranges.end(); ++it) {
+		fail::address_t start = resolve_address(it->first);
+		fail::address_t end = resolve_address(it->second);
+		if((start == 0) || (end == 0)) {
+			m_log << std::hex << "invalid checksum range pointer" << std::endl;
+			continue;
+		}
+		if (start <= addr && addr < end) {
+			return true;
+		}
+	}
+	return false;
+}
+
 void Checkpoint::checksum(uint8_t (&Message_Digest)[20])
 {
 	SHA1Context sha;
@@ -97,7 +121,8 @@ void Checkpoint::checksum(uint8_t (&Message_Digest)[20])
 			continue;
 		}
 
-		//m_log << std::hex << "checksumming 0x" << start << " - 0x" << end << std::endl;
+		// if (start != end)
+		// m_log << std::hex << "checksumming 0x" << start << " - 0x" << end << std::endl;
 
 		for(fail::address_t addr = start; addr < end; addr++) {
 			if(mm.isMapped(addr)) {

src/plugins/checkpoint/Checkpoint.hpp

@@ -41,6 +41,11 @@ private:
 	std::ifstream m_istream; //!< inputfile stream
 	unsigned m_count;
 
+	// In this map, we save the contents of stackpointer-variables to
+	// beginning/end of region markers. We allow this to make those
+	// stackpointer-variables injectable.
+	std::map<fail::address_t, fail::address_t> cached_stackpointer_variables;
+
 public:
 	/**
 	 * Construct Checkpoint Logger in tracing (output) mode.
@@ -97,6 +102,29 @@ public:
 	 */
 	check_result check(const fail::ElfSymbol symbol, fail::address_t ip);
 
+	/**
+	 * Checks whether the given address is currently (according to the
+	 * machine state) within the checked ranges.
+	 *
+	 * @param addr address to check
+	 * @return addr is in checked ranges
+	 */
+	bool in_range(fail::address_t addr);
+
+	/**
+	 * Cache a memory address, which is to be dereferenced by the checkpoint plugin.
+	 *
+	 * @param address of the stackpointer variable
+	 * @param value of the stackpointer variable
+	 */
+	void cache_stackpointer_variable(fail::address_t addr, fail::address_t value) {
+		cached_stackpointer_variables[addr] = value;
+	}
+
+	void uncache_stackpointer_variable(fail::address_t addr) {
+		cached_stackpointer_variables.erase(addr);
+	}
+
 private:
 	//! calulate checksum over memory regions
 	void checksum(uint8_t (&Message_Digest)[20]);