1 files changed, 58 insertions, 57 deletions

diff --git a/daemon/FtraceDriver.cpp b/daemon/FtraceDriver.cpp
index 98bd0a5..7c57cfc 100644
--- a/daemon/FtraceDriver.cpp
+++ b/daemon/FtraceDriver.cpp
@@ -10,22 +10,25 @@
 
 #include <regex.h>
 #include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 
+#include "Config.h"
 #include "DriverSource.h"
 #include "Logging.h"
+#include "SessionData.h"
 #include "Setup.h"
 
 class FtraceCounter : public DriverCounter {
 public:
-	FtraceCounter(DriverCounter *next, char *name, const char *regex, const char *enable);
+	FtraceCounter(DriverCounter *next, char *name, const char *enable);
 	~FtraceCounter();
 
 	void prepare();
-	int read(const char *const line, int64_t *values);
 	void stop();
 
 private:
-	regex_t mReg;
 	char *const mEnable;
 	int mWasEnabled;
 
@@ -34,18 +37,10 @@ private:
 	FtraceCounter &operator=(const FtraceCounter &);
 };
 
-FtraceCounter::FtraceCounter(DriverCounter *next, char *name, const char *regex, const char *enable) : DriverCounter(next, name), mEnable(enable == NULL ? NULL : strdup(enable)) {
-	int result = regcomp(&mReg, regex, REG_EXTENDED);
-	if (result != 0) {
-		char buf[128];
-		regerror(result, &mReg, buf, sizeof(buf));
-		logg->logError("Invalid regex '%s': %s", regex, buf);
-		handleException();
-	}
+FtraceCounter::FtraceCounter(DriverCounter *next, char *name, const char *enable) : DriverCounter(next, name), mEnable(enable == NULL ? NULL : strdup(enable)) {
 }
 
 FtraceCounter::~FtraceCounter() {
-	regfree(&mReg);
 	if (mEnable != NULL) {
 		free(mEnable);
 	}
@@ -57,7 +52,7 @@ void FtraceCounter::prepare() {
 	}
 
 	char buf[1<<10];
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%s/enable", mEnable);
+	snprintf(buf, sizeof(buf), EVENTS_PATH "/%s/enable", mEnable);
 	if ((DriverSource::readIntDriver(buf, &mWasEnabled) != 0) ||
 			(DriverSource::writeDriver(buf, 1) != 0)) {
 		logg->logError("Unable to read or write to %s", buf);
@@ -65,43 +60,17 @@ void FtraceCounter::prepare() {
 	}
 }
 
-int FtraceCounter::read(const char *const line, int64_t *values) {
-	regmatch_t match[2];
-	int result = regexec(&mReg, line, 2, match, 0);
-	if (result != 0) {
-		// No match
-		return 0;
-	}
-
-	int64_t value;
-	if (match[1].rm_so < 0) {
-		value = 1;
-	} else {
-		errno = 0;
-		value = strtoll(line + match[1].rm_so, NULL, 0);
-		if (errno != 0) {
-			logg->logError("Parsing %s failed: %s", getName(), strerror(errno));
-			handleException();
-		}
-	}
-
-	values[0] = getKey();
-	values[1] = value;
-
-	return 1;
-}
-
 void FtraceCounter::stop() {
 	if (mEnable == NULL) {
 		return;
 	}
 
 	char buf[1<<10];
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%s/enable", mEnable);
+	snprintf(buf, sizeof(buf), EVENTS_PATH "/%s/enable", mEnable);
 	DriverSource::writeDriver(buf, mWasEnabled);
 }
 
-FtraceDriver::FtraceDriver() : mValues(NULL) {
+FtraceDriver::FtraceDriver() : mValues(NULL), mSupported(false), mTracingOn(0) {
 }
 
 FtraceDriver::~FtraceDriver() {
@@ -118,10 +87,20 @@ void FtraceDriver::readEvents(mxml_node_t *const xml) {
 
 	// The perf clock was added in 3.10
 	if (KERNEL_VERSION(release[0], release[1], release[2]) < KERNEL_VERSION(3, 10, 0)) {
+		mSupported = false;
 		logg->logMessage("Unsupported kernel version, to use ftrace please upgrade to Linux 3.10 or later");
 		return;
 	}
 
+	// Is debugfs or tracefs available?
+	if (access(TRACING_PATH, R_OK) != 0) {
+		mSupported = false;
+		logg->logMessage("Unable to locate the tracing directory, disabling ftrace");
+		return;
+	}
+
+	mSupported = true;
+
 	mxml_node_t *node = xml;
 	int count = 0;
 	while (true) {
@@ -143,20 +122,28 @@ void FtraceDriver::readEvents(mxml_node_t *const xml) {
 			logg->logError("The regex counter %s is missing the required regex attribute", counter);
 			handleException();
 		}
-		bool addCounter = true;
+
+		const char *tracepoint = mxmlElementGetAttr(node, "tracepoint");
 		const char *enable = mxmlElementGetAttr(node, "enable");
+		if (enable == NULL) {
+			enable = tracepoint;
+		}
+		if (gSessionData->mPerf.isSetup() && tracepoint != NULL) {
+			logg->logMessage("Not using ftrace for counter %s", counter);
+			continue;
+		}
 		if (enable != NULL) {
 			char buf[1<<10];
-			snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%s/enable", enable);
+			snprintf(buf, sizeof(buf), EVENTS_PATH "/%s/enable", enable);
 			if (access(buf, W_OK) != 0) {
 				logg->logMessage("Disabling counter %s, %s not found", counter, buf);
-				addCounter = false;
+				continue;
 			}
 		}
-		if (addCounter) {
-			setCounters(new FtraceCounter(getCounters(), strdup(counter), regex, enable));
-			++count;
-		}
+
+		logg->logMessage("Using ftrace for %s", counter);
+		setCounters(new FtraceCounter(getCounters(), strdup(counter), enable));
+		++count;
 	}
 
 	mValues = new int64_t[2*count];
@@ -169,23 +156,37 @@ void FtraceDriver::prepare() {
 		}
 		counter->prepare();
 	}
-}
 
-int FtraceDriver::read(const char *line, int64_t **buf) {
-	int count = 0;
+	if (DriverSource::readIntDriver(TRACING_PATH "/tracing_on", &mTracingOn)) {
+		logg->logError("Unable to read if ftrace is enabled");
+		handleException();
+	}
 
-	for (FtraceCounter *counter = static_cast<FtraceCounter *>(getCounters()); counter != NULL; counter = static_cast<FtraceCounter *>(counter->getNext())) {
-		if (!counter->isEnabled()) {
-			continue;
+	if (DriverSource::writeDriver(TRACING_PATH "/tracing_on", "0") != 0) {
+		logg->logError("Unable to turn ftrace off before truncating the buffer");
+		handleException();
+	}
+
+	{
+		int fd;
+		fd = open(TRACING_PATH "/trace", O_WRONLY | O_TRUNC | O_CLOEXEC, 0666);
+		if (fd < 0) {
+			logg->logError("Unable truncate ftrace buffer: %s", strerror(errno));
+			handleException();
 		}
-		count += counter->read(line, mValues + 2*count);
+		close(fd);
 	}
 
-	*buf = mValues;
-	return count;
+	if (DriverSource::writeDriver(TRACING_PATH "/trace_clock", "perf") != 0) {
+		logg->logError("Unable to switch ftrace to the perf clock, please ensure you are running Linux 3.10 or later");
+		handleException();
+	}
 }
 
 void FtraceDriver::stop() {
+	DriverSource::writeDriver(TRACING_PATH "/tracing_on", mTracingOn);
+	DriverSource::writeDriver(TRACING_PATH "/trace_clock", "local");
+
 	for (FtraceCounter *counter = static_cast<FtraceCounter *>(getCounters()); counter != NULL; counter = static_cast<FtraceCounter *>(counter->getNext())) {
 		if (!counter->isEnabled()) {
 			continue;