Add events to enumerate kernel symbols

Makefile

@@ -83,6 +83,10 @@ ifneq ($(KERNELRELEASE),)
       -o \( $(VERSION) -eq 3 -a $(PATCHLEVEL) -ge 15 \) ] ; then \
       echo "lttng-tracepoint.o" ; fi;)
 
+  ifneq ($(CONFIG_KALLSYMS),)
+    obj-$(CONFIG_LTTNG) += lttng-kallsyms.o
+  endif
+
   obj-$(CONFIG_LTTNG) += lttng-statedump.o
   lttng-statedump-objs := lttng-statedump-impl.o wrapper/irqdesc.o \
                           wrapper/fdtable.o

instrumentation/events/lttng-module/lttng-kallsyms.h

@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM lttng_kallsyms
+
+#if !defined(LTTNG_TRACE_LTTNG_KALLSYMS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define LTTNG_TRACE_LTTNG_KALLSYMS_H
+
+#include <probes/lttng-tracepoint-event.h>
+
+LTTNG_TRACEPOINT_EVENT(lttng_kallsyms_kernel_symbol,
+
+	TP_PROTO(struct lttng_session *session,
+		unsigned long addr, const char *symbol, const char *module),
+
+	TP_ARGS(session, addr, symbol, module),
+
+	TP_FIELDS(
+		ctf_integer_hex(unsigned long, addr, addr)
+		ctf_string(symbol, symbol)
+		ctf_string(module, module)
+	)
+)
+
+LTTNG_TRACEPOINT_EVENT(lttng_kallsyms_new_module_symbol,
+
+	TP_PROTO(unsigned long addr, const char *symbol, const char *module),
+
+	TP_ARGS(addr, symbol, module),
+
+	TP_FIELDS(
+		ctf_integer_hex(unsigned long, addr, addr)
+		ctf_string(symbol, symbol)
+		ctf_string(module, module)
+	)
+)
+
+LTTNG_TRACEPOINT_EVENT(lttng_kallsyms_module_unloaded,
+
+	TP_PROTO(const char *module),
+
+	TP_ARGS(module),
+
+	TP_FIELDS(
+		ctf_string(module, module)
+	)
+)
+
+#endif /*  LTTNG_TRACE_LTTNG_KALLSYMS_H */
+
+/* This part must be outside protection */
+#include <probes/define_trace.h>

lttng-kallsyms.c

@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * lttng-kallsyms.c
+ *
+ * Copyright (C) 2019 Geneviève Bastien <[email protected]>
+ */
+
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <lttng-events.h>
+#include <lttng-kallsyms.h>
+
+/* Define the tracepoints, but do not build the probes */
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
+#define TRACE_INCLUDE_FILE lttng-kallsyms
+#define LTTNG_INSTRUMENTATION
+#include <instrumentation/events/lttng-module/lttng-kallsyms.h>
+
+DEFINE_TRACE(lttng_kallsyms_kernel_symbol);
+DEFINE_TRACE(lttng_kallsyms_new_module_symbol);
+DEFINE_TRACE(lttng_kallsyms_module_unloaded);
+
+/*
+ * Trace the kernel symbols from a given module
+ *
+ * data: The lttng_session instance
+ * symbol_name: The function name this symbol resolves to
+ * module: The module containing this symbol. Can be NULL
+ * symbol_addr: The symbol address
+ */
+static
+int _lttng_one_symbol_received(void * data, const char * symbol_name,
+		struct module * module, unsigned long symbol_addr)
+{
+	struct lttng_session *session = data;
+
+	if (module) {
+		trace_lttng_kallsyms_kernel_symbol(session, symbol_addr,
+				symbol_name, module->name);
+	} else {
+		trace_lttng_kallsyms_kernel_symbol(session, symbol_addr,
+				symbol_name, "");
+	}
+
+	return 0;
+}
+
+int lttng_enumerate_kernel_symbols(struct lttng_session *session)
+{
+	int ret = 0;
+
+	ret = kallsyms_on_each_symbol(_lttng_one_symbol_received, (void *) session);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_enumerate_kernel_symbols);
+
+#ifdef CONFIG_MODULES
+
+/*
+ * Trace the symbols coming from a specific module
+ *
+ * data: The new module for which we want the symbols
+ * symbol_name: The function name this symbol resolves to
+ * module: The module containing this symbol. Can be NULL
+ * symbol_addr: The symbol address
+ */
+static
+int _lttng_trace_module_symbol(void * data, const char * symbol_name,
+		struct module * module, unsigned long symbol_addr)
+{
+	struct module *mod = data;
+
+	// Trace the symbols from the new module
+	if (mod == module) {
+		trace_lttng_kallsyms_new_module_symbol(symbol_addr, symbol_name, mod->name);
+	}
+	return 0;
+}
+
+static
+int lttng_kallsyms_module_coming(struct module *mod)
+{
+	int ret = 0;
+
+	ret = kallsyms_on_each_symbol(_lttng_trace_module_symbol, (void *) mod);
+
+	return ret;
+}
+
+static
+int lttng_kallsyms_module_going(struct module *mod)
+{
+	trace_lttng_kallsyms_module_unloaded(mod->name);
+	return 0;
+}
+
+static
+int lttng_kallsyms_module_notify(struct notifier_block *self,
+		unsigned long val, void *data)
+{
+	struct module *mod = data;
+	int ret = 0;
+
+	switch (val) {
+	case MODULE_STATE_COMING:
+		ret = lttng_kallsyms_module_coming(mod);
+		break;
+	case MODULE_STATE_GOING:
+		ret = lttng_kallsyms_module_going(mod);
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+static
+struct notifier_block lttng_kallsyms_module_notifier = {
+	.notifier_call = lttng_kallsyms_module_notify,
+	.priority = 0,
+};
+
+static
+int lttng_kallsyms_module_init(void)
+{
+	return register_module_notifier(&lttng_kallsyms_module_notifier);
+}
+
+static
+void lttng_kallsyms_module_exit(void)
+{
+	WARN_ON(unregister_module_notifier(&lttng_kallsyms_module_notifier));
+}
+
+#else /* #ifdef CONFIG_MODULES */
+
+static
+int lttng_kallsyms_module_init(void)
+{
+	return 0;
+}
+
+static
+void lttng_kallsyms_module_exit(void)
+{
+
+}
+
+#endif /* #else #ifdef CONFIG_MODULES */
+
+module_init(lttng_kallsyms_module_init);
+
+module_exit(lttng_kallsyms_module_exit);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Geneviève Bastien <[email protected]");
+MODULE_DESCRIPTION("LTTng kallsyms");
+MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
+	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
+	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
+	LTTNG_MODULES_EXTRAVERSION);

lttng-kallsyms.h

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * lttng-kallsyms.h
+ *
+ * Copyright (C) 2019 Geneviève Bastien <[email protected]>
+ */
+
+#ifndef _LTTNG_KALLSYMS_H
+#define _LTTNG_KALLSYMS_H
+
+#include <lttng-events.h>
+
+#ifdef CONFIG_KALLSYMS
+
+int lttng_enumerate_kernel_symbols(struct lttng_session *session);
+
+#else /* !CONFIG_KALLSYMS */
+
+static inline int lttng_enumerate_kernel_symbols(struct lttng_session *session)
+{
+	return 0;
+}
+
+#endif /* !CONFIG_KALLSYMS */
+
+#endif /* _LTTNG_KALLSYMS_H */

lttng-statedump-impl.c

@@ -54,6 +54,7 @@
 #define TRACE_INCLUDE_FILE lttng-statedump
 #define LTTNG_INSTRUMENTATION
 #include <instrumentation/events/lttng-module/lttng-statedump.h>
+#include <lttng-kallsyms.h>
 
 DEFINE_TRACE(lttng_statedump_block_device);
 DEFINE_TRACE(lttng_statedump_end);
@@ -510,6 +511,9 @@ int do_lttng_statedump(struct lttng_session *session)
 		return ret;
 	}
 	ret = lttng_enumerate_cpu_topology(session);
+	if (ret)
+		return ret;
+	ret = lttng_enumerate_kernel_symbols(session);
 	if (ret)
 		return ret;
 

probes/Kbuild

@@ -214,6 +214,14 @@ endif # CONFIG_VIDEO_V4L2
 
 obj-$(CONFIG_LTTNG) += lttng-probe-workqueue.o
 
+ifneq ($(CONFIG_KALLSYMS),)
+  obj-$(CONFIG_LTTNG) += lttng-probe-kallsyms.o
+else
+  ifdef CONFIG_LOCALVERSION # Check if dot-config is included.
+    $(warning CONFIG_KALLSYMS is disabled, therefore probe "kallsyms" is disabled. Rebuild your kernel with this configuration option enabled in order to trace this subsystem.)
+  endif
+endif # CONFIG_KALLSYMS
+
 ifneq ($(CONFIG_KALLSYMS_ALL),)
   obj-$(CONFIG_LTTNG) += lttng-probe-writeback.o
 else

probes/lttng-probe-kallsyms.c

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * probes/lttng-probe-kallsyms.c
+ *
+ * LTTng kallsyms probes.
+ *
+ * Copyright (C) 2019 Geneviève Bastien <[email protected]>
+ */
+
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <lttng-events.h>
+#include <lttng-tracer.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
+#define TRACE_INCLUDE_FILE lttng-kallsyms
+
+#include <instrumentation/events/lttng-module/lttng-kallsyms.h>
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Geneviève Bastien <[email protected]");
+MODULE_DESCRIPTION("LTTng kallsyms probes");
+MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
+	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
+	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
+	LTTNG_MODULES_EXTRAVERSION);