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Subject[PATCH] tracing/events: Add module tracepoints
Add trace points to trace module_load, module_free, module_get,
module_put and module_request, and use trace_event facility
to get the trace output.

Here's the sample output:

TASK-PID CPU# TIMESTAMP FUNCTION
| | | | |
<...>-42 [000] 1.758380: module_request: fb0 wait=1 call_site=fb_open
...
<...>-60 [000] 3.269403: module_load: scsi_wait_scan
<...>-60 [000] 3.269432: module_put: scsi_wait_scan call_site=sys_init_module refcnt=0
<...>-61 [001] 3.273168: module_free: scsi_wait_scan
...
<...>-1021 [000] 13.836081: module_load: sunrpc
<...>-1021 [000] 13.840589: module_put: sunrpc call_site=sys_init_module refcnt=-1
<...>-1027 [000] 13.848098: module_get: sunrpc call_site=try_module_get refcnt=0
<...>-1027 [000] 13.848308: module_get: sunrpc call_site=get_filesystem refcnt=1
<...>-1027 [000] 13.848692: module_put: sunrpc call_site=put_filesystem refcnt=0
...
modprobe-2587 [001] 1088.437213: module_load: trace_events_sample F
modprobe-2587 [001] 1088.437786: module_put: trace_events_sample call_site=sys_init_module refcnt=0

Note:

- the taints flag can be 'F', 'C' and/or 'P' if mod->taints != 0

- the module refcnt is percpu, so it can be negative in a specific cpu

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
include/linux/module.h | 14 ++++-
include/trace/events/module.h | 126 +++++++++++++++++++++++++++++++++++++++++
kernel/kmod.c | 4 +
kernel/module.c | 11 ++++
4 files changed, 152 insertions(+), 3 deletions(-)
create mode 100644 include/trace/events/module.h
diff --git a/include/linux/module.h b/include/linux/module.h
index 7a5c82c..86863cd 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -17,10 +17,12 @@
#include <linux/moduleparam.h>
#include <linux/marker.h>
#include <linux/tracepoint.h>
-#include <asm/local.h>

+#include <asm/local.h>
#include <asm/module.h>

+#include <trace/events/module.h>
+
/* Not Yet Implemented */
#define MODULE_SUPPORTED_DEVICE(name)

@@ -480,7 +482,10 @@ static inline local_t *__module_ref_addr(struct module *mod, int cpu)
static inline void __module_get(struct module *module)
{
if (module) {
- local_inc(__module_ref_addr(module, get_cpu()));
+ unsigned int cpu = get_cpu();
+ local_inc(__module_ref_addr(module, cpu));
+ trace_module_get(module, _THIS_IP_,
+ local_read(__module_ref_addr(module, cpu)));
put_cpu();
}
}
@@ -491,8 +496,11 @@ static inline int try_module_get(struct module *module)

if (module) {
unsigned int cpu = get_cpu();
- if (likely(module_is_live(module)))
+ if (likely(module_is_live(module))) {
local_inc(__module_ref_addr(module, cpu));
+ trace_module_get(module, _THIS_IP_,
+ local_read(__module_ref_addr(module, cpu)));
+ }
else
ret = 0;
put_cpu();
diff --git a/include/trace/events/module.h b/include/trace/events/module.h
new file mode 100644
index 0000000..84160fb
--- /dev/null
+++ b/include/trace/events/module.h
@@ -0,0 +1,126 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM module
+
+#if !defined(_TRACE_MODULE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MODULE_H
+
+#include <linux/tracepoint.h>
+
+#ifdef CONFIG_MODULES
+
+struct module;
+
+#define show_module_flags(flags) __print_flags(flags, "", \
+ { (1UL << TAINT_PROPRIETARY_MODULE), "P" }, \
+ { (1UL << TAINT_FORCED_MODULE), "F" }, \
+ { (1UL << TAINT_CRAP), "C" })
+
+TRACE_EVENT(module_load,
+
+ TP_PROTO(struct module *mod),
+
+ TP_ARGS(mod),
+
+ TP_STRUCT__entry(
+ __field( unsigned int, taints )
+ __string( name, mod->name )
+ ),
+
+ TP_fast_assign(
+ __entry->taints = mod->taints;
+ __assign_str(name, mod->name);
+ ),
+
+ TP_printk("%s %s", __get_str(name), show_module_flags(__entry->taints))
+);
+
+TRACE_EVENT(module_free,
+
+ TP_PROTO(struct module *mod),
+
+ TP_ARGS(mod),
+
+ TP_STRUCT__entry(
+ __string( name, mod->name )
+ ),
+
+ TP_fast_assign(
+ __assign_str(name, mod->name);
+ ),
+
+ TP_printk("%s", __get_str(name))
+);
+
+TRACE_EVENT(module_get,
+
+ TP_PROTO(struct module *mod, unsigned long ip, int refcnt),
+
+ TP_ARGS(mod, ip, refcnt),
+
+ TP_STRUCT__entry(
+ __field( unsigned long, ip )
+ __field( int, refcnt )
+ __string( name, mod->name )
+ ),
+
+ TP_fast_assign(
+ __entry->ip = ip;
+ __entry->refcnt = refcnt;
+ __assign_str(name, mod->name);
+ ),
+
+ TP_printk("%s call_site=%pf refcnt=%d",
+ __get_str(name), (void *)__entry->ip, __entry->refcnt)
+);
+
+TRACE_EVENT(module_put,
+
+ TP_PROTO(struct module *mod, unsigned long ip, int refcnt),
+
+ TP_ARGS(mod, ip, refcnt),
+
+ TP_STRUCT__entry(
+ __field( unsigned long, ip )
+ __field( int, refcnt )
+ __string( name, mod->name )
+ ),
+
+ TP_fast_assign(
+ __entry->ip = ip;
+ __entry->refcnt = refcnt;
+ __assign_str(name, mod->name);
+ ),
+
+ TP_printk("%s call_site=%pf refcnt=%d",
+ __get_str(name), (void *)__entry->ip, __entry->refcnt)
+);
+
+TRACE_EVENT(module_request,
+
+ TP_PROTO(char *name, bool wait, unsigned long ip),
+
+ TP_ARGS(name, wait, ip),
+
+ TP_STRUCT__entry(
+ __field( bool, wait )
+ __field( unsigned long, ip )
+ __string( name, name )
+ ),
+
+ TP_fast_assign(
+ __entry->wait = wait;
+ __entry->ip = ip;
+ __assign_str(name, name);
+ ),
+
+ TP_printk("%s wait=%d call_site=%pf",
+ __get_str(name), (int)__entry->wait, (void *)__entry->ip)
+);
+
+#endif /* CONFIG_MODULES */
+
+#endif /* _TRACE_MODULE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
+
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 385c31a..a922808 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -37,6 +37,8 @@
#include <linux/suspend.h>
#include <asm/uaccess.h>

+#include <trace/events/module.h>
+
extern int max_threads;

static struct workqueue_struct *khelper_wq;
@@ -108,6 +110,8 @@ int __request_module(bool wait, const char *fmt, ...)
return -ENOMEM;
}

+ trace_module_request(module_name, wait, _RET_IP_);
+
ret = call_usermodehelper(modprobe_path, argv, envp,
wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
diff --git a/kernel/module.c b/kernel/module.c
index 0a04983..38bf87a 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -55,6 +55,11 @@
#include <linux/percpu.h>
#include <linux/kmemleak.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/module.h>
+
+EXPORT_TRACEPOINT_SYMBOL(module_get);
+
#if 0
#define DEBUGP printk
#else
@@ -940,6 +945,8 @@ void module_put(struct module *module)
if (module) {
unsigned int cpu = get_cpu();
local_dec(__module_ref_addr(module, cpu));
+ trace_module_put(module, _RET_IP_,
+ local_read(__module_ref_addr(module, cpu)));
/* Maybe they're waiting for us to drop reference? */
if (unlikely(!module_is_live(module)))
wake_up_process(module->waiter);
@@ -1490,6 +1497,8 @@ static int __unlink_module(void *_mod)
/* Free a module, remove from lists, etc (must hold module_mutex). */
static void free_module(struct module *mod)
{
+ trace_module_free(mod);
+
/* Delete from various lists */
stop_machine(__unlink_module, mod, NULL);
remove_notes_attrs(mod);
@@ -2357,6 +2366,8 @@ static noinline struct module *load_module(void __user *umod,
/* Get rid of temporary copy */
vfree(hdr);

+ trace_module_load(mod);
+
/* Done! */
return mod;

--
1.6.3


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