stap signal && trace point
作者：互联网
执行 ./install/bin/staprun ./sigkill.ko 结果发现脚本执行命令刷屏了！！
debug_bin]$ ./install/bin/staprun ./sigkill.ko sig[17] SIGCHLD was sent to sh (pid:15237) by exec:ps -->:15239 uid:0 sig[17] SIGCHLD was sent to python (pid:12444) by exec:sh -->:15237 uid:0 sig[34] 0x22 was sent to wafd (pid:11041) by exec:swapper/0 -->:0 uid:0 sig[17] SIGCHLD was sent to sh (pid:15242) by exec:bp_tool -->:15243 uid:0 sig[17] SIGCHLD was sent to sh (pid:15242) by exec:awk -->:15244 uid:0 sig[17] SIGCHLD was sent to sh (pid:15240) by exec:ps -->:15241 uid:0 sig[17] SIGCHLD was sent to plat_srv (pid:3990) by exec:sh -->:15242 uid:0 sig[17] SIGCHLD was sent to python (pid:12444) by exec:sh -->:15240 uid:0 sig[17] SIGCHLD was sent to sh (pid:15245) by exec:bp_tool -->:15246 uid:0 sig[17] SIGCHLD was sent to sh (pid:15245) by exec:awk -->:15247 uid:0 sig[17] SIGCHLD was sent to plat_srv (pid:3990) by exec:sh -->:15245 uid:0 sig[17] SIGCHLD was sent to sh (pid:15248) by exec:bp_tool -->:15249 uid:0 sig[17] SIGCHLD was sent to sh (pid:15248) by exec:awk -->:15250 uid:0 sig[17] SIGCHLD was sent to plat_srv (pid:3990) by exec:sh -->:15248 uid:0 sig[17] SIGCHLD was sent to sh (pid:15251) by exec:ps -->:15252 uid:0 sig[17] SIGCHLD was sent to python (pid:12444) by exec:sh -->:15251 uid:0 sig[17] SIGCHLD was sent to sh (pid:15166) by exec:awk -->:15168 uid:0 sig[17] SIGCHLD was sent to sh (pid:15166) by exec:top -->:15167 uid:0 sig[17] SIGCHLD was sent to python (pid:7298) by exec:sh -->:15166 uid:0 sig[17] SIGCHLD was sent to sh (pid:15253) by exec:ps -->:15254 uid:0 sig[17] SIGCHLD was sent to sh (pid:15253) by exec:grep -->:15255 uid:0 sig[17] SIGCHLD was sent to sh (pid:15253) by exec:grep -->:15257 uid:0 sig[17] SIGCHLD was sent to sh (pid:15253) by exec:grep -->:15256 uid:0 sig[17] SIGCHLD was sent to python (pid:8626) by exec:sh -->:15253 uid:0 sig[17] SIGCHLD was sent to sh (pid:15258) by exec:cat -->:15264 uid:0 sig[17] SIGCHLD was sent to sh (pid:15258) by exec:head -->:15265 uid:0 sig[17] SIGCHLD was sent to sh (pid:15258) by exec:awk -->:15266 uid:0 sig[17] SIGCHLD was sent to python (pid:7298) by exec:sh -->:15258 uid:0 sig[17] SIGCHLD was sent to sh (pid:15259) by exec:ps -->:15260 uid:0
----------------------
sig[17] SIGCHLD was sent to python (pid:8626) by exec:sh -->:15278 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15283 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15284 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15285 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15286 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15287 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15288 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15291 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15289 uid:0
sig[17] SIGCHLD was sent to python (pid:6750) by exec:ethtool -->:15294 uid:0
想不通 为啥 要通过命令来获取信息， netlink 不香么！！
顺便看下 trace_event的实现，以kfree_skb为例
TRACE_EVENT(kfree_skb,
TP_PROTO(struct sk_buff *skb, void *location),
TP_ARGS(skb, location),
TP_STRUCT__entry(
__field( void *, skbaddr )
__field( void *, location )
__field( unsigned short, protocol )
),
TP_fast_assign(
__entry->skbaddr = skb;
__entry->location = location;
__entry->protocol = ntohs(skb->protocol);
),
TP_printk("skbaddr=%p protocol=%u location=%p",
__entry->skbaddr, __entry->protocol, __entry->location)
);
其大概意思是 将当前地址堆栈存在location 变量中；最后输出！！
来看下 trace_event的第一层展开：
#define TRACE_EVENT(name, proto, args, struct, assign, print) \
DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define TRACE_EVENT(name, proto, args, tstruct, assign, print) \
DECLARE_EVENT_CLASS(name, \
PARAMS(proto), \
PARAMS(args), \
PARAMS(tstruct), \
PARAMS(assign), \
PARAMS(print)); \
DEFINE_EVENT(name, name, PARAMS(proto), PARAMS(args));
根据tracepoint.h文件 主要函数为：DEFINE_EVENT 宏定义
#define DEFINE_EVENT(template, name, proto, args) \
DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define DECLARE_TRACE(name, proto, args) \
__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
cpu_online(raw_smp_processor_id()), \
PARAMS(void *__data, proto), \
PARAMS(__data, args))
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
extern struct tracepoint __tracepoint_##name; \// tracepoint变量“__tracepoint_##name”本身
static inline void trace_##name(proto) \// tracepoint桩函数“trace_##name”的定义
{ \
if (static_key_false(&__tracepoint_##name.key)) \
__DO_TRACE(&__tracepoint_##name, \
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
TP_CONDITION(cond),,); \
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
rcu_read_lock_sched_notrace(); \
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace(); \
} \
} \
__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
static inline int \// tracepoint的回调函数注册函数"register_trace_##name"
register_trace_##name(void (*probe)(data_proto), void *data) \
{ \
return tracepoint_probe_register(&__tracepoint_##name, \
(void *)probe, data); \
} \
static inline int \
register_trace_prio_##name(void (*probe)(data_proto), void *data,\
int prio) \
{ \
return tracepoint_probe_register_prio(&__tracepoint_##name, \
(void *)probe, data, prio); \
} \
static inline int \// tracepoint的回调函数反注册函数"unregister_trace_##name"
unregister_trace_##name(void (*probe)(data_proto), void *data) \
{ \
return tracepoint_probe_unregister(&__tracepoint_##name,\
(void *)probe, data); \
} \
static inline void \
check_trace_callback_type_##name(void (*cb)(data_proto)) \
{ \
} \
static inline bool \
trace_##name##_enabled(void) \
{ \
return static_key_false(&__tracepoint_##name.key); \
}
//桩函数中，逐个调用回调函数进行执行
#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
do { \
struct tracepoint_func *it_func_ptr; \
void *it_func; \
void *__data; \
\
if (!(cond)) \
return; \
prercu; \
rcu_read_lock_sched_notrace(); \
it_func_ptr = rcu_dereference_sched((tp)->funcs); \
if (it_func_ptr) { \
do { \
it_func = (it_func_ptr)->func; \
__data = (it_func_ptr)->data; \
((void(*)(proto))(it_func))(args); \
} while ((++it_func_ptr)->func); \
} \
rcu_read_unlock_sched_notrace(); \
postrcu; \
} whil
TRACE_EVENT包含5个参数：(name, proto, args, struct, assign, print)
前面两个参数：proto, args，是给定义tracepoint使用的。在linux/tracepoint.h中构造tracepoint桩函数、callback regitser/unregister函数，在trace/define_trace.h中定义tracepoint变量。
后面三个参数：struct, assign, print，是给trace_event使用的。在trace/trace_events.h，构造trace_event的callback函数，注册到tracepoint。
TRACE_EVENT：
- 创建了一个tracepoint，可以放到kernel代码中；
- 创建了一个回调函数，可以被上述tracepoint调用
- 回调函数必须实现以最快的方式将传递给它的数据记录到trace ringbuffer中。
- 必须创建一个函数能解析从ringbuffer读出的数据，转换成便于用户理解的形式。
在define_trace.h中，宏TRACE_EVENT()第二次的展开：
#undef TRACE_EVENT
#define TRACE_EVENT(name, proto, args, tstruct, assign, print) \
DEFINE_TRACE(name)
//重新宏定义展开
#define DEFINE_TRACE(name) \
DEFINE_TRACE_FN(name, NULL, NULL);
/*
* We have no guarantee that gcc and the linker won't up-align the tracepoint
* structures, so we create an array of pointers that will be used for iteration
* on the tracepoints.
*/
#define DEFINE_TRACE_FN(name, reg, unreg) \
static const char __tpstrtab_##name[] \
__attribute__((section("__tracepoints_strings"))) = #name; \// 定义tracepoint变量“__tracepoint_##name”本身
struct tracepoint __tracepoint_##name \
__attribute__((section("__tracepoints"))) = \
{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\// 将tracepoint变量指针"__tracepoint_ptr_##name"存放到section("__tracepoints_ptrs")
static struct tracepoint * const __tracepoint_ptr_##name __used \
__attribute__((section("__tracepoints_ptrs"))) = \
&__tracepoint_##name;
在随后的trace_events.h中，宏TRACE_EVENT()又进行了多次的展开。宏定义重复多次定义多次展开
太恶心了 ！！ 以为很简单 结果一个宏定义都这复杂
tracepoint.h trace_events.h define_trace.h
这几个文件看的有点蒙蔽
下次要是需要写trace_point 在继续研究！！ 继续打游戏
参考：Using the TRACE_EVENT() part1
标签：__,name,trace,--,signal,&&,was,sent,uid 来源： https://www.cnblogs.com/codestack/p/15095828.html