tracing/kprobes: Support custom subsystem for each kprobe event

Support specifying a custom subsystem(group) for each kprobe event.
This allows users to create new group to control several probes
at once, or add events to existing groups as additional tracepoints.

New synopsis:
 p[:[subsys/]event-name] KADDR|KSYM[+offs] [ARGS]

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090910235353.22412.15149.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index a849889..6521681 100644 (file)
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -25,9 +25,10 @@ probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
 
 Synopsis of kprobe_events
 -------------------------
-  p[:EVENT] SYMBOL[+offs]|MEMADDR [FETCHARGS]  : Set a probe
-  r[:EVENT] SYMBOL[+0] [FETCHARGS]             : Set a return probe
+  p[:[GRP/]EVENT] SYMBOL[+offs]|MEMADDR [FETCHARGS]    : Set a probe
+  r[:[GRP/]EVENT] SYMBOL[+0] [FETCHARGS]               : Set a return probe
 
+ GRP           : Group name. If omitted, use "kprobes" for it.
  EVENT         : Event name. If omitted, the event name is generated
                  based on SYMBOL+offs or MEMADDR.
  SYMBOL[+offs] : Symbol+offset where the probe is inserted.

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1746afe..cbc0870 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -36,6 +36,7 @@
 #define MAX_TRACE_ARGS 128
 #define MAX_ARGSTR_LEN 63
 #define MAX_EVENT_NAME_LEN 64
+#define KPROBE_EVENT_SYSTEM "kprobes"
 
 /* currently, trace_kprobe only supports X86. */
 
@@ -265,7 +266,8 @@ static LIST_HEAD(probe_list);
 /*
  * Allocate new trace_probe and initialize it (including kprobes).
  */
-static struct trace_probe *alloc_trace_probe(const char *event,
+static struct trace_probe *alloc_trace_probe(const char *group,
+                                            const char *event,
                                             void *addr,
                                             const char *symbol,
                                             unsigned long offs,
@@ -298,9 +300,16 @@ static struct trace_probe *alloc_trace_probe(const char *event,
        if (!tp->call.name)
                goto error;
 
+       if (!group)
+               goto error;
+       tp->call.system = kstrdup(group, GFP_KERNEL);
+       if (!tp->call.system)
+               goto error;
+
        INIT_LIST_HEAD(&tp->list);
        return tp;
 error:
+       kfree(tp->call.name);
        kfree(tp->symbol);
        kfree(tp);
        return ERR_PTR(-ENOMEM);
@@ -322,6 +331,7 @@ static void free_trace_probe(struct trace_probe *tp)
        for (i = 0; i < tp->nr_args; i++)
                free_probe_arg(&tp->args[i]);
 
+       kfree(tp->call.system);
        kfree(tp->call.name);
        kfree(tp->symbol);
        kfree(tp);
@@ -530,8 +540,8 @@ static int create_trace_probe(int argc, char **argv)
 {
        /*
         * Argument syntax:
-        *  - Add kprobe: p[:EVENT] SYMBOL[+OFFS]|ADDRESS [FETCHARGS]
-        *  - Add kretprobe: r[:EVENT] SYMBOL[+0] [FETCHARGS]
+        *  - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
+        *  - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
         * Fetch args:
         *  aN  : fetch Nth of function argument. (N:0-)
         *  rv  : fetch return value
@@ -549,7 +559,7 @@ static int create_trace_probe(int argc, char **argv)
        struct trace_probe *tp;
        int i, ret = 0;
        int is_return = 0;
-       char *symbol = NULL, *event = NULL, *arg = NULL;
+       char *symbol = NULL, *event = NULL, *arg = NULL, *group = NULL;
        unsigned long offset = 0;
        void *addr = NULL;
        char buf[MAX_EVENT_NAME_LEN];
@@ -566,6 +576,15 @@ static int create_trace_probe(int argc, char **argv)
 
        if (argv[0][1] == ':') {
                event = &argv[0][2];
+               if (strchr(event, '/')) {
+                       group = event;
+                       event = strchr(group, '/') + 1;
+                       event[-1] = '\0';
+                       if (strlen(group) == 0) {
+                               pr_info("Group name is not specifiled\n");
+                               return -EINVAL;
+                       }
+               }
                if (strlen(event) == 0) {
                        pr_info("Event name is not specifiled\n");
                        return -EINVAL;
@@ -592,6 +611,8 @@ static int create_trace_probe(int argc, char **argv)
        argc -= 2; argv += 2;
 
        /* setup a probe */
+       if (!group)
+               group = KPROBE_EVENT_SYSTEM;
        if (!event) {
                /* Make a new event name */
                if (symbol)
@@ -602,7 +623,8 @@ static int create_trace_probe(int argc, char **argv)
                                 is_return ? 'r' : 'p', addr);
                event = buf;
        }
-       tp = alloc_trace_probe(event, addr, symbol, offset, argc, is_return);
+       tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
+                              is_return);
        if (IS_ERR(tp))
                return PTR_ERR(tp);
 
@@ -1217,7 +1239,6 @@ static int register_probe_event(struct trace_probe *tp)
        int ret;
 
        /* Initialize ftrace_event_call */
-       call->system = "kprobes";
        if (probe_is_return(tp)) {
                tp->event.trace = print_kretprobe_event;
                call->raw_init = probe_event_raw_init;