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>

1 files changed, 27 insertions, 6 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1746afeaabf9..cbc0870dcf5d 100644
--- 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;