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Commit f52487e9 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Frederic Weisbecker
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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: default avatarMasami 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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 6e9f23d1

Documentation/trace/kprobetrace.txt

+3 −2
Original line number Diff line number Diff line
@@ -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.

kernel/trace/trace_kprobe.c

+27 −6
Original line number Diff line number Diff line
@@ -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;