[RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support

[RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support

[Masami Hiramatsu]

Hi,

These patches introduce perf kprobe command and update kprobe-tracer.
perf kprobe command allows you to add new probe points by C line number
and local variable names.

Usage
-----
 perf kprobe [<options>] -P PROBEDEF [-P PROBEDEF ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -r, --release <rel>   kernel release
    -P, --probe <p|r:[GRP/]NAME,FUNC[+OFFS][@SRC]|@SRC:LINE,ARG[,ARG,...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Examples
--------
1) Add a new kprobe probe on a line of C source code.
./perf kprobe -P 'p:myprobe,@fs/bio.c:162,bv,idx'
Adding new event: p:myprobe bvec_free_bs+17 bv=%bx idx=%cx

2) Add a new kretprobe probe on a function return.
./perf kprobe -P 'r:myretprobe,vfs_read,$rv'
Adding new event: r:myretprobe vfs_read+0 $rv

3) Check it in the perf list.
./perf list
...
  rNNN                                       [raw hardware event descriptor]

  kprobes:myprobe                            [Tracepoint event]
  kprobes:myretprobe                         [Tracepoint event]
  skb:kfree_skb                              [Tracepoint event]
...

4) Check its format

$ cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
name: myprobe
ID: 687
format:
	field:unsigned short common_type;	offset:0;	size:2;
	field:unsigned char common_flags;	offset:2;	size:1;
	field:unsigned char common_preempt_count;	offset:3;	size:1;
	field:int common_pid;	offset:4;	size:4;
	field:int common_lock_depth;	offset:8;	size:4;

	field: unsigned long __probe_ip;	offset:12;	size:4;
	field: int __probe_nargs;	offset:16;	size:4;
	field: unsigned long bv;	offset:20;	size:4;
	field: unsigned long idx;	offset:24;	size:4;


print fmt: "(%lx) bv=%lx idx=%lx", REC->__probe_ip, REC->bv, REC->idx


Syntax Issue
------------
This version picks '-P event-definition' syntax, but I think
'-p event -a arg' is also possible. I'd like to ask you
which you like or support both?


TODO
----
There are still many enhancements required for catching up
'tracing side' of systemtap. I think it should be done one by one.
I hope that systemtap developers cooperate with us on this
development.

 - Support sys_perf_counter_open (non-root)
 - Type support
 - Non-auto static variable
 - Fields of data structure (var->field)
 - Bit fields
 - Array (var[N])
 - Dynamic array indexing (var[var2])
 - String/dynamic arrays (var:string, var[N..M])
 - Force Type casting ((type)var)
 - Non-inline search
 - libdw, libdwfl

Thank you,

---

Masami Hiramatsu (5):
      perf: kprobe command supports without libdwarf
      perf: Support perf kprobe command for kprobe-event setup helper
      tracing/kprobes: Rename fixed field name
      tracing/kprobes: Avoid field name confliction
      tracing/kprobes: Rename special variables syntax


 Documentation/trace/kprobetrace.txt |   10 -
 kernel/trace/trace_kprobe.c         |  124 +++++-
 tools/perf/Makefile                 |   10 +
 tools/perf/builtin-kprobe.c         |  340 +++++++++++++++++
 tools/perf/builtin.h                |    1 
 tools/perf/perf.c                   |    1 
 tools/perf/util/probe-finder.c      |  684 +++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h      |   70 ++++
 8 files changed, 1200 insertions(+), 40 deletions(-)
 create mode 100644 tools/perf/builtin-kprobe.c
 create mode 100644 tools/perf/util/probe-finder.c
 create mode 100644 tools/perf/util/probe-finder.h

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[RFC PATCH tracing/kprobes 1/5] tracing/kprobes: Rename special variables syntax

[Masami Hiramatsu]

Add $ prefix to the special variables(e.g. sa, rv) of kprobe-tracer.
This resolves consistency issue between kprobe_events and perf-kprobe.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 Documentation/trace/kprobetrace.txt |   10 +++---
 kernel/trace/trace_kprobe.c         |   60 ++++++++++++++++++++++-------------
 2 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 9b8f7c6..40caef0 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -36,13 +36,13 @@ Synopsis of kprobe_events
 
  FETCHARGS	: Arguments. Each probe can have up to 128 args.
   %REG	: Fetch register REG
-  sN	: Fetch Nth entry of stack (N >= 0)
-  sa	: Fetch stack address.
   @ADDR	: Fetch memory at ADDR (ADDR should be in kernel)
   @SYM[+|-offs]	: Fetch memory at SYM +|- offs (SYM should be a data symbol)
-  aN	: Fetch function argument. (N >= 0)(*)
-  rv	: Fetch return value.(**)
-  ra	: Fetch return address.(**)
+  $sN	: Fetch Nth entry of stack (N >= 0)
+  $sa	: Fetch stack address.
+  $aN	: Fetch function argument. (N >= 0)(*)
+  $rv	: Fetch return value.(**)
+  $ra	: Fetch return address.(**)
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
   NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 97309d4..f63ead0 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -220,24 +220,24 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
 	int ret = -EINVAL;
 
 	if (ff->func == fetch_argument)
-		ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$a%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_register) {
 		const char *name;
 		name = regs_query_register_name((unsigned int)((long)ff->data));
 		ret = snprintf(buf, n, "%%%s", name);
 	} else if (ff->func == fetch_stack)
-		ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$s%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_memory)
 		ret = snprintf(buf, n, "@0x%p", ff->data);
 	else if (ff->func == fetch_symbol) {
 		struct symbol_cache *sc = ff->data;
 		ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
 	} else if (ff->func == fetch_retvalue)
-		ret = snprintf(buf, n, "rv");
+		ret = snprintf(buf, n, "$rv");
 	else if (ff->func == fetch_ip)
-		ret = snprintf(buf, n, "ra");
+		ret = snprintf(buf, n, "$ra");
 	else if (ff->func == fetch_stack_address)
-		ret = snprintf(buf, n, "sa");
+		ret = snprintf(buf, n, "$sa");
 	else if (ff->func == fetch_indirect) {
 		struct indirect_fetch_data *id = ff->data;
 		size_t l = 0;
@@ -429,12 +429,10 @@ static int split_symbol_offset(char *symbol, unsigned long *offset)
 #define PARAM_MAX_ARGS 16
 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 
-static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
 {
 	int ret = 0;
 	unsigned long param;
-	long offset;
-	char *tmp;
 
 	switch (arg[0]) {
 	case 'a':	/* argument */
@@ -456,14 +454,6 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 		} else
 			ret = -EINVAL;
 		break;
-	case '%':	/* named register */
-		ret = regs_query_register_offset(arg + 1);
-		if (ret >= 0) {
-			ff->func = fetch_register;
-			ff->data = (void *)(unsigned long)ret;
-			ret = 0;
-		}
-		break;
 	case 's':	/* stack */
 		if (arg[1] == 'a') {
 			ff->func = fetch_stack_address;
@@ -478,6 +468,31 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 			}
 		}
 		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+{
+	int ret = 0;
+	unsigned long param;
+	long offset;
+	char *tmp;
+
+	switch (arg[0]) {
+	case '$':
+		ret = parse_probe_vars(arg + 1, ff, is_return);
+		break;
+	case '%':	/* named register */
+		ret = regs_query_register_offset(arg + 1);
+		if (ret >= 0) {
+			ff->func = fetch_register;
+			ff->data = (void *)(unsigned long)ret;
+			ret = 0;
+		}
+		break;
 	case '@':	/* memory or symbol */
 		if (isdigit(arg[1])) {
 			ret = strict_strtoul(arg + 1, 0, &param);
@@ -489,8 +504,7 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 			ret = split_symbol_offset(arg + 1, &offset);
 			if (ret)
 				break;
-			ff->data = alloc_symbol_cache(arg + 1,
-							      offset);
+			ff->data = alloc_symbol_cache(arg + 1, offset);
 			if (ff->data)
 				ff->func = fetch_symbol;
 			else
@@ -544,11 +558,11 @@ static int create_trace_probe(int argc, char **argv)
 	 *  - 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
-	 *  ra	: fetch return address
-	 *  sa	: fetch stack address
-	 *  sN	: fetch Nth of stack (N:0-)
+	 *  $aN	: fetch Nth of function argument. (N:0-)
+	 *  $rv	: fetch return value
+	 *  $ra	: fetch return address
+	 *  $sa	: fetch stack address
+	 *  $sN	: fetch Nth of stack (N:0-)
 	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)
 	 *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 	 *  %REG	: fetch register REG


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[RFC PATCH tracing/kprobes 2/5] tracing/kprobes: Avoid field name confliction

[Masami Hiramatsu]

Check whether the argument name is conflict with other field names.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 kernel/trace/trace_kprobe.c |   64 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f63ead0..c09411f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -38,6 +38,24 @@
 #define MAX_EVENT_NAME_LEN 64
 #define KPROBE_EVENT_SYSTEM "kprobes"
 
+/* Reserved field names */
+#define FIELD_STRING_IP "ip"
+#define FIELD_STRING_NARGS "nargs"
+#define FIELD_STRING_RETIP "ret_ip"
+#define FIELD_STRING_FUNC "func"
+
+const char *reserved_field_names[] = {
+	"common_type",
+	"common_flags",
+	"common_preempt_count",
+	"common_pid",
+	"common_tgid",
+	FIELD_STRING_IP,
+	FIELD_STRING_NARGS,
+	FIELD_STRING_RETIP,
+	FIELD_STRING_FUNC,
+};
+
 /* currently, trace_kprobe only supports X86. */
 
 struct fetch_func {
@@ -551,6 +569,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 	return ret;
 }
 
+/* Return 1 if name is reserved or already used by another argument */
+static int conflict_field_name(const char *name,
+			       struct probe_arg *args, int narg)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
+		if (!strcmp(reserved_field_names[i], name))
+			return 1;
+	for (i = 0; i < narg; i++)
+		if (!strcmp(args[i].name, name))
+			return 1;
+	return 0;
+}
+
 static int create_trace_probe(int argc, char **argv)
 {
 	/*
@@ -652,6 +684,12 @@ static int create_trace_probe(int argc, char **argv)
 			*arg++ = '\0';
 		else
 			arg = argv[i];
+
+		if (conflict_field_name(argv[i], tp->args, i)) {
+			ret = -EINVAL;
+			goto error;
+		}
+
 		tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
 
 		/* Parse fetch argument */
@@ -1054,8 +1092,8 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
 	if (!ret)
 		return ret;
 
-	DEFINE_FIELD(unsigned long, ip, "ip", 0);
-	DEFINE_FIELD(int, nargs, "nargs", 1);
+	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
 	/* Set argument names as fields */
 	for (i = 0; i < tp->nr_args; i++)
 		DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1072,9 +1110,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
 	if (!ret)
 		return ret;
 
-	DEFINE_FIELD(unsigned long, func, "func", 0);
-	DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
-	DEFINE_FIELD(int, nargs, "nargs", 1);
+	DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
+	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
+	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
 	/* Set argument names as fields */
 	for (i = 0; i < tp->nr_args; i++)
 		DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1123,15 +1161,16 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
 	int ret, i;
 	struct trace_probe *tp = (struct trace_probe *)call->data;
 
-	SHOW_FIELD(unsigned long, ip, "ip");
-	SHOW_FIELD(int, nargs, "nargs");
+	SHOW_FIELD(unsigned long, ip, FIELD_STRING_IP);
+	SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
 
 	/* Show fields */
 	for (i = 0; i < tp->nr_args; i++)
 		SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
 	trace_seq_puts(s, "\n");
 
-	return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
+	return __probe_event_show_format(s, tp, "(%lx)",
+					 "REC->" FIELD_STRING_IP);
 }
 
 static int kretprobe_event_show_format(struct ftrace_event_call *call,
@@ -1141,9 +1180,9 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
 	int ret, i;
 	struct trace_probe *tp = (struct trace_probe *)call->data;
 
-	SHOW_FIELD(unsigned long, func, "func");
-	SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
-	SHOW_FIELD(int, nargs, "nargs");
+	SHOW_FIELD(unsigned long, func, FIELD_STRING_FUNC);
+	SHOW_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP);
+	SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
 
 	/* Show fields */
 	for (i = 0; i < tp->nr_args; i++)
@@ -1151,7 +1190,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
 	trace_seq_puts(s, "\n");
 
 	return __probe_event_show_format(s, tp, "(%lx <- %lx)",
-					  "REC->func, REC->ret_ip");
+					 "REC->" FIELD_STRING_FUNC
+					 ", REC->" FIELD_STRING_RETIP);
 }
 
 #ifdef CONFIG_EVENT_PROFILE


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[RFC PATCH tracing/kprobes 3/5] tracing/kprobes: Rename fixed field name

[Masami Hiramatsu]

Rename probe-common fixed field name to the name harder conflictable,
because current 'ip', 'func', and other probe field names are easy to
conflict with user-specified variable names.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 kernel/trace/trace_kprobe.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c09411f..802effe 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -39,10 +39,10 @@
 #define KPROBE_EVENT_SYSTEM "kprobes"
 
 /* Reserved field names */
-#define FIELD_STRING_IP "ip"
-#define FIELD_STRING_NARGS "nargs"
-#define FIELD_STRING_RETIP "ret_ip"
-#define FIELD_STRING_FUNC "func"
+#define FIELD_STRING_IP "__probe_ip"
+#define FIELD_STRING_NARGS "__probe_nargs"
+#define FIELD_STRING_RETIP "__probe_ret_ip"
+#define FIELD_STRING_FUNC "__probe_func"
 
 const char *reserved_field_names[] = {
 	"common_type",


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[RFC PATCH tracing/kprobes 4/5] perf: Support perf kprobe command for kprobe-event setup helper

[Masami Hiramatsu]

Support perf kprobe command for kprobe-event setup helper. This allows
user to define kprobe events by C expressions (C line numbers, C function
names, and C local variables).

Usage
-----
 perf kprobe [<options>] -P PROBEDEF [-P PROBEDEF ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -r, --release <rel>   kernel release
    -P, --probe <p|r:[GRP/]NAME,FUNC[+OFFS][@SRC]|@SRC:LINE,ARG[,ARG,...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)


Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 tools/perf/Makefile            |   10 +
 tools/perf/builtin-kprobe.c    |  312 ++++++++++++++++++
 tools/perf/builtin.h           |    1 
 tools/perf/perf.c              |    3 
 tools/perf/util/probe-finder.c |  684 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h |   68 ++++
 6 files changed, 1078 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/builtin-kprobe.c
 create mode 100644 tools/perf/util/probe-finder.c
 create mode 100644 tools/perf/util/probe-finder.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index b5f1953..1379e3f 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -419,6 +419,16 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
 	msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel);
 endif
 
+ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+	msg := $(warning No libdwarf.h found, disables kprobe support. Please install libdwarf-dev/libdwarf-devel);
+else
+	EXTLIBS += -lelf -ldwarf
+	LIB_H += util/probe-finder.h
+	LIB_OBJS += util/probe-finder.o
+	BUILTIN_OBJS += builtin-kprobe.o
+	BASIC_CFLAGS += -DSUPPORT_DWARF
+endif
+
 ifdef NO_DEMANGLE
 	BASIC_CFLAGS += -DNO_DEMANGLE
 else
diff --git a/tools/perf/builtin-kprobe.c b/tools/perf/builtin-kprobe.c
new file mode 100644
index 0000000..9e4596b
--- /dev/null
+++ b/tools/perf/builtin-kprobe.c
@@ -0,0 +1,312 @@
+/*
+ * builtin-kprobe.c
+ *
+ * Builtin kprobe command: Set up kprobe events by C expression
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "perf.h"
+#include "builtin.h"
+#include "util/util.h"
+#include "util/parse-options.h"
+#include "util/parse-events.h"	/* For debugfs_path */
+#include "util/probe-finder.h"
+
+/* Default vmlinux search paths */
+#define NR_SEARCH_PATH 3
+const char *default_search_path[NR_SEARCH_PATH] = {
+"/lib/modules/%s/build/vmlinux",		/* Custom build kernel */
+"/usr/lib/debug/lib/modules/%s/vmlinux",	/* Red Hat debuginfo */
+"/boot/vmlinux-debug-%s",			/* Ubuntu */
+};
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBES 128
+
+/* Session management structure */
+static struct {
+	char *vmlinux;
+	char *release;
+	int nr_probe;
+	struct probe_point probes[MAX_PROBES];
+	char *events[MAX_PROBES];
+} session;
+
+static void semantic_error(const char *msg)
+{
+	fprintf(stderr, "Semantic error: %s\n", msg);
+	exit(1);
+}
+
+#define MAX_PROBE_ARGS 128
+
+static int parse_probepoint(const struct option *opt __used,
+			    const char *str, int unset __used)
+{
+	char *argv[MAX_PROBE_ARGS];
+	int argc, i;
+	char *arg, *ptr;
+	struct probe_point *pp;
+	int retp = 0;
+
+	debug("Probe-define(%d): %s\n", session.nr_probe, str);
+	pp = &session.probes[session.nr_probe];
+	if (!str)
+		return 0;
+	ptr = session.events[session.nr_probe] = strdup(str);
+	if (ptr[0] == 'r')
+		retp = 1;
+	else if (ptr[0] != 'p')
+		semantic_error("You must specify 'p'(kprobe) or"
+				" 'r'(kretprobe) first.");
+	argc = 0;
+	while (*++ptr) {
+		if (*ptr == ',') {
+			*ptr = '\0';
+			argv[argc] = ptr + 1;
+			debug("argv[%d]=%s\n", argc, ptr+1);
+			if (++argc == MAX_PROBE_ARGS)
+				semantic_error("Too many arguments");
+		}
+	}
+
+	if (++session.nr_probe == MAX_PROBES)
+		semantic_error("Too many probes");
+
+	arg = argv[0];
+
+	if (arg[0] == '@') {
+		/* Source Line */
+		arg++;
+		ptr = strchr(arg, ':');
+		if (!ptr || ptr[1] == '\0')
+			semantic_error("Line number is required.");
+		*ptr++ = '\0';
+		pp->file = arg;
+		if (strlen(arg) == 0)
+			semantic_error("No file name.");
+		pp->line = atoi(ptr);
+		debug("file:%s line:%d\n", pp->file, pp->line);
+	} else {
+		/* Function name */
+		pp->function = arg;
+		ptr = strchr(arg, '+');
+		if (ptr) {
+			if (ptr[1] == '\0' || ptr[1] == '@')
+				semantic_error("Offset is required.");
+			*ptr++ = '\0';
+			pp->offset = atoi(ptr);
+			arg = ptr;
+		}
+		ptr = strchr(arg, '@');
+		if (ptr) {
+			*ptr++ = '\0';
+			pp->file = ptr;
+		}
+		debug("symbol:%s file:%s offset:%d\n",
+		      pp->function, pp->file, pp->offset);
+	}
+
+	pp->nr_args = argc - 1;
+	if (pp->nr_args > 0) {
+		pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
+		memcpy(pp->args, &argv[1], sizeof(char *) * pp->nr_args);
+	}
+	if (retp)
+		for (i = 0; i < pp->nr_args; i++)
+			if (is_c_varname(pp->args[i]))
+				semantic_error("You can't specify local"
+						" variable for kretprobe");
+	debug("%d arguments\n", pp->nr_args);
+	return 0;
+}
+
+static int open_default_vmlinux(void)
+{
+	struct utsname uts;
+	char fname[MAX_PATH_LEN];
+	int fd, ret, i;
+
+	if (!session.release) {
+		ret = uname(&uts);
+		if (ret) {
+			debug("uname() failed.\n");
+			return -errno;
+		}
+		session.release = uts.release;
+	}
+	for (i = 0; i < NR_SEARCH_PATH; i++) {
+		ret = snprintf(fname, MAX_PATH_LEN,
+			       default_search_path[i], session.release);
+		if (ret >= MAX_PATH_LEN || ret < 0) {
+			debug("Filename(%d,%s) is too long.\n", i, uts.release);
+			errno = E2BIG;
+			return -E2BIG;
+		}
+		debug("try to open %s\n", fname);
+		fd = open(fname, O_RDONLY);
+		if (fd >= 0)
+			break;
+	}
+	return fd;
+}
+
+static const char * const kprobe_usage[] = {
+	"perf kprobe [<options>] -P PROBEDEF [-P PROBEDEF ...]",
+	NULL
+};
+
+static const struct option options[] = {
+	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
+		"vmlinux/module pathname"),
+	OPT_STRING('r', "release", &session.release, "rel", "kernel release"),
+	OPT_CALLBACK('P', "probe", NULL,
+		"p|r:[GRP/]NAME,FUNC[+OFFS][@SRC]|@SRC:LINE,ARG[,ARG,...]",
+		"probe point definition, where\n"
+		"\t\tp:\tkprobe probe\n"
+		"\t\tr:\tkretprobe probe\n"
+		"\t\tGRP:\tGroup name (optional)\n"
+		"\t\tNAME:\tEvent name\n"
+		"\t\tFUNC:\tFunction name\n"
+		"\t\tOFFS:\tOffset from function entry (in byte)\n"
+		"\t\tSRC:\tSource code path\n"
+		"\t\tLINE:\tLine number\n"
+		"\t\tARG:\tProbe argument (local variable name or\n"
+		"\t\t\tkprobe-tracer argument format is supported.)\n",
+		parse_probepoint),
+	OPT_END()
+};
+
+static int write_new_event(int fd, const char *buf)
+{
+	int ret;
+
+	printf("Adding new event: %s\n", buf);
+	ret = write(fd, buf, strlen(buf));
+	if (ret <= 0)
+		perror("Error: Failed to create event");
+
+	return ret;
+}
+
+#define MAX_CMDLEN 256
+
+static int synthesize_probepoint(struct probe_point *pp)
+{
+	char *buf;
+	int i, len, ret;
+	pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
+	len = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
+	for (i = 0; i < pp->nr_args; i++) {
+		ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
+			       pp->args[i]);
+		if (ret <= 0 || ret >= MAX_CMDLEN - len) {
+			free(pp->probes[0]);
+			return -E2BIG;
+		}
+		len += ret;
+	}
+	return pp->found = 1;
+}
+
+int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
+{
+	int i, j, fd, ret, need_dwarf = 0;
+	struct probe_point *pp;
+	char buf[MAX_CMDLEN];
+
+	argc = parse_options(argc, argv, options, kprobe_usage,
+		PARSE_OPT_STOP_AT_NON_OPTION);
+	if (argc || session.nr_probe == 0)
+		usage_with_options(kprobe_usage, options);
+
+	/* Synthesize return probes */
+	for (j = 0; j < session.nr_probe; j++) {
+		if (session.events[j][0] != 'r') {
+			need_dwarf = 1;
+			continue;
+		}
+		ret = synthesize_probepoint(&session.probes[j]);
+		if (ret < 0)
+			semantic_error("probe point is too long.");
+	}
+
+	if (!need_dwarf)
+		goto setup_probes;
+
+	if (session.vmlinux)
+		fd = open(session.vmlinux, O_RDONLY);
+	else
+		fd = open_default_vmlinux();
+	if (fd < 0) {
+		perror("vmlinux/module file open");
+		return -1;
+	}
+
+	/* Searching probe points */
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found)
+			continue;
+
+		lseek(fd, SEEK_SET, 0);
+		ret = find_probepoint(fd, pp);
+		if (ret <= 0) {
+			fprintf(stderr, "Error: No probe point found.\n");
+			return -1;
+		}
+		debug("probe event %s found\n", session.events[j]);
+	}
+	close(fd);
+
+setup_probes:
+	/* Settng up probe points */
+	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
+	fd = open(buf, O_WRONLY, O_APPEND);
+	if (fd < 0) {
+		perror("kprobe_events open");
+		return -1;
+	}
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found == 1) {
+			snprintf(buf, MAX_CMDLEN, "%s %s\n",
+				session.events[j], pp->probes[0]);
+			write_new_event(fd, buf);
+		} else
+			for (i = 0; i < pp->found; i++) {
+				snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
+					session.events[j], i, pp->probes[i]);
+				write_new_event(fd, buf);
+			}
+	}
+	close(fd);
+	return 0;
+}
+
diff --git a/tools/perf/builtin.h b/tools/perf/builtin.h
index e11d8d2..2ebcd9c 100644
--- a/tools/perf/builtin.h
+++ b/tools/perf/builtin.h
@@ -25,5 +25,6 @@ extern int cmd_timechart(int argc, const char **argv, const char *prefix);
 extern int cmd_top(int argc, const char **argv, const char *prefix);
 extern int cmd_trace(int argc, const char **argv, const char *prefix);
 extern int cmd_version(int argc, const char **argv, const char *prefix);
+extern int cmd_kprobe(int argc, const char **argv, const char *prefix);
 
 #endif
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 19fc7fe..c073924 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -295,6 +295,9 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "version", cmd_version, 0 },
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
+#ifdef SUPPORT_DWARF
+		{ "kprobe", cmd_kprobe, 0 },
+#endif
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
new file mode 100644
index 0000000..75edf02
--- /dev/null
+++ b/tools/perf/util/probe-finder.c
@@ -0,0 +1,684 @@
+/*
+ * probe-finder.c : C expression to kprobe event converter
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include "probe-finder.h"
+
+
+/* Dwarf_Die Linkage to parent Die */
+struct die_link {
+	struct die_link *parent;	/* Parent die */
+	Dwarf_Die die;			/* Current die */
+};
+
+static Dwarf_Debug __dw_debug;
+static Dwarf_Error __dw_error;
+
+static void msg_exit(int ret, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "Error:  ");
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	fprintf(stderr, "\n");
+	exit(ret);
+}
+
+
+/*
+ * Generic dwarf analysis helpers
+ */
+
+#define X86_32_MAX_REGS 8
+const char *x86_32_regs_table[X86_32_MAX_REGS] = {
+	"%ax",
+	"%cx",
+	"%dx",
+	"%bx",
+	"$sa",	/* Stack address */
+	"%bp",
+	"%si",
+	"%di",
+};
+
+#define X86_64_MAX_REGS 16
+const char *x86_64_regs_table[X86_64_MAX_REGS] = {
+	"%ax",
+	"%dx",
+	"%cx",
+	"%bx",
+	"%si",
+	"%di",
+	"%bp",
+	"%sp",
+	"%r8",
+	"%r9",
+	"%r10",
+	"%r11",
+	"%r12",
+	"%r13",
+	"%r14",
+	"%r15",
+};
+
+/* TODO: switching by dwarf address size */
+#ifdef __x86_64__
+#define ARCH_MAX_REGS X86_64_MAX_REGS
+#define arch_regs_table x86_64_regs_table
+#else
+#define ARCH_MAX_REGS X86_32_MAX_REGS
+#define arch_regs_table x86_32_regs_table
+#endif
+
+/* Return architecture dependent register string (for kprobe-tracer) */
+static const char *get_arch_regstr(unsigned int n)
+{
+	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
+}
+
+/*
+ * Compare the tail of two strings.
+ * Return 0 if whole of either string is same as another's tail part.
+ */
+static int strtailcmp(const char *s1, const char *s2)
+{
+	int i1 = strlen(s1);
+	int i2 = strlen(s2);
+	while (--i1 > 0 && --i2 > 0) {
+		if (s1[i1] != s2[i2])
+			return s1[i1] - s2[i2];
+	}
+	return 0;
+}
+
+/* Find the fileno of the target file. */
+static Dwarf_Unsigned die_get_fileno(Dwarf_Die cu_die, const char *fname)
+{
+	Dwarf_Signed cnt, i;
+	Dwarf_Unsigned found = 0;
+	char **srcs;
+	int ret;
+
+	if (!fname)
+		return 0;
+
+	ret = dwarf_srcfiles(cu_die, &srcs, &cnt, &__dw_error);
+	if (ret == DW_DLV_OK) {
+		for (i = 0; i < cnt && !found; i++) {
+			if (strtailcmp(srcs[i], fname) == 0)
+				found = i + 1;
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		}
+		for (; i < cnt; i++)
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		dwarf_dealloc(__dw_debug, srcs, DW_DLA_LIST);
+	}
+	if (found)
+		debug("found fno: %d\n", (int)found);
+	return found;
+}
+
+/* Compare diename and tname */
+static int die_compare_name(Dwarf_Die die, const char *tname)
+{
+	char *name;
+	int ret;
+	ret = dwarf_diename(die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = strcmp(tname, name);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else
+		ret = -1;
+	return ret;
+}
+
+/* Check the address is in the subprogram(function). */
+static int die_within_subprogram(Dwarf_Die sp_die, Dwarf_Addr addr,
+				 Dwarf_Signed *offs)
+{
+	Dwarf_Addr lopc, hipc;
+	int ret;
+
+	/* TODO: check ranges */
+	ret = dwarf_lowpc(sp_die, &lopc, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_NO_ENTRY)
+		return 0;
+	ret = dwarf_highpc(sp_die, &hipc, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	if (lopc <= addr && addr < hipc) {
+		*offs = addr - lopc;
+		return 1;
+	} else
+		return 0;
+}
+
+/* Check the die is inlined function */
+static Dwarf_Bool die_inlined_subprogram(Dwarf_Die die)
+{
+	/* TODO: check strictly */
+	Dwarf_Bool inl;
+	int ret;
+
+	ret = dwarf_hasattr(die, DW_AT_inline, &inl, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	return inl;
+}
+
+/* Get the offset of abstruct_origin */
+static Dwarf_Off die_get_abstract_origin(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Off cu_offs;
+	int ret;
+
+	ret = dwarf_attr(die, DW_AT_abstract_origin, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &cu_offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+	return cu_offs;
+}
+
+/* Get entry pc(or low pc, 1st entry of ranges)  of the die */
+static Dwarf_Addr die_get_entrypc(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Addr addr;
+	Dwarf_Off offs;
+	Dwarf_Ranges *ranges;
+	Dwarf_Signed cnt;
+	int ret;
+
+	/* Try to get entry pc */
+	ret = dwarf_attr(die, DW_AT_entry_pc, &attr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = dwarf_formaddr(attr, &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+		return addr;
+	}
+
+	/* Try to get low pc */
+	ret = dwarf_lowpc(die, &addr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return addr;
+
+	/* Try to get ranges */
+	ret = dwarf_attr(die, DW_AT_ranges, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_get_ranges(__dw_debug, offs, &ranges, &cnt, NULL,
+				&__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	addr = ranges[0].dwr_addr1;
+	dwarf_ranges_dealloc(__dw_debug, ranges, cnt);
+	return addr;
+}
+
+/*
+ * Search a Die from Die tree.
+ * Note: cur_link->die should be deallocated in this function.
+ */
+static int __search_die_tree(struct die_link *cur_link,
+			     int (*die_cb)(struct die_link *, void *),
+			     void *data)
+{
+	Dwarf_Die new_die;
+	struct die_link new_link;
+	int ret;
+
+	if (!die_cb)
+		return 0;
+
+	/* Check current die */
+	while (!(ret = die_cb(cur_link, data))) {
+		/* Check child die */
+		ret = dwarf_child(cur_link->die, &new_die, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_OK) {
+			new_link.parent = cur_link;
+			new_link.die = new_die;
+			ret = __search_die_tree(&new_link, die_cb, data);
+			if (ret)
+				break;
+		}
+
+		/* Move to next sibling */
+		ret = dwarf_siblingof(__dw_debug, cur_link->die, &new_die,
+				      &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+		cur_link->die = new_die;
+		if (ret == DW_DLV_NO_ENTRY)
+			return 0;
+	}
+	dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+	return ret;
+}
+
+/* Search a die in its children's die tree */
+static int search_die_from_children(Dwarf_Die parent_die,
+				    int (*die_cb)(struct die_link *, void *),
+				    void *data)
+{
+	struct die_link new_link;
+	int ret;
+
+	new_link.parent = NULL;
+	ret = dwarf_child(parent_die, &new_link.die, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return __search_die_tree(&new_link, die_cb, data);
+	else
+		return 0;
+}
+
+/* Find a locdesc corresponding to the address */
+static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
+			    Dwarf_Addr addr)
+{
+	Dwarf_Signed lcnt;
+	Dwarf_Locdesc **llbuf;
+	int ret, i;
+
+	ret = dwarf_loclist_n(attr, &llbuf, &lcnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = DW_DLV_NO_ENTRY;
+	for (i = 0; i < lcnt; ++i) {
+		if (llbuf[i]->ld_lopc <= addr &&
+		    llbuf[i]->ld_hipc > addr) {
+			memcpy(desc, llbuf[i], sizeof(Dwarf_Locdesc));
+			desc->ld_s =
+				malloc(sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ERR_IF(desc->ld_s == NULL);
+			memcpy(desc->ld_s, llbuf[i]->ld_s,
+				sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ret = DW_DLV_OK;
+			break;
+		}
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	/* Releasing loop */
+	for (; i < lcnt; ++i) {
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	dwarf_dealloc(__dw_debug, llbuf, DW_DLA_LIST);
+	return ret;
+}
+
+/*
+ * Probe finder related functions
+ */
+
+/* Show a location */
+static void show_location(Dwarf_Loc *loc, struct probe_finder *pf)
+{
+	Dwarf_Small op;
+	Dwarf_Unsigned regn;
+	Dwarf_Signed offs;
+	int deref = 0, ret;
+	const char *regs;
+
+	op = loc->lr_atom;
+
+	/* If this is based on frame buffer, set the offset */
+	if (op == DW_OP_fbreg) {
+		deref = 1;
+		offs = (Dwarf_Signed)loc->lr_number;
+		op = pf->fbloc.ld_s[0].lr_atom;
+		loc = &pf->fbloc.ld_s[0];
+	} else
+		offs = 0;
+
+	if (op >= DW_OP_breg0 && op <= DW_OP_breg31) {
+		regn = op - DW_OP_breg0;
+		offs += (Dwarf_Signed)loc->lr_number;
+		deref = 1;
+	} else if (op >= DW_OP_reg0 && op <= DW_OP_reg31) {
+		regn = op - DW_OP_reg0;
+	} else if (op == DW_OP_bregx) {
+		regn = loc->lr_number;
+		offs += (Dwarf_Signed)loc->lr_number2;
+		deref = 1;
+	} else if (op == DW_OP_regx) {
+		regn = loc->lr_number;
+	} else
+		msg_exit(-EINVAL, "Dwarf_OP %d is not supported.\n", op);
+
+	regs = get_arch_regstr(regn);
+	if (!regs)
+		msg_exit(-EINVAL, "%lld exceeds max register number.\n", regn);
+
+	if (deref)
+		ret = snprintf(pf->buf, pf->len,
+				 " %s=%+lld(%s)", pf->var, offs, regs);
+	else
+		ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= pf->len);
+}
+
+/* Show a variables in kprobe event format */
+static void show_variable(Dwarf_Die vr_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Locdesc ld;
+	int ret;
+
+	ret = dwarf_attr(vr_die, DW_AT_location, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
+	ERR_IF(ret != DW_DLV_OK);
+	/* TODO? */
+	ERR_IF(ld.ld_cents != 1);
+	show_location(&ld.ld_s[0], pf);
+	free(ld.ld_s);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+}
+
+static int variable_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if ((tag == DW_TAG_formal_parameter ||
+	     tag == DW_TAG_variable) &&
+	    (die_compare_name(dlink->die, pf->var) == 0)) {
+		show_variable(dlink->die, pf);
+		return 1;
+	}
+	/* TODO: Support struct members and arrays */
+	return 0;
+}
+
+/* Find a variable in a subprogram die */
+static void find_variable(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	int ret;
+
+	if (!is_c_varname(pf->var)) {
+		/* Output raw parameters */
+		ret = snprintf(pf->buf, pf->len, " %s", pf->var);
+		ERR_IF(ret < 0);
+		ERR_IF(ret >= pf->len);
+		return ;
+	}
+
+	debug("Searching '%s' variable in context.\n", pf->var);
+	/* Search child die for local variables and parameters. */
+	ret = search_die_from_children(sp_die, variable_callback, pf);
+	if (!ret)
+		msg_exit(-1, "Failed to find '%s' in this function.\n",
+			 pf->var);
+}
+
+/* Get a frame base on the address */
+static void get_current_frame_base(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	int ret;
+
+	ret = dwarf_attr(sp_die, DW_AT_frame_base, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = attr_get_locdesc(attr, &pf->fbloc, (pf->addr - pf->cu_base));
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+}
+
+static void free_current_frame_base(struct probe_finder *pf)
+{
+	free(pf->fbloc.ld_s);
+	memset(&pf->fbloc, 0, sizeof(Dwarf_Locdesc));
+}
+
+/* Show a probe point to output buffer */
+static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
+			    struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	char *name;
+	char tmp[MAX_PROBE_BUFFER];
+	int ret, i, len;
+
+	/* Output name of probe point */
+	ret = dwarf_diename(sp_die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
+				(unsigned int)offs);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else {
+		/* This function has no name. */
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%llx", pf->addr);
+	}
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= MAX_PROBE_BUFFER);
+	len = ret;
+
+	/* Find each argument */
+	get_current_frame_base(sp_die, pf);
+	for (i = 0; i < pp->nr_args; i++) {
+		pf->var = pp->args[i];
+		pf->buf = &tmp[len];
+		pf->len = MAX_PROBE_BUFFER - len;
+		find_variable(sp_die, pf);
+		len += strlen(pf->buf);
+	}
+	free_current_frame_base(pf);
+
+	pp->probes[pp->found] = strdup(tmp);
+	pp->found++;
+}
+
+static int probeaddr_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	Dwarf_Signed offs;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	/* Check the address is in this subprogram */
+	if (tag == DW_TAG_subprogram &&
+	    die_within_subprogram(dlink->die, pf->addr, &offs)) {
+		show_probepoint(dlink->die, offs, pf);
+		return 1;
+	}
+	return 0;
+}
+
+/* Find probe point from its line number */
+static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	Dwarf_Signed cnt, i;
+	Dwarf_Line *lines;
+	Dwarf_Unsigned lineno = 0;
+	Dwarf_Addr addr;
+	Dwarf_Unsigned fno;
+	int ret;
+
+	ret = dwarf_srclines(cu_die, &lines, &cnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	for (i = 0; i < cnt; i++) {
+		ret = dwarf_line_srcfileno(lines[i], &fno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (fno != pf->fno)
+			continue;
+
+		ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (lineno != (Dwarf_Unsigned)pp->line)
+			continue;
+
+		ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		debug("Probe point found: 0x%llx\n", addr);
+		pf->addr = addr;
+		/* Search a real subprogram including this line, */
+		ret = search_die_from_children(cu_die, probeaddr_callback, pf);
+		if (ret == 0)
+			msg_exit(-1,
+				 "Probe point is not found in subprograms.\n");
+		/* Continuing, because target line might be inlined. */
+	}
+	dwarf_srclines_dealloc(__dw_debug, lines, cnt);
+}
+
+/* Search function from function name */
+static int probefunc_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	struct probe_point *pp = pf->pp;
+	struct die_link *lk;
+	Dwarf_Signed offs;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (tag == DW_TAG_subprogram) {
+		if (die_compare_name(dlink->die, pp->function) == 0) {
+			if (die_inlined_subprogram(dlink->die)) {
+				/* Inlined function, save it. */
+				ret = dwarf_die_CU_offset(dlink->die,
+							  &pf->inl_offs,
+							  &__dw_error);
+				ERR_IF(ret != DW_DLV_OK);
+				debug("inline definition offset %lld\n",
+					pf->inl_offs);
+				return 0;
+			}
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			/* TODO: Check the address in this function */
+			show_probepoint(dlink->die, pp->offset, pf);
+			/* Continue to search */
+		}
+	} else if (tag == DW_TAG_inlined_subroutine && pf->inl_offs) {
+		if (die_get_abstract_origin(dlink->die) == pf->inl_offs) {
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			debug("found inline addr: 0x%llx\n", pf->addr);
+			/* Inlined function. Get a real subprogram */
+			for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
+				tag = 0;
+				dwarf_tag(lk->die, &tag, &__dw_error);
+				ERR_IF(ret == DW_DLV_ERROR);
+				if (tag == DW_TAG_subprogram &&
+				    !die_inlined_subprogram(lk->die))
+					goto found;
+			}
+			msg_exit(-1, "Failed to find real subprogram.\n");
+found:
+			/* Get offset from subprogram */
+			ret = die_within_subprogram(lk->die, pf->addr, &offs);
+			ERR_IF(!ret);
+			show_probepoint(lk->die, offs, pf);
+			/* Continue to search */
+		}
+	}
+	return 0;
+}
+
+static void find_by_func(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	search_die_from_children(cu_die, probefunc_callback, pf);
+}
+
+/* Find a probe point */
+int find_probepoint(int fd, struct probe_point *pp)
+{
+	Dwarf_Half addr_size = 0;
+	Dwarf_Unsigned next_cuh = 0;
+	Dwarf_Die cu_die = 0;
+	int cu_number = 0, ret;
+	struct probe_finder pf = {.pp = pp};
+
+	ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
+	if (ret != DW_DLV_OK)
+		msg_exit(-1, "Failed to call dwarf_init(). "
+			 "Maybe, not a dwarf file?\n");
+
+	pp->found = 0;
+	while (++cu_number) {
+		/* Search CU (Compilation Unit) */
+		ret = dwarf_next_cu_header(__dw_debug, NULL, NULL, NULL,
+			&addr_size, &next_cuh, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_NO_ENTRY)
+			break;
+
+		/* Get the DIE(Debugging Information Entry) of this CU */
+		ret = dwarf_siblingof(__dw_debug, 0, &cu_die, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+
+		/* Check if target file is included. */
+		if (pp->file)
+			pf.fno = die_get_fileno(cu_die, pp->file);
+
+		if (!pp->file || pf.fno) {
+			/* Save CU base address (for frame_base) */
+			ret = dwarf_lowpc(cu_die, &pf.cu_base, &__dw_error);
+			ERR_IF(ret == DW_DLV_ERROR);
+			if (ret == DW_DLV_NO_ENTRY)
+				pf.cu_base = 0;
+			if (pp->line)
+				find_by_line(cu_die, &pf);
+			if (pp->function)
+				find_by_func(cu_die, &pf);
+		}
+		dwarf_dealloc(__dw_debug, cu_die, DW_DLA_DIE);
+	}
+	ret = dwarf_finish(__dw_debug, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	return pp->found;
+}
+
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
new file mode 100644
index 0000000..af920de
--- /dev/null
+++ b/tools/perf/util/probe-finder.h
@@ -0,0 +1,68 @@
+#ifndef _PROBE_FINDER_H
+#define _PROBE_FINDER_H
+
+#define _stringify(n)	#n
+#define stringify(n)	_stringify(n)
+
+#ifdef DEBUG
+#define debug(fmt ...)	\
+	fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
+#else
+#define debug(fmt ...)	do {} while (0)
+#endif
+
+#define ERR_IF(cnd)	\
+	do { if (cnd) {	\
+		fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
+			"): " stringify(cnd) "\n");			\
+		exit(1);						\
+	} } while (0)
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBE_BUFFER 1024
+#define MAX_PROBES 128
+
+static inline int is_c_varname(const char *name)
+{
+	/* TODO */
+	return isalpha(name[0]) || name[0] == '_';
+}
+
+struct probe_point {
+	/* Inputs */
+	char	*file;		/* File name */
+	int	line;		/* Line number */
+
+	char	*function;	/* Function name */
+	int	offset;		/* Offset bytes */
+
+	int	nr_args;	/* Number of arguments */
+	char	**args;		/* Arguments */
+
+	/* Output */
+	int	found;		/* Number of found probe points */
+	char	*probes[MAX_PROBES];	/* Output buffers (will be allocated)*/
+};
+
+extern int find_probepoint(int fd, struct probe_point *pp);
+
+#include <libdwarf/dwarf.h>
+#include <libdwarf/libdwarf.h>
+
+struct probe_finder {
+	struct probe_point	*pp;	/* Target probe point */
+
+	/* For function searching */
+	Dwarf_Addr	addr;		/* Address */
+	Dwarf_Unsigned	fno;		/* File number */
+	Dwarf_Off	inl_offs;	/* Inline offset */
+
+	/* For variable searching */
+	Dwarf_Addr	cu_base;	/* Current CU base address */
+	Dwarf_Locdesc	fbloc;		/* Location of Current Frame Base */
+	const char	*var;		/* Current variable name */
+	char		*buf;		/* Current output buffer */
+	int		len;		/* Length of output buffer */
+};
+
+#endif /*_PROBE_FINDER_H */


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[RFC PATCH tracing/kprobes 5/5] perf: kprobe command supports without libdwarf

[Masami Hiramatsu]

Enables perf-kprobe even if libdwarf is installed. If libdwarf is not found,
perf-kprobe just disables dwarf support. Users can use perf-kprobe to set
up new events by using kprobe_events format.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 tools/perf/Makefile            |    6 +++---
 tools/perf/builtin-kprobe.c    |   42 +++++++++++++++++++++++++++++++++-------
 tools/perf/perf.c              |    2 --
 tools/perf/util/probe-finder.h |    2 ++
 4 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 1379e3f..3b0307a 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -385,6 +385,7 @@ BUILTIN_OBJS += builtin-stat.o
 BUILTIN_OBJS += builtin-timechart.o
 BUILTIN_OBJS += builtin-top.o
 BUILTIN_OBJS += builtin-trace.o
+BUILTIN_OBJS += builtin-kprobe.o
 
 PERFLIBS = $(LIB_FILE)
 
@@ -420,13 +421,12 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
 endif
 
 ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
-	msg := $(warning No libdwarf.h found, disables kprobe support. Please install libdwarf-dev/libdwarf-devel);
+	msg := $(warning No libdwarf.h found, disables dwarf support. Please install libdwarf-dev/libdwarf-devel);
+	BASIC_CFLAGS += -DNO_LIBDWARF
 else
 	EXTLIBS += -lelf -ldwarf
 	LIB_H += util/probe-finder.h
 	LIB_OBJS += util/probe-finder.o
-	BUILTIN_OBJS += builtin-kprobe.o
-	BASIC_CFLAGS += -DSUPPORT_DWARF
 endif
 
 ifdef NO_DEMANGLE
diff --git a/tools/perf/builtin-kprobe.c b/tools/perf/builtin-kprobe.c
index 9e4596b..d8ae476 100644
--- a/tools/perf/builtin-kprobe.c
+++ b/tools/perf/builtin-kprobe.c
@@ -53,6 +53,7 @@ const char *default_search_path[NR_SEARCH_PATH] = {
 static struct {
 	char *vmlinux;
 	char *release;
+	int need_dwarf;
 	int nr_probe;
 	struct probe_point probes[MAX_PROBES];
 	char *events[MAX_PROBES];
@@ -132,21 +133,27 @@ static int parse_probepoint(const struct option *opt __used,
 		debug("symbol:%s file:%s offset:%d\n",
 		      pp->function, pp->file, pp->offset);
 	}
+	if (pp->file)
+		session.need_dwarf = 1;
 
 	pp->nr_args = argc - 1;
 	if (pp->nr_args > 0) {
 		pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
 		memcpy(pp->args, &argv[1], sizeof(char *) * pp->nr_args);
 	}
-	if (retp)
-		for (i = 0; i < pp->nr_args; i++)
-			if (is_c_varname(pp->args[i]))
+	for (i = 0; i < pp->nr_args; i++)
+		if (is_c_varname(pp->args[i])) {
+			if (retp)
 				semantic_error("You can't specify local"
 						" variable for kretprobe");
+			session.need_dwarf = 1;
+		}
+
 	debug("%d arguments\n", pp->nr_args);
 	return 0;
 }
 
+#ifndef NO_LIBDWARF
 static int open_default_vmlinux(void)
 {
 	struct utsname uts;
@@ -176,6 +183,7 @@ static int open_default_vmlinux(void)
 	}
 	return fd;
 }
+#endif
 
 static const char * const kprobe_usage[] = {
 	"perf kprobe [<options>] -P PROBEDEF [-P PROBEDEF ...]",
@@ -183,11 +191,17 @@ static const char * const kprobe_usage[] = {
 };
 
 static const struct option options[] = {
+#ifndef NO_LIBDWARF
 	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 		"vmlinux/module pathname"),
 	OPT_STRING('r', "release", &session.release, "rel", "kernel release"),
+#endif
 	OPT_CALLBACK('P', "probe", NULL,
+#ifdef NO_LIBDWARF
+		"p|r:[GRP/]NAME,FUNC[+OFFS],ARG[,ARG,...]",
+#else
 		"p|r:[GRP/]NAME,FUNC[+OFFS][@SRC]|@SRC:LINE,ARG[,ARG,...]",
+#endif
 		"probe point definition, where\n"
 		"\t\tp:\tkprobe probe\n"
 		"\t\tr:\tkretprobe probe\n"
@@ -195,9 +209,13 @@ static const struct option options[] = {
 		"\t\tNAME:\tEvent name\n"
 		"\t\tFUNC:\tFunction name\n"
 		"\t\tOFFS:\tOffset from function entry (in byte)\n"
+#ifdef NO_LIBDWARF
+		"\t\tARG:\tProbe argument (only \n"
+#else
 		"\t\tSRC:\tSource code path\n"
 		"\t\tLINE:\tLine number\n"
 		"\t\tARG:\tProbe argument (local variable name or\n"
+#endif
 		"\t\t\tkprobe-tracer argument format is supported.)\n",
 		parse_probepoint),
 	OPT_END()
@@ -237,7 +255,7 @@ static int synthesize_probepoint(struct probe_point *pp)
 
 int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
 {
-	int i, j, fd, ret, need_dwarf = 0;
+	int i, j, fd, ret;
 	struct probe_point *pp;
 	char buf[MAX_CMDLEN];
 
@@ -246,18 +264,26 @@ int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
 	if (argc || session.nr_probe == 0)
 		usage_with_options(kprobe_usage, options);
 
-	/* Synthesize return probes */
+#ifdef NO_LIBDWARF
+	if (session.need_dwarf)
+		semantic_error("Dwarf-analysis is not supported");
+#endif
+
+	/* Synthesize probes without dwarf */
 	for (j = 0; j < session.nr_probe; j++) {
+#ifndef NO_LIBDWARF
 		if (session.events[j][0] != 'r') {
-			need_dwarf = 1;
+			session.need_dwarf = 1;
 			continue;
 		}
+#endif
 		ret = synthesize_probepoint(&session.probes[j]);
 		if (ret < 0)
 			semantic_error("probe point is too long.");
 	}
 
-	if (!need_dwarf)
+#ifndef NO_LIBDWARF
+	if (!session.need_dwarf)
 		goto setup_probes;
 
 	if (session.vmlinux)
@@ -286,6 +312,8 @@ int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
 	close(fd);
 
 setup_probes:
+#endif /* !NO_LIBDWARF */
+
 	/* Settng up probe points */
 	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 	fd = open(buf, O_WRONLY, O_APPEND);
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index c073924..dd77faf 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -295,9 +295,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "version", cmd_version, 0 },
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
-#ifdef SUPPORT_DWARF
 		{ "kprobe", cmd_kprobe, 0 },
-#endif
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index af920de..306810c 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -44,6 +44,7 @@ struct probe_point {
 	char	*probes[MAX_PROBES];	/* Output buffers (will be allocated)*/
 };
 
+#ifndef NO_LIBDWARF
 extern int find_probepoint(int fd, struct probe_point *pp);
 
 #include <libdwarf/dwarf.h>
@@ -64,5 +65,6 @@ struct probe_finder {
 	char		*buf;		/* Current output buffer */
 	int		len;		/* Length of output buffer */
 };
+#endif /* NO_LIBDWARF */
 
 #endif /*_PROBE_FINDER_H */


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [RFC PATCH tracing/kprobes 4/5] perf: Support perf kprobe command for kprobe-event setup helper

[Steven Rostedt]

On Fri, 2009-09-25 at 12:15 -0700, Masami Hiramatsu wrote:

> +
> +#define MAX_CMDLEN 256
> +
> +static int synthesize_probepoint(struct probe_point *pp)
> +{
> +	char *buf;
> +	int i, len, ret;
> +	pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
> +	len = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);

What happens if func and offset is too big for MAX_CMDLEN?

> +	for (i = 0; i < pp->nr_args; i++) {

Can you have a case where pp->nr_args == 0?

> +		ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
> +			       pp->args[i]);
> +		if (ret <= 0 || ret >= MAX_CMDLEN - len) {
> +			free(pp->probes[0]);
> +			return -E2BIG;
> +		}
> +		len += ret;
> +	}
> +	return pp->found = 1;
> +}
> +
> +int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
> +{
> +	int i, j, fd, ret, need_dwarf = 0;
> +	struct probe_point *pp;
> +	char buf[MAX_CMDLEN];
> +
> +	argc = parse_options(argc, argv, options, kprobe_usage,
> +		PARSE_OPT_STOP_AT_NON_OPTION);
> +	if (argc || session.nr_probe == 0)
> +		usage_with_options(kprobe_usage, options);
> +
> +	/* Synthesize return probes */
> +	for (j = 0; j < session.nr_probe; j++) {
> +		if (session.events[j][0] != 'r') {
> +			need_dwarf = 1;
> +			continue;
> +		}
> +		ret = synthesize_probepoint(&session.probes[j]);
> +		if (ret < 0)
> +			semantic_error("probe point is too long.");

If we have no args but the func and offset is too big, then this does
not catch it. But this depends on if we can have no args.

-- Steve

> +	}
> +
> 

Re: [RFC PATCH tracing/kprobes 2/5] tracing/kprobes: Avoid field name confliction

[Li Zefan]

> +/* Reserved field names */
> +#define FIELD_STRING_IP "ip"
> +#define FIELD_STRING_NARGS "nargs"
> +#define FIELD_STRING_RETIP "ret_ip"
> +#define FIELD_STRING_FUNC "func"
> +
> +const char *reserved_field_names[] = {
> +	"common_type",
> +	"common_flags",
> +	"common_preempt_count",
> +	"common_pid",
> +	"common_tgid",

There is a new common field "common_lock_depth"

> +	FIELD_STRING_IP,
> +	FIELD_STRING_NARGS,
> +	FIELD_STRING_RETIP,
> +	FIELD_STRING_FUNC,
> +};

Re: [RFC PATCH tracing/kprobes 4/5] perf: Support perf kprobe command for kprobe-event setup helper

[Masami Hiramatsu]

Steven Rostedt wrote:
> On Fri, 2009-09-25 at 12:15 -0700, Masami Hiramatsu wrote:
> 
>> +
>> +#define MAX_CMDLEN 256
>> +
>> +static int synthesize_probepoint(struct probe_point *pp)
>> +{
>> +	char *buf;
>> +	int i, len, ret;
>> +	pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
>> +	len = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
> 
> What happens if func and offset is too big for MAX_CMDLEN?

Oops, it must be checked.

> 
>> +	for (i = 0; i<  pp->nr_args; i++) {
> 
> Can you have a case where pp->nr_args == 0?

Sure, I'll check that.

Thank you!

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [RFC PATCH tracing/kprobes 2/5] tracing/kprobes: Avoid field name confliction

[Masami Hiramatsu]

Li Zefan wrote:
>> +/* Reserved field names */
>> +#define FIELD_STRING_IP "ip"
>> +#define FIELD_STRING_NARGS "nargs"
>> +#define FIELD_STRING_RETIP "ret_ip"
>> +#define FIELD_STRING_FUNC "func"
>> +
>> +const char *reserved_field_names[] = {
>> +	"common_type",
>> +	"common_flags",
>> +	"common_preempt_count",
>> +	"common_pid",
>> +	"common_tgid",
>
> There is a new common field "common_lock_depth"

Thanks, I'll add it.
Perhaps, I might need to have more generic check.
(check in define_field?)

Thank you!

>
>> +	FIELD_STRING_IP,
>> +	FIELD_STRING_NARGS,
>> +	FIELD_STRING_RETIP,
>> +	FIELD_STRING_FUNC,
>> +};

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support

[Masami Hiramatsu]

Masami Hiramatsu wrote:
>
> Hi,
>
> These patches introduce perf kprobe command and update kprobe-tracer.
> perf kprobe command allows you to add new probe points by C line number
> and local variable names.

Last week, Arnaldo and I talked about this command, and he suggested that
the command would be better 'perf probe', because it would be able to
cover both of kernel space (by kprobes) and user space (by uprobes).

Basically, I agree with his idea. But I think we may need to consider
more flexible syntax for that purpose before we support uprobes.
In this area, SystemTap has done big advance, we can see how many
varieties of syntax it has by 'man stapprobes'.

And also, it's hard to decide it without real uprobe-tracer (and uprobes
too!) implementation on ftrace. So, I think it is better to continue
using 'perf kprobe' in this time.

But it's worth to add to todo list. :)

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support

[Ingo Molnar]

* Masami Hiramatsu <mhiramat@redhat.com> wrote:

> Masami Hiramatsu wrote:
>>
>> Hi,
>>
>> These patches introduce perf kprobe command and update kprobe-tracer.
>> perf kprobe command allows you to add new probe points by C line number
>> and local variable names.
>
> Last week, Arnaldo and I talked about this command, and he suggested 
> that the command would be better 'perf probe', because it would be 
> able to cover both of kernel space (by kprobes) and user space (by 
> uprobes).

Agreed.

> Basically, I agree with his idea. But I think we may need to consider 
> more flexible syntax for that purpose before we support uprobes. In 
> this area, SystemTap has done big advance, we can see how many 
> varieties of syntax it has by 'man stapprobes'.
>
> And also, it's hard to decide it without real uprobe-tracer (and 
> uprobes too!) implementation on ftrace. So, I think it is better to 
> continue using 'perf kprobe' in this time.
>
> But it's worth to add to todo list. :)

I'd still name it 'perf probe', even if initially it supports kprobes.

	Ingo

Re: [RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support

[Arnaldo Carvalho de Melo]

Em Wed, Sep 30, 2009 at 02:04:18PM +0200, Ingo Molnar escreveu:
> 
> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
> 
> > Masami Hiramatsu wrote:
> >>
> >> Hi,
> >>
> >> These patches introduce perf kprobe command and update kprobe-tracer.
> >> perf kprobe command allows you to add new probe points by C line number
> >> and local variable names.
> >
> > Last week, Arnaldo and I talked about this command, and he suggested 
> > that the command would be better 'perf probe', because it would be 
> > able to cover both of kernel space (by kprobes) and user space (by 
> > uprobes).
> 
> Agreed.
> 
> > Basically, I agree with his idea. But I think we may need to consider 
> > more flexible syntax for that purpose before we support uprobes. In 
> > this area, SystemTap has done big advance, we can see how many 
> > varieties of syntax it has by 'man stapprobes'.
> >
> > And also, it's hard to decide it without real uprobe-tracer (and 
> > uprobes too!) implementation on ftrace. So, I think it is better to 
> > continue using 'perf kprobe' in this time.
> >
> > But it's worth to add to todo list. :)
> 
> I'd still name it 'perf probe', even if initially it supports kprobes.

Agreed.

- Arnaldo