perf: Add perf probe subcommand, a kprobe-event setup helper

Add perf probe subcommand that implements a kprobe-event setup helper
to the perf command.
This allows user to define kprobe events using C expressions (C line
numbers, C function names, and C local variables).

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [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.)

Changes in v4:
 - Add _GNU_SOURCE macro for strndup().

Changes in v3:
 - Remove -r option because perf always be used for online kernel.
 - Check malloc/calloc results.

Changes in v2:
 - Check synthesized string length.
 - Rename perf kprobe to perf probe.
 - Use spaces for separator and update usage comment.
 - Check error paths in parse_probepoint().
 - Check optimized-out variables.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.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>
LKML-Reference: <20091008211737.29299.14784.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

2 files changed, 758 insertions, 0 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
new file mode 100644
index 000000000000..ec6f53f29e00
--- /dev/null
+++ b/tools/perf/util/probe-finder.c
@@ -0,0 +1,690 @@
+/*
+ * 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",
+	"$stack",	/* Stack address instead of %sp */
+	"%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);
+	if (ret != DW_DLV_OK)
+		goto error;
+	ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
+	if (ret != DW_DLV_OK)
+		goto error;
+	/* 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);
+	return ;
+error:
+	msg_exit(-1, "Failed to find the location of %s at this address.\n"
+		 " Perhaps, it was optimized out.\n", pf->var);
+}
+
+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 000000000000..af920de64866
--- /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 */