perf probe: Show accessible local variables (cf6eb489) · Commits · 戴 / test

tools/perf/Documentation/perf-probe.txt

+7 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,8 @@ or
		'perf probe' --list
		or
		'perf probe' --line='FUNC[:RLN[+NUM\|:RLN2]]\|SRC:ALN[+NUM\|:ALN2]'
		or
		'perf probe' --vars='PROBEPOINT'

		DESCRIPTION
		-----------
		@@ -57,6 +59,11 @@ OPTIONS
		Show source code lines which can be probed. This needs an argument
		which specifies a range of the source code. (see LINE SYNTAX for detail)

		-V::
		--vars=::
		Show available local variables at given probe point. The argument
		syntax is same as PROBE SYNTAX, but NO ARGs.

		-f::
		--force::
		Forcibly add events with existing name.

tools/perf/builtin-probe.c

+54 −7

Original line number	Diff line number	Diff line
		@@ -50,6 +50,8 @@ static struct {
		bool list_events;
		bool force_add;
		bool show_lines;
		bool show_vars;
		bool mod_events;
		int nevents;
		struct perf_probe_event events[MAX_PROBES];
		struct strlist *dellist;
		@@ -57,7 +59,6 @@ static struct {
		int max_probe_points;
		} params;


		/* Parse an event definition. Note that any error must die. */
		static int parse_probe_event(const char *str)
		{
		@@ -92,6 +93,7 @@ static int parse_probe_event_argv(int argc, const char **argv)
		len = 0;
		for (i = 0; i < argc; i++)
		len += sprintf(&buf[len], "%s ", argv[i]);
		params.mod_events = true;
		ret = parse_probe_event(buf);
		free(buf);
		return ret;
		@@ -100,9 +102,10 @@ static int parse_probe_event_argv(int argc, const char **argv)
		static int opt_add_probe_event(const struct option *opt __used,
		const char *str, int unset __used)
		{
		if (str)
		if (str) {
		params.mod_events = true;
		return parse_probe_event(str);
		else
		} else
		return 0;
		}

		@@ -110,6 +113,7 @@ static int opt_del_probe_event(const struct option *opt __used,
		const char *str, int unset __used)
		{
		if (str) {
		params.mod_events = true;
		if (!params.dellist)
		params.dellist = strlist__new(true, NULL);
		strlist__add(params.dellist, str);
		@@ -130,6 +134,25 @@ static int opt_show_lines(const struct option *opt __used,

		return ret;
		}

		static int opt_show_vars(const struct option *opt __used,
		const char *str, int unset __used)
		{
		struct perf_probe_event *pev = &params.events[params.nevents];
		int ret;

		if (!str)
		return 0;

		ret = parse_probe_event(str);
		if (!ret && pev->nargs != 0) {
		pr_err(" Error: '--vars' doesn't accept arguments.\n");
		return -EINVAL;
		}
		params.show_vars = true;

		return ret;
		}
		#endif

		static const char * const probe_usage[] = {
		@@ -139,6 +162,7 @@ static const char * const probe_usage[] = {
		"perf probe --list",
		#ifdef DWARF_SUPPORT
		"perf probe --line 'LINEDESC'",
		"perf probe --vars 'PROBEPOINT'",
		#endif
		NULL
		};
		@@ -180,6 +204,9 @@ static const struct option options[] = {
		OPT_CALLBACK('L', "line", NULL,
		"FUNC[:RLN[+NUM\|-RLN2]]\|SRC:ALN[+NUM\|-ALN2]",
		"Show source code lines.", opt_show_lines),
		OPT_CALLBACK('V', "vars", NULL,
		"FUNC[@SRC][+OFF\|%return\|:RL\|;PT]\|SRC:AL\|SRC;PT",
		"Show accessible variables on PROBEDEF", opt_show_vars),
		OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
		"file", "vmlinux pathname"),
		OPT_STRING('s', "source", &symbol_conf.source_prefix,
		@@ -217,7 +244,7 @@ int cmd_probe(int argc, const char *argv, const char prefix __used)
		usage_with_options(probe_usage, options);

		if (params.list_events) {
		if (params.nevents != 0 \|\| params.dellist) {
		if (params.mod_events) {
		pr_err(" Error: Don't use --list with --add/--del.\n");
		usage_with_options(probe_usage, options);
		}
		@@ -225,6 +252,10 @@ int cmd_probe(int argc, const char *argv, const char prefix __used)
		pr_err(" Error: Don't use --list with --line.\n");
		usage_with_options(probe_usage, options);
		}
		if (params.show_vars) {
		pr_err(" Error: Don't use --list with --vars.\n");
		usage_with_options(probe_usage, options);
		}
		ret = show_perf_probe_events();
		if (ret < 0)
		pr_err(" Error: Failed to show event list. (%d)\n",
		@@ -234,17 +265,33 @@ int cmd_probe(int argc, const char *argv, const char prefix __used)

		#ifdef DWARF_SUPPORT
		if (params.show_lines) {
		if (params.nevents != 0 \|\| params.dellist) {
		pr_warning(" Error: Don't use --line with"
		if (params.mod_events) {
		pr_err(" Error: Don't use --line with"
		" --add/--del.\n");
		usage_with_options(probe_usage, options);
		}
		if (params.show_vars) {
		pr_err(" Error: Don't use --line with --vars.\n");
		usage_with_options(probe_usage, options);
		}

		ret = show_line_range(&params.line_range);
		if (ret < 0)
		pr_err(" Error: Failed to show lines. (%d)\n", ret);
		return ret;
		}
		if (params.show_vars) {
		if (params.mod_events) {
		pr_err(" Error: Don't use --vars with"
		" --add/--del.\n");
		usage_with_options(probe_usage, options);
		}
		ret = show_available_vars(params.events, params.nevents,
		params.max_probe_points);
		if (ret < 0)
		pr_err(" Error: Failed to show vars. (%d)\n", ret);
		return ret;
		}
		#endif

		if (params.dellist) {

tools/perf/util/probe-event.c

+72 −0

Original line number	Diff line number	Diff line
		@@ -378,6 +378,72 @@ end:
		return ret;
		}

		static int show_available_vars_at(int fd, struct perf_probe_event *pev,
		int max_vls)
		{
		char *buf;
		int ret, i;
		struct str_node *node;
		struct variable_list vls = NULL, vl;

		buf = synthesize_perf_probe_point(&pev->point);
		if (!buf)
		return -EINVAL;
		pr_debug("Searching variables at %s\n", buf);

		ret = find_available_vars_at(fd, pev, &vls, max_vls);
		if (ret > 0) {
		/* Some variables were found */
		fprintf(stdout, "Available variables at %s\n", buf);
		for (i = 0; i < ret; i++) {
		vl = &vls[i];
		/*
		* A probe point might be converted to
		* several trace points.
		*/
		fprintf(stdout, "\t@<%s+%lu>\n", vl->point.symbol,
		vl->point.offset);
		free(vl->point.symbol);
		if (vl->vars) {
		strlist__for_each(node, vl->vars)
		fprintf(stdout, "\t\t%s\n", node->s);
		strlist__delete(vl->vars);
		} else
		fprintf(stdout, "(No variables)\n");
		}
		free(vls);
		} else
		pr_err("Failed to find variables at %s (%d)\n", buf, ret);

		free(buf);
		return ret;
		}

		/* Show available variables on given probe point */
		int show_available_vars(struct perf_probe_event *pevs, int npevs,
		int max_vls)
		{
		int i, fd, ret = 0;

		ret = init_vmlinux();
		if (ret < 0)
		return ret;

		fd = open_vmlinux();
		if (fd < 0) {
		pr_warning("Failed to open debuginfo file.\n");
		return fd;
		}

		setup_pager();

		for (i = 0; i < npevs && ret >= 0; i++)
		ret = show_available_vars_at(fd, &pevs[i], max_vls);

		close(fd);
		return ret;
		}

		#else /* !DWARF_SUPPORT */

		static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
		@@ -409,6 +475,12 @@ int show_line_range(struct line_range *lr __unused)
		return -ENOSYS;
		}

		int show_available_vars(struct perf_probe_event *pevs __unused,
		int npevs __unused, int max_probe_points __unused)
		{
		pr_warning("Debuginfo-analysis is not supported.\n");
		return -ENOSYS;
		}
		#endif

		int parse_line_range_desc(const char arg, struct line_range lr)

tools/perf/util/probe-event.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -90,6 +90,12 @@ struct line_range {
		struct list_head line_list; /* Visible lines */
		};

		/* List of variables */
		struct variable_list {
		struct probe_trace_point point; /* Actual probepoint */
		struct strlist vars; / Available variables */
		};

		/* Command string to events */
		extern int parse_perf_probe_command(const char *cmd,
		struct perf_probe_event *pev);
		@@ -115,6 +121,8 @@ extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
		extern int del_perf_probe_events(struct strlist *dellist);
		extern int show_perf_probe_events(void);
		extern int show_line_range(struct line_range *lr);
		extern int show_available_vars(struct perf_probe_event *pevs, int npevs,
		int max_probe_points);


		/* Maximum index number of event-name postfix */

tools/perf/util/probe-finder.c

+317 −95

Original line number	Diff line number	Diff line
		@@ -172,8 +172,8 @@ static Dwarf_Die die_get_type(Dwarf_Die vr_die, Dwarf_Die *die_mem)
		return NULL;
		}

		/* Get type die, but skip qualifiers and typedef */
		static Dwarf_Die die_get_real_type(Dwarf_Die vr_die, Dwarf_Die *die_mem)
		/* Get a type die, but skip qualifiers */
		static Dwarf_Die __die_get_real_type(Dwarf_Die vr_die, Dwarf_Die *die_mem)
		{
		int tag;

		@@ -185,8 +185,17 @@ static Dwarf_Die die_get_real_type(Dwarf_Die vr_die, Dwarf_Die *die_mem)
		} while (tag == DW_TAG_const_type \|\|
		tag == DW_TAG_restrict_type \|\|
		tag == DW_TAG_volatile_type \|\|
		tag == DW_TAG_shared_type \|\|
		tag == DW_TAG_typedef);
		tag == DW_TAG_shared_type);

		return vr_die;
		}

		/* Get a type die, but skip qualifiers and typedef */
		static Dwarf_Die die_get_real_type(Dwarf_Die vr_die, Dwarf_Die *die_mem)
		{
		do {
		vr_die = __die_get_real_type(vr_die, die_mem);
		} while (vr_die && dwarf_tag(vr_die) == DW_TAG_typedef);

		return vr_die;
		}
		@@ -380,6 +389,60 @@ static Dwarf_Die die_find_member(Dwarf_Die st_die, const char *name,
		die_mem);
		}

		/* Get the name of given variable DIE */
		static int die_get_typename(Dwarf_Die vr_die, char buf, int len)
		{
		Dwarf_Die type;
		int tag, ret, ret2;
		const char *tmp = "";

		if (__die_get_real_type(vr_die, &type) == NULL)
		return -ENOENT;

		tag = dwarf_tag(&type);
		if (tag == DW_TAG_array_type \|\| tag == DW_TAG_pointer_type)
		tmp = "*";
		else if (tag == DW_TAG_subroutine_type) {
		/* Function pointer */
		ret = snprintf(buf, len, "(function_type)");
		return (ret >= len) ? -E2BIG : ret;
		} else {
		if (!dwarf_diename(&type))
		return -ENOENT;
		if (tag == DW_TAG_union_type)
		tmp = "union ";
		else if (tag == DW_TAG_structure_type)
		tmp = "struct ";
		/* Write a base name */
		ret = snprintf(buf, len, "%s%s", tmp, dwarf_diename(&type));
		return (ret >= len) ? -E2BIG : ret;
		}
		ret = die_get_typename(&type, buf, len);
		if (ret > 0) {
		ret2 = snprintf(buf + ret, len - ret, "%s", tmp);
		ret = (ret2 >= len - ret) ? -E2BIG : ret2 + ret;
		}
		return ret;
		}

		/* Get the name and type of given variable DIE, stored as "type\tname" */
		static int die_get_varname(Dwarf_Die vr_die, char buf, int len)
		{
		int ret, ret2;

		ret = die_get_typename(vr_die, buf, len);
		if (ret < 0) {
		pr_debug("Failed to get type, make it unknown.\n");
		ret = snprintf(buf, len, "(unknown_type)");
		}
		if (ret > 0) {
		ret2 = snprintf(buf + ret, len - ret, "\t%s",
		dwarf_diename(vr_die));
		ret = (ret2 >= len - ret) ? -E2BIG : ret2 + ret;
		}
		return ret;
		}

		/*
		* Probe finder related functions
		*/
		@@ -393,8 +456,13 @@ static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
		return ref;
		}

		/* Show a location */
		static int convert_variable_location(Dwarf_Die vr_die, struct probe_finder pf)
		/*
		* Convert a location into trace_arg.
		* If tvar == NULL, this just checks variable can be converted.
		*/
		static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
		Dwarf_Op *fb_ops,
		struct probe_trace_arg *tvar)
		{
		Dwarf_Attribute attr;
		Dwarf_Op *op;
		@@ -403,7 +471,6 @@ static int convert_variable_location(Dwarf_Die vr_die, struct probe_finder pf)
		Dwarf_Word offs = 0;
		bool ref = false;
		const char *regs;
		struct probe_trace_arg *tvar = pf->tvar;
		int ret;

		if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
		@@ -411,16 +478,16 @@ static int convert_variable_location(Dwarf_Die vr_die, struct probe_finder pf)

		/* TODO: handle more than 1 exprs */
		if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL \|\|
		dwarf_getlocation_addr(&attr, pf->addr, &op, &nops, 1) <= 0 \|\|
		dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0 \|\|
		nops == 0) {
		/* TODO: Support const_value */
		pr_err("Failed to find the location of %s at this address.\n"
		" Perhaps, it has been optimized out.\n", pf->pvar->var);
		return -ENOENT;
		}

		if (op->atom == DW_OP_addr) {
		static_var:
		if (!tvar)
		return 0;
		/* Static variables on memory (not stack), make @varname */
		ret = strlen(dwarf_diename(vr_die));
		tvar->value = zalloc(ret + 2);
		@@ -435,14 +502,11 @@ static_var:

		/* If this is based on frame buffer, set the offset */
		if (op->atom == DW_OP_fbreg) {
		if (pf->fb_ops == NULL) {
		pr_warning("The attribute of frame base is not "
		"supported.\n");
		if (fb_ops == NULL)
		return -ENOTSUP;
		}
		ref = true;
		offs = op->number;
		op = &pf->fb_ops[0];
		op = &fb_ops[0];
		}

		if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
		@@ -458,13 +522,18 @@ static_var:
		} else if (op->atom == DW_OP_regx) {
		regn = op->number;
		} else {
		pr_warning("DW_OP %x is not supported.\n", op->atom);
		pr_debug("DW_OP %x is not supported.\n", op->atom);
		return -ENOTSUP;
		}

		if (!tvar)
		return 0;

		regs = get_arch_regstr(regn);
		if (!regs) {
		pr_warning("Mapping for DWARF register number %u missing on this architecture.", regn);
		/* This should be a bug in DWARF or this tool */
		pr_warning("Mapping for DWARF register number %u "
		"missing on this architecture.", regn);
		return -ERANGE;
		}

		@@ -689,8 +758,14 @@ static int convert_variable(Dwarf_Die vr_die, struct probe_finder pf)
		pr_debug("Converting variable %s into trace event.\n",
		dwarf_diename(vr_die));

		ret = convert_variable_location(vr_die, pf);
		if (ret == 0 && pf->pvar->field) {
		ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
		pf->tvar);
		if (ret == -ENOENT)
		pr_err("Failed to find the location of %s at this address.\n"
		" Perhaps, it has been optimized out.\n", pf->pvar->var);
		else if (ret == -ENOTSUP)
		pr_err("Sorry, we don't support this variable location yet.\n");
		else if (pf->pvar->field) {
		ret = convert_variable_fields(vr_die, pf->pvar->var,
		pf->pvar->field, &pf->tvar->ref,
		&die_mem);
		@@ -772,34 +847,12 @@ found:
		return ret;
		}

		/* Show a probe point to output buffer */
		static int convert_probe_point(Dwarf_Die sp_die, struct probe_finder pf)
		/* Convert subprogram DIE to trace point */
		static int convert_to_trace_point(Dwarf_Die *sp_die, Dwarf_Addr paddr,
		bool retprobe, struct probe_trace_point *tp)
		{
		struct probe_trace_event *tev;
		Dwarf_Addr eaddr;
		Dwarf_Die die_mem;
		const char *name;
		int ret, i;
		Dwarf_Attribute fb_attr;
		size_t nops;

		if (pf->ntevs == pf->max_tevs) {
		pr_warning("Too many( > %d) probe point found.\n",
		pf->max_tevs);
		return -ERANGE;
		}
		tev = &pf->tevs[pf->ntevs++];

		/* If no real subprogram, find a real one */
		if (!sp_die \|\| dwarf_tag(sp_die) != DW_TAG_subprogram) {
		sp_die = die_find_real_subprogram(&pf->cu_die,
		pf->addr, &die_mem);
		if (!sp_die) {
		pr_warning("Failed to find probe point in any "
		"functions.\n");
		return -ENOENT;
		}
		}

		/* Copy the name of probe point */
		name = dwarf_diename(sp_die);
		@@ -809,26 +862,45 @@ static int convert_probe_point(Dwarf_Die sp_die, struct probe_finder pf)
		dwarf_diename(sp_die));
		return -ENOENT;
		}
		tev->point.symbol = strdup(name);
		if (tev->point.symbol == NULL)
		tp->symbol = strdup(name);
		if (tp->symbol == NULL)
		return -ENOMEM;
		tev->point.offset = (unsigned long)(pf->addr - eaddr);
		tp->offset = (unsigned long)(paddr - eaddr);
		} else
		/* This function has no name. */
		tev->point.offset = (unsigned long)pf->addr;
		tp->offset = (unsigned long)paddr;

		/* Return probe must be on the head of a subprogram */
		if (pf->pev->point.retprobe) {
		if (tev->point.offset != 0) {
		if (retprobe) {
		if (eaddr != paddr) {
		pr_warning("Return probe must be on the head of"
		" a real function\n");
		return -EINVAL;
		}
		tev->point.retprobe = true;
		tp->retprobe = true;
		}

		pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
		tev->point.offset);
		return 0;
		}

		/* Call probe_finder callback with real subprogram DIE */
		static int call_probe_finder(Dwarf_Die sp_die, struct probe_finder pf)
		{
		Dwarf_Die die_mem;
		Dwarf_Attribute fb_attr;
		size_t nops;
		int ret;

		/* If no real subprogram, find a real one */
		if (!sp_die \|\| dwarf_tag(sp_die) != DW_TAG_subprogram) {
		sp_die = die_find_real_subprogram(&pf->cu_die,
		pf->addr, &die_mem);
		if (!sp_die) {
		pr_warning("Failed to find probe point in any "
		"functions.\n");
		return -ENOENT;
		}
		}

		/* Get the frame base attribute/ops */
		dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr);
		@@ -848,22 +920,13 @@ static int convert_probe_point(Dwarf_Die sp_die, struct probe_finder pf)
		#endif
		}

		/* Find each argument */
		tev->nargs = pf->pev->nargs;
		tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
		if (tev->args == NULL)
		return -ENOMEM;
		for (i = 0; i < pf->pev->nargs; i++) {
		pf->pvar = &pf->pev->args[i];
		pf->tvar = &tev->args[i];
		ret = find_variable(sp_die, pf);
		if (ret != 0)
		return ret;
		}
		/* Call finder's callback handler */
		ret = pf->callback(sp_die, pf);

		/* pf->fb_ops will be cached in libdw. Don't free it. /
		pf->fb_ops = NULL;
		return 0;

		return ret;
		}

		/* Find probe point from its line number */
		@@ -899,7 +962,7 @@ static int find_probe_point_by_line(struct probe_finder *pf)
		(int)i, lineno, (uintmax_t)addr);
		pf->addr = addr;

		ret = convert_probe_point(NULL, pf);
		ret = call_probe_finder(NULL, pf);
		/* Continuing, because target line might be inlined. */
		}
		return ret;
		@@ -1012,7 +1075,7 @@ static int find_probe_point_lazy(Dwarf_Die sp_die, struct probe_finder pf)
		(int)i, lineno, (unsigned long long)addr);
		pf->addr = addr;

		ret = convert_probe_point(sp_die, pf);
		ret = call_probe_finder(sp_die, pf);
		/* Continuing, because target line might be inlined. */
		}
		/* TODO: deallocate lines, but how? */
		@@ -1047,7 +1110,7 @@ static int probe_point_inline_cb(Dwarf_Die in_die, void data)
		pr_debug("found inline addr: 0x%jx\n",
		(uintmax_t)pf->addr);

		param->retval = convert_probe_point(in_die, pf);
		param->retval = call_probe_finder(in_die, pf);
		if (param->retval < 0)
		return DWARF_CB_ABORT;
		}
		@@ -1085,7 +1148,7 @@ static int probe_point_search_cb(Dwarf_Die sp_die, void data)
		}
		pf->addr += pp->offset;
		/* TODO: Check the address in this function */
		param->retval = convert_probe_point(sp_die, pf);
		param->retval = call_probe_finder(sp_die, pf);
		}
		} else {
		struct dwarf_callback_param _param = {.data = (void *)pf,
		@@ -1107,70 +1170,229 @@ static int find_probe_point_by_func(struct probe_finder *pf)
		return _param.retval;
		}

		/* Find probe_trace_events specified by perf_probe_event from debuginfo */
		int find_probe_trace_events(int fd, struct perf_probe_event *pev,
		struct probe_trace_event **tevs, int max_tevs)
		/* Find probe points from debuginfo */
		static int find_probes(int fd, struct probe_finder *pf)
		{
		struct probe_finder pf = {.pev = pev, .max_tevs = max_tevs};
		struct perf_probe_point *pp = &pev->point;
		struct perf_probe_point *pp = &pf->pev->point;
		Dwarf_Off off, noff;
		size_t cuhl;
		Dwarf_Die *diep;
		Dwarf *dbg;
		int ret = 0;

		pf.tevs = zalloc(sizeof(struct probe_trace_event) * max_tevs);
		if (pf.tevs == NULL)
		return -ENOMEM;
		*tevs = pf.tevs;
		pf.ntevs = 0;

		dbg = dwarf_begin(fd, DWARF_C_READ);
		if (!dbg) {
		pr_warning("No dwarf info found in the vmlinux - "
		"please rebuild with CONFIG_DEBUG_INFO=y.\n");
		free(pf.tevs);
		*tevs = NULL;
		return -EBADF;
		}

		#if _ELFUTILS_PREREQ(0, 142)
		/* Get the call frame information from this dwarf */
		pf.cfi = dwarf_getcfi(dbg);
		pf->cfi = dwarf_getcfi(dbg);
		#endif

		off = 0;
		line_list__init(&pf.lcache);
		line_list__init(&pf->lcache);
		/* Loop on CUs (Compilation Unit) */
		while (!dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL) &&
		ret >= 0) {
		/* Get the DIE(Debugging Information Entry) of this CU */
		diep = dwarf_offdie(dbg, off + cuhl, &pf.cu_die);
		diep = dwarf_offdie(dbg, off + cuhl, &pf->cu_die);
		if (!diep)
		continue;

		/* Check if target file is included. */
		if (pp->file)
		pf.fname = cu_find_realpath(&pf.cu_die, pp->file);
		pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
		else
		pf.fname = NULL;
		pf->fname = NULL;

		if (!pp->file \|\| pf.fname) {
		if (!pp->file \|\| pf->fname) {
		if (pp->function)
		ret = find_probe_point_by_func(&pf);
		ret = find_probe_point_by_func(pf);
		else if (pp->lazy_line)
		ret = find_probe_point_lazy(NULL, &pf);
		ret = find_probe_point_lazy(NULL, pf);
		else {
		pf.lno = pp->line;
		ret = find_probe_point_by_line(&pf);
		pf->lno = pp->line;
		ret = find_probe_point_by_line(pf);
		}
		}
		off = noff;
		}
		line_list__free(&pf.lcache);
		line_list__free(&pf->lcache);
		dwarf_end(dbg);

		return (ret < 0) ? ret : pf.ntevs;
		return ret;
		}

		/* Add a found probe point into trace event list */
		static int add_probe_trace_event(Dwarf_Die sp_die, struct probe_finder pf)
		{
		struct trace_event_finder *tf =
		container_of(pf, struct trace_event_finder, pf);
		struct probe_trace_event *tev;
		int ret, i;

		/* Check number of tevs */
		if (tf->ntevs == tf->max_tevs) {
		pr_warning("Too many( > %d) probe point found.\n",
		tf->max_tevs);
		return -ERANGE;
		}
		tev = &tf->tevs[tf->ntevs++];

		ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe,
		&tev->point);
		if (ret < 0)
		return ret;

		pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
		tev->point.offset);

		/* Find each argument */
		tev->nargs = pf->pev->nargs;
		tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
		if (tev->args == NULL)
		return -ENOMEM;
		for (i = 0; i < pf->pev->nargs; i++) {
		pf->pvar = &pf->pev->args[i];
		pf->tvar = &tev->args[i];
		ret = find_variable(sp_die, pf);
		if (ret != 0)
		return ret;
		}

		return 0;
		}

		/* Find probe_trace_events specified by perf_probe_event from debuginfo */
		int find_probe_trace_events(int fd, struct perf_probe_event *pev,
		struct probe_trace_event **tevs, int max_tevs)
		{
		struct trace_event_finder tf = {
		.pf = {.pev = pev, .callback = add_probe_trace_event},
		.max_tevs = max_tevs};
		int ret;

		/* Allocate result tevs array */
		tevs = zalloc(sizeof(struct probe_trace_event) max_tevs);
		if (*tevs == NULL)
		return -ENOMEM;

		tf.tevs = *tevs;
		tf.ntevs = 0;

		ret = find_probes(fd, &tf.pf);
		if (ret < 0) {
		free(*tevs);
		*tevs = NULL;
		return ret;
		}

		return (ret < 0) ? ret : tf.ntevs;
		}

		#define MAX_VAR_LEN 64

		/* Collect available variables in this scope */
		static int collect_variables_cb(Dwarf_Die die_mem, void data)
		{
		struct available_var_finder *af = data;
		struct variable_list *vl;
		char buf[MAX_VAR_LEN];
		int tag, ret;

		vl = &af->vls[af->nvls - 1];

		tag = dwarf_tag(die_mem);
		if (tag == DW_TAG_formal_parameter \|\|
		tag == DW_TAG_variable) {
		ret = convert_variable_location(die_mem, af->pf.addr,
		af->pf.fb_ops, NULL);
		if (ret == 0) {
		ret = die_get_varname(die_mem, buf, MAX_VAR_LEN);
		if (ret > 0)
		strlist__add(vl->vars, buf);
		}
		}

		if (dwarf_haspc(die_mem, af->pf.addr))
		return DIE_FIND_CB_CONTINUE;
		else
		return DIE_FIND_CB_SIBLING;
		}

		/* Add a found vars into available variables list */
		static int add_available_vars(Dwarf_Die sp_die, struct probe_finder pf)
		{
		struct available_var_finder *af =
		container_of(pf, struct available_var_finder, pf);
		struct variable_list *vl;
		Dwarf_Die die_mem;
		int ret;

		/* Check number of tevs */
		if (af->nvls == af->max_vls) {
		pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
		return -ERANGE;
		}
		vl = &af->vls[af->nvls++];

		ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe,
		&vl->point);
		if (ret < 0)
		return ret;

		pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
		vl->point.offset);

		/* Find local variables */
		vl->vars = strlist__new(true, NULL);
		if (vl->vars == NULL)
		return -ENOMEM;
		die_find_child(sp_die, collect_variables_cb, (void *)af, &die_mem);

		if (strlist__empty(vl->vars)) {
		strlist__delete(vl->vars);
		vl->vars = NULL;
		}

		return ret;
		}

		/* Find available variables at given probe point */
		int find_available_vars_at(int fd, struct perf_probe_event *pev,
		struct variable_list **vls, int max_vls)
		{
		struct available_var_finder af = {
		.pf = {.pev = pev, .callback = add_available_vars},
		.max_vls = max_vls};
		int ret;

		/* Allocate result vls array */
		vls = zalloc(sizeof(struct variable_list) max_vls);
		if (*vls == NULL)
		return -ENOMEM;

		af.vls = *vls;
		af.nvls = 0;

		ret = find_probes(fd, &af.pf);
		if (ret < 0) {
		/* Free vlist for error */
		while (af.nvls--) {
		if (af.vls[af.nvls].point.symbol)
		free(af.vls[af.nvls].point.symbol);
		if (af.vls[af.nvls].vars)
		strlist__delete(af.vls[af.nvls].vars);
		}
		free(af.vls);
		*vls = NULL;
		return ret;
		}

		return (ret < 0) ? ret : af.nvls;
		}

		/* Reverse search */

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