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Commit 7df2f329 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

perf probe: Add data structure member access support 



Support accessing members in the data structures. With this,
perf-probe accepts data-structure members(IOW, it now accepts
dot '.' and arrow '->' operators) as probe arguemnts.

e.g.

 ./perf probe --add 'schedule:44 rq->curr'

 ./perf probe --add 'vfs_read file->f_op->read file->f_path.dentry'

Note that '>' can be interpreted as redirection in command-line.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100316220626.32050.57552.stgit@localhost6.localdomain6>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent fb1587d8

tools/perf/util/probe-event.c

+86 −4
Original line number Original line Diff line number Diff line
@@ -262,6 +262,49 @@ static void parse_perf_probe_point(char *arg, struct perf_probe_event *pev) 
		 pp->lazy_line);

		 pp->lazy_line);

}

}





/* Parse perf-probe event argument */

static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg)

{

	const char *tmp;

	struct perf_probe_arg_field **fieldp;



	pr_debug("parsing arg: %s into ", str);



	tmp = strpbrk(str, "-.");

	if (!is_c_varname(str) || !tmp) {

		/* A variable, register, symbol or special value */

		arg->name = xstrdup(str);

		pr_debug("%s\n", arg->name);

		return;

	}



	/* Structure fields */

	arg->name = xstrndup(str, tmp - str);

	pr_debug("%s, ", arg->name);

	fieldp = &arg->field;



	do {

		*fieldp = xzalloc(sizeof(struct perf_probe_arg_field));

		if (*tmp == '.') {

			str = tmp + 1;

			(*fieldp)->ref = false;

		} else if (tmp[1] == '>') {

			str = tmp + 2;

			(*fieldp)->ref = true;

		} else

			semantic_error("Argument parse error: %s", str);



		tmp = strpbrk(str, "-.");

		if (tmp) {

			(*fieldp)->name = xstrndup(str, tmp - str);

			pr_debug("%s(%d), ", (*fieldp)->name, (*fieldp)->ref);

			fieldp = &(*fieldp)->next;

		}

	} while (tmp);

	(*fieldp)->name = xstrdup(str);

	pr_debug("%s(%d)\n", (*fieldp)->name, (*fieldp)->ref);

}



/* Parse perf-probe event command */

/* Parse perf-probe event command */

void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)

void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)

{

{
@@ -281,7 +324,7 @@ void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev) 
	pev->nargs = argc - 1;

	pev->nargs = argc - 1;

	pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs);

	pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs);

	for (i = 0; i < pev->nargs; i++) {

	for (i = 0; i < pev->nargs; i++) {

		pev->args[i].name = xstrdup(argv[i + 1]);

		parse_perf_probe_arg(argv[i + 1], &pev->args[i]);

		if (is_c_varname(pev->args[i].name) && pev->point.retprobe)

		if (is_c_varname(pev->args[i].name) && pev->point.retprobe)

			semantic_error("You can't specify local variable for"

			semantic_error("You can't specify local variable for"

				       " kretprobe");

				       " kretprobe");
@@ -353,6 +396,33 @@ void parse_kprobe_trace_command(const char *cmd, struct kprobe_trace_event *tev) 
	argv_free(argv);

	argv_free(argv);

}

}





/* Compose only probe arg */

int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)

{

	struct perf_probe_arg_field *field = pa->field;

	int ret;

	char *tmp = buf;



	ret = e_snprintf(tmp, len, "%s", pa->name);

	if (ret <= 0)

		goto error;

	tmp += ret;

	len -= ret;



	while (field) {

		ret = e_snprintf(tmp, len, "%s%s", field->ref ? "->" : ".",

				 field->name);

		if (ret <= 0)

			goto error;

		tmp += ret;

		len -= ret;

		field = field->next;

	}

	return tmp - buf;

error:

	die("Failed to synthesize perf probe argument: %s", strerror(-ret));

}



/* Compose only probe point (not argument) */

/* Compose only probe point (not argument) */

static char *synthesize_perf_probe_point(struct perf_probe_point *pp)

static char *synthesize_perf_probe_point(struct perf_probe_point *pp)

{

{
@@ -563,6 +633,7 @@ void convert_to_perf_probe_event(struct kprobe_trace_event *tev, 
void clear_perf_probe_event(struct perf_probe_event *pev)

void clear_perf_probe_event(struct perf_probe_event *pev)

{

{

	struct perf_probe_point *pp = &pev->point;

	struct perf_probe_point *pp = &pev->point;

	struct perf_probe_arg_field *field, *next;

	int i;

	int i;





	if (pev->event)

	if (pev->event)
@@ -575,9 +646,18 @@ void clear_perf_probe_event(struct perf_probe_event *pev) 
		free(pp->function);

		free(pp->function);

	if (pp->lazy_line)

	if (pp->lazy_line)

		free(pp->lazy_line);

		free(pp->lazy_line);

	for (i = 0; i < pev->nargs; i++)

	for (i = 0; i < pev->nargs; i++) {

		if (pev->args[i].name)

		if (pev->args[i].name)

			free(pev->args[i].name);

			free(pev->args[i].name);

		field = pev->args[i].field;

		while (field) {

			next = field->next;

			if (field->name)

				free(field->name);

			free(field);

			field = next;

		}

	}

	if (pev->args)

	if (pev->args)

		free(pev->args);

		free(pev->args);

	memset(pev, 0, sizeof(*pev));

	memset(pev, 0, sizeof(*pev));
@@ -682,8 +762,10 @@ static void show_perf_probe_event(struct perf_probe_event *pev) 




	if (pev->nargs > 0) {

	if (pev->nargs > 0) {

		printf(" with");

		printf(" with");

		for (i = 0; i < pev->nargs; i++)

		for (i = 0; i < pev->nargs; i++) {

			printf(" %s", pev->args[i].name);

			synthesize_perf_probe_arg(&pev->args[i], buf, 128);

			printf(" %s", buf);

		}

	}

	}

	printf(")\n");

	printf(")\n");

	free(place);

	free(place);

tools/perf/util/probe-event.h

+11 −1
Original line number Original line Diff line number Diff line
@@ -45,9 +45,17 @@ struct perf_probe_point { 
	bool		retprobe;	/* Return probe flag */

	bool		retprobe;	/* Return probe flag */

};

};





/* Perf probe probing argument field chain */

struct perf_probe_arg_field {

	struct perf_probe_arg_field	*next;	/* Next field */

	char				*name;	/* Name of the field */

	bool				ref;	/* Referencing flag */

};



/* Perf probe probing argument */

/* Perf probe probing argument */

struct perf_probe_arg {

struct perf_probe_arg {

	char				*name;	/* Argument name */

	char				*name;	/* Argument name */

	struct perf_probe_arg_field	*field;	/* Structure fields */

};

};





/* Perf probe probing event (point + arg) */

/* Perf probe probing event (point + arg) */
@@ -86,6 +94,8 @@ extern void parse_kprobe_trace_command(const char *cmd, 
/* Events to command string */

/* Events to command string */

extern char *synthesize_perf_probe_command(struct perf_probe_event *pev);

extern char *synthesize_perf_probe_command(struct perf_probe_event *pev);

extern char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev);

extern char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev);

extern int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf,

				     size_t len);





/* Check the perf_probe_event needs debuginfo */

/* Check the perf_probe_event needs debuginfo */

extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);

extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);

tools/perf/util/probe-finder.c

+104 −1
Original line number Original line Diff line number Diff line
@@ -206,6 +206,28 @@ static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die) 
	return epc;

	return epc;

}

}





/* Get type die, but skip qualifiers and typedef */

static Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)

{

	Dwarf_Attribute attr;

	int tag;



	do {

		if (dwarf_attr(vr_die, DW_AT_type, &attr) == NULL ||

		    dwarf_formref_die(&attr, die_mem) == NULL)

			return NULL;



		tag = dwarf_tag(die_mem);

		vr_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);



	return die_mem;

}



/* Return values for die_find callbacks */

/* Return values for die_find callbacks */

enum {

enum {

	DIE_FIND_CB_FOUND = 0,		/* End of Search */

	DIE_FIND_CB_FOUND = 0,		/* End of Search */
@@ -314,6 +336,25 @@ static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name, 
			      die_mem);

			      die_mem);

}

}





static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)

{

	const char *name = data;



	if ((dwarf_tag(die_mem) == DW_TAG_member) &&

	    (die_compare_name(die_mem, name) == 0))

		return DIE_FIND_CB_FOUND;



	return DIE_FIND_CB_SIBLING;

}



/* Find a member called 'name' */

static Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,

				  Dwarf_Die *die_mem)

{

	return die_find_child(st_die, __die_find_member_cb, (void *)name,

			      die_mem);

}



/*

/*

 * Probe finder related functions

 * Probe finder related functions

 */

 */
@@ -363,6 +404,62 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf) 
	}

	}

}

}





static void convert_variable_fields(Dwarf_Die *vr_die, const char *varname,

				    struct perf_probe_arg_field *field,

				    struct kprobe_trace_arg_ref **ref_ptr)

{

	struct kprobe_trace_arg_ref *ref = *ref_ptr;

	Dwarf_Attribute attr;

	Dwarf_Die member;

	Dwarf_Die type;

	Dwarf_Word offs;



	pr_debug("converting %s in %s\n", field->name, varname);

	if (die_get_real_type(vr_die, &type) == NULL)

		die("Failed to get a type information of %s.", varname);



	/* Check the pointer and dereference */

	if (dwarf_tag(&type) == DW_TAG_pointer_type) {

		if (!field->ref)

			die("Semantic error: %s must be referred by '->'",

			    field->name);

		/* Get the type pointed by this pointer */

		if (die_get_real_type(&type, &type) == NULL)

			die("Failed to get a type information of %s.", varname);



		ref = xzalloc(sizeof(struct kprobe_trace_arg_ref));

		if (*ref_ptr)

			(*ref_ptr)->next = ref;

		else

			*ref_ptr = ref;

	} else {

		if (field->ref)

			die("Semantic error: %s must be referred by '.'",

			    field->name);

		if (!ref)

			die("Structure on a register is not supported yet.");

	}



	/* Verify it is a data structure  */

	if (dwarf_tag(&type) != DW_TAG_structure_type)

		die("%s is not a data structure.", varname);



	if (die_find_member(&type, field->name, &member) == NULL)

		die("%s(tyep:%s) has no member %s.", varname,

		    dwarf_diename(&type), field->name);



	/* Get the offset of the field */

	if (dwarf_attr(&member, DW_AT_data_member_location, &attr) == NULL ||

	    dwarf_formudata(&attr, &offs) != 0)

		die("Failed to get the offset of %s.", field->name);

	ref->offset += (long)offs;



	/* Converting next field */

	if (field->next)

		convert_variable_fields(&member, field->name, field->next,

					&ref);

}



/* Show a variables in kprobe event format */

/* Show a variables in kprobe event format */

static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)

static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)

{

{
@@ -379,6 +476,10 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) 
		goto error;

		goto error;





	convert_location(expr, pf);

	convert_location(expr, pf);



	if (pf->pvar->field)

		convert_variable_fields(vr_die, pf->pvar->name,

					pf->pvar->field, &pf->tvar->ref);

	/* *expr will be cached in libdw. Don't free it. */

	/* *expr will be cached in libdw. Don't free it. */

	return ;

	return ;

error:

error:
@@ -391,13 +492,15 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) 
static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)

static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)

{

{

	Dwarf_Die vr_die;

	Dwarf_Die vr_die;

	char buf[128];





	/* TODO: Support struct members and arrays */

	/* TODO: Support struct members and arrays */

	if (!is_c_varname(pf->pvar->name)) {

	if (!is_c_varname(pf->pvar->name)) {

		/* Copy raw parameters */

		/* Copy raw parameters */

		pf->tvar->value = xstrdup(pf->pvar->name);

		pf->tvar->value = xstrdup(pf->pvar->name);

	} else {

	} else {

		pf->tvar->name = xstrdup(pf->pvar->name);

		synthesize_perf_probe_arg(pf->pvar, buf, 128);

		pf->tvar->name = xstrdup(buf);

		pr_debug("Searching '%s' variable in context.\n",

		pr_debug("Searching '%s' variable in context.\n",

			 pf->pvar->name);

			 pf->pvar->name);

		/* Search child die for local variables and parameters. */

		/* Search child die for local variables and parameters. */