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Commit 7969ec77 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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perf probe: Support "$vars" meta argument syntax for local variables 



Support "$vars" meta argument syntax for tracing all local variables at
probe point.

Now you can trace all available local variables (including function
parameters) at the probe point by passing $vars.

 # perf probe --add foo $vars

This automatically finds all local variables at foo() and adds it as
probe arguments.

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20131011071023.15557.51770.stgit@udc4-manage.rcp.hitachi.co.jp


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c824c433

tools/perf/util/probe-event.c

+0 −1
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ 
#include "session.h"



#define MAX_CMDLEN 256

#define MAX_PROBE_ARGS 128

#define PERFPROBE_GROUP "probe"



bool probe_event_dry_run;	/* Dry run flag */

tools/perf/util/probe-finder.c

+88 −8
Original line number Diff line number Diff line
@@ -1136,12 +1136,78 @@ static int debuginfo__find_probes(struct debuginfo *self, 
	return ret;

}



struct local_vars_finder {

	struct probe_finder *pf;

	struct perf_probe_arg *args;

	int max_args;

	int nargs;

	int ret;

};



/* Collect available variables in this scope */

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

{

	struct local_vars_finder *vf = data;

	int tag;



	tag = dwarf_tag(die_mem);

	if (tag == DW_TAG_formal_parameter ||

	    tag == DW_TAG_variable) {

		if (convert_variable_location(die_mem, vf->pf->addr,

					      vf->pf->fb_ops, NULL) == 0) {

			vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);

			if (vf->args[vf->nargs].var == NULL) {

				vf->ret = -ENOMEM;

				return DIE_FIND_CB_END;

			}

			pr_debug(" %s", vf->args[vf->nargs].var);

			vf->nargs++;

		}

	}



	if (dwarf_haspc(die_mem, vf->pf->addr))

		return DIE_FIND_CB_CONTINUE;

	else

		return DIE_FIND_CB_SIBLING;

}



static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,

			     struct perf_probe_arg *args)

{

	Dwarf_Die die_mem;

	int i;

	int n = 0;

	struct local_vars_finder vf = {.pf = pf, .args = args,

				.max_args = MAX_PROBE_ARGS, .ret = 0};



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

		/* var never be NULL */

		if (strcmp(pf->pev->args[i].var, "$vars") == 0) {

			pr_debug("Expanding $vars into:");

			vf.nargs = n;

			/* Special local variables */

			die_find_child(sc_die, copy_variables_cb, (void *)&vf,

				       &die_mem);

			pr_debug(" (%d)\n", vf.nargs - n);

			if (vf.ret < 0)

				return vf.ret;

			n = vf.nargs;

		} else {

			/* Copy normal argument */

			args[n] = pf->pev->args[i];

			n++;

		}

	}

	return n;

}



/* Add a found probe point into trace event list */

static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)

{

	struct trace_event_finder *tf =

			container_of(pf, struct trace_event_finder, pf);

	struct probe_trace_event *tev;

	struct perf_probe_arg *args;

	int ret, i;



	/* Check number of tevs */
@@ -1161,21 +1227,35 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) 
	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)

	/* Expand special probe argument if exist */

	args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);

	if (args == NULL)

		return -ENOMEM;

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

		pf->pvar = &pf->pev->args[i];



	ret = expand_probe_args(sc_die, pf, args);

	if (ret < 0)

		goto end;



	tev->nargs = ret;

	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);

	if (tev->args == NULL) {

		ret = -ENOMEM;

		goto end;

	}



	/* Find each argument */

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

		pf->pvar = &args[i];

		pf->tvar = &tev->args[i];

		/* Variable should be found from scope DIE */

		ret = find_variable(sc_die, pf);

		if (ret != 0)

			return ret;

			break;

	}



	return 0;

end:

	free(args);

	return ret;

}



/* Find probe_trace_events specified by perf_probe_event from debuginfo */

tools/perf/util/probe-finder.h

+1 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 


#define MAX_PROBE_BUFFER	1024

#define MAX_PROBES		 128

#define MAX_PROBE_ARGS		 128



static inline int is_c_varname(const char *name)

{