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Commit 221d0611 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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perf probe: Fix to search local variables in appropriate scope 

Fix perf probe to search local variables in appropriate local inlined
function scope. For example, pre_schedule() has only 2 local variables,
as below;

$ perf probe -L pre_schedule
<pre_schedule@/home/mhiramat/ksrc/linux-2.6/kernel/sched.c:0>
      0  static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
         {
      2         if (prev->sched_class->pre_schedule)
      3                 prev->sched_class->pre_schedule(rq, prev);
         }

However, current perf probe shows 4 local variables on pre_schedule(),
because it searches variables in the caller(schedule()) scope.

$ perf probe -V pre_schedule
Available variables at pre_schedule
        @<schedule+445>
                int     cpu
                long unsigned int*      switch_count
                struct rq*      rq
                struct task_struct*     prev

This patch fixes this issue by searching variables in the local scope of
the instance of inlined function. Here is the result.

$ perf probe -V pre_schedule
Available variables at pre_schedule
        @<schedule+445>
                struct rq*      rq
                struct task_struct*     prev

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20110811110259.19900.85664.stgit@fedora15


Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 13e27d76

tools/perf/util/dwarf-aux.c

+33 −0
Original line number Original line Diff line number Diff line
@@ -96,6 +96,39 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr, 
	return *lineno ?: -ENOENT;

	return *lineno ?: -ENOENT;

}

}





static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);



/**

 * cu_walk_functions_at - Walk on function DIEs at given address

 * @cu_die: A CU DIE

 * @addr: An address

 * @callback: A callback which called with found DIEs

 * @data: A user data

 *

 * Walk on function DIEs at given @addr in @cu_die. Passed DIEs

 * should be subprogram or inlined-subroutines.

 */

int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,

		    int (*callback)(Dwarf_Die *, void *), void *data)

{

	Dwarf_Die die_mem;

	Dwarf_Die *sc_die;

	int ret = -ENOENT;



	/* Inlined function could be recursive. Trace it until fail */

	for (sc_die = die_find_realfunc(cu_die, addr, &die_mem);

	     sc_die != NULL;

	     sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr,

				     &die_mem)) {

		ret = callback(sc_die, data);

		if (ret)

			break;

	}



	return ret;



}



/**

/**

 * die_compare_name - Compare diename and tname

 * die_compare_name - Compare diename and tname

 * @dw_die: a DIE

 * @dw_die: a DIE

tools/perf/util/dwarf-aux.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -34,6 +34,10 @@ extern const char *cu_get_comp_dir(Dwarf_Die *cu_die); 
extern int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr,

extern int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr,

			    const char **fname, int *lineno);

			    const char **fname, int *lineno);





/* Walk on funcitons at given address */

extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,

			int (*callback)(Dwarf_Die *, void *), void *data);



/* Compare diename and tname */

/* Compare diename and tname */

extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname);

extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname);

tools/perf/util/probe-finder.c

+106 −26
Original line number Original line Diff line number Diff line
@@ -612,8 +612,8 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) 
	return ret;

	return ret;

}

}





/* Find a variable in a subprogram die */

/* Find a variable in a scope DIE */

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

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

{

{

	Dwarf_Die vr_die, *scopes;

	Dwarf_Die vr_die, *scopes;

	char buf[32], *ptr;

	char buf[32], *ptr;
@@ -655,11 +655,11 @@ static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf) 
	pr_debug("Searching '%s' variable in context.\n",

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

		 pf->pvar->var);

		 pf->pvar->var);

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

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

	if (die_find_variable_at(sp_die, pf->pvar->var, pf->addr, &vr_die))

	if (die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die))

		ret = convert_variable(&vr_die, pf);

		ret = convert_variable(&vr_die, pf);

	else {

	else {

		/* Search upper class */

		/* Search upper class */

		nscopes = dwarf_getscopes_die(sp_die, &scopes);

		nscopes = dwarf_getscopes_die(sc_die, &scopes);

		ret = -ENOENT;

		ret = -ENOENT;

		while (nscopes-- > 1) {

		while (nscopes-- > 1) {

			pr_debug("Searching variables in %s\n",

			pr_debug("Searching variables in %s\n",
@@ -717,26 +717,30 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwarf_Addr paddr, 
	return 0;

	return 0;

}

}





/* Call probe_finder callback with real subprogram DIE */

/* Call probe_finder callback with scope DIE */

static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf)

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

{

{

	Dwarf_Die die_mem;

	Dwarf_Attribute fb_attr;

	Dwarf_Attribute fb_attr;

	size_t nops;

	size_t nops;

	int ret;

	int ret;





	/* If no real subprogram, find a real one */

	if (!sc_die) {

	if (!sp_die || dwarf_tag(sp_die) != DW_TAG_subprogram) {

		pr_err("Caller must pass a scope DIE. Program error.\n");

		sp_die = die_find_realfunc(&pf->cu_die, pf->addr, &die_mem);

		return -EINVAL;

		if (!sp_die) {

	}



	/* If not a real subprogram, find a real one */

	if (dwarf_tag(sc_die) != DW_TAG_subprogram) {

		if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {

			pr_warning("Failed to find probe point in any "

			pr_warning("Failed to find probe point in any "

				   "functions.\n");

				   "functions.\n");

			return -ENOENT;

			return -ENOENT;

		}

		}

	}

	} else

		memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));





	/* Get the frame base attribute/ops */

	/* Get the frame base attribute/ops from subprogram */

	dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr);

	dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);

	ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);

	ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);

	if (ret <= 0 || nops == 0) {

	if (ret <= 0 || nops == 0) {

		pf->fb_ops = NULL;

		pf->fb_ops = NULL;
@@ -754,7 +758,7 @@ static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf) 
	}

	}





	/* Call finder's callback handler */

	/* Call finder's callback handler */

	ret = pf->callback(sp_die, pf);

	ret = pf->callback(sc_die, pf);





	/* *pf->fb_ops will be cached in libdw. Don't free it. */

	/* *pf->fb_ops will be cached in libdw. Don't free it. */

	pf->fb_ops = NULL;

	pf->fb_ops = NULL;
@@ -762,17 +766,82 @@ static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf) 
	return ret;

	return ret;

}

}





struct find_scope_param {

	const char *function;

	const char *file;

	int line;

	int diff;

	Dwarf_Die *die_mem;

	bool found;

};



static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)

{

	struct find_scope_param *fsp = data;

	const char *file;

	int lno;



	/* Skip if declared file name does not match */

	if (fsp->file) {

		file = dwarf_decl_file(fn_die);

		if (!file || strcmp(fsp->file, file) != 0)

			return 0;

	}

	/* If the function name is given, that's what user expects */

	if (fsp->function) {

		if (die_compare_name(fn_die, fsp->function)) {

			memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));

			fsp->found = true;

			return 1;

		}

	} else {

		/* With the line number, find the nearest declared DIE */

		dwarf_decl_line(fn_die, &lno);

		if (lno < fsp->line && fsp->diff > fsp->line - lno) {

			/* Keep a candidate and continue */

			fsp->diff = fsp->line - lno;

			memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));

			fsp->found = true;

		}

	}

	return 0;

}



/* Find an appropriate scope fits to given conditions */

static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)

{

	struct find_scope_param fsp = {

		.function = pf->pev->point.function,

		.file = pf->fname,

		.line = pf->lno,

		.diff = INT_MAX,

		.die_mem = die_mem,

		.found = false,

	};



	cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);



	return fsp.found ? die_mem : NULL;

}



static int probe_point_line_walker(const char *fname, int lineno,

static int probe_point_line_walker(const char *fname, int lineno,

				   Dwarf_Addr addr, void *data)

				   Dwarf_Addr addr, void *data)

{

{

	struct probe_finder *pf = data;

	struct probe_finder *pf = data;

	Dwarf_Die *sc_die, die_mem;

	int ret;

	int ret;





	if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)

	if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)

		return 0;

		return 0;





	pf->addr = addr;

	pf->addr = addr;

	ret = call_probe_finder(NULL, pf);

	sc_die = find_best_scope(pf, &die_mem);

	if (!sc_die) {

		pr_warning("Failed to find scope of probe point.\n");

		return -ENOENT;

	}



	ret = call_probe_finder(sc_die, pf);





	/* Continue if no error, because the line will be in inline function */

	/* Continue if no error, because the line will be in inline function */

	return ret < 0 ? ret : 0;

	return ret < 0 ? ret : 0;
@@ -826,6 +895,7 @@ static int probe_point_lazy_walker(const char *fname, int lineno, 
				   Dwarf_Addr addr, void *data)

				   Dwarf_Addr addr, void *data)

{

{

	struct probe_finder *pf = data;

	struct probe_finder *pf = data;

	Dwarf_Die *sc_die, die_mem;

	int ret;

	int ret;





	if (!line_list__has_line(&pf->lcache, lineno) ||

	if (!line_list__has_line(&pf->lcache, lineno) ||
@@ -835,7 +905,14 @@ static int probe_point_lazy_walker(const char *fname, int lineno, 
	pr_debug("Probe line found: line:%d addr:0x%llx\n",

	pr_debug("Probe line found: line:%d addr:0x%llx\n",

		 lineno, (unsigned long long)addr);

		 lineno, (unsigned long long)addr);

	pf->addr = addr;

	pf->addr = addr;

	ret = call_probe_finder(NULL, pf);

	pf->lno = lineno;

	sc_die = find_best_scope(pf, &die_mem);

	if (!sc_die) {

		pr_warning("Failed to find scope of probe point.\n");

		return -ENOENT;

	}



	ret = call_probe_finder(sc_die, pf);





	/*

	/*

	 * Continue if no error, because the lazy pattern will match

	 * Continue if no error, because the lazy pattern will match
@@ -1059,7 +1136,7 @@ static int debuginfo__find_probes(struct debuginfo *self, 
}

}





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

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

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

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

{

{

	struct trace_event_finder *tf =

	struct trace_event_finder *tf =

			container_of(pf, struct trace_event_finder, pf);

			container_of(pf, struct trace_event_finder, pf);
@@ -1074,8 +1151,9 @@ static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf) 
	}

	}

	tev = &tf->tevs[tf->ntevs++];

	tev = &tf->tevs[tf->ntevs++];





	ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe,

	/* Trace point should be converted from subprogram DIE */

				     &tev->point);

	ret = convert_to_trace_point(&pf->sp_die, pf->addr,

				     pf->pev->point.retprobe, &tev->point);

	if (ret < 0)

	if (ret < 0)

		return ret;

		return ret;
@@ -1090,7 +1168,8 @@ static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf) 
	for (i = 0; i < pf->pev->nargs; i++) {

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

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

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

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

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

		ret = find_variable(sp_die, pf);

		/* Variable should be found from scope DIE */

		ret = find_variable(sc_die, pf);

		if (ret != 0)

		if (ret != 0)

			return ret;

			return ret;

	}

	}
@@ -1158,7 +1237,7 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data) 
}

}





/* Add a found vars into available variables list */

/* Add a found vars into available variables list */

static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf)

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

{

{

	struct available_var_finder *af =

	struct available_var_finder *af =

			container_of(pf, struct available_var_finder, pf);

			container_of(pf, struct available_var_finder, pf);
@@ -1173,8 +1252,9 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf) 
	}

	}

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

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





	ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe,

	/* Trace point should be converted from subprogram DIE */

				     &vl->point);

	ret = convert_to_trace_point(&pf->sp_die, pf->addr,

				     pf->pev->point.retprobe, &vl->point);

	if (ret < 0)

	if (ret < 0)

		return ret;

		return ret;
@@ -1186,14 +1266,14 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf) 
	if (vl->vars == NULL)

	if (vl->vars == NULL)

		return -ENOMEM;

		return -ENOMEM;

	af->child = true;

	af->child = true;

	die_find_child(sp_die, collect_variables_cb, (void *)af, &die_mem);

	die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);





	/* Find external variables */

	/* Find external variables */

	if (!af->externs)

	if (!af->externs)

		goto out;

		goto out;

	/* Don't need to search child DIE for externs. */

	/* Don't need to search child DIE for externs. */

	af->child = false;

	af->child = false;

	nscopes = dwarf_getscopes_die(sp_die, &scopes);

	nscopes = dwarf_getscopes_die(sc_die, &scopes);

	while (nscopes-- > 1)

	while (nscopes-- > 1)

		die_find_child(&scopes[nscopes], collect_variables_cb,

		die_find_child(&scopes[nscopes], collect_variables_cb,

			       (void *)af, &die_mem);

			       (void *)af, &die_mem);

tools/perf/util/probe-finder.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -57,7 +57,7 @@ struct probe_finder { 
	struct perf_probe_event	*pev;		/* Target probe event */

	struct perf_probe_event	*pev;		/* Target probe event */





	/* Callback when a probe point is found */

	/* Callback when a probe point is found */

	int (*callback)(Dwarf_Die *sp_die, struct probe_finder *pf);

	int (*callback)(Dwarf_Die *sc_die, struct probe_finder *pf);





	/* For function searching */

	/* For function searching */

	int			lno;		/* Line number */

	int			lno;		/* Line number */