/*
   * 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 <inttypes.h>

  #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 <stdlib.h>
  #include <string.h>
  #include <stdarg.h>

  #include <dwarf-regs.h>

  #include <linux/bitops.h>

  #include "event.h"

  #include "dso.h"

  #include "debug.h"

  #include "intlist.h"

  #include "util.h"

  #include "strlist.h"

  #include "symbol.h"

  #include "probe-finder.h"

  #include "probe-file.h"

  #include "string2.h"

  /* Kprobe tracer basic type is up to u64 */
  #define MAX_BASIC_TYPE_BITS	64

  /* Dwarf FL wrappers */

  static char *debuginfo_path;	/* Currently dummy */
  
  static const Dwfl_Callbacks offline_callbacks = {
  	.find_debuginfo = dwfl_standard_find_debuginfo,
  	.debuginfo_path = &debuginfo_path,
  
  	.section_address = dwfl_offline_section_address,
  
  	/* We use this table for core files too.  */
  	.find_elf = dwfl_build_id_find_elf,
  };

  /* Get a Dwarf from offline image */

  static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,

  					 const char *path)

  {

  	int fd;

  	fd = open(path, O_RDONLY);
  	if (fd < 0)
  		return fd;

  	dbg->dwfl = dwfl_begin(&offline_callbacks);
  	if (!dbg->dwfl)

  		goto error;

  	dwfl_report_begin(dbg->dwfl);

  	dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
  	if (!dbg->mod)

  		goto error;

  	dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
  	if (!dbg->dbg)

  		goto error;

  	dwfl_report_end(dbg->dwfl, NULL, NULL);

  	return 0;

  error:

  	if (dbg->dwfl)
  		dwfl_end(dbg->dwfl);

  	else
  		close(fd);

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

  
  	return -ENOENT;

  }

  static struct debuginfo *__debuginfo__new(const char *path)

  {

  	struct debuginfo *dbg = zalloc(sizeof(*dbg));
  	if (!dbg)

  		return NULL;

  	if (debuginfo__init_offline_dwarf(dbg, path) < 0)
  		zfree(&dbg);

  	if (dbg)
  		pr_debug("Open Debuginfo file: %s
  ", path);

  	return dbg;

  }

  enum dso_binary_type distro_dwarf_types[] = {
  	DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
  	DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
  	DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
  	DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
  	DSO_BINARY_TYPE__NOT_FOUND,
  };
  
  struct debuginfo *debuginfo__new(const char *path)
  {
  	enum dso_binary_type *type;
  	char buf[PATH_MAX], nil = '\0';
  	struct dso *dso;
  	struct debuginfo *dinfo = NULL;
  
  	/* Try to open distro debuginfo files */
  	dso = dso__new(path);
  	if (!dso)
  		goto out;
  
  	for (type = distro_dwarf_types;
  	     !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
  	     type++) {
  		if (dso__read_binary_type_filename(dso, *type, &nil,
  						   buf, PATH_MAX) < 0)
  			continue;
  		dinfo = __debuginfo__new(buf);
  	}

  	dso__put(dso);

  
  out:
  	/* if failed to open all distro debuginfo, open given binary */
  	return dinfo ? : __debuginfo__new(path);
  }

  void debuginfo__delete(struct debuginfo *dbg)

  {

  	if (dbg) {
  		if (dbg->dwfl)
  			dwfl_end(dbg->dwfl);
  		free(dbg);

  	}

  }

  /*
   * Probe finder related functions
   */

  static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)

  {

  	struct probe_trace_arg_ref *ref;
  	ref = zalloc(sizeof(struct probe_trace_arg_ref));

  	if (ref != NULL)
  		ref->offset = offs;
  	return ref;
  }

  /*
   * Convert a location into trace_arg.
   * If tvar == NULL, this just checks variable can be converted.

   * If fentry == true and vr_die is a parameter, do huristic search
   * for the location fuzzed by function entry mcount.

   */
  static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,

  				     Dwarf_Op *fb_ops, Dwarf_Die *sp_die,

  				     unsigned int machine,

  				     struct probe_trace_arg *tvar)

  {

  	Dwarf_Attribute attr;

  	Dwarf_Addr tmp = 0;

  	Dwarf_Op *op;
  	size_t nops;

  	unsigned int regn;
  	Dwarf_Word offs = 0;

  	bool ref = false;

  	const char *regs;

  	int ret, ret2 = 0;

  	if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
  		goto static_var;

  	/* TODO: handle more than 1 exprs */

  	if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
  		return -EINVAL;	/* Broken DIE ? */
  	if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
  		ret = dwarf_entrypc(sp_die, &tmp);

  		if (ret)
  			return -ENOENT;
  
  		if (probe_conf.show_location_range &&
  			(dwarf_tag(vr_die) == DW_TAG_variable)) {
  			ret2 = -ERANGE;
  		} else if (addr != tmp ||
  			dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
  			return -ENOENT;
  		}
  
  		ret = dwarf_highpc(sp_die, &tmp);
  		if (ret)

  			return -ENOENT;
  		/*
  		 * This is fuzzed by fentry mcount. We try to find the
  		 * parameter location at the earliest address.
  		 */
  		for (addr += 1; addr <= tmp; addr++) {
  			if (dwarf_getlocation_addr(&attr, addr, &op,
  						   &nops, 1) > 0)
  				goto found;
  		}

  		return -ENOENT;
  	}

  found:
  	if (nops == 0)
  		/* TODO: Support const_value */
  		return -ENOENT;

  
  	if (op->atom == DW_OP_addr) {

  static_var:

  		if (!tvar)

  			return ret2;

  		/* Static variables on memory (not stack), make @varname */
  		ret = strlen(dwarf_diename(vr_die));
  		tvar->value = zalloc(ret + 2);
  		if (tvar->value == NULL)
  			return -ENOMEM;
  		snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
  		tvar->ref = alloc_trace_arg_ref((long)offs);
  		if (tvar->ref == NULL)
  			return -ENOMEM;

  		return ret2;

  	}

  	/* If this is based on frame buffer, set the offset */

  	if (op->atom == DW_OP_fbreg) {

  		if (fb_ops == NULL)

  			return -ENOTSUP;

  		ref = true;

  		offs = op->number;

  		op = &fb_ops[0];

  	}

  	if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
  		regn = op->atom - DW_OP_breg0;
  		offs += op->number;

  		ref = true;

  	} else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
  		regn = op->atom - DW_OP_reg0;
  	} else if (op->atom == DW_OP_bregx) {
  		regn = op->number;
  		offs += op->number2;

  		ref = true;

  	} else if (op->atom == DW_OP_regx) {
  		regn = op->number;

  	} else {

  		pr_debug("DW_OP %x is not supported.
  ", op->atom);

  		return -ENOTSUP;
  	}

  	if (!tvar)

  		return ret2;

  	regs = get_dwarf_regstr(regn, machine);

  	if (!regs) {

  		/* This should be a bug in DWARF or this tool */

  		pr_warning("Mapping for the register number %u "
  			   "missing on this architecture.
  ", regn);

  		return -ENOTSUP;

  	}

  	tvar->value = strdup(regs);
  	if (tvar->value == NULL)
  		return -ENOMEM;

  	if (ref) {

  		tvar->ref = alloc_trace_arg_ref((long)offs);

  		if (tvar->ref == NULL)
  			return -ENOMEM;

  	}

  	return ret2;

  }

  #define BYTES_TO_BITS(nb)	((nb) * BITS_PER_LONG / sizeof(long))

  static int convert_variable_type(Dwarf_Die *vr_die,

  				 struct probe_trace_arg *tvar,

  				 const char *cast)

  {

  	struct probe_trace_arg_ref **ref_ptr = &tvar->ref;

  	Dwarf_Die type;
  	char buf[16];

  	char sbuf[STRERR_BUFSIZE];

  	int bsize, boffs, total;

  	int ret;

  	char prefix;

  	/* TODO: check all types */

  	if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "x") != 0 &&

  	    strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {

  		/* Non string type is OK */

  		/* and respect signedness/hexadecimal cast */

  		tvar->type = strdup(cast);
  		return (tvar->type == NULL) ? -ENOMEM : 0;
  	}

  	bsize = dwarf_bitsize(vr_die);
  	if (bsize > 0) {

  		/* This is a bitfield */

  		boffs = dwarf_bitoffset(vr_die);
  		total = dwarf_bytesize(vr_die);
  		if (boffs < 0 || total < 0)
  			return -ENOENT;
  		ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
  				BYTES_TO_BITS(total));

  		goto formatted;
  	}

  	if (die_get_real_type(vr_die, &type) == NULL) {
  		pr_warning("Failed to get a type information of %s.
  ",
  			   dwarf_diename(vr_die));
  		return -ENOENT;
  	}

  	pr_debug("%s type is %s.
  ",
  		 dwarf_diename(vr_die), dwarf_diename(&type));

  	if (cast && strcmp(cast, "string") == 0) {	/* String type */
  		ret = dwarf_tag(&type);
  		if (ret != DW_TAG_pointer_type &&
  		    ret != DW_TAG_array_type) {
  			pr_warning("Failed to cast into string: "

  				   "%s(%s) is not a pointer nor array.
  ",

  				   dwarf_diename(vr_die), dwarf_diename(&type));
  			return -EINVAL;
  		}

  		if (die_get_real_type(&type, &type) == NULL) {
  			pr_warning("Failed to get a type"
  				   " information.
  ");
  			return -ENOENT;
  		}

  		if (ret == DW_TAG_pointer_type) {

  			while (*ref_ptr)
  				ref_ptr = &(*ref_ptr)->next;
  			/* Add new reference with offset +0 */

  			*ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));

  			if (*ref_ptr == NULL) {
  				pr_warning("Out of memory error
  ");
  				return -ENOMEM;
  			}
  		}

  		if (!die_compare_name(&type, "char") &&
  		    !die_compare_name(&type, "unsigned char")) {

  			pr_warning("Failed to cast into string: "

  				   "%s is not (unsigned) char *.
  ",

  				   dwarf_diename(vr_die));
  			return -EINVAL;
  		}
  		tvar->type = strdup(cast);
  		return (tvar->type == NULL) ? -ENOMEM : 0;
  	}

  	if (cast && (strcmp(cast, "u") == 0))

  		prefix = 'u';

  	else if (cast && (strcmp(cast, "s") == 0))

  		prefix = 's';
  	else if (cast && (strcmp(cast, "x") == 0) &&
  		 probe_type_is_available(PROBE_TYPE_X))
  		prefix = 'x';

  	else

  		prefix = die_is_signed_type(&type) ? 's' :
  			 probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';

  	ret = dwarf_bytesize(&type);
  	if (ret <= 0)

  		/* No size ... try to use default type */
  		return 0;

  	ret = BYTES_TO_BITS(ret);

  	/* Check the bitwidth */
  	if (ret > MAX_BASIC_TYPE_BITS) {
  		pr_info("%s exceeds max-bitwidth. Cut down to %d bits.
  ",
  			dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
  		ret = MAX_BASIC_TYPE_BITS;

  	}

  	ret = snprintf(buf, 16, "%c%d", prefix, ret);

  
  formatted:
  	if (ret < 0 || ret >= 16) {
  		if (ret >= 16)
  			ret = -E2BIG;
  		pr_warning("Failed to convert variable type: %s
  ",

  			   str_error_r(-ret, sbuf, sizeof(sbuf)));

  		return ret;
  	}
  	tvar->type = strdup(buf);
  	if (tvar->type == NULL)
  		return -ENOMEM;

  	return 0;

  }

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

  				    struct perf_probe_arg_field *field,

  				    struct probe_trace_arg_ref **ref_ptr,

  				    Dwarf_Die *die_mem)

  {

  	struct probe_trace_arg_ref *ref = *ref_ptr;

  	Dwarf_Die type;
  	Dwarf_Word offs;

  	int ret, tag;

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

  	if (die_get_real_type(vr_die, &type) == NULL) {
  		pr_warning("Failed to get the type of %s.
  ", varname);
  		return -ENOENT;
  	}

  	pr_debug2("Var real type: (%x)
  ", (unsigned)dwarf_dieoffset(&type));
  	tag = dwarf_tag(&type);
  
  	if (field->name[0] == '[' &&
  	    (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
  		if (field->next)
  			/* Save original type for next field */
  			memcpy(die_mem, &type, sizeof(*die_mem));
  		/* Get the type of this array */
  		if (die_get_real_type(&type, &type) == NULL) {
  			pr_warning("Failed to get the type of %s.
  ", varname);
  			return -ENOENT;
  		}
  		pr_debug2("Array real type: (%x)
  ",
  			 (unsigned)dwarf_dieoffset(&type));
  		if (tag == DW_TAG_pointer_type) {

  			ref = zalloc(sizeof(struct probe_trace_arg_ref));

  			if (ref == NULL)
  				return -ENOMEM;
  			if (*ref_ptr)
  				(*ref_ptr)->next = ref;
  			else
  				*ref_ptr = ref;
  		}

  		ref->offset += dwarf_bytesize(&type) * field->index;

  		if (!field->next)
  			/* Save vr_die for converting types */
  			memcpy(die_mem, vr_die, sizeof(*die_mem));
  		goto next;
  	} else if (tag == DW_TAG_pointer_type) {
  		/* Check the pointer and dereference */

  		if (!field->ref) {
  			pr_err("Semantic error: %s must be referred by '->'
  ",
  			       field->name);
  			return -EINVAL;
  		}

  		/* Get the type pointed by this pointer */

  		if (die_get_real_type(&type, &type) == NULL) {
  			pr_warning("Failed to get the type of %s.
  ", varname);
  			return -ENOENT;
  		}

  		/* Verify it is a data structure  */

  		tag = dwarf_tag(&type);
  		if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {

  			pr_warning("%s is not a data structure nor a union.
  ",

  				   varname);

  			return -EINVAL;
  		}

  		ref = zalloc(sizeof(struct probe_trace_arg_ref));

  		if (ref == NULL)
  			return -ENOMEM;

  		if (*ref_ptr)
  			(*ref_ptr)->next = ref;
  		else
  			*ref_ptr = ref;
  	} else {

  		/* Verify it is a data structure  */

  		if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {

  			pr_warning("%s is not a data structure nor a union.
  ",

  				   varname);

  			return -EINVAL;
  		}

  		if (field->name[0] == '[') {

  			pr_err("Semantic error: %s is not a pointer"

  			       " nor array.
  ", varname);

  			return -EINVAL;
  		}

  		/* While prcessing unnamed field, we don't care about this */
  		if (field->ref && dwarf_diename(vr_die)) {

  			pr_err("Semantic error: %s must be referred by '.'
  ",
  			       field->name);
  			return -EINVAL;
  		}
  		if (!ref) {
  			pr_warning("Structure on a register is not "
  				   "supported yet.
  ");
  			return -ENOTSUP;
  		}

  	}

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

  		pr_warning("%s(type:%s) has no member %s.
  ", varname,

  			   dwarf_diename(&type), field->name);
  		return -EINVAL;
  	}

  
  	/* Get the offset of the field */

  	if (tag == DW_TAG_union_type) {
  		offs = 0;
  	} else {
  		ret = die_get_data_member_location(die_mem, &offs);
  		if (ret < 0) {
  			pr_warning("Failed to get the offset of %s.
  ",
  				   field->name);
  			return ret;
  		}

  	}

  	ref->offset += (long)offs;

  	/* If this member is unnamed, we need to reuse this field */
  	if (!dwarf_diename(die_mem))
  		return convert_variable_fields(die_mem, varname, field,
  						&ref, die_mem);

  next:

  	/* Converting next field */
  	if (field->next)

  		return convert_variable_fields(die_mem, field->name,

  					field->next, &ref, die_mem);

  	else
  		return 0;

  }

  /* Show a variables in kprobe event format */

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

  {

  	Dwarf_Die die_mem;

  	int ret;

  	pr_debug("Converting variable %s into trace event.
  ",
  		 dwarf_diename(vr_die));

  	ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,

  					&pf->sp_die, pf->machine, pf->tvar);

  	if (ret == -ENOENT || ret == -EINVAL) {
  		pr_err("Failed to find the location of the '%s' variable at this address.
  "
  		       " Perhaps it has been optimized out.
  "
  		       " Use -V with the --range option to show '%s' location range.
  ",
  		       pf->pvar->var, pf->pvar->var);
  	} else if (ret == -ENOTSUP)

  		pr_err("Sorry, we don't support this variable location yet.
  ");

  	else if (ret == 0 && pf->pvar->field) {

  		ret = convert_variable_fields(vr_die, pf->pvar->var,
  					      pf->pvar->field, &pf->tvar->ref,
  					      &die_mem);

  		vr_die = &die_mem;
  	}

  	if (ret == 0)
  		ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type);

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

  	return ret;

  }

  /* Find a variable in a scope DIE */
  static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)

  {

  	Dwarf_Die vr_die;

  	char *buf, *ptr;

  	int ret = 0;

  	/* Copy raw parameters */
  	if (!is_c_varname(pf->pvar->var))
  		return copy_to_probe_trace_arg(pf->tvar, pf->pvar);

  	if (pf->pvar->name)

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

  	else {

  		buf = synthesize_perf_probe_arg(pf->pvar);
  		if (!buf)
  			return -ENOMEM;

  		ptr = strchr(buf, ':');	/* Change type separator to _ */
  		if (ptr)
  			*ptr = '_';

  		pf->tvar->name = buf;

  	}

  	if (pf->tvar->name == NULL)
  		return -ENOMEM;

  	pr_debug("Searching '%s' variable in context.
  ", pf->pvar->var);

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

  	if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
  		/* Search again in global variables */

  		if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
  						0, &vr_die)) {

  			pr_warning("Failed to find '%s' in this function.
  ",
  				   pf->pvar->var);

  			ret = -ENOENT;

  		}

  	}

  	if (ret >= 0)

  		ret = convert_variable(&vr_die, pf);

  	return ret;

  }

  /* Convert subprogram DIE to trace point */

  static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
  				  Dwarf_Addr paddr, bool retprobe,

  				  const char *function,

  				  struct probe_trace_point *tp)

  {

  	Dwarf_Addr eaddr, highaddr;

  	GElf_Sym sym;
  	const char *symbol;
  
  	/* Verify the address is correct */
  	if (dwarf_entrypc(sp_die, &eaddr) != 0) {
  		pr_warning("Failed to get entry address of %s
  ",
  			   dwarf_diename(sp_die));
  		return -ENOENT;
  	}
  	if (dwarf_highpc(sp_die, &highaddr) != 0) {
  		pr_warning("Failed to get end address of %s
  ",
  			   dwarf_diename(sp_die));
  		return -ENOENT;
  	}
  	if (paddr > highaddr) {
  		pr_warning("Offset specified is greater than size of %s
  ",
  			   dwarf_diename(sp_die));
  		return -EINVAL;
  	}

  	symbol = dwarf_diename(sp_die);

  	if (!symbol) {

  		/* Try to get the symbol name from symtab */
  		symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
  		if (!symbol) {
  			pr_warning("Failed to find symbol at 0x%lx
  ",
  				   (unsigned long)paddr);
  			return -ENOENT;
  		}
  		eaddr = sym.st_value;

  	}

  	tp->offset = (unsigned long)(paddr - eaddr);

  	tp->address = (unsigned long)paddr;

  	tp->symbol = strdup(symbol);
  	if (!tp->symbol)
  		return -ENOMEM;

  	/* Return probe must be on the head of a subprogram */

  	if (retprobe) {
  		if (eaddr != paddr) {

  			pr_warning("Failed to find \"%s%%return\",
  "
  				   " because %s is an inlined function and"
  				   " has no return point.
  ", function,
  				   function);

  			return -EINVAL;
  		}

  		tp->retprobe = true;

  	}

  	return 0;
  }

  /* Call probe_finder callback with scope DIE */
  static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)

  {

  	Dwarf_Attribute fb_attr;

  	Dwarf_Frame *frame = NULL;

  	size_t nops;
  	int ret;

  	if (!sc_die) {
  		pr_err("Caller must pass a scope DIE. Program error.
  ");
  		return -EINVAL;
  	}
  
  	/* If not a real subprogram, find a real one */

  	if (!die_is_func_def(sc_die)) {

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

  			if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
  				pr_warning("Ignoring tail call from %s
  ",
  						dwarf_diename(&pf->sp_die));
  				return 0;
  			} else {
  				pr_warning("Failed to find probe point in any "
  					   "functions.
  ");
  				return -ENOENT;
  			}

  		}

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

  	/* Get the frame base attribute/ops from subprogram */
  	dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);

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

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

  		pf->fb_ops = NULL;

  #if _ELFUTILS_PREREQ(0, 142)

  	} else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&

  		   (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
  		if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
  		     (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||

  		    dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {

  			pr_warning("Failed to get call frame on 0x%jx
  ",

  				   (uintmax_t)pf->addr);

  			free(frame);
  			return -ENOENT;

  		}

  #endif

  	}

  	/* Call finder's callback handler */

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

  	/* Since *pf->fb_ops can be a part of frame. we should free it here. */
  	free(frame);

  	pf->fb_ops = NULL;

  
  	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_match_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,
  				   Dwarf_Addr addr, void *data)

  {

  	struct probe_finder *pf = data;

  	Dwarf_Die *sc_die, die_mem;

  	int ret;

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

  	pf->addr = addr;

  	sc_die = find_best_scope(pf, &die_mem);
  	if (!sc_die) {
  		pr_warning("Failed to find scope of probe point.
  ");
  		return -ENOENT;
  	}
  
  	ret = call_probe_finder(sc_die, pf);

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

  	return ret < 0 ? ret : 0;

  }

  /* Find probe point from its line number */
  static int find_probe_point_by_line(struct probe_finder *pf)
  {
  	return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);

  }

  /* Find lines which match lazy pattern */

  static int find_lazy_match_lines(struct intlist *list,

  				 const char *fname, const char *pat)
  {

  	FILE *fp;
  	char *line = NULL;
  	size_t line_len;
  	ssize_t len;
  	int count = 0, linenum = 1;

  	char sbuf[STRERR_BUFSIZE];

  
  	fp = fopen(fname, "r");
  	if (!fp) {

  		pr_warning("Failed to open %s: %s
  ", fname,

  			   str_error_r(errno, sbuf, sizeof(sbuf)));

  		return -errno;

  	}

  	while ((len = getline(&line, &line_len, fp)) > 0) {

  		if (line[len - 1] == '
  ')
  			line[len - 1] = '\0';
  
  		if (strlazymatch(line, pat)) {

  			intlist__add(list, linenum);

  			count++;

  		}

  		linenum++;

  	}

  
  	if (ferror(fp))
  		count = -errno;
  	free(line);
  	fclose(fp);
  
  	if (count == 0)
  		pr_debug("No matched lines found in %s.
  ", fname);
  	return count;

  }

  static int probe_point_lazy_walker(const char *fname, int lineno,
  				   Dwarf_Addr addr, void *data)
  {
  	struct probe_finder *pf = data;

  	Dwarf_Die *sc_die, die_mem;

  	int ret;

  	if (!intlist__has_entry(pf->lcache, lineno) ||

  	    strtailcmp(fname, pf->fname) != 0)
  		return 0;
  
  	pr_debug("Probe line found: line:%d addr:0x%llx
  ",
  		 lineno, (unsigned long long)addr);
  	pf->addr = addr;

  	pf->lno = lineno;
  	sc_die = find_best_scope(pf, &die_mem);
  	if (!sc_die) {
  		pr_warning("Failed to find scope of probe point.
  ");
  		return -ENOENT;
  	}
  
  	ret = call_probe_finder(sc_die, pf);

  
  	/*
  	 * Continue if no error, because the lazy pattern will match
  	 * to other lines
  	 */

  	return ret < 0 ? ret : 0;

  }

  /* Find probe points from lazy pattern  */

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

  {

  	int ret = 0;

  	char *fpath;

  	if (intlist__empty(pf->lcache)) {

  		const char *comp_dir;
  
  		comp_dir = cu_get_comp_dir(&pf->cu_die);
  		ret = get_real_path(pf->fname, comp_dir, &fpath);
  		if (ret < 0) {
  			pr_warning("Failed to find source file path.
  ");
  			return ret;
  		}

  		/* Matching lazy line pattern */

  		ret = find_lazy_match_lines(pf->lcache, fpath,

  					    pf->pev->point.lazy_line);

  		free(fpath);

  		if (ret <= 0)

  			return ret;

  	}

  	return die_walk_lines(sp_die, probe_point_lazy_walker, pf);

  }

  static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
  {
  	struct perf_probe_point *pp = &pf->pev->point;
  
  	/* Not uprobe? */
  	if (!pf->pev->uprobes)
  		return;
  
  	/* Compiled with optimization? */

  	if (die_is_optimized_target(&pf->cu_die))

  		return;
  
  	/* Don't know entrypc? */
  	if (!pf->addr)
  		return;
  
  	/* Only FUNC and FUNC@SRC are eligible. */
  	if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
  	    pp->offset || pp->abs_address)
  		return;
  
  	/* Not interested in func parameter? */
  	if (!perf_probe_with_var(pf->pev))
  		return;
  
  	pr_info("Target program is compiled without optimization. Skipping prologue.
  "
  		"Probe on address 0x%" PRIx64 " to force probing at the function entry.
  
  ",
  		pf->addr);

  	die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);

  }

  static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
  {

  	struct probe_finder *pf = data;

  	struct perf_probe_point *pp = &pf->pev->point;

  	Dwarf_Addr addr;

  	int ret;

  	if (pp->lazy_line)

  		ret = find_probe_point_lazy(in_die, pf);

  	else {
  		/* Get probe address */

  		if (dwarf_entrypc(in_die, &addr) != 0) {

  			pr_warning("Failed to get entry address of %s.
  ",

  				   dwarf_diename(in_die));

  			return -ENOENT;

  		}

  		if (addr == 0) {
  			pr_debug("%s has no valid entry address. skipped.
  ",
  				 dwarf_diename(in_die));
  			return -ENOENT;
  		}

  		pf->addr = addr;

  		pf->addr += pp->offset;
  		pr_debug("found inline addr: 0x%jx
  ",
  			 (uintmax_t)pf->addr);

  		ret = call_probe_finder(in_die, pf);

  	}

  	return ret;

  }

  /* Callback parameter with return value for libdw */
  struct dwarf_callback_param {
  	void *data;
  	int retval;
  };

  /* Search function from function name */

  static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)

  {

  	struct dwarf_callback_param *param = data;
  	struct probe_finder *pf = param->data;

  	struct perf_probe_point *pp = &pf->pev->point;

  	/* Check tag and diename */

  	if (!die_is_func_def(sp_die) ||

  	    !die_match_name(sp_die, pp->function))

  		return DWARF_CB_OK;

  	/* Check declared file */
  	if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
  		return DWARF_CB_OK;

  	pr_debug("Matched function: %s [%lx]
  ", dwarf_diename(sp_die),
  		 (unsigned long)dwarf_dieoffset(sp_die));

  	pf->fname = dwarf_decl_file(sp_die);

  	if (pp->line) { /* Function relative line */

  		dwarf_decl_line(sp_die, &pf->lno);
  		pf->lno += pp->line;

  		param->retval = find_probe_point_by_line(pf);

  	} else if (die_is_func_instance(sp_die)) {
  		/* Instances always have the entry address */
  		dwarf_entrypc(sp_die, &pf->addr);

  		/* But in some case the entry address is 0 */
  		if (pf->addr == 0) {
  			pr_debug("%s has no entry PC. Skipped
  ",
  				 dwarf_diename(sp_die));
  			param->retval = 0;

  		/* Real function */

  		} else if (pp->lazy_line)

  			param->retval = find_probe_point_lazy(sp_die, pf);

  		else {

  			skip_prologue(sp_die, pf);

  			pf->addr += pp->offset;
  			/* TODO: Check the address in this function */

  			param->retval = call_probe_finder(sp_die, pf);

  		}

  	} else if (!probe_conf.no_inlines) {

  		/* Inlined function: search instances */

  		param->retval = die_walk_instances(sp_die,
  					probe_point_inline_cb, (void *)pf);

  		/* This could be a non-existed inline definition */

  		if (param->retval == -ENOENT)

  			param->retval = 0;
  	}
  
  	/* We need to find other candidates */
  	if (strisglob(pp->function) && param->retval >= 0) {
  		param->retval = 0;	/* We have to clear the result */
  		return DWARF_CB_OK;
  	}

  	return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */

  }

  static int find_probe_point_by_func(struct probe_finder *pf)

  {

  	struct dwarf_callback_param _param = {.data = (void *)pf,
  					      .retval = 0};
  	dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
  	return _param.retval;

  }

  struct pubname_callback_param {
  	char *function;
  	char *file;
  	Dwarf_Die *cu_die;
  	Dwarf_Die *sp_die;
  	int found;
  };
  
  static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
  {
  	struct pubname_callback_param *param = data;
  
  	if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
  		if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
  			return DWARF_CB_OK;

  		if (die_match_name(param->sp_die, param->function)) {

  			if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
  				return DWARF_CB_OK;
  
  			if (param->file &&
  			    strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
  				return DWARF_CB_OK;
  
  			param->found = 1;
  			return DWARF_CB_ABORT;
  		}
  	}
  
  	return DWARF_CB_OK;
  }

  static int debuginfo__find_probe_location(struct debuginfo *dbg,

  				  struct probe_finder *pf)

  {

  	struct perf_probe_point *pp = &pf->pev->point;

  	Dwarf_Off off, noff;
  	size_t cuhl;
  	Dwarf_Die *diep;

  	int ret = 0;

  	off = 0;

  	pf->lcache = intlist__new(NULL);
  	if (!pf->lcache)
  		return -ENOMEM;

  
  	/* Fastpath: lookup by function name from .debug_pubnames section */

  	if (pp->function && !strisglob(pp->function)) {

  		struct pubname_callback_param pubname_param = {
  			.function = pp->function,
  			.file	  = pp->file,
  			.cu_die	  = &pf->cu_die,
  			.sp_die	  = &pf->sp_die,

  			.found	  = 0,

  		};
  		struct dwarf_callback_param probe_param = {
  			.data = pf,
  		};

  		dwarf_getpubnames(dbg->dbg, pubname_search_cb,

  				  &pubname_param, 0);

  		if (pubname_param.found) {
  			ret = probe_point_search_cb(&pf->sp_die, &probe_param);
  			if (ret)
  				goto found;
  		}
  	}

  	/* Loop on CUs (Compilation Unit) */

  	while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {

  		/* Get the DIE(Debugging Information Entry) of this CU */

  		diep = dwarf_offdie(dbg->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);

  		else

  			pf->fname = NULL;

  		if (!pp->file || pf->fname) {

  			if (pp->function)

  				ret = find_probe_point_by_func(pf);

  			else if (pp->lazy_line)

  				ret = find_probe_point_lazy(&pf->cu_die, pf);

  			else {

  				pf->lno = pp->line;
  				ret = find_probe_point_by_line(pf);

  			}

  			if (ret < 0)

  				break;

  		}

  		off = noff;

  	}

  
  found:

  	intlist__delete(pf->lcache);
  	pf->lcache = NULL;

  	return ret;
  }

  /* Find probe points from debuginfo */
  static int debuginfo__find_probes(struct debuginfo *dbg,
  				  struct probe_finder *pf)
  {
  	int ret = 0;

  	Elf *elf;
  	GElf_Ehdr ehdr;

  
  	if (pf->cfi_eh || pf->cfi_dbg)
  		return debuginfo__find_probe_location(dbg, pf);
  
  	/* Get the call frame information from this dwarf */
  	elf = dwarf_getelf(dbg->dbg);
  	if (elf == NULL)
  		return -EINVAL;
  
  	if (gelf_getehdr(elf, &ehdr) == NULL)
  		return -EINVAL;

  	pf->machine = ehdr.e_machine;
  
  #if _ELFUTILS_PREREQ(0, 142)
  	do {
  		GElf_Shdr shdr;
  
  		if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
  		    shdr.sh_type == SHT_PROGBITS)
  			pf->cfi_eh = dwarf_getcfi_elf(elf);

  		pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
  	} while (0);

  #endif
  
  	ret = debuginfo__find_probe_location(dbg, pf);
  	return ret;
  }

  struct local_vars_finder {
  	struct probe_finder *pf;
  	struct perf_probe_arg *args;

  	bool vars;

  	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;

  	struct probe_finder *pf = vf->pf;

  	int tag;
  
  	tag = dwarf_tag(die_mem);
  	if (tag == DW_TAG_formal_parameter ||

  	    (tag == DW_TAG_variable && vf->vars)) {

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

  					      vf->pf->fb_ops, &pf->sp_die,

  					      pf->machine, 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, .vars = false,

  				.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, PROBE_ARG_VARS) == 0)
  			vf.vars = true;
  		else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {

  			/* Copy normal argument */
  			args[n] = pf->pev->args[i];
  			n++;

  			continue;

  		}

  		pr_debug("Expanding %s into:", pf->pev->args[i].var);
  		vf.nargs = n;
  		/* Special local variables */
  		die_find_child(sc_die, copy_variables_cb, (void *)&vf,
  			       &die_mem);
  		pr_debug(" (%d)
  ", vf.nargs - n);
  		if (vf.ret < 0)
  			return vf.ret;
  		n = vf.nargs;

  	}
  	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 perf_probe_point *pp = &pf->pev->point;

  	struct probe_trace_event *tev;

  	struct perf_probe_arg *args = NULL;

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

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

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

  				     pp->retprobe, pp->function, &tev->point);

  	if (ret < 0)

  		goto end;

  	tev->point.realname = strdup(dwarf_diename(sc_die));

  	if (!tev->point.realname) {
  		ret = -ENOMEM;
  		goto end;
  	}

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

  	/* Expand special probe argument if exist */
  	args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);

  	if (args == NULL) {
  		ret = -ENOMEM;
  		goto end;
  	}

  
  	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)

  			break;

  	}

  end:

  	if (ret) {
  		clear_probe_trace_event(tev);
  		tf->ntevs--;
  	}

  	free(args);
  	return ret;

  }
  
  /* Find probe_trace_events specified by perf_probe_event from debuginfo */

  int debuginfo__find_trace_events(struct debuginfo *dbg,

  				 struct perf_probe_event *pev,

  				 struct probe_trace_event **tevs)

  {
  	struct trace_event_finder tf = {
  			.pf = {.pev = pev, .callback = add_probe_trace_event},

  			.max_tevs = probe_conf.max_probes, .mod = dbg->mod};

  	int ret, i;

  
  	/* Allocate result tevs array */

  	*tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);

  	if (*tevs == NULL)
  		return -ENOMEM;
  
  	tf.tevs = *tevs;
  	tf.ntevs = 0;

  	ret = debuginfo__find_probes(dbg, &tf.pf);

  	if (ret < 0) {

  		for (i = 0; i < tf.ntevs; i++)
  			clear_probe_trace_event(&tf.tevs[i]);

  		zfree(tevs);

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

  /* 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;

  	struct strbuf buf = STRBUF_INIT;

  	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, &af->pf.sp_die,

  						af->pf.machine, NULL);

  		if (ret == 0 || ret == -ERANGE) {
  			int ret2;
  			bool externs = !af->child;

  			if (strbuf_init(&buf, 64) < 0)
  				goto error;

  
  			if (probe_conf.show_location_range) {

  				if (!externs)
  					ret2 = strbuf_add(&buf,
  						ret ? "[INV]\t" : "[VAL]\t", 6);
  				else
  					ret2 = strbuf_add(&buf, "[EXT]\t", 6);
  				if (ret2)
  					goto error;

  			}
  
  			ret2 = die_get_varname(die_mem, &buf);
  
  			if (!ret2 && probe_conf.show_location_range &&
  				!externs) {

  				if (strbuf_addch(&buf, '\t') < 0)
  					goto error;

  				ret2 = die_get_var_range(&af->pf.sp_die,
  							die_mem, &buf);
  			}
  
  			pr_debug("Add new var: %s
  ", buf.buf);
  			if (ret2 == 0) {

  				strlist__add(vl->vars,
  					strbuf_detach(&buf, NULL));

  			}
  			strbuf_release(&buf);

  		}
  	}

  	if (af->child && dwarf_haspc(die_mem, af->pf.addr))

  		return DIE_FIND_CB_CONTINUE;
  	else
  		return DIE_FIND_CB_SIBLING;

  error:
  	strbuf_release(&buf);
  	pr_debug("Error in strbuf
  ");
  	return DIE_FIND_CB_END;

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

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

  {
  	struct available_var_finder *af =
  			container_of(pf, struct available_var_finder, pf);

  	struct perf_probe_point *pp = &pf->pev->point;

  	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.
  ", af->max_vls);
  		return -ERANGE;
  	}
  	vl = &af->vls[af->nvls++];

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

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

  				     pp->retprobe, pp->function, &vl->point);

  	if (ret < 0)
  		return ret;
  
  	pr_debug("Probe point found: %s+%lu
  ", vl->point.symbol,
  		 vl->point.offset);
  
  	/* Find local variables */

  	vl->vars = strlist__new(NULL, NULL);

  	if (vl->vars == NULL)
  		return -ENOMEM;

  	af->child = true;

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

  	/* Find external variables */

  	if (!probe_conf.show_ext_vars)

  		goto out;

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

  	af->child = false;

  	die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);

  
  out:

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

  /*
   * Find available variables at given probe point
   * Return the number of found probe points. Return 0 if there is no
   * matched probe point. Return <0 if an error occurs.
   */

  int debuginfo__find_available_vars_at(struct debuginfo *dbg,

  				      struct perf_probe_event *pev,

  				      struct variable_list **vls)

  {
  	struct available_var_finder af = {
  			.pf = {.pev = pev, .callback = add_available_vars},

  			.mod = dbg->mod,

  			.max_vls = probe_conf.max_probes};

  	int ret;
  
  	/* Allocate result vls array */

  	*vls = zalloc(sizeof(struct variable_list) * af.max_vls);

  	if (*vls == NULL)
  		return -ENOMEM;
  
  	af.vls = *vls;
  	af.nvls = 0;

  	ret = debuginfo__find_probes(dbg, &af.pf);

  	if (ret < 0) {
  		/* Free vlist for error */
  		while (af.nvls--) {

  			zfree(&af.vls[af.nvls].point.symbol);

  			strlist__delete(af.vls[af.nvls].vars);

  		}

  		zfree(vls);

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

  }

  /* For the kernel module, we need a special code to get a DIE */

  int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
  				bool adjust_offset)

  {
  	int n, i;
  	Elf32_Word shndx;
  	Elf_Scn *scn;
  	Elf *elf;
  	GElf_Shdr mem, *shdr;
  	const char *p;
  
  	elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
  	if (!elf)
  		return -EINVAL;
  
  	/* Get the number of relocations */
  	n = dwfl_module_relocations(dbg->mod);
  	if (n < 0)
  		return -ENOENT;
  	/* Search the relocation related .text section */
  	for (i = 0; i < n; i++) {
  		p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
  		if (strcmp(p, ".text") == 0) {
  			/* OK, get the section header */
  			scn = elf_getscn(elf, shndx);
  			if (!scn)
  				return -ENOENT;
  			shdr = gelf_getshdr(scn, &mem);
  			if (!shdr)
  				return -ENOENT;
  			*offs = shdr->sh_addr;

  			if (adjust_offset)
  				*offs -= shdr->sh_offset;

  		}
  	}
  	return 0;
  }

  /* Reverse search */

  int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,

  				struct perf_probe_point *ppt)