Release 4.10 tools/perf/util/probe-finder.c

/*
 * 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 <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 "symbol.h"
#include "probe-finder.h"
#include "probe-file.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;
}

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masami hiramatsu
masami hiramatsu
155
91.72%
4
80.00%
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arnaldo carvalho de melo
14
8.28%
1
20.00%
Total
169
100.00%
5
100.00%



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\n", path);
	return dbg;
}

Contributors
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masami hiramatsu
masami hiramatsu
57
86.36%
4
66.67%
arnaldo carvalho de melo
arnaldo carvalho de melo
9
13.64%
2
33.33%
Total
66
100.00%
6
100.00%


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);
}

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masami hiramatsu
masami hiramatsu
117
99.15%
1
50.00%
arnaldo carvalho de melo
arnaldo carvalho de melo
1
0.85%
1
50.00%
Total
118
100.00%
2
100.00%



void debuginfo__delete(struct debuginfo *dbg)
{
	if (dbg) {
		if (dbg->dwfl)
			dwfl_end(dbg->dwfl);
		free(dbg);
	}
}

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masami hiramatsu
masami hiramatsu
29
85.29%
1
50.00%
arnaldo carvalho de melo
arnaldo carvalho de melo
5
14.71%
1
50.00%
Total
34
100.00%
2
100.00%

/*
 * 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;
}

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masami hiramatsu
masami hiramatsu
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42
100.00%
5
100.00%

/*
 * 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.\n", 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.\n", 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;
}

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masami hiramatsu
masami hiramatsu
560
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8
88.89%
he kuang
he kuang
52
8.50%
1
11.11%
Total
612
100.00%
9
100.00%


#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.\n",
			   dwarf_diename(vr_die));
		return -ENOENT;
	}

	pr_debug("%s type is %s.\n",
		 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.\n",
				   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.\n");
			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\n");
				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 *.\n",
				   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.\n",
			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\n",
			   str_error_r(-ret, sbuf, sizeof(sbuf)));
		return ret;
	}
	tvar->type = strdup(buf);
	if (tvar->type == NULL)
		return -ENOMEM;
	return 0;
}

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masami hiramatsu
masami hiramatsu
577
88.23%
19
86.36%
naohiro aota
naohiro aota
69
10.55%
1
4.55%
hyeoncheol lee
hyeoncheol lee
7
1.07%
1
4.55%
arnaldo carvalho de melo
arnaldo carvalho de melo
1
0.15%
1
4.55%
Total
654
100.00%
22
100.00%



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\n", field->name, varname);
	if (die_get_real_type(vr_die, &type) == NULL) {
		pr_warning("Failed to get the type of %s.\n", varname);
		return -ENOENT;
	}
	pr_debug2("Var real type: (%x)\n", (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.\n", varname);
			return -ENOENT;
		}
		pr_debug2("Array real type: (%x)\n",
			 (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 '->'\n",
			       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.\n", 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 an union.\n",
				   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 an union.\n",
				   varname);
			return -EINVAL;
		}
		if (field->name[0] == '[') {
			pr_err("Semantic error: %s is not a pointer"
			       " nor array.\n", 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 '.'\n",
			       field->name);
			return -EINVAL;
		}
		if (!ref) {
			pr_warning("Structure on a register is not "
				   "supported yet.\n");
			return -ENOTSUP;
		}
	}

	if (die_find_member(&type, field->name, die_mem) == NULL) {
		pr_warning("%s(type:%s) has no member %s.\n", 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.\n",
				   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;
}

Contributors
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masami hiramatsu
masami hiramatsu
624
94.98%
16
84.21%
hyeoncheol lee
hyeoncheol lee
31
4.72%
1
5.26%
masanari iida
masanari iida
1
0.15%
1
5.26%
arnaldo carvalho de melo
arnaldo carvalho de melo
1
0.15%
1
5.26%
Total
657
100.00%
19
100.00%

/* 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.\n",
		 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.\n"
		       " Perhaps it has been optimized out.\n"
		       " Use -V with the --range option to show '%s' location range.\n",
		       pf->pvar->var, pf->pvar->var);
	} else if (ret == -ENOTSUP)
		pr_err("Sorry, we don't support this variable location yet.\n");
	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;
}

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masami hiramatsu
masami hiramatsu
170
93.92%
9
90.00%
he kuang
he kuang
11
6.08%
1
10.00%
Total
181
100.00%
10
100.00%

/* 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.\n", 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.\n",
				   pf->pvar->var);
			ret = -ENOENT;
		}
	}
	if (ret >= 0)
		ret = convert_variable(&vr_die, pf);

	return ret;
}

Contributors
Person
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masami hiramatsu
masami hiramatsu
226
96.17%
9
75.00%
arnaldo carvalho de melo
arnaldo carvalho de melo
4
1.70%
1
8.33%
wang nan
wang nan
3
1.28%
1
8.33%
he kuang
he kuang
2
0.85%
1
8.33%
Total
235
100.00%
12
100.00%

/* Convert subprogram DIE to trace point */


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