linux/tools/perf/util/probe-finder.c
Naohiro Aota 19f00b0117 perf probe: Support signedness casting
The 'perf probe' tool detects a variable's type and use the detected
type to add a new probe. Then, kprobes prints its variable in
hexadecimal format if the variable is unsigned and prints in decimal if
it is signed.

We sometimes want to see unsigned variable in decimal format (i.e.
sector_t or size_t). In that case, we need to investigate the variable's
size manually to specify just signedness.

This patch add signedness casting support. By specifying "s" or "u" as a
type, perf-probe will investigate variable size as usual and use the
specified signedness.

E.g. without this:

  $ perf probe -a 'submit_bio bio->bi_iter.bi_sector'
  Added new event:
    probe:submit_bio     (on submit_bio with bi_sector=bio->bi_iter.bi_sector)
  You can now use it in all perf tools, such as:
          perf record -e probe:submit_bio -aR sleep 1
  $ cat trace_pipe|head
          dbench-9692  [003] d..1   971.096633: submit_bio: (submit_bio+0x0/0x140) bi_sector=0x3a3d00
          dbench-9692  [003] d..1   971.096685: submit_bio: (submit_bio+0x0/0x140) bi_sector=0x1a3d80
          dbench-9692  [003] d..1   971.096687: submit_bio: (submit_bio+0x0/0x140) bi_sector=0x3a3d80
...
  // need to investigate the variable size
  $ perf probe -a 'submit_bio bio->bi_iter.bi_sector:s64'
  Added new event:
    probe:submit_bio     (on submit_bio with bi_sector=bio->bi_iter.bi_sector:s64)
  You can now use it in all perf tools, such as:
        perf record -e probe:submit_bio -aR sleep 1

  With this:

  // just use "s" to cast its signedness
  $ perf probe -v -a 'submit_bio bio->bi_iter.bi_sector:s'
  Added new event:
    probe:submit_bio     (on submit_bio with bi_sector=bio->bi_iter.bi_sector:s)
  You can now use it in all perf tools, such as:
          perf record -e probe:submit_bio -aR sleep 1
  $ cat trace_pipe|head
          dbench-9689  [001] d..1  1212.391237: submit_bio: (submit_bio+0x0/0x140) bi_sector=128
          dbench-9689  [001] d..1  1212.391252: submit_bio: (submit_bio+0x0/0x140) bi_sector=131072
          dbench-9697  [006] d..1  1212.398611: submit_bio: (submit_bio+0x0/0x140) bi_sector=30208

  This commit also update perf-probe.txt to describe "types". Most parts
  are based on existing documentation: Documentation/trace/kprobetrace.txt

Committer note:

Testing using 'perf trace':

  # perf probe -a 'submit_bio bio->bi_iter.bi_sector'
  Added new event:
    probe:submit_bio     (on submit_bio with bi_sector=bio->bi_iter.bi_sector)

  You can now use it in all perf tools, such as:

	perf record -e probe:submit_bio -aR sleep 1

  # trace --no-syscalls --ev probe:submit_bio
      0.000 probe:submit_bio:(ffffffffac3aee00) bi_sector=0xc133c0)
   3181.861 probe:submit_bio:(ffffffffac3aee00) bi_sector=0x6cffb8)
   3181.881 probe:submit_bio:(ffffffffac3aee00) bi_sector=0x6cffc0)
   3184.488 probe:submit_bio:(ffffffffac3aee00) bi_sector=0x6cffc8)
<SNIP>
   4717.927 probe:submit_bio:(ffffffffac3aee00) bi_sector=0x4dc7a88)
   4717.970 probe:submit_bio:(ffffffffac3aee00) bi_sector=0x4dc7880)
  ^C[root@jouet ~]#

Now, using this new feature:

[root@jouet ~]# perf probe -a 'submit_bio bio->bi_iter.bi_sector:s'
Added new event:
  probe:submit_bio     (on submit_bio with bi_sector=bio->bi_iter.bi_sector:s)

You can now use it in all perf tools, such as:

	perf record -e probe:submit_bio -aR sleep 1

  [root@jouet ~]# trace --no-syscalls --ev probe:submit_bio
     0.000 probe:submit_bio:(ffffffffac3aee00) bi_sector=7145704)
     0.017 probe:submit_bio:(ffffffffac3aee00) bi_sector=7145712)
     0.019 probe:submit_bio:(ffffffffac3aee00) bi_sector=7145720)
     2.567 probe:submit_bio:(ffffffffac3aee00) bi_sector=7145728)
  5631.919 probe:submit_bio:(ffffffffac3aee00) bi_sector=0)
  5631.941 probe:submit_bio:(ffffffffac3aee00) bi_sector=8)
  5631.945 probe:submit_bio:(ffffffffac3aee00) bi_sector=16)
  5631.948 probe:submit_bio:(ffffffffac3aee00) bi_sector=24)
  ^C#

With callchains:

  # trace --no-syscalls --ev probe:submit_bio/max-stack=10/
     0.000 probe:submit_bio:(ffffffffac3aee00) bi_sector=50662544)
                                       submit_bio+0xa8200001 ([kernel.kallsyms])
                                       submit_bh+0xa8200013 ([kernel.kallsyms])
                                       jbd2_journal_commit_transaction+0xa8200691 ([kernel.kallsyms])
                                       kjournald2+0xa82000ca ([kernel.kallsyms])
                                       kthread+0xa82000d8 ([kernel.kallsyms])
                                       ret_from_fork+0xa820001f ([kernel.kallsyms])
     0.023 probe:submit_bio:(ffffffffac3aee00) bi_sector=50662552)
                                       submit_bio+0xa8200001 ([kernel.kallsyms])
                                       submit_bh+0xa8200013 ([kernel.kallsyms])
                                       jbd2_journal_commit_transaction+0xa8200691 ([kernel.kallsyms])
                                       kjournald2+0xa82000ca ([kernel.kallsyms])
                                       kthread+0xa82000d8 ([kernel.kallsyms])
                                       ret_from_fork+0xa820001f ([kernel.kallsyms])
     0.027 probe:submit_bio:(ffffffffac3aee00) bi_sector=50662560)
                                       submit_bio+0xa8200001 ([kernel.kallsyms])
                                       submit_bh+0xa8200013 ([kernel.kallsyms])
                                       jbd2_journal_commit_transaction+0xa8200691 ([kernel.kallsyms])
                                       kjournald2+0xa82000ca ([kernel.kallsyms])
                                       kthread+0xa82000d8 ([kernel.kallsyms])
                                       ret_from_fork+0xa820001f ([kernel.kallsyms])
     2.593 probe:submit_bio:(ffffffffac3aee00) bi_sector=50662568)
                                       submit_bio+0xa8200001 ([kernel.kallsyms])
                                       submit_bh+0xa8200013 ([kernel.kallsyms])
                                       journal_submit_commit_record+0xa82001ac ([kernel.kallsyms])
                                       jbd2_journal_commit_transaction+0xa82012e8 ([kernel.kallsyms])
                                       kjournald2+0xa82000ca ([kernel.kallsyms])
                                       kthread+0xa82000d8 ([kernel.kallsyms])
                                       ret_from_fork+0xa820001f ([kernel.kallsyms])
  ^C#

Signed-off-by: Naohiro Aota <naohiro.aota@hgst.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1470710408-23515-1-git-send-email-naohiro.aota@hgst.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-08-09 10:52:22 -03:00

1829 lines
45 KiB
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"
/* 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\n", 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,
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_arch_regstr(regn);
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;
}
#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 sign;
/* TODO: check all types */
if (cast && strcmp(cast, "string") != 0 &&
strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
/* Non string type is OK */
/* and respect signedness 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))
sign = 'u';
else if (cast && (strcmp(cast, "s") == 0))
sign = 's';
else
sign = die_is_signed_type(&type) ? 's' : '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", sign, 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;
}
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;
}
/* 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->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;
}
/* 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;
}
/* 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\n",
dwarf_diename(sp_die));
return -ENOENT;
}
if (dwarf_highpc(sp_die, &highaddr) != 0) {
pr_warning("Failed to get end address of %s\n",
dwarf_diename(sp_die));
return -ENOENT;
}
if (paddr > highaddr) {
pr_warning("Offset specified is greater than size of %s\n",
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\n",
(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\",\n"
" because %s is an inlined function and"
" has no return point.\n", 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.\n");
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\n",
dwarf_diename(&pf->sp_die));
return 0;
} else {
pr_warning("Failed to find probe point in any "
"functions.\n");
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\n",
(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.\n");
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\n", fname,
str_error_r(errno, sbuf, sizeof(sbuf)));
return -errno;
}
while ((len = getline(&line, &line_len, fp)) > 0) {
if (line[len - 1] == '\n')
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.\n", 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\n",
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.\n");
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.\n");
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 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.\n",
dwarf_diename(in_die));
return -ENOENT;
}
pf->addr = addr;
pf->addr += pp->offset;
pr_debug("found inline addr: 0x%jx\n",
(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\n", dwarf_diename(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);
/* Real function */
if (pp->lazy_line)
param->retval = find_probe_point_lazy(sp_die, pf);
else {
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 && strisglob(pp->function))
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;
#if _ELFUTILS_PREREQ(0, 142)
Elf *elf;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
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;
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);
#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,
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)\n", 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.\n",
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\n", 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,
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\n", 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\n");
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.\n", 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\n", 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 */
static int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs)
{
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;
}
}
return 0;
}
/* Reverse search */
int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
struct perf_probe_point *ppt)
{
Dwarf_Die cudie, spdie, indie;
Dwarf_Addr _addr = 0, baseaddr = 0;
const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
int baseline = 0, lineno = 0, ret = 0;
bool reloc = false;
retry:
/* Find cu die */
if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
if (!reloc && debuginfo__get_text_offset(dbg, &baseaddr) == 0) {
addr += baseaddr;
reloc = true;
goto retry;
}
pr_warning("Failed to find debug information for address %lx\n",
addr);
ret = -EINVAL;
goto end;
}
/* Find a corresponding line (filename and lineno) */
cu_find_lineinfo(&cudie, addr, &fname, &lineno);
/* Don't care whether it failed or not */
/* Find a corresponding function (name, baseline and baseaddr) */
if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
/* Get function entry information */
func = basefunc = dwarf_diename(&spdie);
if (!func ||
dwarf_entrypc(&spdie, &baseaddr) != 0 ||
dwarf_decl_line(&spdie, &baseline) != 0) {
lineno = 0;
goto post;
}
fname = dwarf_decl_file(&spdie);
if (addr == (unsigned long)baseaddr) {
/* Function entry - Relative line number is 0 */
lineno = baseline;
goto post;
}
/* Track down the inline functions step by step */
while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
&indie)) {
/* There is an inline function */
if (dwarf_entrypc(&indie, &_addr) == 0 &&
_addr == addr) {
/*
* addr is at an inline function entry.
* In this case, lineno should be the call-site
* line number. (overwrite lineinfo)
*/
lineno = die_get_call_lineno(&indie);
fname = die_get_call_file(&indie);
break;
} else {
/*
* addr is in an inline function body.
* Since lineno points one of the lines
* of the inline function, baseline should
* be the entry line of the inline function.
*/
tmp = dwarf_diename(&indie);
if (!tmp ||
dwarf_decl_line(&indie, &baseline) != 0)
break;
func = tmp;
spdie = indie;
}
}
/* Verify the lineno and baseline are in a same file */
tmp = dwarf_decl_file(&spdie);
if (!tmp || strcmp(tmp, fname) != 0)
lineno = 0;
}
post:
/* Make a relative line number or an offset */
if (lineno)
ppt->line = lineno - baseline;
else if (basefunc) {
ppt->offset = addr - (unsigned long)baseaddr;
func = basefunc;
}
/* Duplicate strings */
if (func) {
ppt->function = strdup(func);
if (ppt->function == NULL) {
ret = -ENOMEM;
goto end;
}
}
if (fname) {
ppt->file = strdup(fname);
if (ppt->file == NULL) {
zfree(&ppt->function);
ret = -ENOMEM;
goto end;
}
}
end:
if (ret == 0 && (fname || func))
ret = 1; /* Found a point */
return ret;
}
/* Add a line and store the src path */
static int line_range_add_line(const char *src, unsigned int lineno,
struct line_range *lr)
{
/* Copy source path */
if (!lr->path) {
lr->path = strdup(src);
if (lr->path == NULL)
return -ENOMEM;
}
return intlist__add(lr->line_list, lineno);
}
static int line_range_walk_cb(const char *fname, int lineno,
Dwarf_Addr addr __maybe_unused,
void *data)
{
struct line_finder *lf = data;
int err;
if ((strtailcmp(fname, lf->fname) != 0) ||
(lf->lno_s > lineno || lf->lno_e < lineno))
return 0;
err = line_range_add_line(fname, lineno, lf->lr);
if (err < 0 && err != -EEXIST)
return err;
return 0;
}
/* Find line range from its line number */
static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
{
int ret;
ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
/* Update status */
if (ret >= 0)
if (!intlist__empty(lf->lr->line_list))
ret = lf->found = 1;
else
ret = 0; /* Lines are not found */
else {
zfree(&lf->lr->path);
}
return ret;
}
static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
{
int ret = find_line_range_by_line(in_die, data);
/*
* We have to check all instances of inlined function, because
* some execution paths can be optimized out depends on the
* function argument of instances. However, if an error occurs,
* it should be handled by the caller.
*/
return ret < 0 ? ret : 0;
}
/* Search function definition from function name */
static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
{
struct dwarf_callback_param *param = data;
struct line_finder *lf = param->data;
struct line_range *lr = lf->lr;
/* Check declared file */
if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
return DWARF_CB_OK;
if (die_is_func_def(sp_die) &&
die_match_name(sp_die, lr->function)) {
lf->fname = dwarf_decl_file(sp_die);
dwarf_decl_line(sp_die, &lr->offset);
pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
lf->lno_s = lr->offset + lr->start;
if (lf->lno_s < 0) /* Overflow */
lf->lno_s = INT_MAX;
lf->lno_e = lr->offset + lr->end;
if (lf->lno_e < 0) /* Overflow */
lf->lno_e = INT_MAX;
pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
lr->start = lf->lno_s;
lr->end = lf->lno_e;
if (!die_is_func_instance(sp_die))
param->retval = die_walk_instances(sp_die,
line_range_inline_cb, lf);
else
param->retval = find_line_range_by_line(sp_die, lf);
return DWARF_CB_ABORT;
}
return DWARF_CB_OK;
}
static int find_line_range_by_func(struct line_finder *lf)
{
struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
dwarf_getfuncs(&lf->cu_die, line_range_search_cb, &param, 0);
return param.retval;
}
int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
{
struct line_finder lf = {.lr = lr, .found = 0};
int ret = 0;
Dwarf_Off off = 0, noff;
size_t cuhl;
Dwarf_Die *diep;
const char *comp_dir;
/* Fastpath: lookup by function name from .debug_pubnames section */
if (lr->function) {
struct pubname_callback_param pubname_param = {
.function = lr->function, .file = lr->file,
.cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
struct dwarf_callback_param line_range_param = {
.data = (void *)&lf, .retval = 0};
dwarf_getpubnames(dbg->dbg, pubname_search_cb,
&pubname_param, 0);
if (pubname_param.found) {
line_range_search_cb(&lf.sp_die, &line_range_param);
if (lf.found)
goto found;
}
}
/* Loop on CUs (Compilation Unit) */
while (!lf.found && ret >= 0) {
if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
NULL, NULL, NULL) != 0)
break;
/* Get the DIE(Debugging Information Entry) of this CU */
diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
if (!diep)
continue;
/* Check if target file is included. */
if (lr->file)
lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
else
lf.fname = 0;
if (!lr->file || lf.fname) {
if (lr->function)
ret = find_line_range_by_func(&lf);
else {
lf.lno_s = lr->start;
lf.lno_e = lr->end;
ret = find_line_range_by_line(NULL, &lf);
}
}
off = noff;
}
found:
/* Store comp_dir */
if (lf.found) {
comp_dir = cu_get_comp_dir(&lf.cu_die);
if (comp_dir) {
lr->comp_dir = strdup(comp_dir);
if (!lr->comp_dir)
ret = -ENOMEM;
}
}
pr_debug("path: %s\n", lr->path);
return (ret < 0) ? ret : lf.found;
}
/*
* Find a src file from a DWARF tag path. Prepend optional source path prefix
* and chop off leading directories that do not exist. Result is passed back as
* a newly allocated path on success.
* Return 0 if file was found and readable, -errno otherwise.
*/
int get_real_path(const char *raw_path, const char *comp_dir,
char **new_path)
{
const char *prefix = symbol_conf.source_prefix;
if (!prefix) {
if (raw_path[0] != '/' && comp_dir)
/* If not an absolute path, try to use comp_dir */
prefix = comp_dir;
else {
if (access(raw_path, R_OK) == 0) {
*new_path = strdup(raw_path);
return *new_path ? 0 : -ENOMEM;
} else
return -errno;
}
}
*new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
if (!*new_path)
return -ENOMEM;
for (;;) {
sprintf(*new_path, "%s/%s", prefix, raw_path);
if (access(*new_path, R_OK) == 0)
return 0;
if (!symbol_conf.source_prefix) {
/* In case of searching comp_dir, don't retry */
zfree(new_path);
return -errno;
}
switch (errno) {
case ENAMETOOLONG:
case ENOENT:
case EROFS:
case EFAULT:
raw_path = strchr(++raw_path, '/');
if (!raw_path) {
zfree(new_path);
return -ENOENT;
}
continue;
default:
zfree(new_path);
return -errno;
}
}
}