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perf: Add perf probe subcommand, a kprobe-event setup helper

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Add perf probe subcommand that implements a kprobe-event setup helper
to the perf command.
This allows user to define kprobe events using C expressions (C line
numbers, C function names, and C local variables).

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Changes in v4:
 - Add _GNU_SOURCE macro for strndup().

Changes in v3:
 - Remove -r option because perf always be used for online kernel.
 - Check malloc/calloc results.

Changes in v2:
 - Check synthesized string length.
 - Rename perf kprobe to perf probe.
 - Use spaces for separator and update usage comment.
 - Check error paths in parse_probepoint().
 - Check optimized-out variables.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
LKML-Reference: <20091008211737.29299.14784.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Masami Hiramatsu 2009-10-08 17:17:38 -04:00 committed by Frederic Weisbecker
parent e93f4d8539
commit 4ea42b1814
6 changed files with 1130 additions and 0 deletions
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10
tools/perf/Makefile
View file

@ -419,6 +419,16 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel);
endif
ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
msg := $(warning No libdwarf.h found, disables probe subcommand. Please install libdwarf-dev/libdwarf-devel);
else
EXTLIBS += -lelf -ldwarf
LIB_H += util/probe-finder.h
LIB_OBJS += util/probe-finder.o
BUILTIN_OBJS += builtin-probe.o
BASIC_CFLAGS += -DSUPPORT_DWARF
endif
ifdef NO_DEMANGLE
BASIC_CFLAGS += -DNO_DEMANGLE
else

358
tools/perf/builtin-probe.c Normal file
View file

@ -0,0 +1,358 @@
/*
* builtin-probe.c
*
* Builtin probe command: Set up probe events by C expression
*
* 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.
*
*/
#define _GNU_SOURCE
#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>
#undef _GNU_SOURCE
#include "perf.h"
#include "builtin.h"
#include "util/util.h"
#include "util/parse-options.h"
#include "util/parse-events.h" /* For debugfs_path */
#include "util/probe-finder.h"
/* Default vmlinux search paths */
#define NR_SEARCH_PATH 3
const char *default_search_path[NR_SEARCH_PATH] = {
"/lib/modules/%s/build/vmlinux", /* Custom build kernel */
"/usr/lib/debug/lib/modules/%s/vmlinux", /* Red Hat debuginfo */
"/boot/vmlinux-debug-%s", /* Ubuntu */
};
#define MAX_PATH_LEN 256
#define MAX_PROBES 128
/* Session management structure */
static struct {
char *vmlinux;
char *release;
int nr_probe;
struct probe_point probes[MAX_PROBES];
char *events[MAX_PROBES];
} session;
static void semantic_error(const char *msg)
{
fprintf(stderr, "Semantic error: %s\n", msg);
exit(1);
}
static void perror_exit(const char *msg)
{
perror(msg);
exit(1);
}
#define MAX_PROBE_ARGS 128
static int parse_probepoint(const struct option *opt __used,
const char *str, int unset __used)
{
char *argv[MAX_PROBE_ARGS + 2]; /* Event + probe + args */
int argc, i;
char *arg, *ptr;
struct probe_point *pp = &session.probes[session.nr_probe];
char **event = &session.events[session.nr_probe];
int retp = 0;
if (!str) /* The end of probe points */
return 0;
debug("Probe-define(%d): %s\n", session.nr_probe, str);
if (++session.nr_probe == MAX_PROBES)
semantic_error("Too many probes");
/* Separate arguments, similar to argv_split */
argc = 0;
do {
/* Skip separators */
while (isspace(*str))
str++;
/* Add an argument */
if (*str != '\0') {
const char *s = str;
/* Skip the argument */
while (!isspace(*str) && *str != '\0')
str++;
/* Duplicate the argument */
argv[argc] = strndup(s, str - s);
if (argv[argc] == NULL)
perror_exit("strndup");
if (++argc == MAX_PROBE_ARGS)
semantic_error("Too many arguments");
debug("argv[%d]=%s\n", argc, argv[argc - 1]);
}
} while (*str != '\0');
if (argc < 2)
semantic_error("Need event-name and probe-point at least.");
/* Parse the event name */
if (argv[0][0] == 'r')
retp = 1;
else if (argv[0][0] != 'p')
semantic_error("You must specify 'p'(kprobe) or"
" 'r'(kretprobe) first.");
/* TODO: check event name */
*event = argv[0];
/* Parse probe point */
arg = argv[1];
if (arg[0] == '@') {
/* Source Line */
arg++;
ptr = strchr(arg, ':');
if (!ptr || !isdigit(ptr[1]))
semantic_error("Line number is required.");
*ptr++ = '\0';
if (strlen(arg) == 0)
semantic_error("No file name.");
pp->file = strdup(arg);
pp->line = atoi(ptr);
if (!pp->file || !pp->line)
semantic_error("Failed to parse line.");
debug("file:%s line:%d\n", pp->file, pp->line);
} else {
/* Function name */
ptr = strchr(arg, '+');
if (ptr) {
if (!isdigit(ptr[1]))
semantic_error("Offset is required.");
*ptr++ = '\0';
pp->offset = atoi(ptr);
} else
ptr = arg;
ptr = strchr(ptr, '@');
if (ptr) {
*ptr++ = '\0';
pp->file = strdup(ptr);
}
pp->function = strdup(arg);
debug("symbol:%s file:%s offset:%d\n",
pp->function, pp->file, pp->offset);
}
free(argv[1]);
/* Copy arguments */
pp->nr_args = argc - 2;
if (pp->nr_args > 0) {
pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
if (!pp->args)
perror_exit("malloc");
memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
}
/* Ensure return probe has no C argument */
if (retp)
for (i = 0; i < pp->nr_args; i++)
if (is_c_varname(pp->args[i]))
semantic_error("You can't specify local"
" variable for kretprobe");
debug("%d arguments\n", pp->nr_args);
return 0;
}
static int open_default_vmlinux(void)
{
struct utsname uts;
char fname[MAX_PATH_LEN];
int fd, ret, i;
ret = uname(&uts);
if (ret) {
debug("uname() failed.\n");
return -errno;
}
session.release = uts.release;
for (i = 0; i < NR_SEARCH_PATH; i++) {
ret = snprintf(fname, MAX_PATH_LEN,
default_search_path[i], session.release);
if (ret >= MAX_PATH_LEN || ret < 0) {
debug("Filename(%d,%s) is too long.\n", i, uts.release);
errno = E2BIG;
return -E2BIG;
}
debug("try to open %s\n", fname);
fd = open(fname, O_RDONLY);
if (fd >= 0)
break;
}
return fd;
}
static const char * const probe_usage[] = {
"perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
NULL
};
static const struct option options[] = {
OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
"vmlinux/module pathname"),
OPT_CALLBACK('P', "probe", NULL,
"p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
"probe point definition, where\n"
"\t\tp:\tkprobe probe\n"
"\t\tr:\tkretprobe probe\n"
"\t\tGRP:\tGroup name (optional)\n"
"\t\tNAME:\tEvent name\n"
"\t\tFUNC:\tFunction name\n"
"\t\tOFFS:\tOffset from function entry (in byte)\n"
"\t\tSRC:\tSource code path\n"
"\t\tLINE:\tLine number\n"
"\t\tARG:\tProbe argument (local variable name or\n"
"\t\t\tkprobe-tracer argument format is supported.)\n",
parse_probepoint),
OPT_END()
};
static int write_new_event(int fd, const char *buf)
{
int ret;
printf("Adding new event: %s\n", buf);
ret = write(fd, buf, strlen(buf));
if (ret <= 0)
perror("Error: Failed to create event");
return ret;
}
#define MAX_CMDLEN 256
static int synthesize_probepoint(struct probe_point *pp)
{
char *buf;
int i, len, ret;
pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
if (!buf)
perror_exit("calloc");
ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
if (ret <= 0 || ret >= MAX_CMDLEN)
goto error;
len = ret;
for (i = 0; i < pp->nr_args; i++) {
ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
pp->args[i]);
if (ret <= 0 || ret >= MAX_CMDLEN - len)
goto error;
len += ret;
}
pp->found = 1;
return pp->found;
error:
free(pp->probes[0]);
if (ret > 0)
ret = -E2BIG;
return ret;
}
int cmd_probe(int argc, const char **argv, const char *prefix __used)
{
int i, j, fd, ret, need_dwarf = 0;
struct probe_point *pp;
char buf[MAX_CMDLEN];
argc = parse_options(argc, argv, options, probe_usage,
PARSE_OPT_STOP_AT_NON_OPTION);
if (argc || session.nr_probe == 0)
usage_with_options(probe_usage, options);
/* Synthesize return probes */
for (j = 0; j < session.nr_probe; j++) {
if (session.events[j][0] != 'r') {
need_dwarf = 1;
continue;
}
ret = synthesize_probepoint(&session.probes[j]);
if (ret == -E2BIG)
semantic_error("probe point is too long.");
else if (ret < 0) {
perror("snprintf");
return -1;
}
}
if (!need_dwarf)
goto setup_probes;
if (session.vmlinux)
fd = open(session.vmlinux, O_RDONLY);
else
fd = open_default_vmlinux();
if (fd < 0) {
perror("vmlinux/module file open");
return -1;
}
/* Searching probe points */
for (j = 0; j < session.nr_probe; j++) {
pp = &session.probes[j];
if (pp->found)
continue;
lseek(fd, SEEK_SET, 0);
ret = find_probepoint(fd, pp);
if (ret <= 0) {
fprintf(stderr, "Error: No probe point found.\n");
return -1;
}
debug("probe event %s found\n", session.events[j]);
}
close(fd);
setup_probes:
/* Settng up probe points */
snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
fd = open(buf, O_WRONLY, O_APPEND);
if (fd < 0) {
perror("kprobe_events open");
return -1;
}
for (j = 0; j < session.nr_probe; j++) {
pp = &session.probes[j];
if (pp->found == 1) {
snprintf(buf, MAX_CMDLEN, "%s %s\n",
session.events[j], pp->probes[0]);
write_new_event(fd, buf);
} else
for (i = 0; i < pp->found; i++) {
snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
session.events[j], i, pp->probes[i]);
write_new_event(fd, buf);
}
}
close(fd);
return 0;
}

1
tools/perf/builtin.h
View file

@ -25,5 +25,6 @@ extern int cmd_timechart(int argc, const char **argv, const char *prefix);
extern int cmd_top(int argc, const char **argv, const char *prefix);
extern int cmd_trace(int argc, const char **argv, const char *prefix);
extern int cmd_version(int argc, const char **argv, const char *prefix);
extern int cmd_probe(int argc, const char **argv, const char *prefix);
#endif

3
tools/perf/perf.c
View file

@ -295,6 +295,9 @@ static void handle_internal_command(int argc, const char **argv)
{ "version", cmd_version, 0 },
{ "trace", cmd_trace, 0 },
{ "sched", cmd_sched, 0 },
#ifdef SUPPORT_DWARF
{ "probe", cmd_probe, 0 },
#endif
};
unsigned int i;
static const char ext[] = STRIP_EXTENSION;

690
tools/perf/util/probe-finder.c Normal file
View file

@ -0,0 +1,690 @@
/*
* 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 <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <ctype.h>
#include "probe-finder.h"
/* Dwarf_Die Linkage to parent Die */
struct die_link {
struct die_link *parent; /* Parent die */
Dwarf_Die die; /* Current die */
};
static Dwarf_Debug __dw_debug;
static Dwarf_Error __dw_error;
static void msg_exit(int ret, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
fprintf(stderr, "Error: ");
vfprintf(stderr, fmt, ap);
va_end(ap);
fprintf(stderr, "\n");
exit(ret);
}
/*
* Generic dwarf analysis helpers
*/
#define X86_32_MAX_REGS 8
const char *x86_32_regs_table[X86_32_MAX_REGS] = {
"%ax",
"%cx",
"%dx",
"%bx",
"$stack", /* Stack address instead of %sp */
"%bp",
"%si",
"%di",
};
#define X86_64_MAX_REGS 16
const char *x86_64_regs_table[X86_64_MAX_REGS] = {
"%ax",
"%dx",
"%cx",
"%bx",
"%si",
"%di",
"%bp",
"%sp",
"%r8",
"%r9",
"%r10",
"%r11",
"%r12",
"%r13",
"%r14",
"%r15",
};
/* TODO: switching by dwarf address size */
#ifdef __x86_64__
#define ARCH_MAX_REGS X86_64_MAX_REGS
#define arch_regs_table x86_64_regs_table
#else
#define ARCH_MAX_REGS X86_32_MAX_REGS
#define arch_regs_table x86_32_regs_table
#endif
/* Return architecture dependent register string (for kprobe-tracer) */
static const char *get_arch_regstr(unsigned int n)
{
return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
}
/*
* Compare the tail of two strings.
* Return 0 if whole of either string is same as another's tail part.
*/
static int strtailcmp(const char *s1, const char *s2)
{
int i1 = strlen(s1);
int i2 = strlen(s2);
while (--i1 > 0 && --i2 > 0) {
if (s1[i1] != s2[i2])
return s1[i1] - s2[i2];
}
return 0;
}
/* Find the fileno of the target file. */
static Dwarf_Unsigned die_get_fileno(Dwarf_Die cu_die, const char *fname)
{
Dwarf_Signed cnt, i;
Dwarf_Unsigned found = 0;
char **srcs;
int ret;
if (!fname)
return 0;
ret = dwarf_srcfiles(cu_die, &srcs, &cnt, &__dw_error);
if (ret == DW_DLV_OK) {
for (i = 0; i < cnt && !found; i++) {
if (strtailcmp(srcs[i], fname) == 0)
found = i + 1;
dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
}
for (; i < cnt; i++)
dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
dwarf_dealloc(__dw_debug, srcs, DW_DLA_LIST);
}
if (found)
debug("found fno: %d\n", (int)found);
return found;
}
/* Compare diename and tname */
static int die_compare_name(Dwarf_Die die, const char *tname)
{
char *name;
int ret;
ret = dwarf_diename(die, &name, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK) {
ret = strcmp(tname, name);
dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
} else
ret = -1;
return ret;
}
/* Check the address is in the subprogram(function). */
static int die_within_subprogram(Dwarf_Die sp_die, Dwarf_Addr addr,
Dwarf_Signed *offs)
{
Dwarf_Addr lopc, hipc;
int ret;
/* TODO: check ranges */
ret = dwarf_lowpc(sp_die, &lopc, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_NO_ENTRY)
return 0;
ret = dwarf_highpc(sp_die, &hipc, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
if (lopc <= addr && addr < hipc) {
*offs = addr - lopc;
return 1;
} else
return 0;
}
/* Check the die is inlined function */
static Dwarf_Bool die_inlined_subprogram(Dwarf_Die die)
{
/* TODO: check strictly */
Dwarf_Bool inl;
int ret;
ret = dwarf_hasattr(die, DW_AT_inline, &inl, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
return inl;
}
/* Get the offset of abstruct_origin */
static Dwarf_Off die_get_abstract_origin(Dwarf_Die die)
{
Dwarf_Attribute attr;
Dwarf_Off cu_offs;
int ret;
ret = dwarf_attr(die, DW_AT_abstract_origin, &attr, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
ret = dwarf_formref(attr, &cu_offs, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
return cu_offs;
}
/* Get entry pc(or low pc, 1st entry of ranges) of the die */
static Dwarf_Addr die_get_entrypc(Dwarf_Die die)
{
Dwarf_Attribute attr;
Dwarf_Addr addr;
Dwarf_Off offs;
Dwarf_Ranges *ranges;
Dwarf_Signed cnt;
int ret;
/* Try to get entry pc */
ret = dwarf_attr(die, DW_AT_entry_pc, &attr, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK) {
ret = dwarf_formaddr(attr, &addr, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
return addr;
}
/* Try to get low pc */
ret = dwarf_lowpc(die, &addr, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK)
return addr;
/* Try to get ranges */
ret = dwarf_attr(die, DW_AT_ranges, &attr, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
ret = dwarf_formref(attr, &offs, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
ret = dwarf_get_ranges(__dw_debug, offs, &ranges, &cnt, NULL,
&__dw_error);
ERR_IF(ret != DW_DLV_OK);
addr = ranges[0].dwr_addr1;
dwarf_ranges_dealloc(__dw_debug, ranges, cnt);
return addr;
}
/*
* Search a Die from Die tree.
* Note: cur_link->die should be deallocated in this function.
*/
static int __search_die_tree(struct die_link *cur_link,
int (*die_cb)(struct die_link *, void *),
void *data)
{
Dwarf_Die new_die;
struct die_link new_link;
int ret;
if (!die_cb)
return 0;
/* Check current die */
while (!(ret = die_cb(cur_link, data))) {
/* Check child die */
ret = dwarf_child(cur_link->die, &new_die, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK) {
new_link.parent = cur_link;
new_link.die = new_die;
ret = __search_die_tree(&new_link, die_cb, data);
if (ret)
break;
}
/* Move to next sibling */
ret = dwarf_siblingof(__dw_debug, cur_link->die, &new_die,
&__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
cur_link->die = new_die;
if (ret == DW_DLV_NO_ENTRY)
return 0;
}
dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
return ret;
}
/* Search a die in its children's die tree */
static int search_die_from_children(Dwarf_Die parent_die,
int (*die_cb)(struct die_link *, void *),
void *data)
{
struct die_link new_link;
int ret;
new_link.parent = NULL;
ret = dwarf_child(parent_die, &new_link.die, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK)
return __search_die_tree(&new_link, die_cb, data);
else
return 0;
}
/* Find a locdesc corresponding to the address */
static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
Dwarf_Addr addr)
{
Dwarf_Signed lcnt;
Dwarf_Locdesc **llbuf;
int ret, i;
ret = dwarf_loclist_n(attr, &llbuf, &lcnt, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
ret = DW_DLV_NO_ENTRY;
for (i = 0; i < lcnt; ++i) {
if (llbuf[i]->ld_lopc <= addr &&
llbuf[i]->ld_hipc > addr) {
memcpy(desc, llbuf[i], sizeof(Dwarf_Locdesc));
desc->ld_s =
malloc(sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
ERR_IF(desc->ld_s == NULL);
memcpy(desc->ld_s, llbuf[i]->ld_s,
sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
ret = DW_DLV_OK;
break;
}
dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
}
/* Releasing loop */
for (; i < lcnt; ++i) {
dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
}
dwarf_dealloc(__dw_debug, llbuf, DW_DLA_LIST);
return ret;
}
/*
* Probe finder related functions
*/
/* Show a location */
static void show_location(Dwarf_Loc *loc, struct probe_finder *pf)
{
Dwarf_Small op;
Dwarf_Unsigned regn;
Dwarf_Signed offs;
int deref = 0, ret;
const char *regs;
op = loc->lr_atom;
/* If this is based on frame buffer, set the offset */
if (op == DW_OP_fbreg) {
deref = 1;
offs = (Dwarf_Signed)loc->lr_number;
op = pf->fbloc.ld_s[0].lr_atom;
loc = &pf->fbloc.ld_s[0];
} else
offs = 0;
if (op >= DW_OP_breg0 && op <= DW_OP_breg31) {
regn = op - DW_OP_breg0;
offs += (Dwarf_Signed)loc->lr_number;
deref = 1;
} else if (op >= DW_OP_reg0 && op <= DW_OP_reg31) {
regn = op - DW_OP_reg0;
} else if (op == DW_OP_bregx) {
regn = loc->lr_number;
offs += (Dwarf_Signed)loc->lr_number2;
deref = 1;
} else if (op == DW_OP_regx) {
regn = loc->lr_number;
} else
msg_exit(-EINVAL, "Dwarf_OP %d is not supported.\n", op);
regs = get_arch_regstr(regn);
if (!regs)
msg_exit(-EINVAL, "%lld exceeds max register number.\n", regn);
if (deref)
ret = snprintf(pf->buf, pf->len,
" %s=%+lld(%s)", pf->var, offs, regs);
else
ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
ERR_IF(ret < 0);
ERR_IF(ret >= pf->len);
}
/* Show a variables in kprobe event format */
static void show_variable(Dwarf_Die vr_die, struct probe_finder *pf)
{
Dwarf_Attribute attr;
Dwarf_Locdesc ld;
int ret;
ret = dwarf_attr(vr_die, DW_AT_location, &attr, &__dw_error);
if (ret != DW_DLV_OK)
goto error;
ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
if (ret != DW_DLV_OK)
goto error;
/* TODO? */
ERR_IF(ld.ld_cents != 1);
show_location(&ld.ld_s[0], pf);
free(ld.ld_s);
dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
return ;
error:
msg_exit(-1, "Failed to find the location of %s at this address.\n"
" Perhaps, it was optimized out.\n", pf->var);
}
static int variable_callback(struct die_link *dlink, void *data)
{
struct probe_finder *pf = (struct probe_finder *)data;
Dwarf_Half tag;
int ret;
ret = dwarf_tag(dlink->die, &tag, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if ((tag == DW_TAG_formal_parameter ||
tag == DW_TAG_variable) &&
(die_compare_name(dlink->die, pf->var) == 0)) {
show_variable(dlink->die, pf);
return 1;
}
/* TODO: Support struct members and arrays */
return 0;
}
/* Find a variable in a subprogram die */
static void find_variable(Dwarf_Die sp_die, struct probe_finder *pf)
{
int ret;
if (!is_c_varname(pf->var)) {
/* Output raw parameters */
ret = snprintf(pf->buf, pf->len, " %s", pf->var);
ERR_IF(ret < 0);
ERR_IF(ret >= pf->len);
return ;
}
debug("Searching '%s' variable in context.\n", pf->var);
/* Search child die for local variables and parameters. */
ret = search_die_from_children(sp_die, variable_callback, pf);
if (!ret)
msg_exit(-1, "Failed to find '%s' in this function.\n",
pf->var);
}
/* Get a frame base on the address */
static void get_current_frame_base(Dwarf_Die sp_die, struct probe_finder *pf)
{
Dwarf_Attribute attr;
int ret;
ret = dwarf_attr(sp_die, DW_AT_frame_base, &attr, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
ret = attr_get_locdesc(attr, &pf->fbloc, (pf->addr - pf->cu_base));
ERR_IF(ret != DW_DLV_OK);
dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
}
static void free_current_frame_base(struct probe_finder *pf)
{
free(pf->fbloc.ld_s);
memset(&pf->fbloc, 0, sizeof(Dwarf_Locdesc));
}
/* Show a probe point to output buffer */
static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
struct probe_finder *pf)
{
struct probe_point *pp = pf->pp;
char *name;
char tmp[MAX_PROBE_BUFFER];
int ret, i, len;
/* Output name of probe point */
ret = dwarf_diename(sp_die, &name, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_OK) {
ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
(unsigned int)offs);
dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
} else {
/* This function has no name. */
ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%llx", pf->addr);
}
ERR_IF(ret < 0);
ERR_IF(ret >= MAX_PROBE_BUFFER);
len = ret;
/* Find each argument */
get_current_frame_base(sp_die, pf);
for (i = 0; i < pp->nr_args; i++) {
pf->var = pp->args[i];
pf->buf = &tmp[len];
pf->len = MAX_PROBE_BUFFER - len;
find_variable(sp_die, pf);
len += strlen(pf->buf);
}
free_current_frame_base(pf);
pp->probes[pp->found] = strdup(tmp);
pp->found++;
}
static int probeaddr_callback(struct die_link *dlink, void *data)
{
struct probe_finder *pf = (struct probe_finder *)data;
Dwarf_Half tag;
Dwarf_Signed offs;
int ret;
ret = dwarf_tag(dlink->die, &tag, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
/* Check the address is in this subprogram */
if (tag == DW_TAG_subprogram &&
die_within_subprogram(dlink->die, pf->addr, &offs)) {
show_probepoint(dlink->die, offs, pf);
return 1;
}
return 0;
}
/* Find probe point from its line number */
static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
{
struct probe_point *pp = pf->pp;
Dwarf_Signed cnt, i;
Dwarf_Line *lines;
Dwarf_Unsigned lineno = 0;
Dwarf_Addr addr;
Dwarf_Unsigned fno;
int ret;
ret = dwarf_srclines(cu_die, &lines, &cnt, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
for (i = 0; i < cnt; i++) {
ret = dwarf_line_srcfileno(lines[i], &fno, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
if (fno != pf->fno)
continue;
ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
if (lineno != (Dwarf_Unsigned)pp->line)
continue;
ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
debug("Probe point found: 0x%llx\n", addr);
pf->addr = addr;
/* Search a real subprogram including this line, */
ret = search_die_from_children(cu_die, probeaddr_callback, pf);
if (ret == 0)
msg_exit(-1,
"Probe point is not found in subprograms.\n");
/* Continuing, because target line might be inlined. */
}
dwarf_srclines_dealloc(__dw_debug, lines, cnt);
}
/* Search function from function name */
static int probefunc_callback(struct die_link *dlink, void *data)
{
struct probe_finder *pf = (struct probe_finder *)data;
struct probe_point *pp = pf->pp;
struct die_link *lk;
Dwarf_Signed offs;
Dwarf_Half tag;
int ret;
ret = dwarf_tag(dlink->die, &tag, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (tag == DW_TAG_subprogram) {
if (die_compare_name(dlink->die, pp->function) == 0) {
if (die_inlined_subprogram(dlink->die)) {
/* Inlined function, save it. */
ret = dwarf_die_CU_offset(dlink->die,
&pf->inl_offs,
&__dw_error);
ERR_IF(ret != DW_DLV_OK);
debug("inline definition offset %lld\n",
pf->inl_offs);
return 0;
}
/* Get probe address */
pf->addr = die_get_entrypc(dlink->die);
pf->addr += pp->offset;
/* TODO: Check the address in this function */
show_probepoint(dlink->die, pp->offset, pf);
/* Continue to search */
}
} else if (tag == DW_TAG_inlined_subroutine && pf->inl_offs) {
if (die_get_abstract_origin(dlink->die) == pf->inl_offs) {
/* Get probe address */
pf->addr = die_get_entrypc(dlink->die);
pf->addr += pp->offset;
debug("found inline addr: 0x%llx\n", pf->addr);
/* Inlined function. Get a real subprogram */
for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
tag = 0;
dwarf_tag(lk->die, &tag, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (tag == DW_TAG_subprogram &&
!die_inlined_subprogram(lk->die))
goto found;
}
msg_exit(-1, "Failed to find real subprogram.\n");
found:
/* Get offset from subprogram */
ret = die_within_subprogram(lk->die, pf->addr, &offs);
ERR_IF(!ret);
show_probepoint(lk->die, offs, pf);
/* Continue to search */
}
}
return 0;
}
static void find_by_func(Dwarf_Die cu_die, struct probe_finder *pf)
{
search_die_from_children(cu_die, probefunc_callback, pf);
}
/* Find a probe point */
int find_probepoint(int fd, struct probe_point *pp)
{
Dwarf_Half addr_size = 0;
Dwarf_Unsigned next_cuh = 0;
Dwarf_Die cu_die = 0;
int cu_number = 0, ret;
struct probe_finder pf = {.pp = pp};
ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
if (ret != DW_DLV_OK)
msg_exit(-1, "Failed to call dwarf_init(). "
"Maybe, not a dwarf file?\n");
pp->found = 0;
while (++cu_number) {
/* Search CU (Compilation Unit) */
ret = dwarf_next_cu_header(__dw_debug, NULL, NULL, NULL,
&addr_size, &next_cuh, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_NO_ENTRY)
break;
/* Get the DIE(Debugging Information Entry) of this CU */
ret = dwarf_siblingof(__dw_debug, 0, &cu_die, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
/* Check if target file is included. */
if (pp->file)
pf.fno = die_get_fileno(cu_die, pp->file);
if (!pp->file || pf.fno) {
/* Save CU base address (for frame_base) */
ret = dwarf_lowpc(cu_die, &pf.cu_base, &__dw_error);
ERR_IF(ret == DW_DLV_ERROR);
if (ret == DW_DLV_NO_ENTRY)
pf.cu_base = 0;
if (pp->line)
find_by_line(cu_die, &pf);
if (pp->function)
find_by_func(cu_die, &pf);
}
dwarf_dealloc(__dw_debug, cu_die, DW_DLA_DIE);
}
ret = dwarf_finish(__dw_debug, &__dw_error);
ERR_IF(ret != DW_DLV_OK);
return pp->found;
}

68
tools/perf/util/probe-finder.h Normal file
View file

@ -0,0 +1,68 @@
#ifndef _PROBE_FINDER_H
#define _PROBE_FINDER_H
#define _stringify(n) #n
#define stringify(n) _stringify(n)
#ifdef DEBUG
#define debug(fmt ...) \
fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
#else
#define debug(fmt ...) do {} while (0)
#endif
#define ERR_IF(cnd) \
do { if (cnd) { \
fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
"): " stringify(cnd) "\n"); \
exit(1); \
} } while (0)
#define MAX_PATH_LEN 256
#define MAX_PROBE_BUFFER 1024
#define MAX_PROBES 128
static inline int is_c_varname(const char *name)
{
/* TODO */
return isalpha(name[0]) || name[0] == '_';
}
struct probe_point {
/* Inputs */
char *file; /* File name */
int line; /* Line number */
char *function; /* Function name */
int offset; /* Offset bytes */
int nr_args; /* Number of arguments */
char **args; /* Arguments */
/* Output */
int found; /* Number of found probe points */
char *probes[MAX_PROBES]; /* Output buffers (will be allocated)*/
};
extern int find_probepoint(int fd, struct probe_point *pp);
#include <libdwarf/dwarf.h>
#include <libdwarf/libdwarf.h>
struct probe_finder {
struct probe_point *pp; /* Target probe point */
/* For function searching */
Dwarf_Addr addr; /* Address */
Dwarf_Unsigned fno; /* File number */
Dwarf_Off inl_offs; /* Inline offset */
/* For variable searching */
Dwarf_Addr cu_base; /* Current CU base address */
Dwarf_Locdesc fbloc; /* Location of Current Frame Base */
const char *var; /* Current variable name */
char *buf; /* Current output buffer */
int len; /* Length of output buffer */
};
#endif /*_PROBE_FINDER_H */