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    Subject[PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper
    Date
    Add perf probe subcommand for kprobe-event setup helper to perf command.
    This allows user to define kprobe events by 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: Frederic Weisbecker <fweisbec@gmail.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>
    ---

    tools/perf/Makefile | 10 +
    tools/perf/builtin-probe.c | 358 +++++++++++++++++++++
    tools/perf/builtin.h | 1
    tools/perf/perf.c | 3
    tools/perf/util/probe-finder.c | 690 ++++++++++++++++++++++++++++++++++++++++
    tools/perf/util/probe-finder.h | 68 ++++
    6 files changed, 1130 insertions(+), 0 deletions(-)
    create mode 100644 tools/perf/builtin-probe.c
    create mode 100644 tools/perf/util/probe-finder.c
    create mode 100644 tools/perf/util/probe-finder.h

    diff --git a/tools/perf/Makefile b/tools/perf/Makefile
    index b5f1953..6dabcf1 100644
    --- a/tools/perf/Makefile
    +++ b/tools/perf/Makefile
    @@ -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
    diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
    new file mode 100644
    index 0000000..24b64b5
    --- /dev/null
    +++ b/tools/perf/builtin-probe.c
    @@ -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;
    +}
    +
    diff --git a/tools/perf/builtin.h b/tools/perf/builtin.h
    index e11d8d2..ad5f0f4 100644
    --- a/tools/perf/builtin.h
    +++ b/tools/perf/builtin.h
    @@ -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
    diff --git a/tools/perf/perf.c b/tools/perf/perf.c
    index 19fc7fe..f598120 100644
    --- a/tools/perf/perf.c
    +++ b/tools/perf/perf.c
    @@ -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;
    diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
    new file mode 100644
    index 0000000..ec6f53f
    --- /dev/null
    +++ b/tools/perf/util/probe-finder.c
    @@ -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;
    +}
    +
    diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
    new file mode 100644
    index 0000000..af920de
    --- /dev/null
    +++ b/tools/perf/util/probe-finder.h
    @@ -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 */

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com


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      Last update: 2009-10-08 23:25    [W:0.082 / U:2.628 seconds]
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