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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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