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Subject[PATCH v2 5/5] perf-probe: Support escaped character in parser
Date
Support the special characters escaped by '\' in parser.
This allows user to specify versions directly like below.

=====
# ./perf probe -x /lib64/libc-2.25.so malloc_get_state\\@GLIBC_2.2.5
Added new event:
probe_libc:malloc_get_state (on malloc_get_state@GLIBC_2.2.5 in /usr/lib64/libc-2.25.so)

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

perf record -e probe_libc:malloc_get_state -aR sleep 1

=====

Or, you can use separators in source filename, e.g.

=====
# ./perf probe -x /opt/test/a.out foo+bar.c:3
Semantic error :There is non-digit character in offset.
Error: Command Parse Error.
=====

Usually "+" in source file cause parser error, but

=====
# ./perf probe -x /opt/test/a.out foo\\+bar.c:4
Added new event:
probe_a:main (on @foo+bar.c:4 in /opt/test/a.out)

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

perf record -e probe_a:main -aR sleep 1
=====

escaped "\+" allows you to specify that.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v2:
- Add a description and samples in Documentation/perf-probe.txt
---
tools/perf/Documentation/perf-probe.txt | 16 +++++++++
tools/perf/util/probe-event.c | 54 +++++++++++++++++++------------
tools/perf/util/string.c | 46 ++++++++++++++++++++++++++
tools/perf/util/string2.h | 2 +
4 files changed, 97 insertions(+), 21 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index f96382692f42..b6866a05edd2 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -182,6 +182,14 @@ Note that before using the SDT event, the target binary (on which SDT events are
For details of the SDT, see below.
https://sourceware.org/gdb/onlinedocs/gdb/Static-Probe-Points.html

+ESCAPED CHARACTER
+-----------------
+
+In the probe syntax, '=', '@', '+', ':' and ';' are treated as a special character. You can use a backslash ('\') to escape the special characters.
+This is useful if you need to probe on a specific versioned symbols, like @GLIBC_... suffixes, or also you need to specify a source file which includes the special characters.
+Note that usually single backslash is consumed by shell, so you might need to pass double backslash (\\) or wrapping with single quotes (\'AAA\@BBB').
+See EXAMPLES how it is used.
+
PROBE ARGUMENT
--------------
Each probe argument follows below syntax.
@@ -277,6 +285,14 @@ Add a USDT probe to a target process running in a different mount namespace

./perf probe --target-ns <target pid> -x /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el7_3.x86_64/jre/lib/amd64/server/libjvm.so %sdt_hotspot:thread__sleep__end

+Add a probe on specific versioned symbol by backslash escape
+
+ ./perf probe -x /lib64/libc-2.25.so 'malloc_get_state\@GLIBC_2.2.5'
+
+Add a probe in a source file using special characters by backslash escape
+
+ ./perf probe -x /opt/test/a.out 'foo\+bar.c:4'
+

SEE ALSO
--------
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 94acc5846e2a..c082a27982e5 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1325,27 +1325,30 @@ static int parse_perf_probe_event_name(char **arg, struct perf_probe_event *pev)
{
char *ptr;

- ptr = strchr(*arg, ':');
+ ptr = strpbrk_esc(*arg, ":");
if (ptr) {
*ptr = '\0';
if (!pev->sdt && !is_c_func_name(*arg))
goto ng_name;
- pev->group = strdup(*arg);
+ pev->group = strdup_esc(*arg);
if (!pev->group)
return -ENOMEM;
*arg = ptr + 1;
} else
pev->group = NULL;
- if (!pev->sdt && !is_c_func_name(*arg)) {
+
+ pev->event = strdup_esc(*arg);
+ if (pev->event == NULL)
+ return -ENOMEM;
+
+ if (!pev->sdt && !is_c_func_name(pev->event)) {
+ zfree(&pev->event);
ng_name:
+ zfree(&pev->group);
semantic_error("%s is bad for event name -it must "
"follow C symbol-naming rule.\n", *arg);
return -EINVAL;
}
- pev->event = strdup(*arg);
- if (pev->event == NULL)
- return -ENOMEM;
-
return 0;
}

@@ -1373,7 +1376,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
arg++;
}

- ptr = strpbrk(arg, ";=@+%");
+ ptr = strpbrk_esc(arg, ";=@+%");
if (pev->sdt) {
if (ptr) {
if (*ptr != '@') {
@@ -1387,7 +1390,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
pev->target = build_id_cache__origname(tmp);
free(tmp);
} else
- pev->target = strdup(ptr + 1);
+ pev->target = strdup_esc(ptr + 1);
if (!pev->target)
return -ENOMEM;
*ptr = '\0';
@@ -1421,13 +1424,14 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
*
* Otherwise, we consider arg to be a function specification.
*/
- if (!strpbrk(arg, "+@%") && (ptr = strpbrk(arg, ";:")) != NULL) {
+ if (!strpbrk_esc(arg, "+@%")) {
+ ptr = strpbrk_esc(arg, ";:");
/* This is a file spec if it includes a '.' before ; or : */
- if (memchr(arg, '.', ptr - arg))
+ if (ptr && memchr(arg, '.', ptr - arg))
file_spec = true;
}

- ptr = strpbrk(arg, ";:+@%");
+ ptr = strpbrk_esc(arg, ";:+@%");
if (ptr) {
nc = *ptr;
*ptr++ = '\0';
@@ -1436,7 +1440,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
if (arg[0] == '\0')
tmp = NULL;
else {
- tmp = strdup(arg);
+ tmp = strdup_esc(arg);
if (tmp == NULL)
return -ENOMEM;
}
@@ -1469,12 +1473,12 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
arg = ptr;
c = nc;
if (c == ';') { /* Lazy pattern must be the last part */
- pp->lazy_line = strdup(arg);
+ pp->lazy_line = strdup(arg); /* let leave escapes */
if (pp->lazy_line == NULL)
return -ENOMEM;
break;
}
- ptr = strpbrk(arg, ";:+@%");
+ ptr = strpbrk_esc(arg, ";:+@%");
if (ptr) {
nc = *ptr;
*ptr++ = '\0';
@@ -1501,7 +1505,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
semantic_error("SRC@SRC is not allowed.\n");
return -EINVAL;
}
- pp->file = strdup(arg);
+ pp->file = strdup_esc(arg);
if (pp->file == NULL)
return -ENOMEM;
break;
@@ -2803,21 +2807,29 @@ static int find_probe_functions(struct map *map, char *name,
struct rb_node *tmp;
const char *norm, *ver;
char *buf = NULL;
+ bool cut_version = true;

if (map__load(map) < 0)
return 0;

+ /* If user gives a version, don't cut off the version from symbols */
+ if (strchr(name, '@'))
+ cut_version = false;
+
map__for_each_symbol(map, sym, tmp) {
norm = arch__normalize_symbol_name(sym->name);
if (!norm)
continue;

- /* We don't care about default symbol or not */
- ver = strchr(norm, '@');
- if (ver) {
- buf = strndup(norm, ver - norm);
- norm = buf;
+ if (cut_version) {
+ /* We don't care about default symbol or not */
+ ver = strchr(norm, '@');
+ if (ver) {
+ buf = strndup(norm, ver - norm);
+ norm = buf;
+ }
}
+
if (strglobmatch(norm, name)) {
found++;
if (syms && found < probe_conf.max_probes)
diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index aaa08ee8c717..d8bfd0c4d2cb 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -396,3 +396,49 @@ char *asprintf_expr_inout_ints(const char *var, bool in, size_t nints, int *ints
free(expr);
return NULL;
}
+
+/* Like strpbrk(), but not break if it is right after a backslash (escaped) */
+char *strpbrk_esc(char *str, const char *stopset)
+{
+ char *ptr;
+
+ do {
+ ptr = strpbrk(str, stopset);
+ if (ptr == str ||
+ (ptr == str + 1 && *(ptr - 1) != '\\'))
+ break;
+ str = ptr + 1;
+ } while (ptr && *(ptr - 1) == '\\' && *(ptr - 2) != '\\');
+
+ return ptr;
+}
+
+/* Like strdup, but do not copy a single backslash */
+char *strdup_esc(const char *str)
+{
+ char *s, *d, *p, *ret = strdup(str);
+
+ if (!ret)
+ return NULL;
+
+ d = strchr(ret, '\\');
+ if (!d)
+ return ret;
+
+ s = d + 1;
+ do {
+ if (*s == '\0') {
+ *d = '\0';
+ break;
+ }
+ p = strchr(s + 1, '\\');
+ if (p) {
+ memmove(d, s, p - s);
+ d += p - s;
+ s = p + 1;
+ } else
+ memmove(d, s, strlen(s) + 1);
+ } while (p);
+
+ return ret;
+}
diff --git a/tools/perf/util/string2.h b/tools/perf/util/string2.h
index ee14ca5451ab..4c68a09b97e8 100644
--- a/tools/perf/util/string2.h
+++ b/tools/perf/util/string2.h
@@ -39,5 +39,7 @@ static inline char *asprintf_expr_not_in_ints(const char *var, size_t nints, int
return asprintf_expr_inout_ints(var, false, nints, ints);
}

+char *strpbrk_esc(char *str, const char *stopset);
+char *strdup_esc(const char *str);

#endif /* PERF_STRING_H */
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