Re: [PATCH v2 5/5] perf-probe: Support escaped character in parser

From: Masami Hiramatsu
Date: Fri Dec 08 2017 - 10:54:56 EST

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In reply to: Thomas-Mich Richter: "Re: [PATCH v2 5/5] perf-probe: Support escaped character in parser"
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On Fri, 8 Dec 2017 12:45:45 +0100
Thomas-Mich Richter <tmricht@xxxxxxxxxxxxxxxxxx> wrote:

> On 12/07/2017 08:21 AM, Masami Hiramatsu wrote:
> > 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@xxxxxxxxxxx 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@xxxxxxxxxx>
> > ---
> > 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);
>
> Same as before (patch 4)
>
> > if (!norm)
> > continue;
> >
> > - /* We don't care about default symbol or not */
> > - ver = strchr(norm, '@');
> > - if (ver) {
> > - buf = strndup(norm, ver - norm);
> > - norm = buf;
>
> Again strndup() may return a NULL ptr and then strglobmatch() / strchr() below
> dereferences it.

OK, but those will be fixed in patch 4/5.
(Of course below block should be updated)

Anyway, Thank you!

>
> > + 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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> > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
>
>
> --
> Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
> --
> Vorsitzende des Aufsichtsrats: Martina Koederitz
> GeschÃftsfÃhrung: Dirk Wittkopp
> Sitz der Gesellschaft: BÃblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
>

--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>

Next message: Abhishek Sahu: "Re: [PATCH 00/13] Updates for QCOM Alpha PLL"
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In reply to: Thomas-Mich Richter: "Re: [PATCH v2 5/5] perf-probe: Support escaped character in parser"
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