Re: [PATCH v3 5/5] perf-probe: Support escaped character in parser

From: Arnaldo Carvalho de Melo
Date: Mon Dec 11 2017 - 15:03:40 EST

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In reply to: Masami Hiramatsu: "[PATCH v3 5/5] perf-probe: Support escaped character in parser"
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Em Sat, Dec 09, 2017 at 01:28:41AM +0900, Masami Hiramatsu escreveu:
> 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>
> Reviewed-by: Thomas Richter <tmricht@xxxxxxxxxxxxxxxxxx>
> Acked-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Add a description and samples in Documentation/perf-probe.txt
> Changes in v3:
> - Update for new series.
> ---
> tools/perf/Documentation/perf-probe.txt | 16 +++++++++
> tools/perf/util/probe-event.c | 57 ++++++++++++++++++-------------
> tools/perf/util/string.c | 46 +++++++++++++++++++++++++
> tools/perf/util/string2.h | 2 +
> 4 files changed, 98 insertions(+), 23 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 0d6c66d51939..735972e7bc6b 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;
> @@ -2803,23 +2807,30 @@ 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);
> - if (!buf)
> - return -ENOMEM;
> - norm = buf;
> + if (cut_version) {
> + /* We don't care about default symbol or not */
> + ver = strchr(norm, '@');
> + if (ver) {
> + buf = strndup(norm, ver - norm);
> + if (!buf)
> + return -ENOMEM;
> + norm = buf;

You forgot a } here, please check this logic and resubmit just this last
patch, without the string.c and string2.h part, that I already split
from this one and applied.

gcc diagnostics:

LD /tmp/build/perf/perf-in.o
util/probe-event.c: In function âfind_probe_functionsâ:
util/probe-event.c:2848:17: error: declaration of âmapâ shadows a parameter [-Werror=shadow]
struct map *map __maybe_unused,
^~~
util/probe-event.c:2802:45: note: shadowed declaration is here
static int find_probe_functions(struct map *map, char *name,
^~~
util/probe-event.c:2849:20: error: declaration of âsymâ shadows a previous local [-Werror=shadow]
struct symbol *sym __maybe_unused) { }

------------------------

clang's:

CC /tmp/build/perf/util/probe-event.o
util/probe-event.c:2849:40: error: function definition is not allowed here
struct symbol *sym __maybe_unused) { }
^
util/probe-event.c:2857:1: error: function definition is not allowed here
{
^
util/probe-event.c:3009:1: error: function definition is not allowed here
{
^
util/probe-event.c:3098:1: error: function definition is not allowed here
{
^
util/probe-event.c:3112:1: error: function definition is not allowed here

------------------------

Neither are that informative... ;-\

- Arnaldo

> }
> +
> 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 */

Next message: Chris Clayton: "Re: Oops on 4.15-rc[123] on shutdown/reboot"
Previous message: Kees Cook: "Re: [PATCH tip/core/rcu 02/20] torture: Prepare scripting for shift from %p to %pK"
In reply to: Masami Hiramatsu: "[PATCH v3 5/5] perf-probe: Support escaped character in parser"
Next in thread: Masami Hiramatsu: "Re: [PATCH v3 5/5] perf-probe: Support escaped character in parser"
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