linux-kernel - [PATCH 3/6] perf probe: Add supported type casting of running kernel

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Date:	Thu, 18 Aug 2016 17:58:31 +0900
From:	Masami Hiramatsu <mhiramat@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Cc:	Masami Hiramatsu <mhiramat@...nel.org>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Naohiro Aota <naohiro.aota@...t.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Wang Nan <wangnan0@...wei.com>,
	Hemant Kumar <hemant@...ux.vnet.ibm.com>
Subject: [PATCH 3/6] perf probe: Add supported type casting of running kernel

Add a checking routine what types are supported by the
running kernel by finding the pattern in
<debugfs>/tracing/README.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-file.c   |   57 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-file.h   |   10 +++++++
 tools/perf/util/probe-finder.c |    1 +
 3 files changed, 68 insertions(+)

diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 9aed9c3..552e56b 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -855,3 +855,60 @@ int probe_cache__show_all_caches(struct strfilter *filter)
 
 	return 0;
 }
+
+static struct {
+	const char *pattern;
+	bool	avail;
+	bool	checked;
+} probe_type_table[] = {
+#define DEFINE_TYPE(idx, pat, def_avail)	\
+	[idx] = {.pattern = pat, .avail = (def_avail)}
+	DEFINE_TYPE(PROBE_TYPE_U, "* u8/16/32/64,*", true),
+	DEFINE_TYPE(PROBE_TYPE_S, "* s8/16/32/64,*", true),
+	DEFINE_TYPE(PROBE_TYPE_X, "* x8/16/32/64,*", false),
+	DEFINE_TYPE(PROBE_TYPE_STRING, "* string,*", true),
+	DEFINE_TYPE(PROBE_TYPE_BITFIELD,
+		    "* b<bit-width>@<bit-offset>/<container-size>", true),
+};
+
+bool probe_type_is_available(enum probe_type type)
+{
+	FILE *fp;
+	char *buf = NULL;
+	size_t len = 0;
+	bool target_line = false;
+	bool ret = probe_type_table[type].avail;
+
+	if (type < 0 || type >= PROBE_TYPE_END)
+		return false;
+	/* We don't have to check the type which supported by default */
+	if (ret || probe_type_table[type].checked)
+		return ret;
+
+	if (asprintf(&buf, "%s/README", tracing_path) < 0)
+		return ret;
+
+	fp = fopen(buf, "r");
+	if (!fp)
+		goto end;
+
+	zfree(&buf);
+	while (getline(&buf, &len, fp) > 0 && !ret) {
+		if (!target_line) {
+			target_line = !!strstr(buf, " type: ");
+			if (!target_line)
+				continue;
+		} else if (strstr(buf, "\t          ") != buf)
+			break;
+		ret = strglobmatch(buf, probe_type_table[type].pattern);
+	}
+	/* Cache the result */
+	probe_type_table[type].checked = true;
+	probe_type_table[type].avail = ret;
+
+	fclose(fp);
+end:
+	free(buf);
+
+	return ret;
+}
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index 9577b5c..eba44c3 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -19,6 +19,15 @@ struct probe_cache {
 	struct list_head entries;
 };
 
+enum probe_type {
+	PROBE_TYPE_U = 0,
+	PROBE_TYPE_S,
+	PROBE_TYPE_X,
+	PROBE_TYPE_STRING,
+	PROBE_TYPE_BITFIELD,
+	PROBE_TYPE_END,
+};
+
 #define PF_FL_UPROBE	1
 #define PF_FL_RW	2
 #define for_each_probe_cache_entry(entry, pcache) \
@@ -54,6 +63,7 @@ struct probe_cache_entry *probe_cache__find(struct probe_cache *pcache,
 struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
 					const char *group, const char *event);
 int probe_cache__show_all_caches(struct strfilter *filter);
+bool probe_type_is_available(enum probe_type type);
 #else	/* ! HAVE_LIBELF_SUPPORT */
 static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused)
 {
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 5c290c6..24dbe23 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -39,6 +39,7 @@
 #include "util.h"
 #include "symbol.h"
 #include "probe-finder.h"
+#include "probe-file.h"
 
 /* Kprobe tracer basic type is up to u64 */
 #define MAX_BASIC_TYPE_BITS	64