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Message-Id: <20230407230405.2931830-2-irogers@google.com>
Date:   Fri,  7 Apr 2023 16:04:01 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Darren Hart <dvhart@...radead.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        James Clark <james.clark@....com>,
        John Garry <john.g.garry@...cle.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Leo Yan <leo.yan@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Shunsuke Nakamura <nakamura.shun@...itsu.com>,
        Song Liu <song@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Miaoqian Lin <linmq006@...il.com>,
        Stephen Brennan <stephen.s.brennan@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        German Gomez <german.gomez@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, Hao Luo <haoluo@...gle.com>
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH v7 1/5] libperf: Add reference count checking macros.

The macros serve as a way to debug use of a reference counted struct.
The macros add a memory allocated pointer that is interposed between
the reference counted original struct at a get and freed by a put.
The pointer replaces the original struct, so use of the struct name
via APIs remains unchanged.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/lib/perf/include/internal/rc_check.h | 94 ++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 tools/lib/perf/include/internal/rc_check.h

diff --git a/tools/lib/perf/include/internal/rc_check.h b/tools/lib/perf/include/internal/rc_check.h
new file mode 100644
index 000000000000..c0626d8beb59
--- /dev/null
+++ b/tools/lib/perf/include/internal/rc_check.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __LIBPERF_INTERNAL_RC_CHECK_H
+#define __LIBPERF_INTERNAL_RC_CHECK_H
+
+#include <stdlib.h>
+#include <linux/zalloc.h>
+
+/*
+ * Shared reference count checking macros.
+ *
+ * Reference count checking is an approach to sanitizing the use of reference
+ * counted structs. It leverages address and leak sanitizers to make sure gets
+ * are paired with a put. Reference count checking adds a malloc-ed layer of
+ * indirection on a get, and frees it on a put. A missed put will be reported as
+ * a memory leak. A double put will be reported as a double free. Accessing
+ * after a put will cause a use-after-free and/or a segfault.
+ */
+
+#ifndef REFCNT_CHECKING
+/* Replaces "struct foo" so that the pointer may be interposed. */
+#define DECLARE_RC_STRUCT(struct_name)		\
+	struct struct_name
+
+/* Declare a reference counted struct variable. */
+#define RC_STRUCT(struct_name) struct struct_name
+
+/*
+ * Interpose the indirection. Result will hold the indirection and object is the
+ * reference counted struct.
+ */
+#define ADD_RC_CHK(result, object) (result = object, object)
+
+/* Strip the indirection layer. */
+#define RC_CHK_ACCESS(object) object
+
+/* Frees the object and the indirection layer. */
+#define RC_CHK_FREE(object) free(object)
+
+/* A get operation adding the indirection layer. */
+#define RC_CHK_GET(result, object) ADD_RC_CHK(result, object)
+
+/* A put operation removing the indirection layer. */
+#define RC_CHK_PUT(object) {}
+
+#else
+
+/* Replaces "struct foo" so that the pointer may be interposed. */
+#define DECLARE_RC_STRUCT(struct_name)			\
+	struct original_##struct_name;			\
+	struct struct_name {				\
+		struct original_##struct_name *orig;	\
+	};						\
+	struct original_##struct_name
+
+/* Declare a reference counted struct variable. */
+#define RC_STRUCT(struct_name) struct original_##struct_name
+
+/*
+ * Interpose the indirection. Result will hold the indirection and object is the
+ * reference counted struct.
+ */
+#define ADD_RC_CHK(result, object)					\
+	(								\
+		object ? (result = malloc(sizeof(*result)),		\
+			result ? (result->orig = object, result)	\
+			: (result = NULL, NULL))			\
+		: (result = NULL, NULL)					\
+		)
+
+/* Strip the indirection layer. */
+#define RC_CHK_ACCESS(object) object->orig
+
+/* Frees the object and the indirection layer. */
+#define RC_CHK_FREE(object)			\
+	do {					\
+		zfree(&object->orig);		\
+		free(object);			\
+	} while(0)
+
+/* A get operation adding the indirection layer. */
+#define RC_CHK_GET(result, object) ADD_RC_CHK(result, (object ? object->orig : NULL))
+
+/* A put operation removing the indirection layer. */
+#define RC_CHK_PUT(object)			\
+	do {					\
+		if (object) {			\
+			object->orig = NULL;	\
+			free(object);		\
+		}				\
+	} while(0)
+
+#endif
+
+#endif /* __LIBPERF_INTERNAL_RC_CHECK_H */
-- 
2.40.0.577.gac1e443424-goog

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