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Message-Id: <20220211103415.2737789-19-irogers@google.com>
Date: Fri, 11 Feb 2022 02:34:11 -0800
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>,
"André Almeida" <andrealmeid@...labora.com>,
James Clark <james.clark@....com>,
John Garry <john.garry@...wei.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>,
Jin Yao <yao.jin@...ux.intel.com>,
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: eranian@...gle.com, Ian Rogers <irogers@...gle.com>
Subject: [PATCH v3 18/22] 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..30d12f9c7b52
--- /dev/null
+++ b/tools/lib/perf/include/internal/rc_check.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#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 */
--
2.35.1.265.g69c8d7142f-goog
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