linux-kernel - [PATCH v4 2/3] perf tests: avoid storing an absolute path in perf binary

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Message-Id: <20210430133350.20504-2-dzagorui@cisco.com>
Date:   Fri, 30 Apr 2021 06:33:49 -0700
From:   Denys Zagorui <dzagorui@...co.com>
To:     jolsa@...hat.com, linux-kernel@...r.kernel.org,
        peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org
Subject: [PATCH v4 2/3] perf tests: avoid storing an absolute path in perf binary

python binding test uses PYTHONPATH definition to find python/perf.so
library. This definition is an absolute path that makes perf binary
unreproducible. This path can be found during runtime execution.

Signed-off-by: Denys Zagorui <dzagorui@...co.com>
---
 tools/perf/tests/Build        |  2 +-
 tools/perf/tests/python-use.c | 19 ++++++++++++++++++-
 tools/perf/util/util.c        | 21 +++++++++++++++++++++
 tools/perf/util/util.h        |  2 ++
 4 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 650aec19d490..a20098dcdbc4 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -98,5 +98,5 @@ perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
 endif
 
 CFLAGS_attr.o         += -DBINDIR="BUILD_STR($(bindir_SQ))" -DPYTHON="BUILD_STR($(PYTHON_WORD))"
-CFLAGS_python-use.o   += -DPYTHONPATH="BUILD_STR($(OUTPUT)python)" -DPYTHON="BUILD_STR($(PYTHON_WORD))"
+CFLAGS_python-use.o   += -DPYTHON="BUILD_STR($(PYTHON_WORD))"
 CFLAGS_dwarf-unwind.o += -fno-optimize-sibling-calls
diff --git a/tools/perf/tests/python-use.c b/tools/perf/tests/python-use.c
index 98c6d474aa6f..c7a0c9b5366f 100644
--- a/tools/perf/tests/python-use.c
+++ b/tools/perf/tests/python-use.c
@@ -8,18 +8,35 @@
 #include <linux/compiler.h>
 #include "tests.h"
 #include "util/debug.h"
+#include "util/util.h"
+#include <sys/stat.h>
 
 int test__python_use(struct test *test __maybe_unused, int subtest __maybe_unused)
 {
 	char *cmd;
 	int ret;
+	char *exec_path;
+	char *pythonpath;
+	struct stat sb;
+
+	exec_path = perf_exe_path();
+	if (exec_path == NULL)
+		return -1;
+
+	if (asprintf(&pythonpath, "%spython", exec_path) < 0)
+		return -1;
+
+	if (stat(pythonpath, &sb) || !S_ISDIR(sb.st_mode))
+		pythonpath[0] = 0;
 
 	if (asprintf(&cmd, "echo \"import sys ; sys.path.append('%s'); import perf\" | %s %s",
-		     PYTHONPATH, PYTHON, verbose > 0 ? "" : "2> /dev/null") < 0)
+		     pythonpath, PYTHON, verbose > 0 ? "" : "2> /dev/null") < 0)
 		return -1;
 
 	pr_debug("python usage test: \"%s\"\n", cmd);
 	ret = system(cmd) ? -1 : 0;
 	free(cmd);
+	free(exec_path);
+	free(pythonpath);
 	return ret;
 }
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 3bba74e431ed..54e80452887c 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -388,3 +388,24 @@ char *perf_exe(char *buf, int len)
 	}
 	return strcpy(buf, "perf");
 }
+
+char *perf_exe_path(void)
+{
+	int i;
+	char *buf;
+
+	buf = malloc(PATH_MAX);
+	buf = perf_exe(buf, PATH_MAX);
+
+	for (i = strlen(buf) - 1; i != 0 && buf[i] != '/'; i--)
+		;
+
+	if (!i) {
+		free(buf);
+		return NULL;
+	}
+
+	buf[i + 1] = 0;
+
+	return buf;
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 80b194ee6c7d..4e871e890ef8 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -49,6 +49,8 @@ void perf_set_singlethreaded(void);
 void perf_set_multithreaded(void);
 
 char *perf_exe(char *buf, int len);
+/* perf_exe_path return malloc'd string on success, caller must free it */
+char *perf_exe_path(void);
 
 #ifndef O_CLOEXEC
 #ifdef __sparc__
-- 
2.26.2.Cisco