Re: [PATCH 2/3] selftests: vdso: Use a header file to prototype parse_vdso API

From: shuah
Date: Tue May 19 2020 - 13:29:13 EST


On 5/5/20 11:47 AM, Mark Brown wrote:
Both vdso_test_gettimeofday and vdso_standalone_test_x86 use the library in
parse_vdso.c but each separately declares the API it offers which is not
ideal. Create a header file with prototypes of the functions and use it in
both the library and the tests to ensure that the same prototypes are used
throughout.

Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
tools/testing/selftests/vDSO/parse_vdso.c | 24 +-------------
tools/testing/selftests/vDSO/parse_vdso.h | 31 +++++++++++++++++++
.../selftests/vDSO/vdso_standalone_test_x86.c | 4 +--
.../selftests/vDSO/vdso_test_gettimeofday.c | 5 +--
4 files changed, 34 insertions(+), 30 deletions(-)
create mode 100644 tools/testing/selftests/vDSO/parse_vdso.h

diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 1dbb4b87268f..413f75620a35 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -21,29 +21,7 @@
#include <limits.h>
#include <elf.h>
-/*
- * To use this vDSO parser, first call one of the vdso_init_* functions.
- * If you've already parsed auxv, then pass the value of AT_SYSINFO_EHDR
- * to vdso_init_from_sysinfo_ehdr. Otherwise pass auxv to vdso_init_from_auxv.
- * Then call vdso_sym for each symbol you want. For example, to look up
- * gettimeofday on x86_64, use:
- *
- * <some pointer> = vdso_sym("LINUX_2.6", "gettimeofday");
- * or
- * <some pointer> = vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
- *
- * vdso_sym will return 0 if the symbol doesn't exist or if the init function
- * failed or was not called. vdso_sym is a little slow, so its return value
- * should be cached.
- *
- * vdso_sym is threadsafe; the init functions are not.
- *
- * These are the prototypes:
- */
-extern void vdso_init_from_auxv(void *auxv);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void *vdso_sym(const char *version, const char *name);
-
+#include "parse_vdso.h"
/* And here's the code. */
#ifndef ELF_BITS
diff --git a/tools/testing/selftests/vDSO/parse_vdso.h b/tools/testing/selftests/vDSO/parse_vdso.h
new file mode 100644
index 000000000000..ea4b8635bb0b
--- /dev/null
+++ b/tools/testing/selftests/vDSO/parse_vdso.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef PARSE_VDSO_H
+#define PARSE_VDSO_H
+
+#include <stdint.h>
+
+/*
+ * To use this vDSO parser, first call one of the vdso_init_* functions.
+ * If you've already parsed auxv, then pass the value of AT_SYSINFO_EHDR
+ * to vdso_init_from_sysinfo_ehdr. Otherwise pass auxv to vdso_init_from_auxv.
+ * Then call vdso_sym for each symbol you want. For example, to look up
+ * gettimeofday on x86_64, use:
+ *
+ * <some pointer> = vdso_sym("LINUX_2.6", "gettimeofday");
+ * or
+ * <some pointer> = vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
+ *
+ * vdso_sym will return 0 if the symbol doesn't exist or if the init function
+ * failed or was not called. vdso_sym is a little slow, so its return value
+ * should be cached.
+ *
+ * vdso_sym is threadsafe; the init functions are not.
+ *
+ * These are the prototypes:
+ */
+extern void *vdso_sym(const char *version, const char *name);
+extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
+extern void vdso_init_from_auxv(void *auxv);
+

You don't need extern here - this should be in scope?

+#endif
diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
index 5ac4b00acfbc..8a44ff973ee1 100644
--- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
+++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
@@ -16,9 +16,7 @@
#include <unistd.h>
#include <stdint.h>
-extern void *vdso_sym(const char *version, const char *name);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void vdso_init_from_auxv(void *auxv);


thanks,
-- Shuah