[PATCH v2 16/17] selftests: vdso: Make VDSO function call more generic

[Christophe Leroy]

On powerpc, a call to a VDSO function is not a standard C function
call. Unlike x86 that returns a negated error code in case of an
error, powerpc sets CR[SO] and returns the error code as a
positive value.

So use a macro called VDSO_CALL() which takes a pointer to the
function to call, the number of arguments and the arguments.

Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
---
 tools/testing/selftests/vDSO/vdso_call.h           | 12 ++++++++++++
 tools/testing/selftests/vDSO/vdso_test_getrandom.c |  3 ++-
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/vDSO/vdso_call.h

diff --git a/tools/testing/selftests/vDSO/vdso_call.h b/tools/testing/selftests/vDSO/vdso_call.h
new file mode 100644
index 000000000000..ca5db2220925
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_call.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Macro to call vDSO functions
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy at csgroup.eu>, CS GROUP France
+ */
+#ifndef __VDSO_CALL_H__
+#define __VDSO_CALL_H__
+
+#define VDSO_CALL(fn, nr, args...)	fn(args)
+
+#endif
diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
index 02bcffc23e0c..16ad400721c3 100644
--- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c
+++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
@@ -22,6 +22,7 @@
 #include "../kselftest.h"
 #include "parse_vdso.h"
 #include "vdso_config.h"
+#include "vdso_call.h"
 
 #ifndef timespecsub
 #define	timespecsub(tsp, usp, vsp)					\
@@ -147,7 +148,7 @@ static ssize_t vgetrandom(void *buf, size_t len, unsigned long flags)
 			exit(KSFT_FAIL);
 		}
 	}
-	return grnd_ctx.fn(buf, len, flags, state, grnd_ctx.params.size_of_opaque_state);
+	return VDSO_CALL(grnd_ctx.fn, 5, buf, len, flags, state, grnd_ctx.params.size_of_opaque_state);
 }
 
 enum { TRIALS = 25000000, THREADS = 256 };
-- 
2.44.0