selftests: vdso: Add support for vdso_test_random for powerpc

Add the necessary symbolic link and tell Makefile to build
vdso_test_random for powerpc.

In makefile, don't use $(uname_M) which is wrong when cross-building
for powerpc on an x86_64.

Implement the required VDSO_CALL macro to correctly handle errors.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>

tools/arch/powerpc/vdso

@@ -0,0 +1 @@
+../../../arch/powerpc/kernel/vdso/

tools/testing/selftests/vDSO/Makefile

@@ -17,6 +17,12 @@ ifneq ($(SODIUM),)
 TEST_GEN_PROGS += vdso_test_chacha
 endif
 endif
+ifeq ($(ARCH),powerpc)
+TEST_GEN_PROGS += vdso_test_getrandom
+ifneq ($(SODIUM),)
+TEST_GEN_PROGS += vdso_test_chacha
+endif
+endif
 
 CFLAGS := -std=gnu99
 

tools/testing/selftests/vDSO/vdso_call.h

@@ -7,6 +7,46 @@
 #ifndef __VDSO_CALL_H__
 #define __VDSO_CALL_H__
 
+#ifdef __powerpc__
+
+#define LOADARGS_5(fn, __arg1, __arg2, __arg3, __arg4, __arg5) do { 	\
+	_r0 = fn;							\
+	_r3 = (long)__arg1;						\
+	_r4 = (long)__arg2;						\
+	_r5 = (long)__arg3;						\
+	_r6 = (long)__arg4;						\
+	_r7 = (long)__arg5;						\
+} while (0)
+
+#define VDSO_CALL(fn, nr, args...) ({					\
+	register void *_r0 asm ("r0");					\
+	register long _r3 asm ("r3");					\
+	register long _r4 asm ("r4");					\
+	register long _r5 asm ("r5");					\
+	register long _r6 asm ("r6");					\
+	register long _r7 asm ("r7");					\
+	register long _r8 asm ("r8");					\
+	register long _rval asm ("r3");					\
+									\
+	LOADARGS_##nr(fn, args);					\
+									\
+	asm volatile(							\
+		"	mtctr %0\n"					\
+		"	bctrl\n"					\
+		"	bns+	1f\n"					\
+		"	neg	3, 3\n"					\
+		"1:"							\
+		: "+r" (_r0), "=r" (_r3), "+r" (_r4), "+r" (_r5),	\
+		  "+r" (_r6), "+r" (_r7), "+r" (_r8)			\
+		: "r" (_rval)						\
+		: "r9", "r10", "r11", "r12", "cr0", "cr1", "cr5",	\
+		  "cr6", "cr7", "xer", "lr", "ctr", "memory"		\
+	);								\
+	_rval;								\
+})
+
+#else
 #define VDSO_CALL(fn, nr, args...)	fn(args)
+#endif
 
 #endif