selftests/powerpc: Add test for forking inside transaction

This test does a fork syscall inside a transaction. Basic sniff test to see
if we can enter the kernel during a transaction.
Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/tm/.gitignore

@@ -3,3 +3,4 @@ tm-syscall
 tm-signal-msr-resv
 tm-signal-stack
 tm-vmxcopy
+tm-fork

tools/testing/selftests/powerpc/tm/Makefile

-TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack tm-vmxcopy
+TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack tm-vmxcopy tm-fork
 
 all: $(TEST_PROGS)
 

tools/testing/selftests/powerpc/tm/tm-fork.c

+/*
+ * Copyright 2015, Michael Neuling, IBM Corp.
+ * Licensed under GPLv2.
+ *
+ * Edited: Rashmica Gupta, Nov 2015
+ *
+ * This test does a fork syscall inside a transaction. Basic sniff test
+ * to see if we can enter the kernel during a transaction.
+ */
+
+#include <errno.h>
+#include <inttypes.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "utils.h"
+#include "tm.h"
+
+int test_fork(void)
+{
+	SKIP_IF(!have_htm());
+
+	asm __volatile__(
+		"tbegin.;"
+		"blt    1f; "
+		"li     0, 2;"  /* fork syscall */
+		"sc  ;"
+		"tend.;"
+		"1: ;"
+		: : : "memory", "r0");
+	/* If we reach here, we've passed.  Otherwise we've probably crashed
+	 * the kernel */
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	return test_harness(test_fork, "tm_fork");
+}