selftests/powerpc: Fix TM tests when CPU 0 is offline

Several of the TM tests fail spuriously if CPU 0 is offline, because
they blindly try to affinitise to CPU 0.

Fix them by picking any online CPU and using that instead.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200813013445.686464-1-mpe@ellerman.id.au

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

@@ -26,7 +26,7 @@
 
 int tm_poison_test(void)
 {
-	int pid;
+	int cpu, pid;
 	cpu_set_t cpuset;
 	uint64_t poison = 0xdeadbeefc0dec0fe;
 	uint64_t unknown = 0;
@@ -35,10 +35,13 @@ int tm_poison_test(void)
 
 	SKIP_IF(!have_htm());
 
-	/* Attach both Child and Parent to CPU 0 */
+	cpu = pick_online_cpu();
+	FAIL_IF(cpu < 0);
+
+	// Attach both Child and Parent to the same CPU
 	CPU_ZERO(&cpuset);
-	CPU_SET(0, &cpuset);
-	sched_setaffinity(0, sizeof(cpuset), &cpuset);
+	CPU_SET(cpu, &cpuset);
+	FAIL_IF(sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0);
 
 	pid = fork();
 	if (!pid) {

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

@@ -247,8 +247,7 @@ void *pong(void *not_used)
 int tm_trap_test(void)
 {
 	uint16_t k = 1;
-
-	int rc;
+	int cpu, rc;
 
 	pthread_attr_t attr;
 	cpu_set_t cpuset;
@@ -267,9 +266,12 @@ int tm_trap_test(void)
 	usr1_sa.sa_sigaction = usr1_signal_handler;
 	sigaction(SIGUSR1, &usr1_sa, NULL);
 
-	/* Set only CPU 0 in the mask. Both threads will be bound to cpu 0. */
+	cpu = pick_online_cpu();
+	FAIL_IF(cpu < 0);
+
+	// Set only one CPU in the mask. Both threads will be bound to that CPU.
 	CPU_ZERO(&cpuset);
-	CPU_SET(0, &cpuset);
+	CPU_SET(cpu, &cpuset);
 
 	/* Init pthread attribute */
 	rc = pthread_attr_init(&attr);

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

@@ -338,16 +338,19 @@ void test_fp_vec(int fp, int vec, pthread_attr_t *attr)
 
 int tm_unavailable_test(void)
 {
-	int rc, exception; /* FP = 0, VEC = 1, VSX = 2 */
+	int cpu, rc, exception; /* FP = 0, VEC = 1, VSX = 2 */
 	pthread_t t1;
 	pthread_attr_t attr;
 	cpu_set_t cpuset;
 
 	SKIP_IF(!have_htm());
 
-	/* Set only CPU 0 in the mask. Both threads will be bound to CPU 0. */
+	cpu = pick_online_cpu();
+	FAIL_IF(cpu < 0);
+
+	// Set only one CPU in the mask. Both threads will be bound to that CPU.
 	CPU_ZERO(&cpuset);
-	CPU_SET(0, &cpuset);
+	CPU_SET(cpu, &cpuset);
 
 	/* Init pthread attribute. */
 	rc = pthread_attr_init(&attr);