tools headers: Synchronize prctl.h ABI header

The prctl.h ABI header was slightly updated during the development of
the interface. In particular the "immutable" parameter became a bit in
the option argument.

Synchronize prctl.h ABI header again and make use of the definition in
the testsuite and "perf bench futex".

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20250517151455.1065363-5-bigeasy@linutronix.de

Author: Sebastian Andrzej Siewior

tools/include/uapi/linux/prctl.h

@@ -367,6 +367,7 @@ struct prctl_mm_map {
 /* FUTEX hash management */
 #define PR_FUTEX_HASH			78
 # define PR_FUTEX_HASH_SET_SLOTS	1
+# define FH_FLAG_IMMUTABLE		(1ULL << 0)
 # define PR_FUTEX_HASH_GET_SLOTS	2
 # define PR_FUTEX_HASH_GET_IMMUTABLE	3
 

tools/perf/bench/futex.c

@@ -9,12 +9,14 @@
 
 void futex_set_nbuckets_param(struct bench_futex_parameters *params)
 {
+	unsigned long flags;
 	int ret;
 
 	if (params->nbuckets < 0)
 		return;
 
-	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, params->buckets_immutable);
+	flags = params->buckets_immutable ? FH_FLAG_IMMUTABLE : 0;
+	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, flags);
 	if (ret) {
 		printf("Requesting %d hash buckets failed: %d/%m\n",
 		       params->nbuckets, ret);

tools/testing/selftests/futex/functional/futex_priv_hash.c

@@ -26,13 +26,14 @@ static int counter;
 #ifndef PR_FUTEX_HASH
 #define PR_FUTEX_HASH			78
 # define PR_FUTEX_HASH_SET_SLOTS	1
+# define FH_FLAG_IMMUTABLE		(1ULL << 0)
 # define PR_FUTEX_HASH_GET_SLOTS	2
 # define PR_FUTEX_HASH_GET_IMMUTABLE	3
 #endif
 
-static int futex_hash_slots_set(unsigned int slots, int immutable)
+static int futex_hash_slots_set(unsigned int slots, int flags)
 {
-	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, slots, immutable);
+	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, slots, flags);
 }
 
 static int futex_hash_slots_get(void)
@@ -63,13 +64,13 @@ static void futex_hash_slots_set_verify(int slots)
 	ksft_test_result_pass("SET and GET slots %d passed\n", slots);
 }
 
-static void futex_hash_slots_set_must_fail(int slots, int immutable)
+static void futex_hash_slots_set_must_fail(int slots, int flags)
 {
 	int ret;
 
-	ret = futex_hash_slots_set(slots, immutable);
+	ret = futex_hash_slots_set(slots, flags);
 	ksft_test_result(ret < 0, "futex_hash_slots_set(%d, %d)\n",
-			 slots, immutable);
+			 slots, flags);
 }
 
 static void *thread_return_fn(void *arg)
@@ -254,18 +255,18 @@ int main(int argc, char *argv[])
 		ret = futex_hash_slots_set(0, 0);
 		ksft_test_result(ret == 0, "Global hash request\n");
 	} else {
-		ret = futex_hash_slots_set(4, 1);
+		ret = futex_hash_slots_set(4, FH_FLAG_IMMUTABLE);
 		ksft_test_result(ret == 0, "Immutable resize to 4\n");
 	}
 	if (ret != 0)
 		goto out;
 
 	futex_hash_slots_set_must_fail(4, 0);
-	futex_hash_slots_set_must_fail(4, 1);
+	futex_hash_slots_set_must_fail(4, FH_FLAG_IMMUTABLE);
 	futex_hash_slots_set_must_fail(8, 0);
-	futex_hash_slots_set_must_fail(8, 1);
-	futex_hash_slots_set_must_fail(0, 1);
-	futex_hash_slots_set_must_fail(6, 1);
+	futex_hash_slots_set_must_fail(8, FH_FLAG_IMMUTABLE);
+	futex_hash_slots_set_must_fail(0, FH_FLAG_IMMUTABLE);
+	futex_hash_slots_set_must_fail(6, FH_FLAG_IMMUTABLE);
 
 	ret = pthread_barrier_init(&barrier_main, NULL, MAX_THREADS);
 	if (ret != 0) {