sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

3 files changed, 414 insertions, 0 deletions

diff --git a/tools/testing/crypto/chacha20-s390/Makefile b/tools/testing/crypto/chacha20-s390/Makefile
new file mode 100644
index 000000000..db81cd2fb
--- /dev/null
+++ b/tools/testing/crypto/chacha20-s390/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2022 Red Hat, Inc.
+# Author: Vladis Dronov <vdronoff@gmail.com>
+
+obj-m += test_cipher.o
+test_cipher-y := test-cipher.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean
diff --git a/tools/testing/crypto/chacha20-s390/run-tests.sh b/tools/testing/crypto/chacha20-s390/run-tests.sh
new file mode 100644
index 000000000..43108794b
--- /dev/null
+++ b/tools/testing/crypto/chacha20-s390/run-tests.sh
@@ -0,0 +1,34 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2022 Red Hat, Inc.
+# Author: Vladis Dronov <vdronoff@gmail.com>
+#
+# This script runs (via instmod) test-cipher.ko module which invokes
+# generic and s390-native ChaCha20 encryprion algorithms with different
+# size of data. Check 'dmesg' for results.
+#
+# The insmod error is expected:
+# insmod: ERROR: could not insert module test_cipher.ko: Operation not permitted
+
+lsmod | grep chacha | cut -f1 -d' ' | xargs rmmod
+modprobe chacha_generic
+modprobe chacha_s390
+
+# run encryption for different data size, including whole block(s) +/- 1
+insmod test_cipher.ko size=63
+insmod test_cipher.ko size=64
+insmod test_cipher.ko size=65
+insmod test_cipher.ko size=127
+insmod test_cipher.ko size=128
+insmod test_cipher.ko size=129
+insmod test_cipher.ko size=511
+insmod test_cipher.ko size=512
+insmod test_cipher.ko size=513
+insmod test_cipher.ko size=4096
+insmod test_cipher.ko size=65611
+insmod test_cipher.ko size=6291456
+insmod test_cipher.ko size=62914560
+
+# print test logs
+dmesg | tail -170
diff --git a/tools/testing/crypto/chacha20-s390/test-cipher.c b/tools/testing/crypto/chacha20-s390/test-cipher.c
new file mode 100644
index 000000000..9f61454ed
--- /dev/null
+++ b/tools/testing/crypto/chacha20-s390/test-cipher.c
@@ -0,0 +1,368 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2022 Red Hat, Inc.
+ * Author: Vladis Dronov <vdronoff@gmail.com>
+ */
+
+#include <asm/elf.h>
+#include <asm/uaccess.h>
+#include <asm/smp.h>
+#include <crypto/skcipher.h>
+#include <crypto/akcipher.h>
+#include <crypto/acompress.h>
+#include <crypto/rng.h>
+#include <crypto/kpp.h>
+#include <crypto/internal/simd.h>
+#include <crypto/chacha.h>
+#include <crypto/aead.h>
+#include <crypto/hash.h>
+#include <linux/crypto.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/fips.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/scatterlist.h>
+#include <linux/time.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+#include <linux/once.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+static unsigned int data_size __read_mostly = 256;
+static unsigned int debug __read_mostly = 0;
+
+/* tie all skcipher structures together */
+struct skcipher_def {
+	struct scatterlist sginp, sgout;
+	struct crypto_skcipher *tfm;
+	struct skcipher_request *req;
+	struct crypto_wait wait;
+};
+
+/* Perform cipher operations with the chacha lib */
+static int test_lib_chacha(u8 *revert, u8 *cipher, u8 *plain)
+{
+	struct chacha_state chacha_state;
+	u8 iv[16], key[32];
+	u64 start, end;
+
+	memset(key, 'X', sizeof(key));
+	memset(iv, 'I', sizeof(iv));
+
+	if (debug) {
+		print_hex_dump(KERN_INFO, "key: ", DUMP_PREFIX_OFFSET,
+			       16, 1, key, 32, 1);
+
+		print_hex_dump(KERN_INFO, "iv:  ", DUMP_PREFIX_OFFSET,
+			       16, 1, iv, 16, 1);
+	}
+
+	/* Encrypt */
+	chacha_init(&chacha_state, (u32 *)key, iv);
+
+	start = ktime_get_ns();
+	chacha_crypt_arch(&chacha_state, cipher, plain, data_size, 20);
+	end = ktime_get_ns();
+
+
+	if (debug)
+		print_hex_dump(KERN_INFO, "encr:", DUMP_PREFIX_OFFSET,
+			       16, 1, cipher,
+			       (data_size > 64 ? 64 : data_size), 1);
+
+	pr_info("lib encryption took: %lld nsec", end - start);
+
+	/* Decrypt */
+	chacha_init(&chacha_state, (u32 *)key, iv);
+
+	start = ktime_get_ns();
+	chacha_crypt_arch(&chacha_state, revert, cipher, data_size, 20);
+	end = ktime_get_ns();
+
+	if (debug)
+		print_hex_dump(KERN_INFO, "decr:", DUMP_PREFIX_OFFSET,
+			       16, 1, revert,
+			       (data_size > 64 ? 64 : data_size), 1);
+
+	pr_info("lib decryption took: %lld nsec", end - start);
+
+	return 0;
+}
+
+/* Perform cipher operations with skcipher */
+static unsigned int test_skcipher_encdec(struct skcipher_def *sk,
+					 int enc)
+{
+	int rc;
+
+	if (enc) {
+		rc = crypto_wait_req(crypto_skcipher_encrypt(sk->req),
+				     &sk->wait);
+		if (rc)
+			pr_info("skcipher encrypt returned with result"
+				"%d\n", rc);
+	}
+	else
+	{
+		rc = crypto_wait_req(crypto_skcipher_decrypt(sk->req),
+				     &sk->wait);
+		if (rc)
+			pr_info("skcipher decrypt returned with result"
+				"%d\n", rc);
+	}
+
+	return rc;
+}
+
+/* Initialize and trigger cipher operations */
+static int test_skcipher(char *name, u8 *revert, u8 *cipher, u8 *plain)
+{
+	struct skcipher_def sk;
+	struct crypto_skcipher *skcipher = NULL;
+	struct skcipher_request *req = NULL;
+	u8 iv[16], key[32];
+	u64 start, end;
+	int ret = -EFAULT;
+
+	skcipher = crypto_alloc_skcipher(name, 0, 0);
+	if (IS_ERR(skcipher)) {
+		pr_info("could not allocate skcipher %s handle\n", name);
+		return PTR_ERR(skcipher);
+	}
+
+	req = skcipher_request_alloc(skcipher, GFP_KERNEL);
+	if (!req) {
+		pr_info("could not allocate skcipher request\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+					  crypto_req_done,
+					  &sk.wait);
+
+	memset(key, 'X', sizeof(key));
+	memset(iv, 'I', sizeof(iv));
+
+	if (crypto_skcipher_setkey(skcipher, key, 32)) {
+		pr_info("key could not be set\n");
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	if (debug) {
+		print_hex_dump(KERN_INFO, "key: ", DUMP_PREFIX_OFFSET,
+			       16, 1, key, 32, 1);
+
+		print_hex_dump(KERN_INFO, "iv:  ", DUMP_PREFIX_OFFSET,
+			       16, 1, iv, 16, 1);
+	}
+
+	sk.tfm = skcipher;
+	sk.req = req;
+
+	/* Encrypt in one pass */
+	sg_init_one(&sk.sginp, plain, data_size);
+	sg_init_one(&sk.sgout, cipher, data_size);
+	skcipher_request_set_crypt(req, &sk.sginp, &sk.sgout,
+				   data_size, iv);
+	crypto_init_wait(&sk.wait);
+
+	/* Encrypt data */
+	start = ktime_get_ns();
+	ret = test_skcipher_encdec(&sk, 1);
+	end = ktime_get_ns();
+
+	if (ret)
+		goto out;
+
+	pr_info("%s tfm encryption successful, took %lld nsec\n", name, end - start);
+
+	if (debug)
+		print_hex_dump(KERN_INFO, "encr:", DUMP_PREFIX_OFFSET,
+			       16, 1, cipher,
+			       (data_size > 64 ? 64 : data_size), 1);
+
+	/* Prepare for decryption */
+	memset(iv, 'I', sizeof(iv));
+
+	sg_init_one(&sk.sginp, cipher, data_size);
+	sg_init_one(&sk.sgout, revert, data_size);
+	skcipher_request_set_crypt(req, &sk.sginp, &sk.sgout,
+				   data_size, iv);
+	crypto_init_wait(&sk.wait);
+
+	/* Decrypt data */
+	start = ktime_get_ns();
+	ret = test_skcipher_encdec(&sk, 0);
+	end = ktime_get_ns();
+
+	if (ret)
+		goto out;
+
+	pr_info("%s tfm decryption successful, took %lld nsec\n", name, end - start);
+
+	if (debug)
+		print_hex_dump(KERN_INFO, "decr:", DUMP_PREFIX_OFFSET,
+			       16, 1, revert,
+			       (data_size > 64 ? 64 : data_size), 1);
+
+	/* Dump some internal skcipher data */
+	if (debug)
+		pr_info("skcipher %s: cryptlen %d blksize %d stride %d "
+			"ivsize %d alignmask 0x%x\n",
+			name, sk.req->cryptlen,
+			crypto_skcipher_blocksize(sk.tfm),
+			crypto_skcipher_alg(sk.tfm)->walksize,
+			crypto_skcipher_ivsize(sk.tfm),
+			crypto_skcipher_alignmask(sk.tfm));
+
+out:
+	if (skcipher)
+		crypto_free_skcipher(skcipher);
+	if (req)
+		skcipher_request_free(req);
+	return ret;
+}
+
+static int __init chacha_s390_test_init(void)
+{
+	u8 *plain = NULL, *revert = NULL;
+	u8 *cipher_generic = NULL, *cipher_s390 = NULL;
+	int ret = -1;
+
+	pr_info("s390 ChaCha20 test module: size=%d debug=%d\n",
+		data_size, debug);
+
+	/* Allocate and fill buffers */
+	plain = vmalloc(data_size);
+	if (!plain) {
+		pr_info("could not allocate plain buffer\n");
+		ret = -2;
+		goto out;
+	}
+	memset(plain, 'a', data_size);
+	get_random_bytes(plain, (data_size > 256 ? 256 : data_size));
+
+	cipher_generic = vzalloc(data_size);
+	if (!cipher_generic) {
+		pr_info("could not allocate cipher_generic buffer\n");
+		ret = -2;
+		goto out;
+	}
+
+	cipher_s390 = vzalloc(data_size);
+	if (!cipher_s390) {
+		pr_info("could not allocate cipher_s390 buffer\n");
+		ret = -2;
+		goto out;
+	}
+
+	revert = vzalloc(data_size);
+	if (!revert) {
+		pr_info("could not allocate revert buffer\n");
+		ret = -2;
+		goto out;
+	}
+
+	if (debug)
+		print_hex_dump(KERN_INFO, "src: ", DUMP_PREFIX_OFFSET,
+			       16, 1, plain,
+			       (data_size > 64 ? 64 : data_size), 1);
+
+	/* Use chacha20 generic */
+	ret = test_skcipher("chacha20-generic", revert, cipher_generic, plain);
+	if (ret)
+		goto out;
+
+	if (memcmp(plain, revert, data_size)) {
+		pr_info("generic en/decryption check FAILED\n");
+		ret = -2;
+		goto out;
+	}
+	else
+		pr_info("generic en/decryption check OK\n");
+
+	memset(revert, 0, data_size);
+
+	/* Use chacha20 s390 */
+	ret = test_skcipher("chacha20-s390", revert, cipher_s390, plain);
+	if (ret)
+		goto out;
+
+	if (memcmp(plain, revert, data_size)) {
+		pr_info("s390 en/decryption check FAILED\n");
+		ret = -2;
+		goto out;
+	}
+	else
+		pr_info("s390 en/decryption check OK\n");
+
+	if (memcmp(cipher_generic, cipher_s390, data_size)) {
+		pr_info("s390 vs generic check FAILED\n");
+		ret = -2;
+		goto out;
+	}
+	else
+		pr_info("s390 vs generic check OK\n");
+
+	memset(cipher_s390, 0, data_size);
+	memset(revert, 0, data_size);
+
+	/* Use chacha20 lib */
+	test_lib_chacha(revert, cipher_s390, plain);
+
+	if (memcmp(plain, revert, data_size)) {
+		pr_info("lib en/decryption check FAILED\n");
+		ret = -2;
+		goto out;
+	}
+	else
+		pr_info("lib en/decryption check OK\n");
+
+	if (memcmp(cipher_generic, cipher_s390, data_size)) {
+		pr_info("lib vs generic check FAILED\n");
+		ret = -2;
+		goto out;
+	}
+	else
+		pr_info("lib vs generic check OK\n");
+
+	pr_info("--- chacha20 s390 test end ---\n");
+
+out:
+	if (plain)
+		vfree(plain);
+	if (cipher_generic)
+		vfree(cipher_generic);
+	if (cipher_s390)
+		vfree(cipher_s390);
+	if (revert)
+		vfree(revert);
+
+	return -1;
+}
+
+static void __exit chacha_s390_test_exit(void)
+{
+	pr_info("s390 ChaCha20 test module exit\n");
+}
+
+module_param_named(size, data_size, uint, 0660);
+module_param(debug, int, 0660);
+MODULE_PARM_DESC(size, "Size of a plaintext");
+MODULE_PARM_DESC(debug, "Debug level (0=off,1=on)");
+
+module_init(chacha_s390_test_init);
+module_exit(chacha_s390_test_exit);
+
+MODULE_DESCRIPTION("s390 ChaCha20 self-test");
+MODULE_AUTHOR("Vladis Dronov <vdronoff@gmail.com>");
+MODULE_LICENSE("GPL v2");