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>

1 files changed, 86 insertions, 0 deletions

diff --git a/include/crypto/internal/rsa.h b/include/crypto/internal/rsa.h
new file mode 100644
index 000000000..071a1951b
--- /dev/null
+++ b/include/crypto/internal/rsa.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * RSA internal helpers
+ *
+ * Copyright (c) 2015, Intel Corporation
+ * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
+ */
+#ifndef _RSA_HELPER_
+#define _RSA_HELPER_
+#include <linux/types.h>
+#include <crypto/akcipher.h>
+
+/**
+ * rsa_key - RSA key structure
+ * @n           : RSA modulus raw byte stream
+ * @e           : RSA public exponent raw byte stream
+ * @d           : RSA private exponent raw byte stream
+ * @p           : RSA prime factor p of n raw byte stream
+ * @q           : RSA prime factor q of n raw byte stream
+ * @dp          : RSA exponent d mod (p - 1) raw byte stream
+ * @dq          : RSA exponent d mod (q - 1) raw byte stream
+ * @qinv        : RSA CRT coefficient q^(-1) mod p raw byte stream
+ * @n_sz        : length in bytes of RSA modulus n
+ * @e_sz        : length in bytes of RSA public exponent
+ * @d_sz        : length in bytes of RSA private exponent
+ * @p_sz        : length in bytes of p field
+ * @q_sz        : length in bytes of q field
+ * @dp_sz       : length in bytes of dp field
+ * @dq_sz       : length in bytes of dq field
+ * @qinv_sz     : length in bytes of qinv field
+ */
+struct rsa_key {
+	const u8 *n;
+	const u8 *e;
+	const u8 *d;
+	const u8 *p;
+	const u8 *q;
+	const u8 *dp;
+	const u8 *dq;
+	const u8 *qinv;
+	size_t n_sz;
+	size_t e_sz;
+	size_t d_sz;
+	size_t p_sz;
+	size_t q_sz;
+	size_t dp_sz;
+	size_t dq_sz;
+	size_t qinv_sz;
+};
+
+int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
+		      unsigned int key_len);
+
+int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
+		       unsigned int key_len);
+
+#define RSA_PUB (true)
+#define RSA_PRIV (false)
+
+static inline int rsa_set_key(struct crypto_akcipher *child,
+			      unsigned int *key_size, bool is_pubkey,
+			      const void *key, unsigned int keylen)
+{
+	int err;
+
+	*key_size = 0;
+
+	if (is_pubkey)
+		err = crypto_akcipher_set_pub_key(child, key, keylen);
+	else
+		err = crypto_akcipher_set_priv_key(child, key, keylen);
+	if (err)
+		return err;
+
+	/* Find out new modulus size from rsa implementation */
+	err = crypto_akcipher_maxsize(child);
+	if (err > PAGE_SIZE)
+		return -ENOTSUPP;
+
+	*key_size = err;
+	return 0;
+}
+
+extern struct crypto_template rsa_pkcs1pad_tmpl;
+extern struct crypto_template rsassa_pkcs1_tmpl;
+#endif