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, 394 insertions, 0 deletions

diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c
new file mode 100644
index 000000000..9f3724429
--- /dev/null
+++ b/crypto/pcrypt.c
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * pcrypt - Parallel crypto wrapper.
+ *
+ * Copyright (C) 2009 secunet Security Networks AG
+ * Copyright (C) 2009 Steffen Klassert <steffen.klassert@secunet.com>
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/internal/aead.h>
+#include <linux/atomic.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kobject.h>
+#include <linux/cpu.h>
+#include <crypto/pcrypt.h>
+
+static struct padata_instance *pencrypt;
+static struct padata_instance *pdecrypt;
+static struct kset           *pcrypt_kset;
+
+struct pcrypt_instance_ctx {
+	struct crypto_aead_spawn spawn;
+	struct padata_shell *psenc;
+	struct padata_shell *psdec;
+	atomic_t tfm_count;
+};
+
+struct pcrypt_aead_ctx {
+	struct crypto_aead *child;
+	unsigned int cb_cpu;
+};
+
+static inline struct pcrypt_instance_ctx *pcrypt_tfm_ictx(
+	struct crypto_aead *tfm)
+{
+	return aead_instance_ctx(aead_alg_instance(tfm));
+}
+
+static int pcrypt_aead_setkey(struct crypto_aead *parent,
+			      const u8 *key, unsigned int keylen)
+{
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(parent);
+
+	return crypto_aead_setkey(ctx->child, key, keylen);
+}
+
+static int pcrypt_aead_setauthsize(struct crypto_aead *parent,
+				   unsigned int authsize)
+{
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(parent);
+
+	return crypto_aead_setauthsize(ctx->child, authsize);
+}
+
+static void pcrypt_aead_serial(struct padata_priv *padata)
+{
+	struct pcrypt_request *preq = pcrypt_padata_request(padata);
+	struct aead_request *req = pcrypt_request_ctx(preq);
+
+	aead_request_complete(req->base.data, padata->info);
+}
+
+static void pcrypt_aead_done(void *data, int err)
+{
+	struct aead_request *req = data;
+	struct pcrypt_request *preq = aead_request_ctx(req);
+	struct padata_priv *padata = pcrypt_request_padata(preq);
+
+	if (err == -EINPROGRESS)
+		return;
+
+	padata->info = err;
+
+	padata_do_serial(padata);
+}
+
+static void pcrypt_aead_enc(struct padata_priv *padata)
+{
+	struct pcrypt_request *preq = pcrypt_padata_request(padata);
+	struct aead_request *req = pcrypt_request_ctx(preq);
+	int ret;
+
+	ret = crypto_aead_encrypt(req);
+
+	if (ret == -EINPROGRESS || ret == -EBUSY)
+		return;
+
+	padata->info = ret;
+	padata_do_serial(padata);
+}
+
+static int pcrypt_aead_encrypt(struct aead_request *req)
+{
+	int err;
+	struct pcrypt_request *preq = aead_request_ctx(req);
+	struct aead_request *creq = pcrypt_request_ctx(preq);
+	struct padata_priv *padata = pcrypt_request_padata(preq);
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
+	u32 flags = aead_request_flags(req);
+	struct pcrypt_instance_ctx *ictx;
+
+	ictx = pcrypt_tfm_ictx(aead);
+
+	memset(padata, 0, sizeof(struct padata_priv));
+
+	padata->parallel = pcrypt_aead_enc;
+	padata->serial = pcrypt_aead_serial;
+
+	aead_request_set_tfm(creq, ctx->child);
+	aead_request_set_callback(creq, flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
+				  pcrypt_aead_done, req);
+	aead_request_set_crypt(creq, req->src, req->dst,
+			       req->cryptlen, req->iv);
+	aead_request_set_ad(creq, req->assoclen);
+
+	err = padata_do_parallel(ictx->psenc, padata, &ctx->cb_cpu);
+	if (!err)
+		return -EINPROGRESS;
+	if (err == -EBUSY) {
+		/* try non-parallel mode */
+		aead_request_set_callback(creq, flags, req->base.complete,
+					  req->base.data);
+		return crypto_aead_encrypt(creq);
+	}
+
+	return err;
+}
+
+static void pcrypt_aead_dec(struct padata_priv *padata)
+{
+	struct pcrypt_request *preq = pcrypt_padata_request(padata);
+	struct aead_request *req = pcrypt_request_ctx(preq);
+	int ret;
+
+	ret = crypto_aead_decrypt(req);
+
+	if (ret == -EINPROGRESS || ret == -EBUSY)
+		return;
+
+	padata->info = ret;
+	padata_do_serial(padata);
+}
+
+static int pcrypt_aead_decrypt(struct aead_request *req)
+{
+	int err;
+	struct pcrypt_request *preq = aead_request_ctx(req);
+	struct aead_request *creq = pcrypt_request_ctx(preq);
+	struct padata_priv *padata = pcrypt_request_padata(preq);
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
+	u32 flags = aead_request_flags(req);
+	struct pcrypt_instance_ctx *ictx;
+
+	ictx = pcrypt_tfm_ictx(aead);
+
+	memset(padata, 0, sizeof(struct padata_priv));
+
+	padata->parallel = pcrypt_aead_dec;
+	padata->serial = pcrypt_aead_serial;
+
+	aead_request_set_tfm(creq, ctx->child);
+	aead_request_set_callback(creq, flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
+				  pcrypt_aead_done, req);
+	aead_request_set_crypt(creq, req->src, req->dst,
+			       req->cryptlen, req->iv);
+	aead_request_set_ad(creq, req->assoclen);
+
+	err = padata_do_parallel(ictx->psdec, padata, &ctx->cb_cpu);
+	if (!err)
+		return -EINPROGRESS;
+	if (err == -EBUSY) {
+		/* try non-parallel mode */
+		aead_request_set_callback(creq, flags, req->base.complete,
+					  req->base.data);
+		return crypto_aead_decrypt(creq);
+	}
+
+	return err;
+}
+
+static int pcrypt_aead_init_tfm(struct crypto_aead *tfm)
+{
+	int cpu_index;
+	struct aead_instance *inst = aead_alg_instance(tfm);
+	struct pcrypt_instance_ctx *ictx = aead_instance_ctx(inst);
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(tfm);
+	struct crypto_aead *cipher;
+
+	cpu_index = (unsigned int)atomic_inc_return(&ictx->tfm_count) %
+		    cpumask_weight(cpu_online_mask);
+
+	ctx->cb_cpu = cpumask_nth(cpu_index, cpu_online_mask);
+	cipher = crypto_spawn_aead(&ictx->spawn);
+
+	if (IS_ERR(cipher))
+		return PTR_ERR(cipher);
+
+	ctx->child = cipher;
+	crypto_aead_set_reqsize(tfm, sizeof(struct pcrypt_request) +
+				     sizeof(struct aead_request) +
+				     crypto_aead_reqsize(cipher));
+
+	return 0;
+}
+
+static void pcrypt_aead_exit_tfm(struct crypto_aead *tfm)
+{
+	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(tfm);
+
+	crypto_free_aead(ctx->child);
+}
+
+static void pcrypt_free(struct aead_instance *inst)
+{
+	struct pcrypt_instance_ctx *ctx = aead_instance_ctx(inst);
+
+	crypto_drop_aead(&ctx->spawn);
+	padata_free_shell(ctx->psdec);
+	padata_free_shell(ctx->psenc);
+	kfree(inst);
+}
+
+static int pcrypt_init_instance(struct crypto_instance *inst,
+				struct crypto_alg *alg)
+{
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "pcrypt(%s)", alg->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+		return -ENAMETOOLONG;
+
+	memcpy(inst->alg.cra_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);
+
+	inst->alg.cra_priority = alg->cra_priority + 100;
+	inst->alg.cra_blocksize = alg->cra_blocksize;
+	inst->alg.cra_alignmask = alg->cra_alignmask;
+
+	return 0;
+}
+
+static int pcrypt_create_aead(struct crypto_template *tmpl, struct rtattr **tb,
+			      struct crypto_attr_type *algt)
+{
+	struct pcrypt_instance_ctx *ctx;
+	struct aead_instance *inst;
+	struct aead_alg *alg;
+	u32 mask = crypto_algt_inherited_mask(algt);
+	int err;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	err = -ENOMEM;
+
+	ctx = aead_instance_ctx(inst);
+	ctx->psenc = padata_alloc_shell(pencrypt);
+	if (!ctx->psenc)
+		goto err_free_inst;
+
+	ctx->psdec = padata_alloc_shell(pdecrypt);
+	if (!ctx->psdec)
+		goto err_free_inst;
+
+	err = crypto_grab_aead(&ctx->spawn, aead_crypto_instance(inst),
+			       crypto_attr_alg_name(tb[1]), 0, mask);
+	if (err)
+		goto err_free_inst;
+
+	alg = crypto_spawn_aead_alg(&ctx->spawn);
+	err = pcrypt_init_instance(aead_crypto_instance(inst), &alg->base);
+	if (err)
+		goto err_free_inst;
+
+	inst->alg.base.cra_flags |= CRYPTO_ALG_ASYNC;
+
+	inst->alg.ivsize = crypto_aead_alg_ivsize(alg);
+	inst->alg.maxauthsize = crypto_aead_alg_maxauthsize(alg);
+
+	inst->alg.base.cra_ctxsize = sizeof(struct pcrypt_aead_ctx);
+
+	inst->alg.init = pcrypt_aead_init_tfm;
+	inst->alg.exit = pcrypt_aead_exit_tfm;
+
+	inst->alg.setkey = pcrypt_aead_setkey;
+	inst->alg.setauthsize = pcrypt_aead_setauthsize;
+	inst->alg.encrypt = pcrypt_aead_encrypt;
+	inst->alg.decrypt = pcrypt_aead_decrypt;
+
+	inst->free = pcrypt_free;
+
+	err = aead_register_instance(tmpl, inst);
+	if (err) {
+err_free_inst:
+		pcrypt_free(inst);
+	}
+	return err;
+}
+
+static int pcrypt_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+	struct crypto_attr_type *algt;
+
+	algt = crypto_get_attr_type(tb);
+	if (IS_ERR(algt))
+		return PTR_ERR(algt);
+
+	switch (algt->type & algt->mask & CRYPTO_ALG_TYPE_MASK) {
+	case CRYPTO_ALG_TYPE_AEAD:
+		return pcrypt_create_aead(tmpl, tb, algt);
+	}
+
+	return -EINVAL;
+}
+
+static int pcrypt_sysfs_add(struct padata_instance *pinst, const char *name)
+{
+	int ret;
+
+	pinst->kobj.kset = pcrypt_kset;
+	ret = kobject_add(&pinst->kobj, NULL, "%s", name);
+	if (!ret)
+		kobject_uevent(&pinst->kobj, KOBJ_ADD);
+
+	return ret;
+}
+
+static int pcrypt_init_padata(struct padata_instance **pinst, const char *name)
+{
+	int ret = -ENOMEM;
+
+	*pinst = padata_alloc(name);
+	if (!*pinst)
+		return ret;
+
+	ret = pcrypt_sysfs_add(*pinst, name);
+	if (ret)
+		padata_free(*pinst);
+
+	return ret;
+}
+
+static struct crypto_template pcrypt_tmpl = {
+	.name = "pcrypt",
+	.create = pcrypt_create,
+	.module = THIS_MODULE,
+};
+
+static int __init pcrypt_init(void)
+{
+	int err = -ENOMEM;
+
+	pcrypt_kset = kset_create_and_add("pcrypt", NULL, kernel_kobj);
+	if (!pcrypt_kset)
+		goto err;
+
+	err = pcrypt_init_padata(&pencrypt, "pencrypt");
+	if (err)
+		goto err_unreg_kset;
+
+	err = pcrypt_init_padata(&pdecrypt, "pdecrypt");
+	if (err)
+		goto err_deinit_pencrypt;
+
+	return crypto_register_template(&pcrypt_tmpl);
+
+err_deinit_pencrypt:
+	padata_free(pencrypt);
+err_unreg_kset:
+	kset_unregister(pcrypt_kset);
+err:
+	return err;
+}
+
+static void __exit pcrypt_exit(void)
+{
+	crypto_unregister_template(&pcrypt_tmpl);
+
+	padata_free(pencrypt);
+	padata_free(pdecrypt);
+
+	kset_unregister(pcrypt_kset);
+}
+
+module_init(pcrypt_init);
+module_exit(pcrypt_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
+MODULE_DESCRIPTION("Parallel crypto wrapper");
+MODULE_ALIAS_CRYPTO("pcrypt");