selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/arch/powerpc/crypto/vmx.c b/arch/powerpc/crypto/vmx.c
new file mode 100644
index 000000000..08da5311d
--- /dev/null
+++ b/arch/powerpc/crypto/vmx.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Routines supporting VMX instructions on the Power 8
+ *
+ * Copyright (C) 2015 International Business Machines Inc.
+ *
+ * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/cpufeature.h>
+#include <linux/crypto.h>
+#include <asm/cputable.h>
+#include <crypto/internal/skcipher.h>
+
+#include "aesp8-ppc.h"
+
+static int __init p8_init(void)
+{
+	int ret;
+
+	ret = crypto_register_skcipher(&p8_aes_cbc_alg);
+	if (ret)
+		goto err;
+
+	ret = crypto_register_skcipher(&p8_aes_ctr_alg);
+	if (ret)
+		goto err_unregister_aes_cbc;
+
+	ret = crypto_register_skcipher(&p8_aes_xts_alg);
+	if (ret)
+		goto err_unregister_aes_ctr;
+
+	return 0;
+
+err_unregister_aes_ctr:
+	crypto_unregister_skcipher(&p8_aes_ctr_alg);
+err_unregister_aes_cbc:
+	crypto_unregister_skcipher(&p8_aes_cbc_alg);
+err:
+	return ret;
+}
+
+static void __exit p8_exit(void)
+{
+	crypto_unregister_skcipher(&p8_aes_xts_alg);
+	crypto_unregister_skcipher(&p8_aes_ctr_alg);
+	crypto_unregister_skcipher(&p8_aes_cbc_alg);
+}
+
+module_cpu_feature_match(PPC_MODULE_FEATURE_VEC_CRYPTO, p8_init);
+module_exit(p8_exit);
+
+MODULE_AUTHOR("Marcelo Cerri<mhcerri@br.ibm.com>");
+MODULE_DESCRIPTION("IBM VMX cryptographic acceleration instructions "
+		   "support on Power 8");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0.0");