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, 51 insertions, 0 deletions

diff --git a/arch/x86/pci/init.c b/arch/x86/pci/init.c
new file mode 100644
index 000000000..0bb3b8b44
--- /dev/null
+++ b/arch/x86/pci/init.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/pci.h>
+#include <linux/init.h>
+#include <asm/pci_x86.h>
+#include <asm/x86_init.h>
+#include <asm/irqdomain.h>
+
+/* arch_initcall has too random ordering, so call the initializers
+   in the right sequence from here. */
+static __init int pci_arch_init(void)
+{
+	int type, pcbios = 1;
+
+	type = pci_direct_probe();
+
+	if (!(pci_probe & PCI_PROBE_NOEARLY))
+		pci_mmcfg_early_init();
+
+	if (x86_init.pci.arch_init)
+		pcbios = x86_init.pci.arch_init();
+
+	/*
+	 * Must happen after x86_init.pci.arch_init(). Xen sets up the
+	 * x86_init.irqs.create_pci_msi_domain there.
+	 */
+	x86_create_pci_msi_domain();
+
+	if (!pcbios)
+		return 0;
+
+	pci_pcbios_init();
+
+	/*
+	 * don't check for raw_pci_ops here because we want pcbios as last
+	 * fallback, yet it's needed to run first to set pcibios_last_bus
+	 * in case legacy PCI probing is used. otherwise detecting peer busses
+	 * fails.
+	 */
+	pci_direct_init(type);
+
+	if (!raw_pci_ops && !raw_pci_ext_ops)
+		printk(KERN_ERR
+		"PCI: Fatal: No config space access function found\n");
+
+	dmi_check_pciprobe();
+
+	dmi_check_skip_isa_align();
+
+	return 0;
+}
+arch_initcall(pci_arch_init);