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, 55 insertions, 0 deletions

diff --git a/arch/mips/pci/pci.c b/arch/mips/pci/pci.c
new file mode 100644
index 000000000..feebc6eee
--- /dev/null
+++ b/arch/mips/pci/pci.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) 2003, 04, 11 Ralf Baechle (ralf@linux-mips.org)
+ * Copyright (C) 2011 Wind River Systems,
+ *   written by Ralf Baechle (ralf@linux-mips.org)
+ */
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/memblock.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/pci.h>
+#include <linux/of_address.h>
+
+#include <asm/cpu-info.h>
+
+unsigned long PCIBIOS_MIN_IO;
+EXPORT_SYMBOL(PCIBIOS_MIN_IO);
+
+unsigned long PCIBIOS_MIN_MEM;
+EXPORT_SYMBOL(PCIBIOS_MIN_MEM);
+
+static int __init pcibios_set_cache_line_size(void)
+{
+	unsigned int lsize;
+
+	/*
+	 * Set PCI cacheline size to that of the highest level in the
+	 * cache hierarchy.
+	 */
+	lsize = cpu_dcache_line_size();
+	lsize = cpu_scache_line_size() ? : lsize;
+	lsize = cpu_tcache_line_size() ? : lsize;
+
+	BUG_ON(!lsize);
+
+	pci_dfl_cache_line_size = lsize >> 2;
+
+	pr_debug("PCI: pci_cache_line_size set to %d bytes\n", lsize);
+	return 0;
+}
+arch_initcall(pcibios_set_cache_line_size);
+
+void pci_resource_to_user(const struct pci_dev *dev, int bar,
+			  const struct resource *rsrc, resource_size_t *start,
+			  resource_size_t *end)
+{
+	phys_addr_t size = resource_size(rsrc);
+
+	*start = fixup_bigphys_addr(rsrc->start, size);
+	*end = rsrc->start + size - 1;
+}