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, 47 insertions, 0 deletions

diff --git a/arch/powerpc/perf/hv-common.h b/arch/powerpc/perf/hv-common.h
new file mode 100644
index 000000000..2cce17bc3
--- /dev/null
+++ b/arch/powerpc/perf/hv-common.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LINUX_POWERPC_PERF_HV_COMMON_H_
+#define LINUX_POWERPC_PERF_HV_COMMON_H_
+
+#include <linux/perf_event.h>
+#include <linux/types.h>
+
+struct hv_perf_caps {
+	u16 version;
+	u16 collect_privileged:1,
+	    ga:1,
+	    expanded:1,
+	    lab:1,
+	    unused:12;
+};
+
+unsigned long hv_perf_caps_get(struct hv_perf_caps *caps);
+
+
+#define EVENT_DEFINE_RANGE_FORMAT(name, attr_var, bit_start, bit_end)	\
+PMU_FORMAT_ATTR(name, #attr_var ":" #bit_start "-" #bit_end);		\
+EVENT_DEFINE_RANGE(name, attr_var, bit_start, bit_end)
+
+/*
+ * The EVENT_DEFINE_RANGE_FORMAT() macro above includes helper functions
+ * for the fields (eg: event_get_starting_index()). For some fields we
+ * need the bit-range definition, but no the helper functions. Define a
+ * lite version of the above macro without the helpers and silence
+ * compiler warnings unused static functions.
+ */
+#define EVENT_DEFINE_RANGE_FORMAT_LITE(name, attr_var, bit_start, bit_end) \
+PMU_FORMAT_ATTR(name, #attr_var ":" #bit_start "-" #bit_end);
+
+#define EVENT_DEFINE_RANGE(name, attr_var, bit_start, bit_end)	\
+static u64 event_get_##name##_max(void)					\
+{									\
+	BUILD_BUG_ON((bit_start > bit_end)				\
+		    || (bit_end >= (sizeof(1ull) * 8)));		\
+	return (((1ull << (bit_end - bit_start)) - 1) << 1) + 1;	\
+}									\
+static u64 event_get_##name(struct perf_event *event)			\
+{									\
+	return (event->attr.attr_var >> (bit_start)) &			\
+		event_get_##name##_max();				\
+}
+
+#endif