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, 64 insertions, 0 deletions

diff --git a/drivers/iommu/intel/perfmon.h b/drivers/iommu/intel/perfmon.h
new file mode 100644
index 000000000..58606af9a
--- /dev/null
+++ b/drivers/iommu/intel/perfmon.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * PERFCFGOFF_REG, PERFFRZOFF_REG
+ * PERFOVFOFF_REG, PERFCNTROFF_REG
+ */
+#define IOMMU_PMU_NUM_OFF_REGS			4
+#define IOMMU_PMU_OFF_REGS_STEP			4
+
+#define IOMMU_PMU_FILTER_REQUESTER_ID		0x01
+#define IOMMU_PMU_FILTER_DOMAIN			0x02
+#define IOMMU_PMU_FILTER_PASID			0x04
+#define IOMMU_PMU_FILTER_ATS			0x08
+#define IOMMU_PMU_FILTER_PAGE_TABLE		0x10
+
+#define IOMMU_PMU_FILTER_EN			BIT(31)
+
+#define IOMMU_PMU_CFG_OFFSET			0x100
+#define IOMMU_PMU_CFG_CNTRCAP_OFFSET		0x80
+#define IOMMU_PMU_CFG_CNTREVCAP_OFFSET		0x84
+#define IOMMU_PMU_CFG_SIZE			0x8
+#define IOMMU_PMU_CFG_FILTERS_OFFSET		0x4
+
+#define IOMMU_PMU_CAP_REGS_STEP			8
+
+#define iommu_cntrcap_pcc(p)			((p) & 0x1)
+#define iommu_cntrcap_cw(p)			(((p) >> 8) & 0xff)
+#define iommu_cntrcap_ios(p)			(((p) >> 16) & 0x1)
+#define iommu_cntrcap_egcnt(p)			(((p) >> 28) & 0xf)
+
+#define IOMMU_EVENT_CFG_EGI_SHIFT		8
+#define IOMMU_EVENT_CFG_ES_SHIFT		32
+#define IOMMU_EVENT_CFG_INT			BIT_ULL(1)
+
+#define iommu_event_select(p)			((p) & 0xfffffff)
+#define iommu_event_group(p)			(((p) >> 28) & 0xf)
+
+#ifdef CONFIG_INTEL_IOMMU_PERF_EVENTS
+int alloc_iommu_pmu(struct intel_iommu *iommu);
+void free_iommu_pmu(struct intel_iommu *iommu);
+void iommu_pmu_register(struct intel_iommu *iommu);
+void iommu_pmu_unregister(struct intel_iommu *iommu);
+#else
+static inline int
+alloc_iommu_pmu(struct intel_iommu *iommu)
+{
+	return 0;
+}
+
+static inline void
+free_iommu_pmu(struct intel_iommu *iommu)
+{
+}
+
+static inline void
+iommu_pmu_register(struct intel_iommu *iommu)
+{
+}
+
+static inline void
+iommu_pmu_unregister(struct intel_iommu *iommu)
+{
+}
+#endif /* CONFIG_INTEL_IOMMU_PERF_EVENTS */