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, 119 insertions, 0 deletions

diff --git a/drivers/dma/idxd/perfmon.h b/drivers/dma/idxd/perfmon.h
new file mode 100644
index 000000000..9a081a1bc
--- /dev/null
+++ b/drivers/dma/idxd/perfmon.h
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright(c) 2020 Intel Corporation. All rights rsvd. */
+
+#ifndef _PERFMON_H_
+#define _PERFMON_H_
+
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/sbitmap.h>
+#include <linux/dmaengine.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/wait.h>
+#include <linux/cdev.h>
+#include <linux/uuid.h>
+#include <linux/idxd.h>
+#include <linux/perf_event.h>
+#include "registers.h"
+
+static inline struct idxd_pmu *event_to_pmu(struct perf_event *event)
+{
+	struct idxd_pmu *idxd_pmu;
+	struct pmu *pmu;
+
+	pmu = event->pmu;
+	idxd_pmu = container_of(pmu, struct idxd_pmu, pmu);
+
+	return idxd_pmu;
+}
+
+static inline struct idxd_device *event_to_idxd(struct perf_event *event)
+{
+	struct idxd_pmu *idxd_pmu;
+	struct pmu *pmu;
+
+	pmu = event->pmu;
+	idxd_pmu = container_of(pmu, struct idxd_pmu, pmu);
+
+	return idxd_pmu->idxd;
+}
+
+static inline struct idxd_device *pmu_to_idxd(struct pmu *pmu)
+{
+	struct idxd_pmu *idxd_pmu;
+
+	idxd_pmu = container_of(pmu, struct idxd_pmu, pmu);
+
+	return idxd_pmu->idxd;
+}
+
+enum dsa_perf_events {
+	DSA_PERF_EVENT_WQ = 0,
+	DSA_PERF_EVENT_ENGINE,
+	DSA_PERF_EVENT_ADDR_TRANS,
+	DSA_PERF_EVENT_OP,
+	DSA_PERF_EVENT_COMPL,
+	DSA_PERF_EVENT_MAX,
+};
+
+enum filter_enc {
+	FLT_WQ = 0,
+	FLT_TC,
+	FLT_PG_SZ,
+	FLT_XFER_SZ,
+	FLT_ENG,
+	FLT_MAX,
+};
+
+#define CONFIG_RESET		0x0000000000000001
+#define CNTR_RESET		0x0000000000000002
+#define CNTR_ENABLE		0x0000000000000001
+#define INTR_OVFL		0x0000000000000002
+
+#define COUNTER_FREEZE		0x00000000FFFFFFFF
+#define COUNTER_UNFREEZE	0x0000000000000000
+#define OVERFLOW_SIZE		32
+
+#define CNTRCFG_ENABLE		BIT(0)
+#define CNTRCFG_IRQ_OVERFLOW	BIT(1)
+#define CNTRCFG_CATEGORY_SHIFT	8
+#define CNTRCFG_EVENT_SHIFT	32
+
+#define PERFMON_TABLE_OFFSET(_idxd)				\
+({								\
+	typeof(_idxd) __idxd = (_idxd);				\
+	((__idxd)->reg_base + (__idxd)->perfmon_offset);	\
+})
+#define PERFMON_REG_OFFSET(idxd, offset)			\
+	(PERFMON_TABLE_OFFSET(idxd) + (offset))
+
+#define PERFCAP_REG(idxd)	(PERFMON_REG_OFFSET(idxd, IDXD_PERFCAP_OFFSET))
+#define PERFRST_REG(idxd)	(PERFMON_REG_OFFSET(idxd, IDXD_PERFRST_OFFSET))
+#define OVFSTATUS_REG(idxd)	(PERFMON_REG_OFFSET(idxd, IDXD_OVFSTATUS_OFFSET))
+#define PERFFRZ_REG(idxd)	(PERFMON_REG_OFFSET(idxd, IDXD_PERFFRZ_OFFSET))
+
+#define FLTCFG_REG(idxd, cntr, flt)				\
+	(PERFMON_REG_OFFSET(idxd, IDXD_FLTCFG_OFFSET) +	((cntr) * 32) + ((flt) * 4))
+
+#define CNTRCFG_REG(idxd, cntr)					\
+	(PERFMON_REG_OFFSET(idxd, IDXD_CNTRCFG_OFFSET) + ((cntr) * 8))
+#define CNTRDATA_REG(idxd, cntr)					\
+	(PERFMON_REG_OFFSET(idxd, IDXD_CNTRDATA_OFFSET) + ((cntr) * 8))
+#define CNTRCAP_REG(idxd, cntr)					\
+	(PERFMON_REG_OFFSET(idxd, IDXD_CNTRCAP_OFFSET) + ((cntr) * 8))
+
+#define EVNTCAP_REG(idxd, category) \
+	(PERFMON_REG_OFFSET(idxd, IDXD_EVNTCAP_OFFSET) + ((category) * 8))
+
+#define DEFINE_PERFMON_FORMAT_ATTR(_name, _format)			\
+static ssize_t __perfmon_idxd_##_name##_show(struct kobject *kobj,	\
+				struct kobj_attribute *attr,		\
+				char *page)				\
+{									\
+	BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE);			\
+	return sprintf(page, _format "\n");				\
+}									\
+static struct kobj_attribute format_attr_idxd_##_name =			\
+	__ATTR(_name, 0444, __perfmon_idxd_##_name##_show, NULL)
+
+#endif