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, 88 insertions, 0 deletions

diff --git a/drivers/soc/ti/pruss.h b/drivers/soc/ti/pruss.h
new file mode 100644
index 000000000..6c55987e0
--- /dev/null
+++ b/drivers/soc/ti/pruss.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * PRU-ICSS Subsystem user interfaces
+ *
+ * Copyright (C) 2015-2023 Texas Instruments Incorporated - http://www.ti.com
+ *	MD Danish Anwar <danishanwar@ti.com>
+ */
+
+#ifndef _SOC_TI_PRUSS_H_
+#define _SOC_TI_PRUSS_H_
+
+#include <linux/bits.h>
+#include <linux/regmap.h>
+
+/*
+ * PRU_ICSS_CFG registers
+ * SYSCFG, ISRP, ISP, IESP, IECP, SCRP applicable on AMxxxx devices only
+ */
+#define PRUSS_CFG_REVID         0x00
+#define PRUSS_CFG_SYSCFG        0x04
+#define PRUSS_CFG_GPCFG(x)      (0x08 + (x) * 4)
+#define PRUSS_CFG_CGR           0x10
+#define PRUSS_CFG_ISRP          0x14
+#define PRUSS_CFG_ISP           0x18
+#define PRUSS_CFG_IESP          0x1C
+#define PRUSS_CFG_IECP          0x20
+#define PRUSS_CFG_SCRP          0x24
+#define PRUSS_CFG_PMAO          0x28
+#define PRUSS_CFG_MII_RT        0x2C
+#define PRUSS_CFG_IEPCLK        0x30
+#define PRUSS_CFG_SPP           0x34
+#define PRUSS_CFG_PIN_MX        0x40
+
+/* PRUSS_GPCFG register bits */
+#define PRUSS_GPCFG_PRU_GPI_MODE_MASK           GENMASK(1, 0)
+#define PRUSS_GPCFG_PRU_GPI_MODE_SHIFT          0
+
+#define PRUSS_GPCFG_PRU_MUX_SEL_SHIFT           26
+#define PRUSS_GPCFG_PRU_MUX_SEL_MASK            GENMASK(29, 26)
+
+/* PRUSS_MII_RT register bits */
+#define PRUSS_MII_RT_EVENT_EN                   BIT(0)
+
+/* PRUSS_SPP register bits */
+#define PRUSS_SPP_XFER_SHIFT_EN                 BIT(1)
+#define PRUSS_SPP_PRU1_PAD_HP_EN                BIT(0)
+#define PRUSS_SPP_RTU_XFR_SHIFT_EN              BIT(3)
+
+/**
+ * pruss_cfg_read() - read a PRUSS CFG sub-module register
+ * @pruss: the pruss instance handle
+ * @reg: register offset within the CFG sub-module
+ * @val: pointer to return the value in
+ *
+ * Reads a given register within the PRUSS CFG sub-module and
+ * returns it through the passed-in @val pointer
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+static int pruss_cfg_read(struct pruss *pruss, unsigned int reg, unsigned int *val)
+{
+	if (IS_ERR_OR_NULL(pruss))
+		return -EINVAL;
+
+	return regmap_read(pruss->cfg_regmap, reg, val);
+}
+
+/**
+ * pruss_cfg_update() - configure a PRUSS CFG sub-module register
+ * @pruss: the pruss instance handle
+ * @reg: register offset within the CFG sub-module
+ * @mask: bit mask to use for programming the @val
+ * @val: value to write
+ *
+ * Programs a given register within the PRUSS CFG sub-module
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+static int pruss_cfg_update(struct pruss *pruss, unsigned int reg,
+			    unsigned int mask, unsigned int val)
+{
+	if (IS_ERR_OR_NULL(pruss))
+		return -EINVAL;
+
+	return regmap_update_bits(pruss->cfg_regmap, reg, mask, val);
+}
+
+#endif  /* _SOC_TI_PRUSS_H_ */