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, 61 insertions, 0 deletions

diff --git a/arch/arm/mach-davinci/clock.h b/arch/arm/mach-davinci/clock.h
new file mode 100644
index 000000000..54f5663b0
--- /dev/null
+++ b/arch/arm/mach-davinci/clock.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * TI DaVinci clock definitions
+ *
+ * Copyright (C) 2006-2007 Texas Instruments.
+ * Copyright (C) 2008-2009 Deep Root Systems, LLC
+ */
+
+#ifndef __ARCH_ARM_DAVINCI_CLOCK_H
+#define __ARCH_ARM_DAVINCI_CLOCK_H
+
+/* PLL/Reset register offsets */
+#define PLLCTL          0x100
+#define PLLCTL_PLLEN    BIT(0)
+#define PLLCTL_PLLPWRDN	BIT(1)
+#define PLLCTL_PLLRST	BIT(3)
+#define PLLCTL_PLLDIS	BIT(4)
+#define PLLCTL_PLLENSRC	BIT(5)
+#define PLLCTL_CLKMODE  BIT(8)
+
+#define PLLM		0x110
+#define PLLM_PLLM_MASK  0xff
+
+#define PREDIV          0x114
+#define PLLDIV1         0x118
+#define PLLDIV2         0x11c
+#define PLLDIV3         0x120
+#define POSTDIV         0x128
+#define BPDIV           0x12c
+#define PLLCMD		0x138
+#define PLLSTAT		0x13c
+#define PLLALNCTL	0x140
+#define PLLDCHANGE	0x144
+#define PLLCKEN		0x148
+#define PLLCKSTAT	0x14c
+#define PLLSYSTAT	0x150
+#define PLLDIV4         0x160
+#define PLLDIV5         0x164
+#define PLLDIV6         0x168
+#define PLLDIV7         0x16c
+#define PLLDIV8         0x170
+#define PLLDIV9         0x174
+#define PLLDIV_EN       BIT(15)
+#define PLLDIV_RATIO_MASK 0x1f
+
+/*
+ * OMAP-L138 system reference guide recommends a wait for 4 OSCIN/CLKIN
+ * cycles to ensure that the PLLC has switched to bypass mode. Delay of 1us
+ * ensures we are good for all > 4MHz OSCIN/CLKIN inputs. Typically the input
+ * is ~25MHz. Units are micro seconds.
+ */
+#define PLL_BYPASS_TIME		1
+/* From OMAP-L138 datasheet table 6-4. Units are micro seconds */
+#define PLL_RESET_TIME		1
+/*
+ * From OMAP-L138 datasheet table 6-4; assuming prediv = 1, sqrt(pllm) = 4
+ * Units are micro seconds.
+ */
+#define PLL_LOCK_TIME		20
+
+#endif