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, 51 insertions, 0 deletions

diff --git a/arch/arm/nwfpe/fpopcode.c b/arch/arm/nwfpe/fpopcode.c
new file mode 100644
index 000000000..c680bf1bb
--- /dev/null
+++ b/arch/arm/nwfpe/fpopcode.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+    NetWinder Floating Point Emulator
+    (c) Rebel.COM, 1998,1999
+
+    Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
+
+*/
+
+#include "fpa11.h"
+#include "softfloat.h"
+#include "fpopcode.h"
+#include "fpsr.h"
+#include "fpmodule.h"
+#include "fpmodule.inl"
+
+#ifdef CONFIG_FPE_NWFPE_XP
+const floatx80 floatx80Constant[] = {
+	{ .high = 0x0000, .low = 0x0000000000000000ULL},/* extended 0.0 */
+	{ .high = 0x3fff, .low = 0x8000000000000000ULL},/* extended 1.0 */
+	{ .high = 0x4000, .low = 0x8000000000000000ULL},/* extended 2.0 */
+	{ .high = 0x4000, .low = 0xc000000000000000ULL},/* extended 3.0 */
+	{ .high = 0x4001, .low = 0x8000000000000000ULL},/* extended 4.0 */
+	{ .high = 0x4001, .low = 0xa000000000000000ULL},/* extended 5.0 */
+	{ .high = 0x3ffe, .low = 0x8000000000000000ULL},/* extended 0.5 */
+	{ .high = 0x4002, .low = 0xa000000000000000ULL},/* extended 10.0 */
+};
+#endif
+
+const float64 float64Constant[] = {
+	0x0000000000000000ULL,	/* double 0.0 */
+	0x3ff0000000000000ULL,	/* double 1.0 */
+	0x4000000000000000ULL,	/* double 2.0 */
+	0x4008000000000000ULL,	/* double 3.0 */
+	0x4010000000000000ULL,	/* double 4.0 */
+	0x4014000000000000ULL,	/* double 5.0 */
+	0x3fe0000000000000ULL,	/* double 0.5 */
+	0x4024000000000000ULL	/* double 10.0 */
+};
+
+const float32 float32Constant[] = {
+	0x00000000,		/* single 0.0 */
+	0x3f800000,		/* single 1.0 */
+	0x40000000,		/* single 2.0 */
+	0x40400000,		/* single 3.0 */
+	0x40800000,		/* single 4.0 */
+	0x40a00000,		/* single 5.0 */
+	0x3f000000,		/* single 0.5 */
+	0x41200000		/* single 10.0 */
+};
+