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, 19 insertions, 0 deletions

diff --git a/arch/arm/nwfpe/Makefile b/arch/arm/nwfpe/Makefile
new file mode 100644
index 000000000..2aec85ab1
--- /dev/null
+++ b/arch/arm/nwfpe/Makefile
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 1998, 1999, 2001 Philip Blundell
+#
+
+obj-$(CONFIG_FPE_NWFPE)		+= nwfpe.o
+
+nwfpe-y				+= fpa11.o fpa11_cpdo.o fpa11_cpdt.o \
+				   fpa11_cprt.o fpmodule.o fpopcode.o \
+				   softfloat.o single_cpdo.o double_cpdo.o \
+				   entry.o
+
+nwfpe-$(CONFIG_FPE_NWFPE_XP)	+= extended_cpdo.o
+
+# Try really hard to avoid generating calls to __aeabi_uldivmod() from
+# float64_rem() due to loop elision.
+ifdef CONFIG_CC_IS_CLANG
+CFLAGS_softfloat.o	+= -mllvm -replexitval=never
+endif