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, 22 insertions, 0 deletions

diff --git a/arch/powerpc/Kbuild b/arch/powerpc/Kbuild
new file mode 100644
index 000000000..b010ccb07
--- /dev/null
+++ b/arch/powerpc/Kbuild
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror -Wa,--fatal-warnings
+subdir-asflags-$(CONFIG_PPC_WERROR) := -Wa,--fatal-warnings
+
+obj-y += kernel/
+obj-y += mm/
+obj-y += lib/
+obj-y += sysdev/
+obj-y += platforms/
+obj-y += math-emu/
+obj-y += crypto/
+obj-y += net/
+
+obj-$(CONFIG_XMON) += xmon/
+obj-$(CONFIG_KVM)  += kvm/
+
+obj-$(CONFIG_PERF_EVENTS) += perf/
+obj-$(CONFIG_KEXEC_CORE)  += kexec/
+obj-$(CONFIG_KEXEC_FILE)  += purgatory/
+
+# for cleaning
+subdir- += boot tools