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, 57 insertions, 0 deletions

diff --git a/arch/arm/tools/Makefile b/arch/arm/tools/Makefile
new file mode 100644
index 000000000..28b6da8ac
--- /dev/null
+++ b/arch/arm/tools/Makefile
@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# linux/arch/arm/tools/Makefile
+#
+# Copyright (C) 2001 Russell King
+#
+
+gen := arch/$(ARCH)/include/generated
+kapi := $(gen)/asm
+uapi := $(gen)/uapi/asm
+syshdr := $(srctree)/scripts/syscallhdr.sh
+sysnr := $(src)/syscallnr.sh
+systbl := $(srctree)/scripts/syscalltbl.sh
+syscall := $(src)/syscall.tbl
+
+gen-y := $(gen)/calls-oabi.S
+gen-y += $(gen)/calls-eabi.S
+kapi-hdrs-y := $(kapi)/unistd-nr.h
+kapi-hdrs-y += $(kapi)/mach-types.h
+uapi-hdrs-y += $(uapi)/unistd-oabi.h
+uapi-hdrs-y += $(uapi)/unistd-eabi.h
+
+targets += $(addprefix ../../../,$(gen-y) $(kapi-hdrs-y) $(uapi-hdrs-y))
+
+PHONY += kapi uapi
+
+kapi:	$(kapi-hdrs-y) $(gen-y)
+
+uapi:	$(uapi-hdrs-y)
+
+# Create output directory if not already present
+$(shell mkdir -p $(kapi) $(uapi))
+
+quiet_cmd_gen_mach = GEN     $@
+      cmd_gen_mach = $(AWK) -f $(real-prereqs) > $@
+
+$(kapi)/mach-types.h: $(src)/gen-mach-types $(src)/mach-types FORCE
+	$(call if_changed,gen_mach)
+
+quiet_cmd_syshdr = SYSHDR  $@
+      cmd_syshdr = $(CONFIG_SHELL) $(syshdr) --abis common,$* \
+		   --offset __NR_SYSCALL_BASE $< $@
+
+quiet_cmd_systbl = SYSTBL  $@
+      cmd_systbl = $(CONFIG_SHELL) $(systbl) --abis common,$* $< $@
+
+quiet_cmd_sysnr  = SYSNR   $@
+      cmd_sysnr  = $(CONFIG_SHELL) $(sysnr) $< $@
+
+$(uapi)/unistd-%.h: $(syscall) $(syshdr) FORCE
+	$(call if_changed,syshdr)
+
+$(kapi)/unistd-nr.h: $(syscall) $(sysnr) FORCE
+	$(call if_changed,sysnr)
+
+$(gen)/calls-%.S: $(syscall) $(systbl) FORCE
+	$(call if_changed,systbl)