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, 26 insertions, 0 deletions

diff --git a/arch/powerpc/boot/4xx.h b/arch/powerpc/boot/4xx.h
new file mode 100644
index 000000000..62df496b7
--- /dev/null
+++ b/arch/powerpc/boot/4xx.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PowerPC 4xx related functions
+ *
+ * Copyright 2007 IBM Corporation.
+ * Josh Boyer <jwboyer@linux.vnet.ibm.com>
+ */
+#ifndef _POWERPC_BOOT_4XX_H_
+#define _POWERPC_BOOT_4XX_H_
+
+void ibm4xx_sdram_fixup_memsize(void);
+void ibm440spe_fixup_memsize(void);
+void ibm4xx_denali_fixup_memsize(void);
+void ibm44x_dbcr_reset(void);
+void ibm4xx_quiesce_eth(u32 *emac0, u32 *emac1);
+void ibm4xx_fixup_ebc_ranges(const char *ebc);
+
+void ibm440gp_fixup_clocks(unsigned int sys_clk, unsigned int ser_clk);
+void ibm440ep_fixup_clocks(unsigned int sys_clk, unsigned int ser_clk,
+			   unsigned int tmr_clk);
+void ibm440gx_fixup_clocks(unsigned int sys_clk, unsigned int ser_clk,
+			   unsigned int tmr_clk);
+void ibm440spe_fixup_clocks(unsigned int sys_clk, unsigned int ser_clk,
+			    unsigned int tmr_clk);
+
+#endif /* _POWERPC_BOOT_4XX_H_ */