From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- arch/powerpc/boot/reg.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 arch/powerpc/boot/reg.h (limited to 'arch/powerpc/boot/reg.h') diff --git a/arch/powerpc/boot/reg.h b/arch/powerpc/boot/reg.h new file mode 100644 index 000000000..fd8f4fcbf --- /dev/null +++ b/arch/powerpc/boot/reg.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _PPC_BOOT_REG_H +#define _PPC_BOOT_REG_H +/* + * Copyright 2007 Davud Gibson, IBM Corporation. + */ + +static inline u32 mfpvr(void) +{ + u32 pvr; + asm volatile ("mfpvr %0" : "=r"(pvr)); + return pvr; +} + +#define __stringify_1(x) #x +#define __stringify(x) __stringify_1(x) + +#define mfspr(rn) ({unsigned long rval; \ + asm volatile("mfspr %0," __stringify(rn) \ + : "=r" (rval)); rval; }) +#define mtspr(rn, v) asm volatile("mtspr " __stringify(rn) ",%0" : : "r" (v)) + +register void *__stack_pointer asm("r1"); +#define get_sp() (__stack_pointer) + +#endif /* _PPC_BOOT_REG_H */ -- cgit v1.3.1