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/arc/lib/strcpy-700.S | 67 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/arc/lib/strcpy-700.S (limited to 'arch/arc/lib/strcpy-700.S') diff --git a/arch/arc/lib/strcpy-700.S b/arch/arc/lib/strcpy-700.S new file mode 100644 index 000000000..6e2294d13 --- /dev/null +++ b/arch/arc/lib/strcpy-700.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +/* If dst and src are 4 byte aligned, copy 8 bytes at a time. + If the src is 4, but not 8 byte aligned, we first read 4 bytes to get + it 8 byte aligned. Thus, we can do a little read-ahead, without + dereferencing a cache line that we should not touch. + Note that short and long instructions have been scheduled to avoid + branch stalls. + The beq_s to r3z could be made unaligned & long to avoid a stall + there, but the it is not likely to be taken often, and it + would also be likey to cost an unaligned mispredict at the next call. */ + +#include + +ENTRY_CFI(strcpy) + or r2,r0,r1 + bmsk_s r2,r2,1 + brne.d r2,0,charloop + mov_s r10,r0 + ld_s r3,[r1,0] + mov r8,0x01010101 + bbit0.d r1,2,loop_start + ror r12,r8 + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne r3z + mov_s r4,r3 + .balign 4 +loop: + ld.a r3,[r1,4] + st.ab r4,[r10,4] +loop_start: + ld.a r4,[r1,4] + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne_s r3z + st.ab r3,[r10,4] + sub r2,r4,r8 + bic r2,r2,r4 + tst r2,r12 + beq loop + mov_s r3,r4 +#ifdef __LITTLE_ENDIAN__ +r3z: bmsk.f r1,r3,7 + lsr_s r3,r3,8 +#else +r3z: lsr.f r1,r3,24 + asl_s r3,r3,8 +#endif + bne.d r3z + stb.ab r1,[r10,1] + j_s [blink] + + .balign 4 +charloop: + ldb.ab r3,[r1,1] + + + brne.d r3,0,charloop + stb.ab r3,[r10,1] + j [blink] +END_CFI(strcpy) -- cgit v1.3.1