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/microblaze/lib/mulsi3.S | 47 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 arch/microblaze/lib/mulsi3.S (limited to 'arch/microblaze/lib/mulsi3.S') diff --git a/arch/microblaze/lib/mulsi3.S b/arch/microblaze/lib/mulsi3.S new file mode 100644 index 000000000..d6703a4d9 --- /dev/null +++ b/arch/microblaze/lib/mulsi3.S @@ -0,0 +1,47 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include + +/* + * Multiply operation for 32 bit integers. + * Input : Operand1 in Reg r5 + * Operand2 in Reg r6 + * Output: Result [op1 * op2] in Reg r3 + */ + .text + .globl __mulsi3 + .type __mulsi3, @function + .ent __mulsi3 + +__mulsi3: + .frame r1, 0, r15 + add r3, r0, r0 + beqi r5, result_is_zero /* multiply by zero */ + beqi r6, result_is_zero /* multiply by zero */ + bgeid r5, r5_pos + xor r4, r5, r6 /* get the sign of the result */ + rsubi r5, r5, 0 /* make r5 positive */ +r5_pos: + bgei r6, r6_pos + rsubi r6, r6, 0 /* make r6 positive */ +r6_pos: + bri l1 +l2: + add r5, r5, r5 +l1: + srl r6, r6 + addc r7, r0, r0 + beqi r7, l2 + bneid r6, l2 + add r3, r3, r5 + blti r4, negateresult + rtsd r15, 8 + nop +negateresult: + rtsd r15, 8 + rsub r3, r3, r0 +result_is_zero: + rtsd r15, 8 + addi r3, r0, 0 + +.size __mulsi3, . - __mulsi3 +.end __mulsi3 -- cgit v1.3.1