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/udivsi3.S | 85 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 arch/microblaze/lib/udivsi3.S (limited to 'arch/microblaze/lib/udivsi3.S') diff --git a/arch/microblaze/lib/udivsi3.S b/arch/microblaze/lib/udivsi3.S new file mode 100644 index 000000000..acdc66723 --- /dev/null +++ b/arch/microblaze/lib/udivsi3.S @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include + +/* +* Unsigned divide operation. +* Input : Divisor in Reg r5 +* Dividend in Reg r6 +* Output: Result in Reg r3 +*/ + + .text + .globl __udivsi3 + .type __udivsi3, @function + .ent __udivsi3 + +__udivsi3: + + .frame r1, 0, r15 + + addik r1, r1, -12 + swi r29, r1, 0 + swi r30, r1, 4 + swi r31, r1, 8 + + beqi r6, div_by_zero /* div_by_zero /* division error */ + beqid r5, result_is_zero /* result is zero */ + addik r30, r0, 0 /* clear mod */ + addik r29, r0, 32 /* initialize the loop count */ + +/* check if r6 and r5 are equal - if yes, return 1 */ + rsub r18, r5, r6 + beqid r18, return_here + addik r3, r0, 1 + +/* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */ + xor r18, r5, r6 + bgeid r18, 16 + add r3, r0, r0 /* we would anyways clear r3 */ + blti r6, return_here /* r6[bit 31 = 1] hence is greater */ + bri checkr6 + rsub r18, r6, r5 /* microblazecmp */ + blti r18, return_here + +/* if r6 [bit 31] is set, then return result as 1 */ +checkr6: + bgti r6, div0 + brid return_here + addik r3, r0, 1 + +/* first part try to find the first '1' in the r5 */ +div0: + blti r5, div2 +div1: + add r5, r5, r5 /* left shift logical r5 */ + bgtid r5, div1 + addik r29, r29, -1 +div2: +/* left shift logical r5 get the '1' into the carry */ + add r5, r5, r5 + addc r30, r30, r30 /* move that bit into the mod register */ + rsub r31, r6, r30 /* try to subtract (r30 a r6) */ + blti r31, mod_too_small +/* move the r31 to mod since the result was positive */ + or r30, r0, r31 + addik r3, r3, 1 +mod_too_small: + addik r29, r29, -1 + beqi r29, loop_end + add r3, r3, r3 /* shift in the '1' into div */ + bri div2 /* div2 */ +loop_end: + bri return_here +div_by_zero: +result_is_zero: + or r3, r0, r0 /* set result to 0 */ +return_here: +/* restore values of csrs and that of r3 and the divisor and the dividend */ + lwi r29, r1, 0 + lwi r30, r1, 4 + lwi r31, r1, 8 + rtsd r15, 8 + addik r1, r1, 12 + +.size __udivsi3, . - __udivsi3 +.end __udivsi3 -- cgit v1.3.1