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| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-09-04 10:43:19 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-04 07:58:36 -0700 |
| commit | 6668ed271eaefaa63e686bdfbedaeb7b8e492722 (patch) | |
| tree | 58e8288fead484f6755ad0815fc74c3742663761 /arch/powerpc/lib/quad.S | |
| download | linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.tar.gz linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.zip | |
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>
Diffstat (limited to 'arch/powerpc/lib/quad.S')
| -rw-r--r-- | arch/powerpc/lib/quad.S | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/powerpc/lib/quad.S b/arch/powerpc/lib/quad.S new file mode 100644 index 000000000..da71760e5 --- /dev/null +++ b/arch/powerpc/lib/quad.S @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Quadword loads and stores + * for use in instruction emulation. + * + * Copyright 2017 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> + */ + +#include <asm/processor.h> +#include <asm/ppc_asm.h> +#include <asm/ppc-opcode.h> +#include <asm/reg.h> +#include <asm/asm-offsets.h> +#include <linux/errno.h> + +/* do_lq(unsigned long ea, unsigned long *regs) */ +_GLOBAL(do_lq) +1: lq r6, 0(r3) + std r6, 0(r4) + std r7, 8(r4) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_stq(unsigned long ea, unsigned long val0, unsigned long val1) */ +_GLOBAL(do_stq) +1: stq r4, 0(r3) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_lqarx(unsigned long ea, unsigned long *regs) */ +_GLOBAL(do_lqarx) +1: PPC_LQARX(6, 0, 3, 0) + std r6, 0(r4) + std r7, 8(r4) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_stqcx(unsigned long ea, unsigned long val0, unsigned long val1, + unsigned int *crp) */ + +_GLOBAL(do_stqcx) +1: PPC_STQCX(4, 0, 3) + mfcr r5 + stw r5, 0(r6) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) |