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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/riscv/lib/tishift.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/riscv/lib/tishift.S')
| -rw-r--r-- | arch/riscv/lib/tishift.S | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/arch/riscv/lib/tishift.S b/arch/riscv/lib/tishift.S new file mode 100644 index 000000000..c8294bf72 --- /dev/null +++ b/arch/riscv/lib/tishift.S @@ -0,0 +1,76 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2018 Free Software Foundation, Inc. + */ + +#include <linux/linkage.h> +#include <linux/export.h> + +SYM_FUNC_START(__lshrti3) + beqz a2, .L1 + li a5,64 + sub a5,a5,a2 + sext.w a4,a5 + blez a5, .L2 + sext.w a2,a2 + srl a0,a0,a2 + sll a4,a1,a4 + srl a2,a1,a2 + or a0,a0,a4 + mv a1,a2 +.L1: + ret +.L2: + negw a0,a4 + li a2,0 + srl a0,a1,a0 + mv a1,a2 + ret +SYM_FUNC_END(__lshrti3) +EXPORT_SYMBOL(__lshrti3) + +SYM_FUNC_START(__ashrti3) + beqz a2, .L3 + li a5,64 + sub a5,a5,a2 + sext.w a4,a5 + blez a5, .L4 + sext.w a2,a2 + srl a0,a0,a2 + sll a4,a1,a4 + sra a2,a1,a2 + or a0,a0,a4 + mv a1,a2 +.L3: + ret +.L4: + negw a0,a4 + srai a2,a1,0x3f + sra a0,a1,a0 + mv a1,a2 + ret +SYM_FUNC_END(__ashrti3) +EXPORT_SYMBOL(__ashrti3) + +SYM_FUNC_START(__ashlti3) + beqz a2, .L5 + li a5,64 + sub a5,a5,a2 + sext.w a4,a5 + blez a5, .L6 + sext.w a2,a2 + sll a1,a1,a2 + srl a4,a0,a4 + sll a2,a0,a2 + or a1,a1,a4 + mv a0,a2 +.L5: + ret +.L6: + negw a1,a4 + li a2,0 + sll a1,a0,a1 + mv a0,a2 + ret +SYM_FUNC_END(__ashlti3) +EXPORT_SYMBOL(__ashlti3) |