From: George Guo <[email protected]>
This series adds three LoongArch BPF JIT features, plus the accompanying
selftest changes:
1. Gate the arena instructions the JIT does not implement (atomics and
sign-extending loads on arena pointers) via bpf_jit_supports_insn(),
so the verifier rejects such programs early with a clear message
instead of letting them fail late in the JIT.
2. Per-program private stack (bpf_jit_supports_private_stack()): the BPF
stack of deep/recursive tracing programs is moved off the kernel
stack into a per-CPU allocation bracketed by overflow/underflow
guards that are checked on teardown.
3. Exceptions / bpf_throw (bpf_jit_supports_exceptions()): unwind to the
exception boundary program via arch_bpf_stack_walk() (built on the
ORC unwinder) and reuse its frame in the exception callback. Gated on
CONFIG_UNWINDER_ORC.
Patches 4-5 are the selftests side: a LoongArch deny list (arena_atomics,
which patch 1 deliberately rejects) and enabling the struct_ops private
stack test on LoongArch. They touch tools/testing/selftests/bpf, hence the
bpf@vger / linux-kselftest Cc.
The series is independent of the earlier "LoongArch: BPF: Support
internal-only MOV to resolve per-CPU addrs" / "Add timed may_goto support"
patches [1] (no functional or apply dependency) and targets the LoongArch
tree.
Testing on a LoongArch board (test_progs):
- exceptions: 117 subtests, 0 failed
- struct_ops_private_stack: private_stack / _fail / _recur, 0 failed
- arena list/htab/strsearch and verifier_arena*: pass
- arena_atomics: rejected by the verifier as expected
("BPF_ATOMIC stores into Rn arena is not allowed"), hence the
deny-list entry in patch 4
[1] <https://lore.kernel.org/all/[email protected]/>
George Guo (5):
LoongArch: BPF: Gate unsupported arena instructions via
bpf_jit_supports_insn()
LoongArch: BPF: Add private stack support
LoongArch: BPF: Add exceptions (bpf_throw) support
selftests/bpf: Add LoongArch deny list
selftests/bpf: Enable struct_ops private stack test for LoongArch
arch/loongarch/kernel/stacktrace.c | 52 ++++++
arch/loongarch/net/bpf_jit.c | 172 +++++++++++++++++-
arch/loongarch/net/bpf_jit.h | 1 +
.../testing/selftests/bpf/DENYLIST.loongarch | 2 +
.../bpf/prog_tests/struct_ops_private_stack.c | 2 +-
5 files changed, 222 insertions(+), 7 deletions(-)
create mode 100644 tools/testing/selftests/bpf/DENYLIST.loongarch
base-commit: 186d3c4e92242351afc24d9784f31cb4cd08a4b7
--
2.25.1
