On 7/16/23 6:39 PM, Eduard Zingerman wrote:
On Wed, 2023-07-12 at 23:07 -0700, Yonghong Song wrote:
In previous discussion ([1]), it is agreed that we should introduce
cpu version 4 (llvm flag -mcpu=v4) which contains some instructions
which can simplify code, make code easier to understand, fix the
existing problem, or simply for feature completeness. More specifically,
the following new insns are proposed:
. sign extended load
. sign extended mov
. bswap
. signed div/mod
. ja with 32-bit offset
This patch set added kernel support for insns proposed in [1] except
BPF_ST which already has full kernel support. Beside the above proposed
insns, LLVM will generate BPF_ST insn as well under -mcpu=v4 ([2]).
The patchset implements interpreter and jit support for these new
insns as well as necessary verifier support.
Hi Yonghong,
Sorry for delayed response, I'm still in the middle of the series.
I've tested this patch-set using updated LLVM version and have
a few notes:
- kernel/bpf/disasm.c needs an update to handle new instructions;
Thanks for pointing this out. My bad. I have disasm.c patch in
RFCv1, but somehow during cherry-pick process, I missed it in v2.
Will add it back to next revision.
- test_verifier test 'invalid 64-bit BPF_END' from basic_instr.c
is failing because '.code = BPF_ALU64 | BPF_END | BPF_TO_LE'
is now valid;
I didn't run 'test_verifier'. Thanks for pointing it out.
Will run it and fix the problem in the next revision.
- I've looked through the usage of BPF_LDX and found that there
is a function seccomp.c:seccomp_check_filter(), that directly
checks possible CLASS / CODE combinations. Should this function
be updated to handle new instructions?
Thanks,
Eduard
To test this patch set, you need to have latest llvm from 'main' branch
of llvm-project repo and apply [2] on top of it.
[1] https://lore.kernel.org/bpf/4bfe98be-5333-1c7e-2f6d-42486c8ec039@xxxxxxxx/
[2] https://reviews.llvm.org/D144829
Changelogs:
RFCv1 -> v2:
. add more verifier supports for signed extend load and mov insns.
. rename some insn names to be more consistent with intel practice.
. add cpuv4 test runner for test progs.
. add more unit and C tests.
. add documentation.
Yonghong Song (15):
bpf: Support new sign-extension load insns
bpf: Fix sign-extension ctx member accesses
bpf: Support new sign-extension mov insns
bpf: Support new unconditional bswap instruction
bpf: Support new signed div/mod instructions.
bpf: Fix jit blinding with new sdiv/smov insns
bpf: Support new 32bit offset jmp instruction
selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing
selftests/bpf: Add unit tests for new sign-extension load insns
selftests/bpf: Add unit tests for new sign-extension mov insns
selftests/bpf: Add unit tests for new bswap insns
selftests/bpf: Add unit tests for new sdiv/smod insns
selftests/bpf: Add unit tests for new gotol insn
selftests/bpf: Test ldsx with more complex cases
docs/bpf: Add documentation for new instructions
Documentation/bpf/bpf_design_QA.rst | 5 -
.../bpf/standardization/instruction-set.rst | 100 ++-
arch/x86/net/bpf_jit_comp.c | 131 ++-
include/linux/filter.h | 14 +-
include/uapi/linux/bpf.h | 1 +
kernel/bpf/cgroup.c | 14 +-
kernel/bpf/core.c | 174 +++-
kernel/bpf/verifier.c | 315 ++++++--
tools/include/uapi/linux/bpf.h | 1 +
tools/testing/selftests/bpf/.gitignore | 2 +
tools/testing/selftests/bpf/Makefile | 18 +-
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 9 +-
.../selftests/bpf/prog_tests/test_ldsx_insn.c | 88 ++
.../selftests/bpf/prog_tests/verifier.c | 10 +
.../selftests/bpf/progs/test_ldsx_insn.c | 75 ++
.../selftests/bpf/progs/verifier_bswap.c | 45 ++
.../selftests/bpf/progs/verifier_gotol.c | 30 +
.../selftests/bpf/progs/verifier_ldsx.c | 115 +++
.../selftests/bpf/progs/verifier_movsx.c | 177 ++++
.../selftests/bpf/progs/verifier_sdiv.c | 763 ++++++++++++++++++
20 files changed, 1929 insertions(+), 158 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_ldsx_insn.c
create mode 100644 tools/testing/selftests/bpf/progs/test_ldsx_insn.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_bswap.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_gotol.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_ldsx.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_movsx.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_sdiv.c
