On 7/27/21 12:53 AM, Andrii Nakryiko wrote:
On Mon, Jul 26, 2021 at 1:18 AM Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx> wrote:Greetings, During my work with the 32-bit MIPS JIT implementation I also added a number of new test cases in the test_bpf kernel module. I found it valuable to be able to throughly test the JIT on a low level with minimum dependency on user space tooling. If you think it would be useful, I have prepared a patch set with my additions. I have verified it on x86_64 and i386, with/without JIT and JIT hardening. The interpreter passes all tests. The JITs do too, with one exception, see NOTE below. The result for the x86_64 JIT is summarized below. test_bpf: Summary: 577 PASSED, 0 FAILED, [565/565 JIT'ed] test_bpf: test_tail_calls: Summary: 6 PASSED, 1 FAILED, [7/7 JIT'ed] I have inserted the new tests in the location where related tests are run, rather than putting them at the end. I have also tried to use the same description style as the surrounding tests. Below is a summary of the new tests. * Operations not previously covered JMP32, ALU32 ARSH, remaining ATOMIC operations including XCHG and CMPXCHG. * ALU operations with edge cases 32-bit JITs implement ALU64 operations with two 32-bit registers per operand. Even "trivial" operations like bit shifts are non-trivial to implement. Test different input values that may trigger different JIT code paths. JITs may also implement BPF_K operations differently depending on if the immediate fits the corresponding field width of the native CPU instruction or not, so test that too. * Word order in load/store The word order should follow endianness. Test that DW load/store operations result in the expected word order in memory. * 32-bit eBPF argument zero extension On a 32-bit JIT the eBPF argument is a 32-bit pointer. If passed in a CPU register only one register in the mapped pair contains valid data. Verify that value is properly zero-extended. * Long conditional jumps Test to trigger the relative-to-absolute branch conversion in MIPS JITs, when the PC-relative offset overflows the field width of the MIPS branch instruction. * Tail calls A new test suite to test tail calls. Also test error paths and TCC limit. NOTE: There is a minor discrepancy between the interpreter and the (x86) JITs. With MAX_TAIL_CALL_CNT = 32, the interpreter seems to allow up to 33 tail calls, whereas the JITs stop at 32. This causes the max TCCGiven the intended case was to allow 32, let's fix up the interpreter to be in line with JITs?
Yes, lets fix up the interpreter. Could you send a fix for the latter, Johan, along with this series? Big thanks for adding all the new tests by the way!
test to fail for the JITs, since I used the interpreter as reference. Either we change the interpreter behavior, change the JITs, or relax the test to allow both behaviors. Let me know what you think. Cheers, Johan Johan Almbladh (14): bpf/tests: add BPF_JMP32 test cases bpf/tests: add BPF_MOV tests for zero and sign extension bpf/tests: fix typos in test case descriptions bpf/tests: add more tests of ALU32 and ALU64 bitwise operations bpf/tests: add more ALU32 tests for BPF_LSH/RSH/ARSH bpf/tests: add more BPF_LSH/RSH/ARSH tests for ALU64 bpf/tests: add more ALU64 BPF_MUL tests bpf/tests: add tests for ALU operations implemented with function calls bpf/tests: add word-order tests for load/store of double words bpf/tests: add branch conversion JIT test bpf/tests: add test for 32-bit context pointer argument passing bpf/tests: add tests for atomic operations bpf/tests: add tests for BPF_CMPXCHG bpf/tests: add tail call test suite lib/test_bpf.c | 2732 +++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 2475 insertions(+), 257 deletions(-) -- 2.25.1
