Re: [PATCH bpf-next] selftests/bpf: Remove two infinite loop bound check cases

[Xu Kuohai <xukuohai@xxxxxxxxxxxxxxx>]

On 3/27/2023 11:20 AM, Andrii Nakryiko wrote:
> On Sun, Mar 26, 2023 at 7:45 PM Xu Kuohai <xukuohai@xxxxxxxxxxxxxxx> wrote:
> > From: Xu Kuohai <xukuohai@xxxxxxxxxx>
> >
> > The two infinite loop bound check cases added by commit
> > 1a3148fc171f ("selftests/bpf: Check when bounds are not in the 32-bit range")
> > take a long time to execute but don't add much value.
> >
> > Remove them to reduce run time of test_verifier.
>
> Summary: 2042 PASSED, 0 SKIPPED, 1 FAILED
>
> real    0m4.780s
> user    0m0.458s
> sys     0m3.871s
>
>
> 5 seconds isn't such a long time, especially when we compare it to
> test_progs (even with parallelization).

Well, I actually don't know if it is "long time".

This patch was sent to address Alexei's concern about the run time
of test_verifier in mail [1].

[1] https://lore.kernel.org/bpf/20230322213056.2470-1-daniel@xxxxxxxxxxxxx/T/#mb3d6363a693ccd63d416d9d787db17f8fdcb8442

> > Fixes: 1a3148fc171f ("selftests/bpf: Check when bounds are not in the 32-bit range")
> > Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> > ---
> >   tools/testing/selftests/bpf/verifier/bounds.c | 50 -------------------
> >   1 file changed, 50 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/verifier/bounds.c b/tools/testing/selftests/bpf/verifier/bounds.c
> > index 74b1917d4208..515a8222f08f 100644
> > --- a/tools/testing/selftests/bpf/verifier/bounds.c
> > +++ b/tools/testing/selftests/bpf/verifier/bounds.c
> > @@ -777,31 +777,6 @@
> >          .result = ACCEPT,
> >          .prog_type = BPF_PROG_TYPE_XDP,
> >   },
> > -{
> > -       "bound check with JMP_JSLT for crossing 64-bit signed boundary",
> > -       .insns = {
> > -       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, offsetof(struct xdp_md, data)),
> > -       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, offsetof(struct xdp_md, data_end)),
> > -       BPF_MOV64_REG(BPF_REG_1, BPF_REG_2),
> > -       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 1),
> > -       BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_3, 8),
> > -
> > -       BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_2, 0),
> > -       BPF_LD_IMM64(BPF_REG_0, 0x7fffffffffffff10),
> > -       BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_0),
> > -
> > -       BPF_LD_IMM64(BPF_REG_0, 0x8000000000000000),
> > -       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 1),
> > -       /* r1 signed range is [S64_MIN, S64_MAX] */
> > -       BPF_JMP_REG(BPF_JSLT, BPF_REG_0, BPF_REG_1, -2),
> > -
> > -       BPF_MOV64_IMM(BPF_REG_0, 0),
> > -       BPF_EXIT_INSN(),
> > -       },
> > -       .errstr = "BPF program is too large",
> > -       .result = REJECT,
> > -       .prog_type = BPF_PROG_TYPE_XDP,
> > -},
> >   {
> >          "bound check for loop upper bound greater than U32_MAX",
> >          .insns = {
> > @@ -849,28 +824,3 @@
> >          .result = ACCEPT,
> >          .prog_type = BPF_PROG_TYPE_XDP,
> >   },
> > -{
> > -       "bound check with JMP32_JSLT for crossing 32-bit signed boundary",
> > -       .insns = {
> > -       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, offsetof(struct xdp_md, data)),
> > -       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1, offsetof(struct xdp_md, data_end)),
> > -       BPF_MOV64_REG(BPF_REG_1, BPF_REG_2),
> > -       BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 1),
> > -       BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_3, 6),
> > -
> > -       BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_2, 0),
> > -       BPF_MOV32_IMM(BPF_REG_0, 0x7fffff10),
> > -       BPF_ALU32_REG(BPF_ADD, BPF_REG_1, BPF_REG_0),
> > -
> > -       BPF_MOV32_IMM(BPF_REG_0, 0x80000000),
> > -       BPF_ALU32_IMM(BPF_ADD, BPF_REG_0, 1),
> > -       /* r1 signed range is [S32_MIN, S32_MAX] */
> > -       BPF_JMP32_REG(BPF_JSLT, BPF_REG_0, BPF_REG_1, -2),
> > -
> > -       BPF_MOV64_IMM(BPF_REG_0, 0),
> > -       BPF_EXIT_INSN(),
> > -       },
> > -       .errstr = "BPF program is too large",
> > -       .result = REJECT,
> > -       .prog_type = BPF_PROG_TYPE_XDP,
> > -},
> > --
> > 2.30.2
> .