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

Xu Kuohai <xukuohai@xxxxxxxxxxxxxxx> · Mon, 27 Mar 2023 14:20:39 +0800

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

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