netdev - [PATCH bpf-next 2/2] bpf: Add loop test case with 32 bit reg comparison against 0

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Date:   Thu,  3 Oct 2019 01:45:12 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     ast@...nel.org
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf-next 2/2] bpf: Add loop test case with 32 bit reg comparison against 0

Add a loop test with 32 bit register against 0 immediate:

  # ./test_verifier 631
  #631/p taken loop with back jump to 1st insn, 2 OK

Disassembly:

  [...]
  1b:	test   %edi,%edi
  1d:	jne    0x0000000000000014
  [...]

Pretty much similar to prior "taken loop with back jump to 1st
insn" test case just as jmp32 variant.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
---
 tools/testing/selftests/bpf/verifier/loops1.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/loops1.c b/tools/testing/selftests/bpf/verifier/loops1.c
index 1fc4e61e9f9f..1af37187dc12 100644
--- a/tools/testing/selftests/bpf/verifier/loops1.c
+++ b/tools/testing/selftests/bpf/verifier/loops1.c
@@ -187,3 +187,20 @@
 	.prog_type = BPF_PROG_TYPE_XDP,
 	.retval = 55,
 },
+{
+	"taken loop with back jump to 1st insn, 2",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 10),
+	BPF_MOV64_IMM(BPF_REG_2, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 1),
+	BPF_EXIT_INSN(),
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1),
+	BPF_ALU64_IMM(BPF_SUB, BPF_REG_1, 1),
+	BPF_JMP32_IMM(BPF_JNE, BPF_REG_1, 0, -3),
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_XDP,
+	.retval = 55,
+},
-- 
2.17.1