netdev - [PATCH bpf-next v2 09/13] bpf/tests: Add JMP tests with small offsets

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Message-Id: <20210907222339.4130924-10-johan.almbladh@anyfinetworks.com>
Date:   Wed,  8 Sep 2021 00:23:35 +0200
From:   Johan Almbladh <johan.almbladh@...finetworks.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org
Cc:     kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, iii@...ux.ibm.com,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        Johan Almbladh <johan.almbladh@...finetworks.com>
Subject: [PATCH bpf-next v2 09/13] bpf/tests: Add JMP tests with small offsets

This patch adds a set of tests for JMP to verify that the JITed jump
offset is calculated correctly. We pretend that the verifier has inserted
any zero extensions to make the jump-over operations JIT to one
instruction each, in order to control the exact JITed jump offset.

Signed-off-by: Johan Almbladh <johan.almbladh@...finetworks.com>
---
 lib/test_bpf.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 26f7c244c78a..7286cf347b95 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -10709,6 +10709,77 @@ static struct bpf_test tests[] = {
 		.fill_helper = bpf_fill_jmp32_jsle_reg,
 		.nr_testruns = NR_PATTERN_RUNS,
 	},
+	/* Short relative jumps */
+	{
+		"Short relative jump: offset=0",
+		.u.insns_int = {
+			BPF_ALU64_IMM(BPF_MOV, R0, 0),
+			BPF_JMP_IMM(BPF_JEQ, R0, 0, 0),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, -1),
+		},
+		INTERNAL | FLAG_NO_DATA | FLAG_VERIFIER_ZEXT,
+		{ },
+		{ { 0, 0 } },
+	},
+	{
+		"Short relative jump: offset=1",
+		.u.insns_int = {
+			BPF_ALU64_IMM(BPF_MOV, R0, 0),
+			BPF_JMP_IMM(BPF_JEQ, R0, 0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, -1),
+		},
+		INTERNAL | FLAG_NO_DATA | FLAG_VERIFIER_ZEXT,
+		{ },
+		{ { 0, 0 } },
+	},
+	{
+		"Short relative jump: offset=2",
+		.u.insns_int = {
+			BPF_ALU64_IMM(BPF_MOV, R0, 0),
+			BPF_JMP_IMM(BPF_JEQ, R0, 0, 2),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, -1),
+		},
+		INTERNAL | FLAG_NO_DATA | FLAG_VERIFIER_ZEXT,
+		{ },
+		{ { 0, 0 } },
+	},
+	{
+		"Short relative jump: offset=3",
+		.u.insns_int = {
+			BPF_ALU64_IMM(BPF_MOV, R0, 0),
+			BPF_JMP_IMM(BPF_JEQ, R0, 0, 3),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, -1),
+		},
+		INTERNAL | FLAG_NO_DATA | FLAG_VERIFIER_ZEXT,
+		{ },
+		{ { 0, 0 } },
+	},
+	{
+		"Short relative jump: offset=4",
+		.u.insns_int = {
+			BPF_ALU64_IMM(BPF_MOV, R0, 0),
+			BPF_JMP_IMM(BPF_JEQ, R0, 0, 4),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_ALU32_IMM(BPF_ADD, R0, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, -1),
+		},
+		INTERNAL | FLAG_NO_DATA | FLAG_VERIFIER_ZEXT,
+		{ },
+		{ { 0, 0 } },
+	},
 	/* Staggered jump sequences, immediate */
 	{
 		"Staggered jumps: JMP_JA",
-- 
2.25.1