[PATCH v7 bpf-next 08/16] selftests: bpf: adjust several test_verifier helpers for insn insertion

[Jiong Wang <jiong.wang@netronome.com>]

  - bpf_fill_ld_abs_vlan_push_pop:
    Prevent zext happens inside PUSH_CNT loop. This could happen because
    of BPF_LD_ABS (32-bit def) + BPF_JMP (64-bit use), or BPF_LD_ABS +
    EXIT (64-bit use of R0). So, change BPF_JMP to BPF_JMP32 and redefine
    R0 at exit path to cut off the data-flow from inside the loop.

  - bpf_fill_jump_around_ld_abs:
    Jump range is limited to 16 bit. every ld_abs is replaced by 6 insns,
    but on arches like arm, ppc etc, there will be one BPF_ZEXT inserted
    to extend the error value of the inlined ld_abs sequence which then
    contains 7 insns. so, set the dividend to 7 so the testcase could
    work on all arches.

  - bpf_fill_scale1/bpf_fill_scale2:
    Both contains ~1M BPF_ALU32_IMM which will trigger ~1M insn patcher
    call because of hi32 randomization later when BPF_F_TEST_RND_HI32 is
    set for bpf selftests. Insn patcher is not efficient that 1M call to
    it will hang computer. So , change to BPF_ALU64_IMM to avoid hi32
    randomization.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
---
 tools/testing/selftests/bpf/test_verifier.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index ccd896b..3dcdfd4 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -138,32 +138,36 @@ static void bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self)
 loop:
 	for (j = 0; j < PUSH_CNT; j++) {
 		insn[i++] = BPF_LD_ABS(BPF_B, 0);
-		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0x34, len - i - 2);
+		/* jump to error label */
+		insn[i] = BPF_JMP32_IMM(BPF_JNE, BPF_REG_0, 0x34, len - i - 3);
 		i++;
 		insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6);
 		insn[i++] = BPF_MOV64_IMM(BPF_REG_2, 1);
 		insn[i++] = BPF_MOV64_IMM(BPF_REG_3, 2);
 		insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 					 BPF_FUNC_skb_vlan_push),
-		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, len - i - 2);
+		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, len - i - 3);
 		i++;
 	}
 
 	for (j = 0; j < PUSH_CNT; j++) {
 		insn[i++] = BPF_LD_ABS(BPF_B, 0);
-		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0x34, len - i - 2);
+		insn[i] = BPF_JMP32_IMM(BPF_JNE, BPF_REG_0, 0x34, len - i - 3);
 		i++;
 		insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6);
 		insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 					 BPF_FUNC_skb_vlan_pop),
-		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, len - i - 2);
+		insn[i] = BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, len - i - 3);
 		i++;
 	}
 	if (++k < 5)
 		goto loop;
 
-	for (; i < len - 1; i++)
-		insn[i] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 0xbef);
+	for (; i < len - 3; i++)
+		insn[i] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 0xbef);
+	insn[len - 3] = BPF_JMP_A(1);
+	/* error label */
+	insn[len - 2] = BPF_MOV32_IMM(BPF_REG_0, 0);
 	insn[len - 1] = BPF_EXIT_INSN();
 	self->prog_len = len;
 }
@@ -171,8 +175,13 @@ static void bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self)
 static void bpf_fill_jump_around_ld_abs(struct bpf_test *self)
 {
 	struct bpf_insn *insn = self->fill_insns;
-	/* jump range is limited to 16 bit. every ld_abs is replaced by 6 insns */
-	unsigned int len = (1 << 15) / 6;
+	/* jump range is limited to 16 bit. every ld_abs is replaced by 6 insns,
+	 * but on arches like arm, ppc etc, there will be one BPF_ZEXT inserted
+	 * to extend the error value of the inlined ld_abs sequence which then
+	 * contains 7 insns. so, set the dividend to 7 so the testcase could
+	 * work on all arches.
+	 */
+	unsigned int len = (1 << 15) / 7;
 	int i = 0;
 
 	insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
@@ -230,7 +239,7 @@ static void bpf_fill_scale1(struct bpf_test *self)
 	 * within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
 	 */
 	while (i < MAX_TEST_INSNS - 1025)
-		insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
+		insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 42);
 	insn[i] = BPF_EXIT_INSN();
 	self->prog_len = i + 1;
 	self->retval = 42;
@@ -261,7 +270,7 @@ static void bpf_fill_scale2(struct bpf_test *self)
 	 * within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
 	 */
 	while (i < MAX_TEST_INSNS - 1025)
-		insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
+		insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 42);
 	insn[i] = BPF_EXIT_INSN();
 	self->prog_len = i + 1;
 	self->retval = 42;
-- 
2.7.4