selftests/bpf: adjust verifier scale test

Adjust scale tests to check for new jmp sequence limit.

BPF_JGT had to be changed to BPF_JEQ because the verifier was
too smart. It tracked the known safe range of R0 values
and pruned the search earlier before hitting exact 8192 limit.
bpf_semi_rand_get() was too (un)?lucky.

k = 0; was missing in bpf_fill_scale2.
It was testing a bit shorter sequence of jumps than intended.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index ccd896b..6e2fec8 100644 (file)
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -210,33 +210,35 @@ static void bpf_fill_rand_ld_dw(struct bpf_test *self)
        self->retval = (uint32_t)res;
 }
 
-/* test the sequence of 1k jumps */
+#define MAX_JMP_SEQ 8192
+
+/* test the sequence of 8k jumps */
 static void bpf_fill_scale1(struct bpf_test *self)
 {
        struct bpf_insn *insn = self->fill_insns;
        int i = 0, k = 0;
 
        insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
-       /* test to check that the sequence of 1024 jumps is acceptable */
-       while (k++ < 1024) {
+       /* test to check that the long sequence of jumps is acceptable */
+       while (k++ < MAX_JMP_SEQ) {
                insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
                                         BPF_FUNC_get_prandom_u32);
-               insn[i++] = BPF_JMP_IMM(BPF_JGT, BPF_REG_0, bpf_semi_rand_get(), 2);
+               insn[i++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, bpf_semi_rand_get(), 2);
                insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_10);
                insn[i++] = BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6,
                                        -8 * (k % 64 + 1));
        }
-       /* every jump adds 1024 steps to insn_processed, so to stay exactly
-        * within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
+       /* every jump adds 1 step to insn_processed, so to stay exactly
+        * within 1m limit add MAX_TEST_INSNS - MAX_JMP_SEQ - 1 MOVs and 1 EXIT
         */
-       while (i < MAX_TEST_INSNS - 1025)
+       while (i < MAX_TEST_INSNS - MAX_JMP_SEQ - 1)
                insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
        insn[i] = BPF_EXIT_INSN();
        self->prog_len = i + 1;
        self->retval = 42;
 }
 
-/* test the sequence of 1k jumps in inner most function (function depth 8)*/
+/* test the sequence of 8k jumps in inner most function (function depth 8)*/
 static void bpf_fill_scale2(struct bpf_test *self)
 {
        struct bpf_insn *insn = self->fill_insns;
@@ -248,19 +250,20 @@ static void bpf_fill_scale2(struct bpf_test *self)
                insn[i++] = BPF_EXIT_INSN();
        }
        insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
-       /* test to check that the sequence of 1024 jumps is acceptable */
-       while (k++ < 1024) {
+       /* test to check that the long sequence of jumps is acceptable */
+       k = 0;
+       while (k++ < MAX_JMP_SEQ) {
                insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
                                         BPF_FUNC_get_prandom_u32);
-               insn[i++] = BPF_JMP_IMM(BPF_JGT, BPF_REG_0, bpf_semi_rand_get(), 2);
+               insn[i++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, bpf_semi_rand_get(), 2);
                insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_10);
                insn[i++] = BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6,
                                        -8 * (k % (64 - 4 * FUNC_NEST) + 1));
        }
-       /* every jump adds 1024 steps to insn_processed, so to stay exactly
-        * within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
+       /* every jump adds 1 step to insn_processed, so to stay exactly
+        * within 1m limit add MAX_TEST_INSNS - MAX_JMP_SEQ - 1 MOVs and 1 EXIT
         */
-       while (i < MAX_TEST_INSNS - 1025)
+       while (i < MAX_TEST_INSNS - MAX_JMP_SEQ - 1)
                insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
        insn[i] = BPF_EXIT_INSN();
        self->prog_len = i + 1;