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Subject[PATCH AUTOSEL 5.2 024/249] selftests/bpf: adjust verifier scale test
Date
From: Alexei Starovoitov <ast@kernel.org>

[ Upstream commit 7c0c6095d48dcd0e67c917aa73cdbb2715aafc36 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/bpf/test_verifier.c | 31 +++++++++++----------
1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 288cb740e005..6438d4dc8ae1 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -207,33 +207,35 @@ 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;
@@ -245,19 +247,20 @@ 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;
--
2.20.1
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