[PATCH bpf v4 13/14] bpf/tests: Fix error in tail call limit tests
From: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Date: 2021-09-14 09:19:41
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), library code, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Andrew Morton, Linus Torvalds
This patch fixes an error in the tail call limit test that caused the
test to fail on for x86-64 JIT. Previously, the register R0 was used to
report the total number of tail calls made. However, after a tail call
fall-through, the value of the R0 register is undefined. Now, all tail
call error path tests instead use context state to store the count.
Fixes: 874be05f525e ("bpf, tests: Add tail call test suite")
Reported-by: Paul Chaignon <redacted>
Reported-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
---
lib/test_bpf.c | 37 +++++++++++++++++++++++++++----------
1 file changed, 27 insertions(+), 10 deletions(-)
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 7475abfd2186..ddb9a8089d2e 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c@@ -12179,10 +12179,15 @@ static __init int test_bpf(void) struct tail_call_test { const char *descr; struct bpf_insn insns[MAX_INSNS]; + int flags; int result; int stack_depth; }; +/* Flags that can be passed to tail call test cases */ +#define FLAG_NEED_STATE BIT(0) +#define FLAG_RESULT_IN_STATE BIT(1) + /* * Magic marker used in test snippets for tail calls below. * BPF_LD/MOV to R2 and R2 with this immediate value is replaced
@@ -12252,32 +12257,38 @@ static struct tail_call_test tail_call_tests[] = { { "Tail call error path, max count reached", .insns = { - BPF_ALU64_IMM(BPF_ADD, R1, 1), - BPF_ALU64_REG(BPF_MOV, R0, R1), + BPF_LDX_MEM(BPF_W, R2, R1, 0), + BPF_ALU64_IMM(BPF_ADD, R2, 1), + BPF_STX_MEM(BPF_W, R1, R2, 0), TAIL_CALL(0), BPF_EXIT_INSN(), }, - .result = MAX_TAIL_CALL_CNT + 1, + .flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE, + .result = (MAX_TAIL_CALL_CNT + 1 + 1) * MAX_TESTRUNS, }, { "Tail call error path, NULL target", .insns = { - BPF_ALU64_IMM(BPF_MOV, R0, -1), + BPF_LDX_MEM(BPF_W, R2, R1, 0), + BPF_ALU64_IMM(BPF_ADD, R2, 1), + BPF_STX_MEM(BPF_W, R1, R2, 0), TAIL_CALL(TAIL_CALL_NULL), - BPF_ALU64_IMM(BPF_MOV, R0, 1), BPF_EXIT_INSN(), }, - .result = 1, + .flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE, + .result = MAX_TESTRUNS, }, { "Tail call error path, index out of range", .insns = { - BPF_ALU64_IMM(BPF_MOV, R0, -1), + BPF_LDX_MEM(BPF_W, R2, R1, 0), + BPF_ALU64_IMM(BPF_ADD, R2, 1), + BPF_STX_MEM(BPF_W, R1, R2, 0), TAIL_CALL(TAIL_CALL_INVALID), - BPF_ALU64_IMM(BPF_MOV, R0, 1), BPF_EXIT_INSN(), }, - .result = 1, + .flags = FLAG_NEED_STATE | FLAG_RESULT_IN_STATE, + .result = MAX_TESTRUNS, }, };
@@ -12383,6 +12394,8 @@ static __init int test_tail_calls(struct bpf_array *progs) for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++) { struct tail_call_test *test = &tail_call_tests[i]; struct bpf_prog *fp = progs->ptrs[i]; + int *data = NULL; + int state = 0; u64 duration; int ret;
@@ -12399,7 +12412,11 @@ static __init int test_tail_calls(struct bpf_array *progs) if (fp->jited) jit_cnt++; - ret = __run_one(fp, NULL, MAX_TESTRUNS, &duration); + if (test->flags & FLAG_NEED_STATE) + data = &state; + ret = __run_one(fp, data, MAX_TESTRUNS, &duration); + if (test->flags & FLAG_RESULT_IN_STATE) + ret = state; if (ret == test->result) { pr_cont("%lld PASS", duration); pass_cnt++;
--
2.30.2