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Date: Tue, 26 Oct 2021 13:18:44 +0200
From: Johan Almbladh <johan.almbladh@...finetworks.com>
To: Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>
Subject: Re: [PATCH bpf-next v6] test_bpf: Add module parameter test_suite
On Mon, Oct 18, 2021 at 2:55 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>
> After commit 9298e63eafea ("bpf/tests: Add exhaustive tests of ALU
> operand magnitudes"), when modprobe test_bpf.ko with jit on mips64,
> there exists segment fault due to the following reason:
>
> ALU64_MOV_X: all register value magnitudes jited:1
> Break instruction in kernel code[#1]
>
> It seems that the related jit implementations of some test cases
> in test_bpf() have problems. At this moment, I do not care about
> the segment fault while I just want to verify the test cases of
> tail calls.
>
> Based on the above background and motivation, add the following
> module parameter test_suite to the test_bpf.ko:
> test_suite=<string>: only the specified test suite will be run, the
> string can be "test_bpf", "test_tail_calls" or "test_skb_segment".
>
> If test_suite is not specified, but test_id, test_name or test_range
> is specified, set 'test_bpf' as the default test suite.
>
> This is useful to only test the corresponding test suite when specify
> the valid test_suite string.
>
> Any invalid test suite will result in -EINVAL being returned and no
> tests being run. If the test_suite is not specified or specified as
> empty string, it does not change the current logic, all of the test
> cases will be run.
>
> Here are some test results:
> # dmesg -c
> # modprobe test_bpf
> # dmesg | grep Summary
> test_bpf: Summary: 1009 PASSED, 0 FAILED, [0/997 JIT'ed]
> test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
> test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_bpf
> # dmesg | tail -1
> test_bpf: Summary: 1009 PASSED, 0 FAILED, [0/997 JIT'ed]
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_tail_calls
> # dmesg
> test_bpf: #0 Tail call leaf jited:0 21 PASS
> [...]
> test_bpf: #7 Tail call error path, index out of range jited:0 32 PASS
> test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_skb_segment
> # dmesg
> test_bpf: #0 gso_with_rx_frags PASS
> test_bpf: #1 gso_linear_no_head_frag PASS
> test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_id=1
> # dmesg
> test_bpf: test_bpf: set 'test_bpf' as the default test_suite.
> test_bpf: #1 TXA jited:0 54 51 50 PASS
> test_bpf: Summary: 1 PASSED, 0 FAILED, [0/1 JIT'ed]
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_bpf test_name=TXA
> # dmesg
> test_bpf: #1 TXA jited:0 54 50 51 PASS
> test_bpf: Summary: 1 PASSED, 0 FAILED, [0/1 JIT'ed]
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_tail_calls test_range=6,7
> # dmesg
> test_bpf: #6 Tail call error path, NULL target jited:0 41 PASS
> test_bpf: #7 Tail call error path, index out of range jited:0 32 PASS
> test_bpf: test_tail_calls: Summary: 2 PASSED, 0 FAILED, [0/2 JIT'ed]
>
> # rmmod test_bpf
> # dmesg -c
> # modprobe test_bpf test_suite=test_skb_segment test_id=1
> # dmesg
> test_bpf: #1 gso_linear_no_head_frag PASS
> test_bpf: test_skb_segment: Summary: 1 PASSED, 0 FAILED
>
> By the way, the above segment fault has been fixed in the latest bpf-next
> tree.
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
> ---
>
> v6:
> -- Compute the valid range once in the beginning of prepare_bpf_tests(),
> suggested by Johan Almbladh, thank you.
>
> v5:
> -- Remove some duplicated code, suggested by Johan Almbladh,
> thank you.
> -- Initialize test_range[2] to {0, INT_MAX}.
> -- If test_suite is specified, but test_range is not specified,
> set the upper limit of each test_suite to overwrite INT_MAX.
>
> v4:
> -- Fix the following checkpatch issues:
> CHECK: Alignment should match open parenthesis
> CHECK: Please don't use multiple blank lines
>
> ./scripts/checkpatch.pl --strict *.patch
> total: 0 errors, 0 warnings, 0 checks, 299 lines checked
>
> the default max-line-length is 100 in ./scripts/checkpatch.pl,
> but it seems that the netdev/checkpatch is 80:
> https://patchwork.hopto.org/static/nipa/559961/12545157/checkpatch/stdout
>
> v3:
> -- Use test_suite instead of test_type as module parameter
> -- Make test_id, test_name and test_range selection applied to each test suite
>
> v2:
> -- Fix typo in the commit message
> -- Use my private email to send
>
> lib/test_bpf.c | 230 ++++++++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 154 insertions(+), 76 deletions(-)
>
> diff --git a/lib/test_bpf.c b/lib/test_bpf.c
> index e5b10fd..06f9b66 100644
> --- a/lib/test_bpf.c
> +++ b/lib/test_bpf.c
> @@ -14316,72 +14316,9 @@ module_param_string(test_name, test_name, sizeof(test_name), 0);
> static int test_id = -1;
> module_param(test_id, int, 0);
>
> -static int test_range[2] = { 0, ARRAY_SIZE(tests) - 1 };
> +static int test_range[2] = { 0, INT_MAX };
> module_param_array(test_range, int, NULL, 0);
>
> -static __init int find_test_index(const char *test_name)
> -{
> - int i;
> -
> - for (i = 0; i < ARRAY_SIZE(tests); i++) {
> - if (!strcmp(tests[i].descr, test_name))
> - return i;
> - }
> - return -1;
> -}
> -
> -static __init int prepare_bpf_tests(void)
> -{
> - if (test_id >= 0) {
> - /*
> - * if a test_id was specified, use test_range to
> - * cover only that test.
> - */
> - if (test_id >= ARRAY_SIZE(tests)) {
> - pr_err("test_bpf: invalid test_id specified.\n");
> - return -EINVAL;
> - }
> -
> - test_range[0] = test_id;
> - test_range[1] = test_id;
> - } else if (*test_name) {
> - /*
> - * if a test_name was specified, find it and setup
> - * test_range to cover only that test.
> - */
> - int idx = find_test_index(test_name);
> -
> - if (idx < 0) {
> - pr_err("test_bpf: no test named '%s' found.\n",
> - test_name);
> - return -EINVAL;
> - }
> - test_range[0] = idx;
> - test_range[1] = idx;
> - } else {
> - /*
> - * check that the supplied test_range is valid.
> - */
> - if (test_range[0] >= ARRAY_SIZE(tests) ||
> - test_range[1] >= ARRAY_SIZE(tests) ||
> - test_range[0] < 0 || test_range[1] < 0) {
> - pr_err("test_bpf: test_range is out of bound.\n");
> - return -EINVAL;
> - }
> -
> - if (test_range[1] < test_range[0]) {
> - pr_err("test_bpf: test_range is ending before it starts.\n");
> - return -EINVAL;
> - }
> - }
> -
> - return 0;
> -}
> -
> -static __init void destroy_bpf_tests(void)
> -{
> -}
> -
> static bool exclude_test(int test_id)
> {
> return test_id < test_range[0] || test_id > test_range[1];
> @@ -14553,6 +14490,10 @@ static __init int test_skb_segment(void)
> for (i = 0; i < ARRAY_SIZE(skb_segment_tests); i++) {
> const struct skb_segment_test *test = &skb_segment_tests[i];
>
> + cond_resched();
> + if (exclude_test(i))
> + continue;
> +
> pr_info("#%d %s ", i, test->descr);
>
> if (test_skb_segment_single(test)) {
> @@ -14934,6 +14875,8 @@ static __init int test_tail_calls(struct bpf_array *progs)
> int ret;
>
> cond_resched();
> + if (exclude_test(i))
> + continue;
>
> pr_info("#%d %s ", i, test->descr);
> if (!fp) {
> @@ -14966,29 +14909,164 @@ static __init int test_tail_calls(struct bpf_array *progs)
> return err_cnt ? -EINVAL : 0;
> }
>
> +static char test_suite[32];
> +module_param_string(test_suite, test_suite, sizeof(test_suite), 0);
> +
> +static __init int find_test_index(const char *test_name)
> +{
> + int i;
> +
> + if (!strcmp(test_suite, "test_bpf")) {
> + for (i = 0; i < ARRAY_SIZE(tests); i++) {
> + if (!strcmp(tests[i].descr, test_name))
> + return i;
> + }
> + }
> +
> + if (!strcmp(test_suite, "test_tail_calls")) {
> + for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++) {
> + if (!strcmp(tail_call_tests[i].descr, test_name))
> + return i;
> + }
> + }
> +
> + if (!strcmp(test_suite, "test_skb_segment")) {
> + for (i = 0; i < ARRAY_SIZE(skb_segment_tests); i++) {
> + if (!strcmp(skb_segment_tests[i].descr, test_name))
> + return i;
> + }
> + }
> +
> + return -1;
> +}
> +
> +static __init int prepare_bpf_tests(void)
> +{
> + int valid_range;
> +
> + if (!strcmp(test_suite, "test_bpf"))
> + valid_range = ARRAY_SIZE(tests);
> + else if (!strcmp(test_suite, "test_tail_calls"))
> + valid_range = ARRAY_SIZE(tail_call_tests);
> + else if (!strcmp(test_suite, "test_skb_segment"))
> + valid_range = ARRAY_SIZE(skb_segment_tests);
What if none of the above branches are taken?
> +
> + if (test_id >= 0) {
> + /*
> + * if a test_id was specified, use test_range to
> + * cover only that test.
> + */
> + if (test_id >= valid_range) {
> + pr_err("test_bpf: invalid test_id specified for '%s' suite.\n",
> + test_suite);
> + return -EINVAL;
> + }
> +
> + test_range[0] = test_id;
> + test_range[1] = test_id;
> + } else if (*test_name) {
> + /*
> + * if a test_name was specified, find it and setup
> + * test_range to cover only that test.
> + */
> + int idx = find_test_index(test_name);
> +
> + if (idx < 0) {
> + pr_err("test_bpf: no test named '%s' found for '%s' suite.\n",
> + test_name, test_suite);
> + return -EINVAL;
> + }
> + test_range[0] = idx;
> + test_range[1] = idx;
> + } else {
Here I would make the "else" branch conditional on test_range being specified.
> + /*
> + * check that the supplied test_range is valid.
> + */
> + if (strlen(test_suite)) {
> + if (test_range[0] >= valid_range ||
> + test_range[1] >= valid_range ||
> + test_range[0] < 0 || test_range[1] < 0) {
It is sufficient to check for test_range[0] < 0 or test_range[1] >=
valid_range here, since the bounds ordering is checked below.
> + pr_err("test_bpf: test_range is out of bound for '%s' suite.\n",
> + test_suite);
> + return -EINVAL;
> + }
> + }
> +
> + if (test_range[1] < test_range[0]) {
> + pr_err("test_bpf: test_range is ending before it starts.\n");
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
The function above used to prepare the range selection for the
"test_bpf" suite. Now, the range selection applies to other suites as
well. I would suggest changing the function name to something more
descriptive, like prepare_test_range().
> +
> +static __init void destroy_bpf_tests(void)
> +{
> +}
This is not needed. Remove.
> +
> static int __init test_bpf_init(void)
> {
> struct bpf_array *progs = NULL;
> int ret;
>
> + if (strlen(test_suite) &&
> + strcmp(test_suite, "test_bpf") &&
> + strcmp(test_suite, "test_tail_calls") &&
> + strcmp(test_suite, "test_skb_segment")) {
> + pr_err("test_bpf: invalid test_suite '%s' specified.\n", test_suite);
> + return -EINVAL;
> + }
> +
> + /*
> + * if test_suite is not specified, but test_id, test_name or test_range
> + * is specified, set 'test_bpf' as the default test suite.
> + */
> + if (!strlen(test_suite) &&
> + (test_id != -1 || strlen(test_name) ||
> + (test_range[0] != 0 || test_range[1] != INT_MAX))) {
> + pr_info("test_bpf: set 'test_bpf' as the default test_suite.\n");
> + strcpy(test_suite, "test_bpf");
> + }
> +
> + /*
> + * if test_suite is specified, but test_range is not specified,
> + * set the upper limit of each test_suite to overwrite INT_MAX.
> + */
> + if (strlen(test_suite) && test_range[0] == 0 && test_range[1] == INT_MAX) {
> + if (!strcmp(test_suite, "test_bpf"))
> + test_range[1] = ARRAY_SIZE(tests) - 1;
> + else if (!strcmp(test_suite, "test_tail_calls"))
> + test_range[1] = ARRAY_SIZE(tail_call_tests) - 1;
> + else if (!strcmp(test_suite, "test_skb_segment"))
> + test_range[1] = ARRAY_SIZE(skb_segment_tests) - 1;
> + }
The computation above is already performed in another location. It is
also not necessary to limit test_range since it is a filter. I would
remove it.
> +
> ret = prepare_bpf_tests();
> if (ret < 0)
> return ret;
>
> - ret = test_bpf();
> - destroy_bpf_tests();
> - if (ret)
> - return ret;
> + if (!strlen(test_suite) || !strcmp(test_suite, "test_bpf")) {
> + ret = test_bpf();
> + destroy_bpf_tests();
> + if (ret)
> + return ret;
> + }
>
> - ret = prepare_tail_call_tests(&progs);
> - if (ret)
> - return ret;
> - ret = test_tail_calls(progs);
> - destroy_tail_call_tests(progs);
> - if (ret)
> - return ret;
> + if (!strlen(test_suite) || !strcmp(test_suite, "test_tail_calls")) {
> + ret = prepare_tail_call_tests(&progs);
> + if (ret)
> + return ret;
> + ret = test_tail_calls(progs);
> + destroy_tail_call_tests(progs);
> + if (ret)
> + return ret;
> + }
>
> - return test_skb_segment();
> + if (!strlen(test_suite) || !strcmp(test_suite, "test_skb_segment"))
> + return test_skb_segment();
> +
> + return 0;
> }
>
> static void __exit test_bpf_exit(void)
> --
> 2.1.0
>
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