[PATCH V2] tools/perf/tests: Skip perf BPF test if clang is not present

[Ian Rogers]

On Thu, May 12, 2022 at 11:16 PM Disha Goel <disgoel at linux.vnet.ibm.com> wrote:
>
>
>
> -----Original Message-----
> From: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
> To: acme at kernel.org, jolsa at kernel.org
> Cc: mpe at ellerman.id.au, linux-perf-users at vger.kernel.org, linuxppc-dev at lists.ozlabs.org, maddy at linux.vnet.ibm.com, rnsastry at linux.ibm.com, kjain at linux.ibm.com, disgoel at linux.vnet.ibm.com, irogers at google.com
> Subject: [PATCH V2] tools/perf/tests: Skip perf BPF test if clang is not present
> Date: Wed, 11 May 2022 17:24:38 +0530
>
> Perf BPF filter test fails in environment where "clang"
>
> is not installed.
>
>
> Test failure logs:
>
>
> <<>>
>
>  42: BPF filter                    :
>
>  42.1: Basic BPF filtering         : Skip
>
>  42.2: BPF pinning                 : FAILED!
>
>  42.3: BPF prologue generation     : FAILED!
>
> <<>>
>
>
> Enabling verbose option provided debug logs which says
>
> clang/llvm needs to be installed. Snippet of verbose logs:
>
>
> <<>>
>
>  42.2: BPF pinning                  :
>
>  --- start ---
>
> test child forked, pid 61423
>
> ERROR: unable to find clang.
>
> Hint: Try to install latest clang/llvm to support BPF.
>
>         Check your $PATH
>
>
> <<logs_here>>
>
>
> Failed to compile test case: 'Basic BPF llvm compile'
>
> Unable to get BPF object, fix kbuild first
>
> test child finished with -1
>
>  ---- end ----
>
> BPF filter subtest 2: FAILED!
>
> <<>>
>
>
> Here subtests, "BPF pinning" and "BPF prologue generation"
>
> failed and logs shows clang/llvm is needed. After installing
>
> clang, testcase passes.
>
>
> Reason on why subtest failure happens though logs has proper
>
> debug information:
>
> Main function __test__bpf calls test_llvm__fetch_bpf_obj by
>
> passing 4th argument as true ( 4th arguments maps to parameter
>
> "force" in test_llvm__fetch_bpf_obj ). But this will cause
>
> test_llvm__fetch_bpf_obj to skip the check for clang/llvm.
>
>
> Snippet of code part which checks for clang based on
>
> parameter "force" in test_llvm__fetch_bpf_obj:
>
>
> <<>>
>
> if (!force && (!llvm_param.user_set_param &&
>
> <<>>
>
>
> Since force is set to "false", test won't get skipped and
>
> fails to compile test case. The BPF code compilation needs
>
> clang, So pass the fourth argument as "false" and also skip
>
> the test if reason for return is "TEST_SKIP"
>
>
> After the patch:
>
>
> <<>>
>
>  42: BPF filter                    :
>
>  42.1: Basic BPF filtering         : Skip
>
>  42.2: BPF pinning                 : Skip
>
>  42.3: BPF prologue generation     : Skip
>
> <<>>
>
>
> Fixes: ba1fae431e74 ("perf test: Add 'perf test BPF'")
>
> Signed-off-by: Athira Rajeev <
>
> atrajeev at linux.vnet.ibm.com
>
> >
>
> ---
>
> Changelog:
>
>  Addressed review comments from Arnaldo by adding
>
>  reason for skipping of testcase.
>
>
>  tools/perf/tests/bpf.c | 10 ++++++----
>
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
>
> Tested the patch on powerpc and powernv, perf BPF test works fine with the patch.
>
> Tested-by: Disha Goel <disgoel at linux.vnet.ibm.com>

Acked-by: Ian Rogers <irogers at google.com>

Thanks!
Ian

> diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
>
> index 57b9591f7cbb..17c023823713 100644
>
> --- a/tools/perf/tests/bpf.c
>
> +++ b/tools/perf/tests/bpf.c
>
> @@ -222,11 +222,11 @@ static int __test__bpf(int idx)
>
>
>   ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
>
>         bpf_testcase_table[idx].prog_id,
>
> -       true, NULL);
>
> +       false, NULL);
>
>   if (ret != TEST_OK || !obj_buf || !obj_buf_sz) {
>
>   pr_debug("Unable to get BPF object, %s\n",
>
>   bpf_testcase_table[idx].msg_compile_fail);
>
> - if (idx == 0)
>
> + if ((idx == 0) || (ret == TEST_SKIP))
>
>   return TEST_SKIP;
>
>   else
>
>   return TEST_FAIL;
>
> @@ -364,9 +364,11 @@ static int test__bpf_prologue_test(struct test_suite *test __maybe_unused,
>
>  static struct test_case bpf_tests[] = {
>
>  #ifdef HAVE_LIBBPF_SUPPORT
>
>   TEST_CASE("Basic BPF filtering", basic_bpf_test),
>
> - TEST_CASE("BPF pinning", bpf_pinning),
>
> + TEST_CASE_REASON("BPF pinning", bpf_pinning,
>
> + "clang isn't installed or environment missing BPF support"),
>
>  #ifdef HAVE_BPF_PROLOGUE
>
> - TEST_CASE("BPF prologue generation", bpf_prologue_test),
>
> + TEST_CASE_REASON("BPF prologue generation", bpf_prologue_test,
>
> + "clang isn't installed or environment missing BPF support"),
>
>  #else
>
>   TEST_CASE_REASON("BPF prologue generation", bpf_prologue_test, "not compiled in"),
>
>  #endif