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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Z+A4SCNAFToljw8w/XJH2Ymoq34r4ypOMBE3039GCcY=; b=g/+AZkSx5OaymCW9vZCUEB5oNo7JfAXZzFzZHFccW7qYPDXPGvmnO1Uj3u7zAjLEb7 UrQwMOkOAadts++hdnOReSxhAWTGbXha+oYammbIdhiLv1efiH3R+cU/EIefDTc+12LX csfa2Ij/WGfjeRlGQHptTgLb+FOFqE3PDLC55VAeznApmm/awbzZm0ZojDTpLs0+ZNHb Mj48uaxJcq6JcwJhKyjx1q0BpmrmGY9AAmWXy7ecpcipQIP8WYIDFlnV2yszlli5hWkV iAhxc0IrhJrnr0bUhYwTY39zgaNl2ciyPNpLoogaPMdpy4/ECYQuuMqXPuyNVHAuCct6 6gFw== X-Gm-Message-State: AOAM530j/TZRNTRe7bdQfv6UNkluLllsW6DkNKvc096/Bvi47I4k6INB L1p+XsfDNlTtFzJgWehrxKoj4Cchz0XknWvHEGc= X-Google-Smtp-Source: ABdhPJxOkyBIjcvJ8q21FaDnMqdsx2F8RfxM90h2Ivq4wFUFBDJWeUsv9xyhVWup6sGcrscWrYAW4oKT58GhHKQmE5g= X-Received: by 2002:a25:e655:: with SMTP id d82mr17256744ybh.347.1599776541456; Thu, 10 Sep 2020 15:22:21 -0700 (PDT) MIME-Version: 1.0 References: <20200910122224.1683258-1-jolsa@kernel.org> In-Reply-To: <20200910122224.1683258-1-jolsa@kernel.org> From: Andrii Nakryiko Date: Thu, 10 Sep 2020 15:22:10 -0700 Message-ID: Subject: Re: [PATCH bpf-next] selftests/bpf: Check trampoline execution in d_path test To: Jiri Olsa Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Sep 10, 2020 at 5:25 AM Jiri Olsa wrote: > > Some kernels builds might inline vfs_getattr call within > fstat syscall code path, so fentry/vfs_getattr trampoline > is not called. > > I'm not sure how to handle this in some generic way other > than use some other function, but that might get inlined at > some point as well. > > Adding flags that indicate trampolines were called and failing > the test if neither of them got called. > > $ sudo ./test_progs -t d_path > test_d_path:PASS:setup 0 nsec > ... > trigger_fstat_events:PASS:trigger 0 nsec > test_d_path:FAIL:124 trampolines not called > #22 d_path:FAIL > Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED > > If only one trampoline is called, it's still enough to test > the helper, so only warn about missing trampoline call and > continue in test. > > $ sudo ./test_progs -t d_path -v > test_d_path:PASS:setup 0 nsec > ... > trigger_fstat_events:PASS:trigger 0 nsec > fentry/vfs_getattr not called > #22 d_path:OK > Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED > > Signed-off-by: Jiri Olsa > --- Acked-by: Andrii Nakryiko > .../testing/selftests/bpf/prog_tests/d_path.c | 25 +++++++++++++++---- > .../testing/selftests/bpf/progs/test_d_path.c | 7 ++++++ > 2 files changed, 27 insertions(+), 5 deletions(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/d_path.c b/tools/testing/selftests/bpf/prog_tests/d_path.c > index fc12e0d445ff..ec15f7d1dd0a 100644 > --- a/tools/testing/selftests/bpf/prog_tests/d_path.c > +++ b/tools/testing/selftests/bpf/prog_tests/d_path.c > @@ -120,26 +120,41 @@ void test_d_path(void) > if (err < 0) > goto cleanup; > > + if (!bss->called_stat && !bss->called_close) { > + PRINT_FAIL("trampolines not called\n"); > + goto cleanup; > + } > + > + if (!bss->called_stat) { > + fprintf(stdout, "fentry/vfs_getattr not called\n"); > + goto cleanup; > + } > + > + if (!bss->called_close) { > + fprintf(stdout, "fentry/filp_close not called\n"); > + goto cleanup; > + } not sure why you didn't go with `if (CHECK(!bss->called_close, ...` for these checks, would even save you some typing. > + > for (int i = 0; i < MAX_FILES; i++) { > - CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN), > + CHECK(bss->called_stat && strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN), > "check", > "failed to get stat path[%d]: %s vs %s\n", > i, src.paths[i], bss->paths_stat[i]); > - CHECK(strncmp(src.paths[i], bss->paths_close[i], MAX_PATH_LEN), > + CHECK(bss->called_close && strncmp(src.paths[i], bss->paths_close[i], MAX_PATH_LEN), > "check", > "failed to get close path[%d]: %s vs %s\n", > i, src.paths[i], bss->paths_close[i]); > /* The d_path helper returns size plus NUL char, hence + 1 */ > - CHECK(bss->rets_stat[i] != strlen(bss->paths_stat[i]) + 1, > + CHECK(bss->called_stat && bss->rets_stat[i] != strlen(bss->paths_stat[i]) + 1, > "check", > "failed to match stat return [%d]: %d vs %zd [%s]\n", > i, bss->rets_stat[i], strlen(bss->paths_stat[i]) + 1, > bss->paths_stat[i]); > - CHECK(bss->rets_close[i] != strlen(bss->paths_stat[i]) + 1, > + CHECK(bss->called_close && bss->rets_close[i] != strlen(bss->paths_close[i]) + 1, > "check", > "failed to match stat return [%d]: %d vs %zd [%s]\n", > i, bss->rets_close[i], strlen(bss->paths_close[i]) + 1, > - bss->paths_stat[i]); > + bss->paths_close[i]); those `bss->called_xxx` guard conditions are a bit lost on reading, if you reordered CHECKs, you could be more explicit: if (bss->called_stat) { CHECK(...); CHECK(...); } if (bss->called_close) { ... } > } > > cleanup: > diff --git a/tools/testing/selftests/bpf/progs/test_d_path.c b/tools/testing/selftests/bpf/progs/test_d_path.c > index 61f007855649..9e7223b4a555 100644 > --- a/tools/testing/selftests/bpf/progs/test_d_path.c > +++ b/tools/testing/selftests/bpf/progs/test_d_path.c > @@ -15,6 +15,9 @@ char paths_close[MAX_FILES][MAX_PATH_LEN] = {}; > int rets_stat[MAX_FILES] = {}; > int rets_close[MAX_FILES] = {}; > > +int called_stat = 0; > +int called_close = 0; > + > SEC("fentry/vfs_getattr") > int BPF_PROG(prog_stat, struct path *path, struct kstat *stat, > __u32 request_mask, unsigned int query_flags) > @@ -23,6 +26,8 @@ int BPF_PROG(prog_stat, struct path *path, struct kstat *stat, > __u32 cnt = cnt_stat; > int ret; > > + called_stat = 1; > + > if (pid != my_pid) > return 0; > > @@ -42,6 +47,8 @@ int BPF_PROG(prog_close, struct file *file, void *id) > __u32 cnt = cnt_close; > int ret; > > + called_close = 1; > + > if (pid != my_pid) > return 0; > > -- > 2.26.2 >