linux-kernel - Re: [PATCHv3 bpf-next 9/9] selftests/bpf: Add file_build

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Message-ID: <478a8e03-dea3-ebca-8376-6b7e3b616b5e@iogearbox.net>
Date:   Thu, 16 Mar 2023 20:59:21 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Hao Luo <haoluo@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Matthew Wilcox <willy@...radead.org>
Cc:     bpf@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-perf-users@...r.kernel.org, Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Namhyung Kim <namhyung@...il.com>,
        Dave Chinner <david@...morbit.com>
Subject: Re: [PATCHv3 bpf-next 9/9] selftests/bpf: Add file_build_id test

On 3/16/23 6:01 PM, Jiri Olsa wrote:
> The test attaches bpf program to sched_process_exec tracepoint
> and gets build of executed file from bprm->file object.
> 
> We use urandom_read as the test program and in addition we also
> attach uprobe to liburandom_read.so:urandlib_read_without_sema
> and retrieve and check build id of that shared library.
> 
> Also executing the no_build_id binary to verify the bpf program
> gets the error properly.
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/file_build_id.c b/tools/testing/selftests/bpf/progs/file_build_id.c
> new file mode 100644
> index 000000000000..6dc10c8e17ac
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/file_build_id.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "vmlinux.h"
> +#include "err.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <linux/string.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +int pid;
> +
> +u32 build_id_bin_size;
> +u32 build_id_lib_size;
> +
> +char build_id_bin[BUILD_ID_SIZE_MAX];
> +char build_id_lib[BUILD_ID_SIZE_MAX];
> +
> +long build_id_bin_err;
> +long build_id_lib_err;
> +
> +static int store_build_id(struct file *file, char *build_id, u32 *sz, long *err)
> +{
> +	struct build_id *bid;
> +
> +	bid = file->f_build_id;
> +	if (IS_ERR_OR_NULL(bid)) {

I think you might need to enable this also in the CI config:

   [...]
     CLNG-BPF [test_maps] btf_dump_test_case_multidim.bpf.o
     CLNG-BPF [test_maps] ima.bpf.o
     CLNG-BPF [test_maps] bpf_cubic.bpf.o
   progs/bpf_iter_task_vma_buildid.c:46:27: error: no member named 'f_build_id' in 'struct file'
           if (IS_ERR_OR_NULL(file->f_build_id)) {
                              ~~~~  ^
   progs/bpf_iter_task_vma_buildid.c:51:37: error: no member named 'f_build_id' in 'struct file'
                   __builtin_memcpy(&build_id, file->f_build_id, sizeof(*file->f_build_id));
                                               ~~~~  ^
   progs/bpf_iter_task_vma_buildid.c:51:63: error: no member named 'f_build_id' in 'struct file'
                   __builtin_memcpy(&build_id, file->f_build_id, sizeof(*file->f_build_id));
                                                                         ~~~~  ^
   3 errors generated.
   make: *** [Makefile:578: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf_iter_task_vma_buildid.bpf.o] Error 1
   make: *** Waiting for unfinished jobs....
   make: Leaving directory '/tmp/work/bpf/bpf/tools/testing/selftests/bpf'
   Error: Process completed with exit code 2.

Thanks,
Daniel