From patchwork Thu Aug 24 06:34:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13363604 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12AF424522 for ; Thu, 24 Aug 2023 06:34:34 +0000 (UTC) Received: from 69-171-232-180.mail-mxout.facebook.com (69-171-232-180.mail-mxout.facebook.com [69.171.232.180]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4E21A8 for ; Wed, 23 Aug 2023 23:34:30 -0700 (PDT) Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 740D3254E5B42; Wed, 23 Aug 2023 23:34:17 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau , Dave Marchevsky Subject: [PATCH bpf-next v2 1/2] bpf: Remove a WARN_ON_ONCE warning related to local kptr Date: Wed, 23 Aug 2023 23:34:17 -0700 Message-Id: <20230824063417.201925-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_BLOCKED,RDNS_DYNAMIC,SPF_HELO_PASS,SPF_SOFTFAIL, TVD_RCVD_IP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net Currently, in function bpf_obj_free_fields(), for local kptr, a warning will be issued if the struct does not contain any special fields. But actually the kernel seems totally okay with a local kptr without any special fields. Permitting no special fields also aligns with future percpu kptr which also allows no special fields. Acked-by: Dave Marchevsky Signed-off-by: Yonghong Song --- kernel/bpf/syscall.c | 1 - 1 file changed, 1 deletion(-) NOTE: I didn't put a fix tag since except the warning there is no correctness issue here. diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 10666d17b9e3..ebeb0695305a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -657,7 +657,6 @@ void bpf_obj_free_fields(const struct btf_record *rec, void *obj) if (!btf_is_kernel(field->kptr.btf)) { pointee_struct_meta = btf_find_struct_meta(field->kptr.btf, field->kptr.btf_id); - WARN_ON_ONCE(!pointee_struct_meta); migrate_disable(); __bpf_obj_drop_impl(xchgd_field, pointee_struct_meta ? pointee_struct_meta->record : From patchwork Thu Aug 24 06:34:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13363605 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E47111C26 for ; Thu, 24 Aug 2023 06:34:38 +0000 (UTC) Received: from 66-220-155-178.mail-mxout.facebook.com (66-220-155-178.mail-mxout.facebook.com [66.220.155.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28399A8 for ; Wed, 23 Aug 2023 23:34:36 -0700 (PDT) Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 9A538254E5BB4; Wed, 23 Aug 2023 23:34:22 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau Subject: [PATCH bpf-next v2 2/2] selftests/bpf: Add a local kptr test with no special fields Date: Wed, 23 Aug 2023 23:34:22 -0700 Message-Id: <20230824063422.203097-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230824063417.201925-1-yonghong.song@linux.dev> References: <20230824063417.201925-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_BLOCKED,RDNS_DYNAMIC,SPF_HELO_PASS,SPF_SOFTFAIL, TVD_RCVD_IP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net Add a local kptr test with no special fields in the struct. Without the previous patch, the following warning will hit: [ 44.683877] WARNING: CPU: 3 PID: 485 at kernel/bpf/syscall.c:660 bpf_obj_free_fields+0x220/0x240 [ 44.684640] Modules linked in: bpf_testmod(OE) [ 44.685044] CPU: 3 PID: 485 Comm: kworker/u8:5 Tainted: G OE 6.5.0-rc5-01703-g260d855e9b90 #248 [ 44.685827] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 44.686693] Workqueue: events_unbound bpf_map_free_deferred [ 44.687297] RIP: 0010:bpf_obj_free_fields+0x220/0x240 [ 44.687775] Code: e8 55 17 1f 00 49 8b 74 24 08 4c 89 ef e8 e8 14 05 00 e8 a3 da e2 ff e9 55 fe ff ff 0f 0b e9 4e fe ff ff 0f 0b e9 47 fe ff ff <0f> 0b e8 d9 d9 e2 ff 31 f6 eb d5 48 83 c4 10 5b 41 5c e [ 44.689353] RSP: 0018:ffff888106467cb8 EFLAGS: 00010246 [ 44.689806] RAX: 0000000000000000 RBX: ffff888112b3a200 RCX: 0000000000000001 [ 44.690433] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffff8881128ad988 [ 44.691094] RBP: 0000000000000002 R08: ffffffff81370bd0 R09: 1ffff110216231a5 [ 44.691643] R10: dffffc0000000000 R11: ffffed10216231a6 R12: ffff88810d68a488 [ 44.692245] R13: ffff88810767c288 R14: ffff88810d68a400 R15: ffff88810d68a418 [ 44.692829] FS: 0000000000000000(0000) GS:ffff8881f7580000(0000) knlGS:0000000000000000 [ 44.693484] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 44.693964] CR2: 000055c7f2afce28 CR3: 000000010fee4002 CR4: 0000000000370ee0 [ 44.694513] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 44.695102] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 44.695747] Call Trace: [ 44.696001] [ 44.696183] ? __warn+0xfe/0x270 [ 44.696447] ? bpf_obj_free_fields+0x220/0x240 [ 44.696817] ? report_bug+0x220/0x2d0 [ 44.697180] ? handle_bug+0x3d/0x70 [ 44.697507] ? exc_invalid_op+0x1a/0x50 [ 44.697887] ? asm_exc_invalid_op+0x1a/0x20 [ 44.698282] ? btf_find_struct_meta+0xd0/0xd0 [ 44.698634] ? bpf_obj_free_fields+0x220/0x240 [ 44.699027] ? bpf_obj_free_fields+0x1e2/0x240 [ 44.699414] array_map_free+0x1a3/0x260 [ 44.699763] bpf_map_free_deferred+0x7b/0xe0 [ 44.700154] process_one_work+0x46d/0x750 [ 44.700523] worker_thread+0x49e/0x900 [ 44.700892] ? pr_cont_work+0x270/0x270 [ 44.701224] kthread+0x1ae/0x1d0 [ 44.701516] ? kthread_blkcg+0x50/0x50 [ 44.701860] ret_from_fork+0x34/0x50 [ 44.702178] ? kthread_blkcg+0x50/0x50 [ 44.702508] ret_from_fork_asm+0x11/0x20 [ 44.702880] With the previous patch, there is no warnings. Signed-off-by: Yonghong Song --- .../bpf/prog_tests/local_kptr_stash.c | 23 +++++++++++++++ .../selftests/bpf/progs/local_kptr_stash.c | 28 +++++++++++++++++++ 2 files changed, 51 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/local_kptr_stash.c b/tools/testing/selftests/bpf/prog_tests/local_kptr_stash.c index 158616c94658..b25b870f87ba 100644 --- a/tools/testing/selftests/bpf/prog_tests/local_kptr_stash.c +++ b/tools/testing/selftests/bpf/prog_tests/local_kptr_stash.c @@ -27,6 +27,27 @@ static void test_local_kptr_stash_simple(void) local_kptr_stash__destroy(skel); } +static void test_local_kptr_stash_plain(void) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts, + .data_in = &pkt_v4, + .data_size_in = sizeof(pkt_v4), + .repeat = 1, + ); + struct local_kptr_stash *skel; + int ret; + + skel = local_kptr_stash__open_and_load(); + if (!ASSERT_OK_PTR(skel, "local_kptr_stash__open_and_load")) + return; + + ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.stash_plain), &opts); + ASSERT_OK(ret, "local_kptr_stash_add_plain run"); + ASSERT_OK(opts.retval, "local_kptr_stash_add_plain retval"); + + local_kptr_stash__destroy(skel); +} + static void test_local_kptr_stash_unstash(void) { LIBBPF_OPTS(bpf_test_run_opts, opts, @@ -61,6 +82,8 @@ void test_local_kptr_stash(void) { if (test__start_subtest("local_kptr_stash_simple")) test_local_kptr_stash_simple(); + if (test__start_subtest("local_kptr_stash_plain")) + test_local_kptr_stash_plain(); if (test__start_subtest("local_kptr_stash_unstash")) test_local_kptr_stash_unstash(); if (test__start_subtest("local_kptr_stash_fail")) diff --git a/tools/testing/selftests/bpf/progs/local_kptr_stash.c b/tools/testing/selftests/bpf/progs/local_kptr_stash.c index 06838083079c..b567a666d2b8 100644 --- a/tools/testing/selftests/bpf/progs/local_kptr_stash.c +++ b/tools/testing/selftests/bpf/progs/local_kptr_stash.c @@ -14,10 +14,16 @@ struct node_data { struct bpf_rb_node node; }; +struct plain_local { + long key; + long data; +}; + struct map_value { struct prog_test_ref_kfunc *not_kptr; struct prog_test_ref_kfunc __kptr *val; struct node_data __kptr *node; + struct plain_local __kptr *plain; }; /* This is necessary so that LLVM generates BTF for node_data struct @@ -66,6 +72,28 @@ long stash_rb_nodes(void *ctx) return create_and_stash(0, 41) ?: create_and_stash(1, 42); } +SEC("tc") +long stash_plain(void *ctx) +{ + struct map_value *mapval; + struct plain_local *res; + int idx = 0; + + mapval = bpf_map_lookup_elem(&some_nodes, &idx); + if (!mapval) + return 1; + + res = bpf_obj_new(typeof(*res)); + if (!res) + return 1; + res->key = 41; + + res = bpf_kptr_xchg(&mapval->plain, res); + if (res) + bpf_obj_drop(res); + return 0; +} + SEC("tc") long unstash_rb_node(void *ctx) {