From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E2BDC433ED for ; Fri, 16 Apr 2021 20:24:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1550D613CD for ; Fri, 16 Apr 2021 20:24:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343560AbhDPUZN convert rfc822-to-8bit (ORCPT ); Fri, 16 Apr 2021 16:25:13 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:41294 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343632AbhDPUZE (ORCPT ); Fri, 16 Apr 2021 16:25:04 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 13GKMacs024601 for ; Fri, 16 Apr 2021 13:24:39 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 37yb9y2drj-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 16 Apr 2021 13:24:39 -0700 Received: from intmgw002.25.frc3.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 16 Apr 2021 13:24:39 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id C03312ED4EE0; Fri, 16 Apr 2021 13:24:36 -0700 (PDT) From: Andrii Nakryiko To: , , , CC: , Subject: [PATCH v2 bpf-next 15/17] selftests/bpf: add function linking selftest Date: Fri, 16 Apr 2021 13:24:02 -0700 Message-ID: <20210416202404.3443623-16-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210416202404.3443623-1-andrii@kernel.org> References: <20210416202404.3443623-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: 1w7pdA6gzMoYlxFcGH9Z3FQ6NDvb_Pra X-Proofpoint-GUID: 1w7pdA6gzMoYlxFcGH9Z3FQ6NDvb_Pra X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-16_09:2021-04-16,2021-04-16 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 spamscore=0 priorityscore=1501 phishscore=0 adultscore=0 lowpriorityscore=0 bulkscore=0 mlxscore=0 suspectscore=0 impostorscore=0 mlxlogscore=999 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104160143 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Add selftest validating various aspects of statically linking functions: - no conflicts and correct resolution for name-conflicting static funcs; - correct resolution of extern functions; - correct handling of weak functions, both resolution itself and libbpf's handling of unused weak function that "lost" (it leaves gaps in code with no ELF symbols); - correct handling of hidden visibility to turn global function into "static" for the purpose of BPF verification. Signed-off-by: Andrii Nakryiko --- tools/testing/selftests/bpf/Makefile | 3 +- .../selftests/bpf/prog_tests/linked_funcs.c | 42 +++++++++++ .../selftests/bpf/progs/linked_funcs1.c | 73 +++++++++++++++++++ .../selftests/bpf/progs/linked_funcs2.c | 73 +++++++++++++++++++ 4 files changed, 190 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/linked_funcs.c create mode 100644 tools/testing/selftests/bpf/progs/linked_funcs1.c create mode 100644 tools/testing/selftests/bpf/progs/linked_funcs2.c diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 666b462c1218..427ccfec1a6a 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -308,9 +308,10 @@ endef SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c -LINKED_SKELS := test_static_linked.skel.h +LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o +linked_funcs.skel.h-deps := linked_funcs1.o linked_funcs2.o LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps))) diff --git a/tools/testing/selftests/bpf/prog_tests/linked_funcs.c b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c new file mode 100644 index 000000000000..03bf8ef131ce --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ + +#include +#include +#include "linked_funcs.skel.h" + +void test_linked_funcs(void) +{ + int err; + struct linked_funcs *skel; + + skel = linked_funcs__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + skel->rodata->my_tid = syscall(SYS_gettid); + skel->rodata->syscall_id = SYS_getpgid; + + err = linked_funcs__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto cleanup; + + err = linked_funcs__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto cleanup; + + /* trigger */ + syscall(SYS_getpgid); + + ASSERT_EQ(skel->bss->output_val1, 2000 + 2000, "output_val1"); + ASSERT_EQ(skel->bss->output_ctx1, SYS_getpgid, "output_ctx1"); + ASSERT_EQ(skel->bss->output_weak1, 42, "output_weak1"); + + ASSERT_EQ(skel->bss->output_val2, 2 * 1000 + 2 * (2 * 1000), "output_val2"); + ASSERT_EQ(skel->bss->output_ctx2, SYS_getpgid, "output_ctx2"); + /* output_weak2 should never be updated */ + ASSERT_EQ(skel->bss->output_weak2, 0, "output_weak2"); + +cleanup: + linked_funcs__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/linked_funcs1.c b/tools/testing/selftests/bpf/progs/linked_funcs1.c new file mode 100644 index 000000000000..cc621d4e4d82 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/linked_funcs1.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ + +#include "vmlinux.h" +#include +#include + +/* weak and shared between two files */ +const volatile int my_tid __weak = 0; +const volatile long syscall_id __weak = 0; + +int output_val1 = 0; +int output_ctx1 = 0; +int output_weak1 = 0; + +/* same "subprog" name in all files, but it's ok because they all are static */ +static __noinline int subprog(int x) +{ + /* but different formula */ + return x * 1; +} + +/* Global functions can't be void */ +int set_output_val1(int x) +{ + output_val1 = x + subprog(x); + return x; +} + +/* This function can't be verified as global, as it assumes raw_tp/sys_enter + * context and accesses syscall id (second argument). So we mark it as + * __hidden, so that libbpf will mark it as static in the final object file, + * right before verifying it in the kernel. + * + * But we don't mark it as __hidden here, rather at extern site. __hidden is + * "contaminating" visibility, so it will get propagated from either extern or + * actual definition (including from the losing __weak definition). + */ +void set_output_ctx1(__u64 *ctx) +{ + output_ctx1 = ctx[1]; /* long id, same as in BPF_PROG below */ +} + +/* this weak instance should win because it's the first one */ +__weak int set_output_weak(int x) +{ + output_weak1 = x; + return x; +} + +extern int set_output_val2(int x); + +/* here we'll force set_output_ctx2() to be __hidden in the final obj file */ +__hidden extern void set_output_ctx2(__u64 *ctx); + +SEC("raw_tp/sys_enter") +int BPF_PROG(handler1, struct pt_regs *regs, long id) +{ + if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id) + return 0; + + set_output_val2(1000); + set_output_ctx2(ctx); /* ctx definition is hidden in BPF_PROG macro */ + + /* keep input value the same across both files to avoid dependency on + * handler call order; differentiate by output_weak1 vs output_weak2. + */ + set_output_weak(42); + + return 0; +} + +char LICENSE[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/linked_funcs2.c b/tools/testing/selftests/bpf/progs/linked_funcs2.c new file mode 100644 index 000000000000..a5a935a4f748 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/linked_funcs2.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ + +#include "vmlinux.h" +#include +#include + +/* weak and shared between both files */ +const volatile int my_tid __weak = 0; +const volatile long syscall_id __weak = 0; + +int output_val2 = 0; +int output_ctx2 = 0; +int output_weak2 = 0; /* should stay zero */ + +/* same "subprog" name in all files, but it's ok because they all are static */ +static __noinline int subprog(int x) +{ + /* but different formula */ + return x * 2; +} + +/* Global functions can't be void */ +int set_output_val2(int x) +{ + output_val2 = 2 * x + 2 * subprog(x); + return 2 * x; +} + +/* This function can't be verified as global, as it assumes raw_tp/sys_enter + * context and accesses syscall id (second argument). So we mark it as + * __hidden, so that libbpf will mark it as static in the final object file, + * right before verifying it in the kernel. + * + * But we don't mark it as __hidden here, rather at extern site. __hidden is + * "contaminating" visibility, so it will get propagated from either extern or + * actual definition (including from the losing __weak definition). + */ +void set_output_ctx2(__u64 *ctx) +{ + output_ctx2 = ctx[1]; /* long id, same as in BPF_PROG below */ +} + +/* this weak instance should lose, because it will be processed second */ +__weak int set_output_weak(int x) +{ + output_weak2 = x; + return 2 * x; +} + +extern int set_output_val1(int x); + +/* here we'll force set_output_ctx1() to be __hidden in the final obj file */ +__hidden extern void set_output_ctx1(__u64 *ctx); + +SEC("raw_tp/sys_enter") +int BPF_PROG(handler2, struct pt_regs *regs, long id) +{ + if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id) + return 0; + + set_output_val1(2000); + set_output_ctx1(ctx); /* ctx definition is hidden in BPF_PROG macro */ + + /* keep input value the same across both files to avoid dependency on + * handler call order; differentiate by output_weak1 vs output_weak2. + */ + set_output_weak(42); + + return 0; +} + +char LICENSE[] SEC("license") = "GPL"; -- 2.30.2