From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next 10/10] selftests/bpf: add libbpf's log fixup logic selftests
Date: Mon, 25 Apr 2022 17:45:11 -0700 [thread overview]
Message-ID: <20220426004511.2691730-11-andrii@kernel.org> (raw)
In-Reply-To: <20220426004511.2691730-1-andrii@kernel.org>
Add tests validating that libbpf is indeed patching up BPF verifier log
with CO-RE relocation details. Also test partial and full truncation
scenarios.
This test might be a bit fragile due to changing BPF verifier log
format. If that proves to be frequently breaking, we can simplify tests
or remove the truncation subtests. But for now it seems useful to test
it in those conditions that are otherwise rarely occuring in practice.
Also test CO-RE relo failure in a subprog as that excercises subprogram CO-RE
relocation mapping logic which doesn't work out of the box without extra
relo storage previously done only for gen_loader case.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../selftests/bpf/prog_tests/log_fixup.c | 114 ++++++++++++++++++
.../selftests/bpf/progs/test_log_fixup.c | 38 ++++++
tools/testing/selftests/bpf/test_progs.h | 11 ++
3 files changed, 163 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/log_fixup.c
create mode 100644 tools/testing/selftests/bpf/progs/test_log_fixup.c
diff --git a/tools/testing/selftests/bpf/prog_tests/log_fixup.c b/tools/testing/selftests/bpf/prog_tests/log_fixup.c
new file mode 100644
index 000000000000..be3a956cb3a5
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/log_fixup.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <bpf/btf.h>
+
+#include "test_log_fixup.skel.h"
+
+enum trunc_type {
+ TRUNC_NONE,
+ TRUNC_PARTIAL,
+ TRUNC_FULL,
+};
+
+static void bad_core_relo(size_t log_buf_size, enum trunc_type trunc_type)
+{
+ char log_buf[8 * 1024];
+ struct test_log_fixup* skel;
+ int err;
+
+ skel = test_log_fixup__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ bpf_program__set_autoload(skel->progs.bad_relo, true);
+ memset(log_buf, 0, sizeof(log_buf));
+ bpf_program__set_log_buf(skel->progs.bad_relo, log_buf, log_buf_size ?: sizeof(log_buf));
+
+ err = test_log_fixup__load(skel);
+ if (!ASSERT_ERR(err, "load_fail"))
+ goto cleanup;
+
+ ASSERT_HAS_SUBSTR(log_buf,
+ "0: <invalid CO-RE relocation>\n"
+ "failed to resolve CO-RE relocation <byte_sz> ",
+ "log_buf_part1");
+
+ switch (trunc_type) {
+ case TRUNC_NONE:
+ ASSERT_HAS_SUBSTR(log_buf,
+ "struct task_struct___bad.fake_field (0:1 @ offset 4)\n",
+ "log_buf_part2");
+ ASSERT_HAS_SUBSTR(log_buf,
+ "max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n",
+ "log_buf_end");
+ break;
+ case TRUNC_PARTIAL:
+ /* we should get full libbpf message patch */
+ ASSERT_HAS_SUBSTR(log_buf,
+ "struct task_struct___bad.fake_field (0:1 @ offset 4)\n",
+ "log_buf_part2");
+ /* we shouldn't get full end of BPF verifier log */
+ ASSERT_NULL(strstr(log_buf, "max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n"),
+ "log_buf_end");
+ break;
+ case TRUNC_FULL:
+ /* we shouldn't get second part of libbpf message patch */
+ ASSERT_NULL(strstr(log_buf, "struct task_struct___bad.fake_field (0:1 @ offset 4)\n"),
+ "log_buf_part2");
+ /* we shouldn't get full end of BPF verifier log */
+ ASSERT_NULL(strstr(log_buf, "max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n"),
+ "log_buf_end");
+ break;
+ }
+
+ if (env.verbosity > VERBOSE_NONE)
+ printf("LOG: \n=================\n%s=================\n", log_buf);
+cleanup:
+ test_log_fixup__destroy(skel);
+}
+
+static void bad_core_relo_subprog(void)
+{
+ char log_buf[8 * 1024];
+ struct test_log_fixup* skel;
+ int err;
+
+ skel = test_log_fixup__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ bpf_program__set_autoload(skel->progs.bad_relo_subprog, true);
+ bpf_program__set_log_buf(skel->progs.bad_relo_subprog, log_buf, sizeof(log_buf));
+
+ err = test_log_fixup__load(skel);
+ if (!ASSERT_ERR(err, "load_fail"))
+ goto cleanup;
+
+ /* there should be no prog loading log because we specified per-prog log buf */
+ ASSERT_HAS_SUBSTR(log_buf,
+ ": <invalid CO-RE relocation>\n"
+ "failed to resolve CO-RE relocation <byte_off> ",
+ "log_buf");
+ ASSERT_HAS_SUBSTR(log_buf,
+ "struct task_struct___bad.fake_field_subprog (0:2 @ offset 8)\n",
+ "log_buf");
+
+ if (env.verbosity > VERBOSE_NONE)
+ printf("LOG: \n=================\n%s=================\n", log_buf);
+
+cleanup:
+ test_log_fixup__destroy(skel);
+}
+
+void test_log_fixup(void)
+{
+ if (test__start_subtest("bad_core_relo_trunc_none"))
+ bad_core_relo(0, TRUNC_NONE /* full buf */);
+ if (test__start_subtest("bad_core_relo_trunc_partial"))
+ bad_core_relo(300, TRUNC_PARTIAL /* truncate original log a bit */);
+ if (test__start_subtest("bad_core_relo_trunc_full"))
+ bad_core_relo(250, TRUNC_FULL /* truncate also libbpf's message patch */);
+ if (test__start_subtest("bad_core_relo_subprog"))
+ bad_core_relo_subprog();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_log_fixup.c b/tools/testing/selftests/bpf/progs/test_log_fixup.c
new file mode 100644
index 000000000000..a78980d897b3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_log_fixup.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+struct task_struct___bad {
+ int pid;
+ int fake_field;
+ void *fake_field_subprog;
+} __attribute__((preserve_access_index));
+
+SEC("?raw_tp/sys_enter")
+int bad_relo(const void *ctx)
+{
+ static struct task_struct___bad *t;
+
+ return bpf_core_field_size(t->fake_field);
+}
+
+static __noinline int bad_subprog(void)
+{
+ static struct task_struct___bad *t;
+
+ /* ugliness below is a field offset relocation */
+ return (void *)&t->fake_field_subprog - (void *)t;
+}
+
+SEC("?raw_tp/sys_enter")
+int bad_relo_subprog(const void *ctx)
+{
+ static struct task_struct___bad *t;
+
+ return bad_subprog() + bpf_core_field_size(t->pid);
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 0a102ce460d6..d3fee3b98888 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -292,6 +292,17 @@ int test__join_cgroup(const char *path);
___ok; \
})
+#define ASSERT_HAS_SUBSTR(str, substr, name) ({ \
+ static int duration = 0; \
+ const char *___str = str; \
+ const char *___substr = substr; \
+ bool ___ok = strstr(___str, ___substr) != NULL; \
+ CHECK(!___ok, (name), \
+ "unexpected %s: '%s' is not a substring of '%s'\n", \
+ (name), ___substr, ___str); \
+ ___ok; \
+})
+
#define ASSERT_OK(res, name) ({ \
static int duration = 0; \
long long ___res = (res); \
--
2.30.2
next prev parent reply other threads:[~2022-04-26 0:45 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 0:45 [PATCH bpf-next 00/10] Teach libbpf to "fix up" BPF verifier log Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 01/10] libbpf: fix anonymous type check in CO-RE logic Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 02/10] libbpf: drop unhelpful "program too large" guess Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 03/10] libbpf: fix logic for finding matching program for CO-RE relocation Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 04/10] libbpf: avoid joining .BTF.ext data with BPF programs by section name Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 05/10] selftests/bpf: add CO-RE relos and SEC("?...") to linked_funcs selftests Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 06/10] libbpf: record subprog-resolved CO-RE relocations unconditionally Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 07/10] libbpf: refactor CO-RE relo human description formatting routine Andrii Nakryiko
2022-04-26 18:52 ` Alexei Starovoitov
2022-04-26 22:20 ` Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 08/10] libbpf: simplify bpf_core_parse_spec() signature Andrii Nakryiko
2022-04-26 0:45 ` [PATCH bpf-next 09/10] libbpf: fix up verifier log for unguarded failed CO-RE relos Andrii Nakryiko
2022-04-26 18:59 ` Alexei Starovoitov
2022-04-26 22:16 ` Andrii Nakryiko
2022-04-26 0:45 ` Andrii Nakryiko [this message]
2022-04-26 22:50 ` [PATCH bpf-next 00/10] Teach libbpf to "fix up" BPF verifier log patchwork-bot+netdevbpf
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