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From: Hou Tao <hotforest@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org, houtao1@huawei.com,
	Zi Shen Lim <zlim.lnx@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH bpf-next v3 3/3] selftests/bpf: check whether s32 is sufficient for kfunc offset
Date: Sun, 30 Jan 2022 17:29:17 +0800	[thread overview]
Message-ID: <20220130092917.14544-4-hotforest@gmail.com> (raw)
In-Reply-To: <20220130092917.14544-1-hotforest@gmail.com>

From: Hou Tao <houtao1@huawei.com>

In add_kfunc_call(), bpf_kfunc_desc->imm with type s32 is used to
represent the offset of called kfunc from __bpf_call_base, so
add a test to ensure that the offset will not be overflowed.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 .../selftests/bpf/prog_tests/ksyms_module.c   | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
index 997aa90dea64..955a9ede4756 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
@@ -3,9 +3,49 @@
 
 #include <test_progs.h>
 #include <network_helpers.h>
+#include <trace_helpers.h>
 #include "test_ksyms_module.lskel.h"
 #include "test_ksyms_module.skel.h"
 
+/*
+ * Check whether or not s32 in bpf_kfunc_desc is sufficient
+ * to represent the offset between bpf_testmod_test_mod_kfunc
+ * and __bpf_call_base.
+ */
+static void test_ksyms_module_valid_offset(void)
+{
+	struct test_ksyms_module *skel;
+	unsigned long long kfunc_addr;
+	unsigned long long base_addr;
+	long long actual_offset;
+	int used_offset;
+	int err;
+
+	if (!env.has_testmod) {
+		test__skip();
+		return;
+	}
+
+	/* Ensure kfunc call is supported */
+	skel = test_ksyms_module__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "test_ksyms_module__open"))
+		return;
+
+	err = kallsyms_find("bpf_testmod_test_mod_kfunc", &kfunc_addr);
+	if (!ASSERT_OK(err, "find kfunc addr"))
+		goto cleanup;
+
+	err = kallsyms_find("__bpf_call_base", &base_addr);
+	if (!ASSERT_OK(err, "find base addr"))
+		goto cleanup;
+
+	used_offset = kfunc_addr - base_addr;
+	actual_offset = kfunc_addr - base_addr;
+	ASSERT_EQ((long long)used_offset, actual_offset, "kfunc offset overflowed");
+cleanup:
+	test_ksyms_module__destroy(skel);
+}
+
 static void test_ksyms_module_lskel(void)
 {
 	struct test_ksyms_module_lskel *skel;
@@ -55,6 +95,8 @@ static void test_ksyms_module_libbpf(void)
 
 void test_ksyms_module(void)
 {
+	if (test__start_subtest("valid_offset"))
+		test_ksyms_module_valid_offset();
 	if (test__start_subtest("lskel"))
 		test_ksyms_module_lskel();
 	if (test__start_subtest("libbpf"))
-- 
2.20.1


  parent reply	other threads:[~2022-01-30  9:30 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-30  9:29 [PATCH bpf-next v3 0/3] bpf, arm64: enable kfunc call Hou Tao
2022-01-30  9:29 ` [PATCH bpf-next v3 1/3] " Hou Tao
2022-02-04 15:42   ` Daniel Borkmann
2022-01-30  9:29 ` [PATCH bpf-next v3 2/3] selftests/bpf: do not export subtest as standalone test Hou Tao
2022-01-30  9:29 ` Hou Tao [this message]
2022-02-04 15:40 ` [PATCH bpf-next v3 0/3] bpf, arm64: enable kfunc call patchwork-bot+netdevbpf

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