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From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next 16/17] selftests/bpf: add global variables linking selftest
Date: Wed, 14 Apr 2021 13:01:45 -0700	[thread overview]
Message-ID: <20210414200146.2663044-17-andrii@kernel.org> (raw)
In-Reply-To: <20210414200146.2663044-1-andrii@kernel.org>

Add selftest validating various aspects of statically linking global
variables:
  - correct resolution of extern variables across .bss, .data, and .rodata
    sections;
  - correct handling of weak definitions;
  - correct de-duplication of repeating special externs (.kconfig, .ksyms).

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  3 +-
 .../selftests/bpf/prog_tests/linked_vars.c    | 43 +++++++++++++
 .../selftests/bpf/progs/linked_vars1.c        | 60 ++++++++++++++++++
 .../selftests/bpf/progs/linked_vars2.c        | 61 +++++++++++++++++++
 4 files changed, 166 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/linked_vars.c
 create mode 100644 tools/testing/selftests/bpf/progs/linked_vars1.c
 create mode 100644 tools/testing/selftests/bpf/progs/linked_vars2.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index c5d25aef1074..a690fd125c6d 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -303,10 +303,11 @@ endef
 
 SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
 
-LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h
+LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h linked_vars.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_vars.skel.h-deps := linked_vars1.o linked_vars2.o
 
 LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_vars.c b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
new file mode 100644
index 000000000000..4122ec330039
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <sys/syscall.h>
+#include "linked_vars.skel.h"
+
+void test_linked_vars(void)
+{
+	int err;
+	struct linked_vars* skel;
+
+	skel = linked_vars__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->bss->input_bss1 = 1000;
+	skel->bss->input_bss2 = 2000;
+	skel->bss->input_bss_weak = 3000;
+
+	err = linked_vars__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	err = linked_vars__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto cleanup;
+
+	/* trigger */
+	syscall(SYS_getpgid);
+
+	ASSERT_EQ(skel->bss->output_bss1, 1000 + 2000 + 3000, "output_bss1");
+	ASSERT_EQ(skel->bss->output_bss2, 1000 + 2000 + 3000, "output_bss2");
+	/* 10 comes from "winner" input_data_weak in first obj file */
+	ASSERT_EQ(skel->bss->output_data1, 1 + 2 + 10, "output_bss1");
+	ASSERT_EQ(skel->bss->output_data2, 1 + 2 + 10, "output_bss2");
+	/* 10 comes from "winner" input_rodata_weak in first obj file */
+	ASSERT_EQ(skel->bss->output_rodata1, 11 + 22 + 100 , "output_weak1");
+	ASSERT_EQ(skel->bss->output_rodata2, 11 + 22 + 100 , "output_weak2");
+
+cleanup:
+	linked_vars__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/linked_vars1.c b/tools/testing/selftests/bpf/progs/linked_vars1.c
new file mode 100644
index 000000000000..e3865047ed5d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars1.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* this weak extern will be strict due to the other file's strong extern */
+extern bool CONFIG_BPF_SYSCALL __kconfig __weak;
+extern const void bpf_link_fops __ksym __weak;
+/* make sure special extern funcs are handled as well */
+/* extern int bpf_kfunc_call_test2(struct sock *, __u32, __u32) __ksym; */
+
+/* static name conflicts are not handled by BPF skeleton well yet */
+/* static volatile int input_bss_static = 0; */
+
+int input_bss1 = 0;
+int input_data1 = 1;
+const volatile int input_rodata1 = 11;
+
+int input_bss_weak __weak = 0;
+/* these two definitions should win */
+int input_data_weak __weak = 10;
+const volatile int input_rodata_weak __weak = 100;
+
+extern int input_bss2;
+extern int input_data2;
+extern const int input_rodata2;
+
+int output_bss1 = 0;
+int output_data1 = 0;
+int output_rodata1 = 0;
+
+long output_sink1 = 0;
+
+static __noinline int get_bss_res(void)
+{
+	/* just make sure all the relocations work against .text as well */
+	return /*input_bss_static +*/ input_bss1 + input_bss2 + input_bss_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler1)
+{
+	output_bss1 = get_bss_res();
+	output_data1 = input_data1 + input_data2 + input_data_weak;
+	output_rodata1 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+	/* make sure we actually use above special externs, otherwise compiler
+	 * will optimize them out
+	 */
+	output_sink1 = LINUX_KERNEL_VERSION
+		       + CONFIG_BPF_SYSCALL
+		       + (long)&bpf_link_fops;
+		       /* + (long)&bpf_kfunc_call_test2; */
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_vars2.c b/tools/testing/selftests/bpf/progs/linked_vars2.c
new file mode 100644
index 000000000000..18880b54bc29
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars2.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* when an extern is defined as both strong and weak, resulting symbol will be strong */
+extern bool CONFIG_BPF_SYSCALL __kconfig;
+extern const void __start_BTF __ksym;
+/* make sure special extern funcs are handled as well */
+/*extern int bpf_kfunc_call_test2(struct sock *, __u32, __u32) __ksym;*/
+
+/* static naming conflicts are not handled by BPF skeleton yet */
+/* static volatile int input_bss_static = 0; */
+
+int input_bss2 = 0;
+int input_data2 = 2;
+const volatile int input_rodata2 = 22;
+
+int input_bss_weak __weak = 0;
+/* these two weak variables should lose */
+int input_data_weak __weak = 20;
+const volatile int input_rodata_weak __weak = 200;
+
+extern int input_bss1;
+extern int input_data1;
+extern const int input_rodata1;
+
+int output_bss2 = 0;
+int output_data2 = 0;
+int output_rodata2 = 0;
+
+int output_sink2 = 0;
+
+static __noinline int get_data_res(void)
+{
+	/* just make sure all the relocations work against .text as well */
+	return input_data1 + input_data2 + input_data_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler2)
+{
+	output_bss2 = /*input_bss_static +*/ input_bss1 + input_bss2 + input_bss_weak;
+	output_data2 = get_data_res();
+	output_rodata2 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+	/* make sure we actually use above special externs, otherwise compiler
+	 * will optimize them out
+	 */
+	output_sink2 = LINUX_KERNEL_VERSION
+		       + CONFIG_BPF_SYSCALL
+		       + (long)&__start_BTF;
+		       /*+ (long)&bpf_kfunc_call_test2;*/
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
-- 
2.30.2


  parent reply	other threads:[~2021-04-14 20:03 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14 20:01 [PATCH bpf-next 00/17] BPF static linker: support externs Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 01/17] bpftool: support dumping BTF VAR's "extern" linkage Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 02/17] bpftool: dump more info about DATASEC members Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 03/17] libbpf: suppress compiler warning when using SEC() macro with externs Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 04/17] libbpf: mark BPF subprogs with hidden visibility as static for BPF verifier Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 05/17] libbpf: allow gaps in BPF program sections to support overriden weak functions Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 06/17] libbpf: refactor BTF map definition parsing Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 07/17] libbpf: factor out symtab and relos sanity checks Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 08/17] libbpf: make few internal helpers available outside of libbpf.c Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 09/17] libbpf: extend sanity checking ELF symbols with externs validation Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 10/17] libbpf: tighten BTF type ID rewriting with error checking Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 11/17] libbpf: add linker extern resolution support for functions and global variables Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 12/17] libbpf: support extern resolution for BTF-defined maps in .maps section Andrii Nakryiko
2021-04-14 22:00   ` Alexei Starovoitov
2021-04-14 23:48     ` Andrii Nakryiko
2021-04-15  2:01       ` Alexei Starovoitov
2021-04-15 20:35         ` Andrii Nakryiko
2021-04-15 20:57           ` Alexei Starovoitov
2021-04-14 20:01 ` [PATCH bpf-next 13/17] selftests/bpf: use -O0 instead of -Og in selftests builds Andrii Nakryiko
2021-04-14 22:02   ` Alexei Starovoitov
2021-04-14 22:15   ` David Laight
2021-04-15  0:03     ` Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 14/17] selftests/bpf: omit skeleton generation for multi-linked BPF object files Andrii Nakryiko
2021-04-14 20:01 ` [PATCH bpf-next 15/17] selftests/bpf: add function linking selftest Andrii Nakryiko
2021-04-14 20:01 ` Andrii Nakryiko [this message]
2021-04-14 20:01 ` [PATCH bpf-next 17/17] sleftests/bpf: add map " Andrii Nakryiko
2021-04-15  0:21 ` [PATCH bpf-next 00/17] BPF static linker: support externs Andrii Nakryiko

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