[PATCH v5 bpf-next 9/9] selftests/bpf: Add test for resolve_btfids

Jiri Olsa
2020-07-03T09:52:08Z

Adding resolve_btfids test under test_progs suite.

It's possible to use btf_ids.h header and its logic in
user space application, so we can add easy test for it.

The test defines BTF_ID_LIST and checks it gets properly
resolved.

For this reason the test_progs binary (and other binaries
that use TRUNNER* macros) is processed with resolve_btfids
tool, which resolves BTF IDs in .BTF.ids section.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/testing/selftests/bpf/Makefile | 22 ++-
.../selftests/bpf/prog_tests/resolve_btfids.c | 170 ++++++++++++++++++
2 files changed, 190 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/resolve_btfids.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 1f9c696b3edf..b47a685d12bd 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -190,6 +190,16 @@ else
cp "$(VMLINUX_H)" $@
endif

+$(SCRATCH_DIR)/resolve_btfids: $(BPFOBJ) \
+ $(TOOLSDIR)/bpf/resolve_btfids/main.c \
+ $(TOOLSDIR)/lib/rbtree.c \
+ $(TOOLSDIR)/lib/zalloc.c \
+ $(TOOLSDIR)/lib/string.c \
+ $(TOOLSDIR)/lib/ctype.c \
+ $(TOOLSDIR)/lib/str_error_r.c
+ $(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/resolve_btfids \
+ OUTPUT=$(SCRATCH_DIR)/ BPFOBJ=$(BPFOBJ)
+
# Get Clang's default includes on this system, as opposed to those seen by
# '-target bpf'. This fixes "missing" files on some architectures/distros,
# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
@@ -333,7 +343,8 @@ $(TRUNNER_TEST_OBJS): $(TRUNNER_OUTPUT)/%.test.o: \
$(TRUNNER_BPF_SKELS) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
$$(call msg,TEST-OBJ,$(TRUNNER_BINARY),$$@)
- cd $$(@D) && $$(CC) -I. $$(CFLAGS) -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)
+ cd $$(@D) && $$(CC) -I. $$(CFLAGS) $(TRUNNER_EXTRA_CFLAGS) \
+ -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F)

$(TRUNNER_EXTRA_OBJS): $(TRUNNER_OUTPUT)/%.o: \
%.c \
@@ -355,6 +366,7 @@ $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS) \
| $(TRUNNER_BINARY)-extras
$$(call msg,BINARY,,$$@)
$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
+ $(TRUNNER_BINARY_EXTRA_CMD)

endef

@@ -365,7 +377,10 @@ TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \
network_helpers.c testing_helpers.c \
flow_dissector_load.h
TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read \
- $(wildcard progs/btf_dump_test_case_*.c)
+ $(wildcard progs/btf_dump_test_case_*.c) \
+ $(SCRATCH_DIR)/resolve_btfids
+TRUNNER_EXTRA_CFLAGS := -D"BUILD_STR(s)=\#s" -DVMLINUX_BTF="BUILD_STR($(VMLINUX_BTF))"
+TRUNNER_BINARY_EXTRA_CMD := $(SCRATCH_DIR)/resolve_btfids --btf $(VMLINUX_BTF) test_progs
TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
TRUNNER_BPF_LDFLAGS := -mattr=+alu32
@@ -373,6 +388,7 @@ $(eval $(call DEFINE_TEST_RUNNER,test_progs))

# Define test_progs-no_alu32 test runner.
TRUNNER_BPF_BUILD_RULE := CLANG_NOALU32_BPF_BUILD_RULE
+TRUNNER_BINARY_EXTRA_CMD := $(SCRATCH_DIR)/resolve_btfids --btf $(VMLINUX_BTF) test_progs-no_alu32
TRUNNER_BPF_LDFLAGS :=
$(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))

@@ -392,6 +408,8 @@ TRUNNER_EXTRA_FILES :=
TRUNNER_BPF_BUILD_RULE := $$(error no BPF objects should be built)
TRUNNER_BPF_CFLAGS :=
TRUNNER_BPF_LDFLAGS :=
+TRUNNER_EXTRA_CFLAGS :=
+TRUNNER_BINARY_EXTRA_CMD :=
$(eval $(call DEFINE_TEST_RUNNER,test_maps))

# Define test_verifier test runner.
diff --git a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
new file mode 100644
index 000000000000..6b7b5f736181
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <linux/err.h>
+#include <stdlib.h>
+#include <bpf/btf.h>
+#include <bpf/libbpf.h>
+#include <linux/btf.h>
+#include <linux/kernel.h>
+#include <linux/btf_ids.h>
+#include "test_progs.h"
+
+static int duration;
+
+static struct btf *btf__parse_raw(const char *file)
+{
+ struct btf *btf;
+ struct stat st;
+ __u8 *buf;
+ FILE *f;
+
+ if (stat(file, &st))
+ return NULL;
+
+ f = fopen(file, "rb");
+ if (!f)
+ return NULL;
+
+ buf = malloc(st.st_size);
+ if (!buf) {
+ btf = ERR_PTR(-ENOMEM);
+ goto exit_close;
+ }
+
+ if ((size_t) st.st_size != fread(buf, 1, st.st_size, f)) {
+ btf = ERR_PTR(-EINVAL);
+ goto exit_free;
+ }
+
+ btf = btf__new(buf, st.st_size);
+
+exit_free:
+ free(buf);
+exit_close:
+ fclose(f);
+ return btf;
+}
+
+static bool is_btf_raw(const char *file)
+{
+ __u16 magic = 0;
+ int fd, nb_read;
+
+ fd = open(file, O_RDONLY);
+ if (fd < 0)
+ return false;
+
+ nb_read = read(fd, &magic, sizeof(magic));
+ close(fd);
+ return nb_read == sizeof(magic) && magic == BTF_MAGIC;
+}
+
+static struct btf *btf_open(const char *path)
+{
+ if (is_btf_raw(path))
+ return btf__parse_raw(path);
+ else
+ return btf__parse_elf(path, NULL);
+}
+
+BTF_ID_LIST(test_list)
+BTF_ID_UNUSED
+BTF_ID(typedef, pid_t)
+BTF_ID(struct, sk_buff)
+BTF_ID(union, thread_union)
+BTF_ID(func, memcpy)
+
+struct symbol {
+ const char *name;
+ int type;
+ int id;
+};
+
+struct symbol test_symbols[] = {
+ { "unused", -1, 0 },
+ { "pid_t", BTF_KIND_TYPEDEF, -1 },
+ { "sk_buff", BTF_KIND_STRUCT, -1 },
+ { "thread_union", BTF_KIND_UNION, -1 },
+ { "memcpy", BTF_KIND_FUNC, -1 },
+};
+
+static int
+__resolve_symbol(struct btf *btf, int type_id)
+{
+ const struct btf_type *type;
+ const char *str;
+ unsigned int i;
+
+ type = btf__type_by_id(btf, type_id);
+ if (!type) {
+ PRINT_FAIL("Failed to get type for ID %d\n", type_id);
+ return -1;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(test_symbols); i++) {
+ if (test_symbols[i].id != -1)
+ continue;
+
+ if (BTF_INFO_KIND(type->info) != test_symbols[i].type)
+ continue;
+
+ str = btf__name_by_offset(btf, type->name_off);
+ if (!str) {
+ PRINT_FAIL("Failed to get name for BTF ID %d\n", type_id);
+ return -1;
+ }
+
+ if (!strcmp(str, test_symbols[i].name))
+ test_symbols[i].id = type_id;
+ }
+
+ return 0;
+}
+
+static int resolve_symbols(void)
+{
+ const char *path = VMLINUX_BTF;
+ struct btf *btf;
+ int type_id;
+ __u32 nr;
+
+ btf = btf_open(path);
+ if (CHECK(libbpf_get_error(btf), "resolve",
+ "Failed to load BTF from %s\n", path))
+ return -1;
+
+ nr = btf__get_nr_types(btf);
+
+ for (type_id = 1; type_id <= nr; type_id++) {
+ if (__resolve_symbol(btf, type_id))
+ break;
+ }
+
+ btf__free(btf);
+ return 0;
+}
+
+int test_resolve_btfids(void)
+{
+ unsigned int i;
+ int ret = 0;
+
+ if (resolve_symbols())
+ return -1;
+
+ /* Check BTF_ID_LIST(test_list) IDs */
+ for (i = 0; i < ARRAY_SIZE(test_symbols) && !ret; i++) {
+ ret = CHECK(test_list[i] != test_symbols[i].id,
+ "id_check",
+ "wrong ID for %s (%d != %d)\n", test_symbols[i].name,
+ test_list[i], test_symbols[i].id);
+ }
+
+ return 0;
+}
--
2.25.4