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. The BTF
data are taken from btf_data.o object rceated from
progs/btf_data.c.

Signed-off-by: Jiri Olsa <jo...@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  14 ++-
 .../selftests/bpf/prog_tests/resolve_btfids.c | 107 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/btf_data.c  |  26 +++++
 3 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
 create mode 100644 tools/testing/selftests/bpf/progs/btf_data.c

diff --git a/tools/testing/selftests/bpf/Makefile 
b/tools/testing/selftests/bpf/Makefile
index 1f9c696b3edf..2eae482b2713 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.
@@ -355,6 +365,7 @@ $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS)           
        \
                             | $(TRUNNER_BINARY)-extras
        $$(call msg,BINARY,,$$@)
        $$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
+       $(SCRATCH_DIR)/resolve_btfids --no-fail --btf btf_data.o $$@
 
 endef
 
@@ -365,7 +376,8 @@ 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_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
 TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
 TRUNNER_BPF_LDFLAGS := -mattr=+alu32
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..060264c96601
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/err.h>
+#include <string.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;
+
+struct symbol {
+       const char      *name;
+       int              type;
+       int              id;
+};
+
+struct symbol test_symbols[] = {
+       { "unused",  BTF_KIND_UNKN,     0 },
+       { "T",       BTF_KIND_TYPEDEF, -1 },
+       { "S",       BTF_KIND_STRUCT,  -1 },
+       { "U",       BTF_KIND_UNION,   -1 },
+       { "func",    BTF_KIND_FUNC,    -1 },
+};
+
+BTF_ID_LIST(test_list)
+BTF_ID_UNUSED
+BTF_ID(typedef, T)
+BTF_ID(struct,  S)
+BTF_ID(union,   U)
+BTF_ID(func,    func)
+
+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)
+{
+       struct btf *btf;
+       int type_id;
+       __u32 nr;
+
+       btf = btf__parse_elf("btf_data.o", NULL);
+       if (CHECK(libbpf_get_error(btf), "resolve",
+                 "Failed to load BTF from btf_data.o\n"))
+               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 ret;
+}
diff --git a/tools/testing/selftests/bpf/progs/btf_data.c 
b/tools/testing/selftests/bpf/progs/btf_data.c
new file mode 100644
index 000000000000..26b85f45e584
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf_data.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+struct S {
+       int     a;
+       int     b;
+       int     c;
+};
+
+union U {
+       int     a;
+       int     b;
+       int     c;
+};
+
+typedef int T;
+
+struct root_struct {
+       T               m_1;
+       struct S        m_2;
+       union U         m_3;
+};
+
+int func(struct root_struct *root)
+{
+       return 0;
+}
-- 
2.25.4

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