Add selftests validating libbpf's auto-resizing of load/store instructions
when used with CO-RE relocations. An explicit and manual approach with using
bpf_core_read() is also demonstrated and tested. Separate BPF program is
supposed to fail due to using signed integers of sizes that differ from
kernel's sizes.
To reliably simulate 32-bit BTF (i.e., the one with sizeof(long) ==
sizeof(void *) == 4), selftest generates its own custom BTF and passes it as
a replacement for real kernel BTF. This allows to test 32/64-bitness mix on
all architectures.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
.../selftests/bpf/prog_tests/core_autosize.c | 199 ++++++++++++++++++
.../selftests/bpf/progs/test_core_autosize.c | 148 +++++++++++++
2 files changed, 347 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/core_autosize.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_autosize.c
diff --git a/tools/testing/selftests/bpf/prog_tests/core_autosize.c b/tools/testing/selftests/bpf/prog_tests/core_autosize.c
new file mode 100644
index 000000000000..2155c12bd83e
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/core_autosize.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include <test_progs.h>
+#include "test_core_autosize.skel.h"
+#include <bpf/btf.h>
+
+static int duration = 0;
+
+static struct {
+ unsigned long long ptr_samesized;
+ unsigned long long val1_samesized;
+ unsigned long long val2_samesized;
+ unsigned long long val3_samesized;
+ unsigned long long val4_samesized;
+
+ unsigned long long ptr_downsized;
+ unsigned long long val1_downsized;
+ unsigned long long val2_downsized;
+ unsigned long long val3_downsized;
+ unsigned long long val4_downsized;
+
+ unsigned long long ptr_probed;
+ unsigned long long val1_probed;
+ unsigned long long val2_probed;
+ unsigned long long val3_probed;
+ unsigned long long val4_probed;
+
+ unsigned long long ptr_signed;
+ unsigned long long val1_signed;
+ unsigned long long val2_signed;
+ unsigned long long val3_signed;
+ unsigned long long val4_signed;
+} out;
+
+void test_core_autosize(void)
+{
+ char btf_file[] = "/tmp/core_autosize.btf.XXXXXX";
+ int err, fd = -1, zero = 0;
+ int char_id, short_id, int_id, long_long_id, void_ptr_id, id;
+ struct test_core_autosize* skel = NULL;
+ struct bpf_object_load_attr load_attr = {};
+ struct bpf_program *prog;
+ struct bpf_map *bss_map;
+ struct btf *btf = NULL;
+ size_t written;
+ const void *raw_data;
+ __u32 raw_sz;
+ FILE *f = NULL;
+
+ btf = btf__new_empty();
+ if (!ASSERT_OK_PTR(btf, "empty_btf"))
+ return;
+ /* Emit the following struct with 32-bit pointer size:
+ *
+ * struct test_struct {
+ * void *ptr;
+ * unsigned long val2;
+ * unsigned long long val1;
+ * unsigned short val3;
+ * unsigned char val4;
+ * char: 8;
+ * };
+ *
+ * This struct is going to be used as the "kernel BTF" for this test.
+ */
+
+ /* force 32-bit pointer size */
+ btf__set_pointer_size(btf, 4);
+
+ char_id = btf__add_int(btf, "unsigned char", 1, 0);
+ ASSERT_EQ(char_id, 1, "char_id");
+ short_id = btf__add_int(btf, "unsigned short", 2, 0);
+ ASSERT_EQ(short_id, 2, "short_id");
+ /* "long unsigned int" of 4 byte size tells BTF that sizeof(void *) == 4 */
+ int_id = btf__add_int(btf, "long unsigned int", 4, 0);
+ ASSERT_EQ(int_id, 3, "int_id");
+ long_long_id = btf__add_int(btf, "unsigned long long", 8, 0);
+ ASSERT_EQ(long_long_id, 4, "long_long_id");
+ void_ptr_id = btf__add_ptr(btf, 0);
+ ASSERT_EQ(void_ptr_id, 5, "void_ptr_id");
+
+ id = btf__add_struct(btf, "test_struct", 20 /* bytes */);
+ ASSERT_EQ(id, 6, "struct_id");
+ err = btf__add_field(btf, "ptr", void_ptr_id, 0, 0);
+ err = err ?: btf__add_field(btf, "val2", int_id, 32, 0);
+ err = err ?: btf__add_field(btf, "val1", long_long_id, 64, 0);
+ err = err ?: btf__add_field(btf, "val3", short_id, 128, 0);
+ err = err ?: btf__add_field(btf, "val4", char_id, 144, 0);
+ ASSERT_OK(err, "struct_fields");
+
+ fd = mkstemp(btf_file);
+ if (CHECK(fd < 0, "btf_tmp", "failed to create file: %d\n", fd))
+ goto cleanup;
+ f = fdopen(fd, "w");
+ if (!ASSERT_OK_PTR(f, "btf_fdopen"))
+ goto cleanup;
+
+ raw_data = btf__get_raw_data(btf, &raw_sz);
+ if (!ASSERT_OK_PTR(raw_data, "raw_data"))
+ goto cleanup;
+ written = fwrite(raw_data, 1, raw_sz, f);
+ if (CHECK(written != raw_sz, "btf_write", "written: %zu, errno: %d\n", written, errno))
+ goto cleanup;
+ fflush(f);
+ fclose(f);
+ f = NULL;
+ close(fd);
+ fd = -1;
+
+ /* open and load BPF program with custom BTF as the kernel BTF */
+ skel = test_core_autosize__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ /* disable handle_signed() for now */
+ prog = bpf_object__find_program_by_name(skel->obj, "handle_signed");
+ if (!ASSERT_OK_PTR(prog, "prog_find"))
+ goto cleanup;
+ bpf_program__set_autoload(prog, false);
+
+ load_attr.obj = skel->obj;
+ load_attr.target_btf_path = btf_file;
+ err = bpf_object__load_xattr(&load_attr);
+ if (!ASSERT_OK(err, "prog_load"))
+ goto cleanup;
+
+ prog = bpf_object__find_program_by_name(skel->obj, "handle_samesize");
+ if (!ASSERT_OK_PTR(prog, "prog_find"))
+ goto cleanup;
+ skel->links.handle_samesize = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(skel->links.handle_samesize, "prog_attach"))
+ goto cleanup;
+
+ prog = bpf_object__find_program_by_name(skel->obj, "handle_downsize");
+ if (!ASSERT_OK_PTR(prog, "prog_find"))
+ goto cleanup;
+ skel->links.handle_downsize = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(skel->links.handle_downsize, "prog_attach"))
+ goto cleanup;
+
+ prog = bpf_object__find_program_by_name(skel->obj, "handle_probed");
+ if (!ASSERT_OK_PTR(prog, "prog_find"))
+ goto cleanup;
+ skel->links.handle_probed = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(skel->links.handle_probed, "prog_attach"))
+ goto cleanup;
+
+ usleep(1);
+
+ bss_map = bpf_object__find_map_by_name(skel->obj, "test_cor.bss");
+ if (!ASSERT_OK_PTR(bss_map, "bss_map_find"))
+ goto cleanup;
+
+ err = bpf_map_lookup_elem(bpf_map__fd(bss_map), &zero, (void *)&out);
+ if (!ASSERT_OK(err, "bss_lookup"))
+ goto cleanup;
+
+ ASSERT_EQ(out.ptr_samesized, 0x01020304, "ptr_samesized");
+ ASSERT_EQ(out.val1_samesized, 0x1020304050607080, "val1_samesized");
+ ASSERT_EQ(out.val2_samesized, 0x0a0b0c0d, "val2_samesized");
+ ASSERT_EQ(out.val3_samesized, 0xfeed, "val3_samesized");
+ ASSERT_EQ(out.val4_samesized, 0xb9, "val4_samesized");
+
+ ASSERT_EQ(out.ptr_downsized, 0x01020304, "ptr_downsized");
+ ASSERT_EQ(out.val1_downsized, 0x1020304050607080, "val1_downsized");
+ ASSERT_EQ(out.val2_downsized, 0x0a0b0c0d, "val2_downsized");
+ ASSERT_EQ(out.val3_downsized, 0xfeed, "val3_downsized");
+ ASSERT_EQ(out.val4_downsized, 0xb9, "val4_downsized");
+
+ ASSERT_EQ(out.ptr_probed, 0x01020304, "ptr_probed");
+ ASSERT_EQ(out.val1_probed, 0x1020304050607080, "val1_probed");
+ ASSERT_EQ(out.val2_probed, 0x0a0b0c0d, "val2_probed");
+ ASSERT_EQ(out.val3_probed, 0xfeed, "val3_probed");
+ ASSERT_EQ(out.val4_probed, 0xb9, "val4_probed");
+
+ test_core_autosize__destroy(skel);
+ skel = NULL;
+
+ /* now re-load with handle_signed() enabled, it should fail loading */
+ skel = test_core_autosize__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ load_attr.obj = skel->obj;
+ load_attr.target_btf_path = btf_file;
+ err = bpf_object__load_xattr(&load_attr);
+ if (!ASSERT_ERR(err, "bad_prog_load"))
+ goto cleanup;
+
+cleanup:
+ if (f)
+ fclose(f);
+ if (fd >= 0)
+ close(fd);
+ remove(btf_file);
+ btf__free(btf);
+ test_core_autosize__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_core_autosize.c b/tools/testing/selftests/bpf/progs/test_core_autosize.c
new file mode 100644
index 000000000000..1afeae83da1d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_autosize.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+/* fields of exactly the same size */
+struct test_struct___samesize {
+ void *ptr;
+ unsigned long long val1;
+ unsigned int val2;
+ unsigned short val3;
+ unsigned char val4;
+} __attribute((preserve_access_index));
+
+/* unsigned fields that have to be downsized by libbpf */
+struct test_struct___downsize {
+ void *ptr;
+ unsigned long val1;
+ unsigned long val2;
+ unsigned long val3;
+ unsigned long val4;
+ /* total sz: 40 */
+} __attribute__((preserve_access_index));
+
+/* fields with signed integers of wrong size, should be rejected */
+struct test_struct___signed {
+ void *ptr;
+ long val1;
+ long val2;
+ long val3;
+ long val4;
+} __attribute((preserve_access_index));
+
+/* real layout and sizes according to test's (32-bit) BTF */
+struct {
+ unsigned int ptr; /* can't use `void *`, it is always 8 byte in BPF target */
+ unsigned int val2;
+ unsigned long long val1;
+ unsigned short val3;
+ unsigned char val4;
+ unsigned char _pad;
+ /* total sz: 20 */
+} input = {
+ .ptr = 0x01020304,
+ .val1 = 0x1020304050607080,
+ .val2 = 0x0a0b0c0d,
+ .val3 = 0xfeed,
+ .val4 = 0xb9,
+ ._pad = 0xff, /* make sure no accidental zeros are present */
+};
+
+unsigned long long ptr_samesized = 0;
+unsigned long long val1_samesized = 0;
+unsigned long long val2_samesized = 0;
+unsigned long long val3_samesized = 0;
+unsigned long long val4_samesized = 0;
+
+unsigned long long ptr_downsized = 0;
+unsigned long long val1_downsized = 0;
+unsigned long long val2_downsized = 0;
+unsigned long long val3_downsized = 0;
+unsigned long long val4_downsized = 0;
+
+unsigned long long ptr_probed = 0;
+unsigned long long val1_probed = 0;
+unsigned long long val2_probed = 0;
+unsigned long long val3_probed = 0;
+unsigned long long val4_probed = 0;
+
+unsigned long long ptr_signed = 0;
+unsigned long long val1_signed = 0;
+unsigned long long val2_signed = 0;
+unsigned long long val3_signed = 0;
+unsigned long long val4_signed = 0;
+
+SEC("raw_tp/sys_exit")
+int handle_samesize(void *ctx)
+{
+ struct test_struct___samesize *in = (void *)&input;
+
+ ptr_samesized = (unsigned long long)in->ptr;
+ val1_samesized = in->val1;
+ val2_samesized = in->val2;
+ val3_samesized = in->val3;
+ val4_samesized = in->val4;
+
+ return 0;
+}
+
+SEC("raw_tp/sys_exit")
+int handle_downsize(void *ctx)
+{
+ struct test_struct___downsize *in = (void *)&input;
+
+ ptr_downsized = (unsigned long long)in->ptr;
+ val1_downsized = in->val1;
+ val2_downsized = in->val2;
+ val3_downsized = in->val3;
+ val4_downsized = in->val4;
+
+ return 0;
+}
+
+SEC("raw_tp/sys_enter")
+int handle_probed(void *ctx)
+{
+ struct test_struct___downsize *in = (void *)&input;
+ __u64 tmp;
+
+ tmp = 0;
+ bpf_core_read(&tmp, bpf_core_field_size(in->ptr), &in->ptr);
+ ptr_probed = tmp;
+
+ tmp = 0;
+ bpf_core_read(&tmp, bpf_core_field_size(in->val1), &in->val1);
+ val1_probed = tmp;
+
+ tmp = 0;
+ bpf_core_read(&tmp, bpf_core_field_size(in->val2), &in->val2);
+ val2_probed = tmp;
+
+ tmp = 0;
+ bpf_core_read(&tmp, bpf_core_field_size(in->val3), &in->val3);
+ val3_probed = tmp;
+
+ tmp = 0;
+ bpf_core_read(&tmp, bpf_core_field_size(in->val4), &in->val4);
+ val4_probed = tmp;
+
+ return 0;
+}
+
+SEC("raw_tp/sys_enter")
+int handle_signed(void *ctx)
+{
+ struct test_struct___signed *in = (void *)&input;
+
+ val2_signed = in->val2;
+ val3_signed = in->val3;
+ val4_signed = in->val4;
+
+ return 0;
+}
--
2.24.1
