On 03/01/2019 08:13 PM, Andrii Nakryiko wrote:

On Thu, Feb 28, 2019 at 3:32 PM Daniel Borkmann [off-list ref] wrote:

quoted

From: Joe Stringer <redacted>

Add tests for libbpf relocation of static variable references
into the .data, .rodata and .bss sections of the ELF. Tests with
different offsets are all passing:

  # ./test_progs
  [...]
  test_static_data_access:PASS:load program 0 nsec
  test_static_data_access:PASS:pass packet 278 nsec
  test_static_data_access:PASS:relocate .bss reference 1 278 nsec
  test_static_data_access:PASS:relocate .data reference 1 278 nsec
  test_static_data_access:PASS:relocate .rodata reference 1 278 nsec
  test_static_data_access:PASS:relocate .bss reference 2 278 nsec
  test_static_data_access:PASS:relocate .data reference 2 278 nsec
  test_static_data_access:PASS:relocate .rodata reference 2 278 nsec
  test_static_data_access:PASS:relocate .bss reference 3 278 nsec
  test_static_data_access:PASS:relocate .bss reference 4 278 nsec
  Summary: 223 PASSED, 0 FAILED

Joint work with Daniel Borkmann.

Signed-off-by: Joe Stringer <redacted>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 tools/testing/selftests/bpf/bpf_helpers.h     |  2 +-
 .../selftests/bpf/progs/test_global_data.c    | 61 +++++++++++++++++++
 tools/testing/selftests/bpf/test_progs.c      | 50 +++++++++++++++
 3 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_data.c

diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index d9999f1ed1d2..0463662935f9 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h

@@ -11,7 +11,7 @@
 /* helper functions called from eBPF programs written in C */
 static void *(*bpf_map_lookup_elem)(void *map, void *key) =
        (void *) BPF_FUNC_map_lookup_elem;
-static int (*bpf_map_update_elem)(void *map, void *key, void *value,
+static int (*bpf_map_update_elem)(void *map, const void *key, const void *value,
                                  unsigned long long flags) =
        (void *) BPF_FUNC_map_update_elem;
 static int (*bpf_map_delete_elem)(void *map, void *key) =

diff --git a/tools/testing/selftests/bpf/progs/test_global_data.c b/tools/testing/selftests/bpf/progs/test_global_data.c
new file mode 100644
index 000000000000..2a7cf40b8efb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_data.c

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Isovalent, Inc.
+
+#include <linux/bpf.h>
+#include <linux/pkt_cls.h>
+#include <string.h>
+
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") result = {
+       .type           = BPF_MAP_TYPE_ARRAY,
+       .key_size       = sizeof(__u32),
+       .value_size     = sizeof(__u64),
+       .max_entries    = 9,
+};
+
+static       __u64 static_bss     = 0;         /* Reloc reference to .bss  section   */
+static       __u64 static_data    = 42;                /* Reloc reference to .data section   */
+static const __u64 static_rodata  = 24;                /* Reloc reference to .rodata section */
+static       __u64 static_bss2    = 0;         /* Reloc reference to .bss  section   */
+static       __u64 static_data2   = 0xffeeff;  /* Reloc reference to .data section   */
+static const __u64 static_rodata2 = 0xabab;    /* Reloc reference to .rodata section */
+static const __u64 static_rodata3 = 0xab;      /* Reloc reference to .rodata section */

In the light of Yonghong's explanation about static vs non-static
globals, it would be nice to add test for non-static initialized
globals here as well?

Yes, agree, I'll add them as well and integrate the correct offset
for libbpf along with it.

Cheers,
Daniel