selftests/bpf: add CO-RE relocs ptr-as-array tests

Add test validating correct relocation handling for cases where pointer
to something is used as an array. E.g.:

  int *ptr = ...;
  int x = ptr[42];

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index 9dadf46..2cfe0bd 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -129,6 +129,22 @@
        .output_len = sizeof(struct core_reloc_mods_output),            \
 }
 
+#define PTR_AS_ARR_CASE(name) {                                                \
+       .case_name = #name,                                             \
+       .bpf_obj_file = "test_core_reloc_ptr_as_arr.o",                 \
+       .btf_src_file = "btf__core_reloc_" #name ".o",                  \
+       .input = (const char *)&(struct core_reloc_##name []){          \
+               { .a = 1 },                                             \
+               { .a = 2 },                                             \
+               { .a = 3 },                                             \
+       },                                                              \
+       .input_len = 3 * sizeof(struct core_reloc_##name),              \
+       .output = STRUCT_TO_CHAR_PTR(core_reloc_ptr_as_arr) {           \
+               .a = 3,                                                 \
+       },                                                              \
+       .output_len = sizeof(struct core_reloc_ptr_as_arr),             \
+}
+
 struct core_reloc_test_case {
        const char *case_name;
        const char *bpf_obj_file;
@@ -200,6 +216,10 @@ static struct core_reloc_test_case test_cases[] = {
        MODS_CASE(mods),
        MODS_CASE(mods___mod_swap),
        MODS_CASE(mods___typedefs),
+
+       /* handling "ptr is an array" semantics */
+       PTR_AS_ARR_CASE(ptr_as_arr),
+       PTR_AS_ARR_CASE(ptr_as_arr___diff_sz),
 };
 
 struct data {

diff --git a/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr.c b/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr.c
new file mode 100644 (file)
index 0000000..8da5243
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr.c
@@ -0,0 +1,3 @@
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_ptr_as_arr x) {}

diff --git a/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr___diff_sz.c b/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr___diff_sz.c
new file mode 100644 (file)
index 0000000..003acfc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr___diff_sz.c
@@ -0,0 +1,3 @@
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_ptr_as_arr___diff_sz x) {}

diff --git a/tools/testing/selftests/bpf/progs/core_reloc_types.h b/tools/testing/selftests/bpf/progs/core_reloc_types.h
index 3401e83..c17c927 100644 (file)
--- a/tools/testing/selftests/bpf/progs/core_reloc_types.h
+++ b/tools/testing/selftests/bpf/progs/core_reloc_types.h
@@ -526,3 +526,16 @@ struct core_reloc_mods___typedefs {
        int3_t b;
        int3_t a;
 };
+
+/*
+ * PTR_AS_ARR
+ */
+struct core_reloc_ptr_as_arr {
+       int a;
+};
+
+struct core_reloc_ptr_as_arr___diff_sz {
+       int :32; /* padding */
+       char __some_more_padding;
+       int a;
+};

diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_ptr_as_arr.c b/tools/testing/selftests/bpf/progs/test_core_reloc_ptr_as_arr.c
new file mode 100644 (file)
index 0000000..526b7dd
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_ptr_as_arr.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+static volatile struct data {
+       char in[256];
+       char out[256];
+} data;
+
+struct core_reloc_ptr_as_arr {
+       int a;
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_ptr_as_arr(void *ctx)
+{
+       struct core_reloc_ptr_as_arr *in = (void *)&data.in;
+       struct core_reloc_ptr_as_arr *out = (void *)&data.out;
+
+       if (BPF_CORE_READ(&out->a, &in[2].a))
+               return 1;
+
+       return 0;
+}
+