On Sat, Aug 22, 2020 at 12:27 AM Hao Luo haoluo@google.com wrote:
On Fri, Aug 21, 2020 at 4:03 PM Andrii Nakryiko andrii.nakryiko@gmail.com wrote:
On Thu, Aug 20, 2020 at 10:32 AM Yonghong Song yhs@fb.com wrote:
On 8/19/20 3:40 PM, Hao Luo wrote:
Selftests for typed ksyms. Tests two types of ksyms: one is a struct, the other is a plain int. This tests two paths in the kernel. Struct ksyms will be converted into PTR_TO_BTF_ID by the verifier while int typed ksyms will be converted into PTR_TO_MEM.
Signed-off-by: Hao Luo haoluo@google.com
.../selftests/bpf/prog_tests/ksyms_btf.c | 77 +++++++++++++++++++ .../selftests/bpf/progs/test_ksyms_btf.c | 23 ++++++ 2 files changed, 100 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms_btf.c create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf.c
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c new file mode 100644 index 000000000000..1dad61ba7e99 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Google */
+#include <test_progs.h> +#include <bpf/libbpf.h> +#include <bpf/btf.h> +#include "test_ksyms_btf.skel.h"
+static int duration;
+static __u64 kallsyms_find(const char *sym) +{
char type, name[500];__u64 addr, res = 0;FILE *f;f = fopen("/proc/kallsyms", "r");if (CHECK(!f, "kallsyms_fopen", "failed to open: %d\n", errno))return 0;could you check whether libbpf API can provide this functionality for you? As far as I know, libbpf does parse /proc/kallsyms.
No need to use libbpf's implementation. We already have kallsyms_find() in prog_tests/ksyms.c and a combination of load_kallsyms() + ksym_get_addr() in trace_helpers.c. It would be good to switch to one implementation for both prog_tests/ksyms.c and this one.
Ack. I can do some refactoring. The least thing that I can do is moving kallsyms_find() to a header for both prog_tests/ksyms.c and this test to use.
Please no extra headers. Just put kallsyms_find() in trace_helpers.c, along other kallsyms-related functions.
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c new file mode 100644 index 000000000000..e04e31117f84 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Google */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+__u64 out__runqueues = -1; +__u64 out__bpf_prog_active = -1;
+extern const struct rq runqueues __ksym; /* struct type global var. */ +extern const int bpf_prog_active __ksym; /* int type global var. */
+SEC("raw_tp/sys_enter") +int handler(const void *ctx) +{
out__runqueues = (__u64)&runqueues;out__bpf_prog_active = (__u64)&bpf_prog_active;You didn't test accessing any of the members of runqueues, because BTF only has per-CPU variables, right? Adding global/static variables was adding too much data to BTF or something like that, is that right?
Right. With some experiments, I found the address of a percpu variable doesn't necessarily point to a valid structure. So it doesn't make sense to dereference runqueues and access its members. However, right now there are only percpu variables encoded in BTF, so I can't test accessing members of general global/static variables unfortunately.
Hao