Re: [PATCH bpf-next v1 5/8] bpf/selftests: ksyms_btf to test typed ksyms

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.

• while (fscanf(f, "%llx %c %499s%*[^\n]\n", &addr, &type, name) > 0) {

• if (strcmp(name, sym) == 0) {
  

• 	res = addr;
  

• 	goto out;
  

• }
  

• }
• CHECK(false, "not_found", "symbol %s not found\n", sym);

+out:

• fclose(f);
• return res;

+}

+void test_ksyms_btf(void) +{

• __u64 runqueues_addr = kallsyms_find("runqueues");
• __u64 bpf_prog_active_addr = kallsyms_find("bpf_prog_active");
• struct test_ksyms_btf *skel;
• struct test_ksyms_btf__data *data;
• struct btf *btf;
• int percpu_datasec;
• int err;
• btf = libbpf_find_kernel_btf();
• if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n",

•   PTR_ERR(btf)))
  

• return;
  

• percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu",

• 				BTF_KIND_DATASEC);
  

• if (percpu_datasec < 0) {

• printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n",
  

•        __func__);
  

• test__skip();
  

• return;
  

• }
• skel = test_ksyms_btf__open_and_load();
• if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n"))

• return;
  

• err = test_ksyms_btf__attach(skel);
• if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))

• goto cleanup;
  

• /* trigger tracepoint */
• usleep(1);
• data = skel->data;
• CHECK(data->out__runqueues != runqueues_addr, "runqueues",

•      "got %llu, exp %llu\n", data->out__runqueues, runqueues_addr);
  

• CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active",

•      "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr);
  

+cleanup:

• test_ksyms_btf__destroy(skel);

+} 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;
• return 0;

+}

+char _license[] SEC("license") = "GPL";