selftests/bpf: Ksyms_btf to test typed ksyms

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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-4-haoluo@google.com

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms.c b/tools/testing/selftests/bpf/prog_tests/ksyms.c
index b771804b23428503c2fcff67ce927288a633726a..b295969b263b3b6769cbcfcdd50ac8f63213869f 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/ksyms.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms.c
@@ -7,40 +7,28 @@
 
 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;
-
-       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(void)
 {
-       __u64 per_cpu_start_addr = kallsyms_find("__per_cpu_start");
-       __u64 link_fops_addr = kallsyms_find("bpf_link_fops");
        const char *btf_path = "/sys/kernel/btf/vmlinux";
        struct test_ksyms *skel;
        struct test_ksyms__data *data;
+       __u64 link_fops_addr, per_cpu_start_addr;
        struct stat st;
        __u64 btf_size;
        int err;
 
+       err = kallsyms_find("bpf_link_fops", &link_fops_addr);
+       if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+               return;
+       if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_link_fops' not found\n"))
+               return;
+
+       err = kallsyms_find("__per_cpu_start", &per_cpu_start_addr);
+       if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+               return;
+       if (CHECK(err == -ENOENT, "ksym_find", "symbol 'per_cpu_start' not found\n"))
+               return;
+
        if (CHECK(stat(btf_path, &st), "stat_btf", "err %d\n", errno))
                return;
        btf_size = st.st_size;

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 (file)
index 0000000..c6ef06c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -0,0 +1,70 @@
+// 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;
+
+void test_ksyms_btf(void)
+{
+       __u64 runqueues_addr, bpf_prog_active_addr;
+       struct test_ksyms_btf *skel = NULL;
+       struct test_ksyms_btf__data *data;
+       struct btf *btf;
+       int percpu_datasec;
+       int err;
+
+       err = kallsyms_find("runqueues", &runqueues_addr);
+       if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+               return;
+       if (CHECK(err == -ENOENT, "ksym_find", "symbol 'runqueues' not found\n"))
+               return;
+
+       err = kallsyms_find("bpf_prog_active", &bpf_prog_active_addr);
+       if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+               return;
+       if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_prog_active' not found\n"))
+               return;
+
+       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();
+               goto cleanup;
+       }
+
+       skel = test_ksyms_btf__open_and_load();
+       if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n"))
+               goto cleanup;
+
+       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_addr != runqueues_addr, "runqueues_addr",
+             "got %llu, exp %llu\n",
+             (unsigned long long)data->out__runqueues_addr,
+             (unsigned long long)runqueues_addr);
+       CHECK(data->out__bpf_prog_active_addr != bpf_prog_active_addr, "bpf_prog_active_addr",
+             "got %llu, exp %llu\n",
+             (unsigned long long)data->out__bpf_prog_active_addr,
+             (unsigned long long)bpf_prog_active_addr);
+
+cleanup:
+       btf__free(btf);
+       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 (file)
index 0000000..7dde208
--- /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_addr = -1;
+__u64 out__bpf_prog_active_addr = -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_addr = (__u64)&runqueues;
+       out__bpf_prog_active_addr = (__u64)&bpf_prog_active;
+
+       return 0;
+}
+
+char _license[] SEC("license") = "GPL";

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 4d0e913bbb227f057ac83811aa0ddf15e1dcdb83..1bbd1d9830c852b133ab164c3aa613e1986a7fa5 100644 (file)
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -90,6 +90,33 @@ long ksym_get_addr(const char *name)
        return 0;
 }
 
+/* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
+ * this is faster than load + find.
+ */
+int kallsyms_find(const char *sym, unsigned long long *addr)
+{
+       char type, name[500];
+       unsigned long long value;
+       int err = 0;
+       FILE *f;
+
+       f = fopen("/proc/kallsyms", "r");
+       if (!f)
+               return -EINVAL;
+
+       while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
+               if (strcmp(name, sym) == 0) {
+                       *addr = value;
+                       goto out;
+               }
+       }
+       err = -ENOENT;
+
+out:
+       fclose(f);
+       return err;
+}
+
 void read_trace_pipe(void)
 {
        int trace_fd;

diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 25ef597dd03fdb1264d4ebcdb12c28137f72def9..f62fdef9e589c14cdf1b796adca00a015448f0b3 100644 (file)
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -12,6 +12,10 @@ struct ksym {
 int load_kallsyms(void);
 struct ksym *ksym_search(long key);
 long ksym_get_addr(const char *name);
+
+/* open kallsyms and find addresses on the fly, faster than load + search. */
+int kallsyms_find(const char *sym, unsigned long long *addr);
+
 void read_trace_pipe(void);
 
 #endif