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    SubjectRe: [PATCH bpf-next v1 5/8] bpf/selftests: ksyms_btf to test typed ksyms
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    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";
    >

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