Messages in this thread | | | Subject | Re: [PATCH bpf-next v1 5/8] bpf/selftests: ksyms_btf to test typed ksyms | From | Yonghong Song <> | Date | Thu, 20 Aug 2020 10:28:04 -0700 |
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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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