From b7ddfab20a6af3a0e366000eada63adf6a7683e7 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 19 Jun 2020 16:16:57 -0700 Subject: [PATCH] selftests/bpf: Add __ksym extern selftest Validate libbpf is able to handle weak and strong kernel symbol externs in BPF code correctly. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Reviewed-by: Hao Luo Link: https://lore.kernel.org/bpf/20200619231703.738941-4-andriin@fb.com --- .../testing/selftests/bpf/prog_tests/ksyms.c | 71 +++++++++++++++++++ .../testing/selftests/bpf/progs/test_ksyms.c | 32 +++++++++ 2 files changed, 103 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms.c create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms.c diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms.c b/tools/testing/selftests/bpf/prog_tests/ksyms.c new file mode 100644 index 000000000000..e3d6777226a8 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/ksyms.c @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ + +#include +#include "test_ksyms.skel.h" +#include + +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 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; + struct stat st; + __u64 btf_size; + int err; + + if (CHECK(stat(btf_path, &st), "stat_btf", "err %d\n", errno)) + return; + btf_size = st.st_size; + + skel = test_ksyms__open_and_load(); + if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n")) + return; + + err = test_ksyms__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__bpf_link_fops != link_fops_addr, "bpf_link_fops", + "got 0x%llx, exp 0x%llx\n", + data->out__bpf_link_fops, link_fops_addr); + CHECK(data->out__bpf_link_fops1 != 0, "bpf_link_fops1", + "got %llu, exp %llu\n", data->out__bpf_link_fops1, (__u64)0); + CHECK(data->out__btf_size != btf_size, "btf_size", + "got %llu, exp %llu\n", data->out__btf_size, btf_size); + CHECK(data->out__per_cpu_start != 0, "__per_cpu_start", + "got %llu, exp %llu\n", data->out__per_cpu_start, (__u64)0); + +cleanup: + test_ksyms__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_ksyms.c b/tools/testing/selftests/bpf/progs/test_ksyms.c new file mode 100644 index 000000000000..6c9cbb5a3bdf --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ksyms.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ + +#include +#include +#include + +__u64 out__bpf_link_fops = -1; +__u64 out__bpf_link_fops1 = -1; +__u64 out__btf_size = -1; +__u64 out__per_cpu_start = -1; + +extern const void bpf_link_fops __ksym; +extern const void __start_BTF __ksym; +extern const void __stop_BTF __ksym; +extern const void __per_cpu_start __ksym; +/* non-existing symbol, weak, default to zero */ +extern const void bpf_link_fops1 __ksym __weak; + +SEC("raw_tp/sys_enter") +int handler(const void *ctx) +{ + out__bpf_link_fops = (__u64)&bpf_link_fops; + out__btf_size = (__u64)(&__stop_BTF - &__start_BTF); + out__per_cpu_start = (__u64)&__per_cpu_start; + + out__bpf_link_fops1 = (__u64)&bpf_link_fops1; + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.20.1