diff options
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/legacy_printk.c | 65 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_legacy_printk.c | 73 |
2 files changed, 138 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/legacy_printk.c b/tools/testing/selftests/bpf/prog_tests/legacy_printk.c new file mode 100644 index 000000000000..ec6e45f2a644 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/legacy_printk.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ +#include <test_progs.h> +#include "test_legacy_printk.skel.h" + +static int execute_one_variant(bool legacy) +{ + struct test_legacy_printk *skel; + int err, zero = 0, my_pid = getpid(), res, map_fd; + + skel = test_legacy_printk__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return -errno; + + bpf_program__set_autoload(skel->progs.handle_legacy, legacy); + bpf_program__set_autoload(skel->progs.handle_modern, !legacy); + + err = test_legacy_printk__load(skel); + /* no ASSERT_OK, we expect one of two variants can fail here */ + if (err) + goto err_out; + + if (legacy) { + map_fd = bpf_map__fd(skel->maps.my_pid_map); + err = bpf_map_update_elem(map_fd, &zero, &my_pid, BPF_ANY); + if (!ASSERT_OK(err, "my_pid_map_update")) + goto err_out; + err = bpf_map_lookup_elem(map_fd, &zero, &res); + } else { + skel->bss->my_pid_var = my_pid; + } + + err = test_legacy_printk__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto err_out; + + usleep(1); /* trigger */ + + if (legacy) { + map_fd = bpf_map__fd(skel->maps.res_map); + err = bpf_map_lookup_elem(map_fd, &zero, &res); + if (!ASSERT_OK(err, "res_map_lookup")) + goto err_out; + } else { + res = skel->bss->res_var; + } + + if (!ASSERT_GT(res, 0, "res")) { + err = -EINVAL; + goto err_out; + } + +err_out: + test_legacy_printk__destroy(skel); + return err; +} + +void test_legacy_printk(void) +{ + /* legacy variant should work everywhere */ + ASSERT_OK(execute_one_variant(true /* legacy */), "legacy_case"); + + /* execute modern variant, can fail the load on old kernels */ + execute_one_variant(false); +} diff --git a/tools/testing/selftests/bpf/progs/test_legacy_printk.c b/tools/testing/selftests/bpf/progs/test_legacy_printk.c new file mode 100644 index 000000000000..64c2d9ced529 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_legacy_printk.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ + +#include <linux/bpf.h> +#define BPF_NO_GLOBAL_DATA +#include <bpf/bpf_helpers.h> + +char LICENSE[] SEC("license") = "GPL"; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, int); + __uint(max_entries, 1); +} my_pid_map SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, int); + __uint(max_entries, 1); +} res_map SEC(".maps"); + +volatile int my_pid_var = 0; +volatile int res_var = 0; + +SEC("tp/raw_syscalls/sys_enter") +int handle_legacy(void *ctx) +{ + int zero = 0, *my_pid, cur_pid, *my_res; + + my_pid = bpf_map_lookup_elem(&my_pid_map, &zero); + if (!my_pid) + return 1; + + cur_pid = bpf_get_current_pid_tgid() >> 32; + if (cur_pid != *my_pid) + return 1; + + my_res = bpf_map_lookup_elem(&res_map, &zero); + if (!my_res) + return 1; + + if (*my_res == 0) + /* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to + * force .rodata.str1.1 section that previously caused + * problems on old kernels due to libbpf always tried to + * create a global data map for it + */ + bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid); + *my_res = 1; + + return *my_res; +} + +SEC("tp/raw_syscalls/sys_enter") +int handle_modern(void *ctx) +{ + int zero = 0, cur_pid; + + cur_pid = bpf_get_current_pid_tgid() >> 32; + if (cur_pid != my_pid_var) + return 1; + + if (res_var == 0) + /* we need bpf_printk() to validate libbpf logic around unused + * global maps and legacy kernels; see comment in handle_legacy() + */ + bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid); + res_var = 1; + + return res_var; +} |