selftests/bpf: Add tests for libbpf-provided externs
Add a set of tests validating libbpf-provided extern variables. One crucial feature that's tested is dead code elimination together with using invalid BPF helper. CONFIG_MISSING is not supposed to exist and should always be specified by libbpf as zero, which allows BPF verifier to correctly do branch pruning and not fail validation, when invalid BPF helper is called from dead if branch. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014710.3449601-5-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
parent
2ad97d473d
commit
330a73a7b6
195
tools/testing/selftests/bpf/prog_tests/core_extern.c
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195
tools/testing/selftests/bpf/prog_tests/core_extern.c
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@ -0,0 +1,195 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <test_progs.h>
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#include <sys/mman.h>
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#include <sys/utsname.h>
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#include <linux/version.h>
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#include "test_core_extern.skel.h"
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static uint32_t get_kernel_version(void)
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{
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uint32_t major, minor, patch;
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struct utsname info;
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uname(&info);
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if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
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return 0;
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return KERNEL_VERSION(major, minor, patch);
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}
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#define CFG "CONFIG_BPF_SYSCALL=n\n"
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static struct test_case {
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const char *name;
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const char *cfg;
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const char *cfg_path;
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bool fails;
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struct test_core_extern__data data;
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} test_cases[] = {
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{ .name = "default search path", .cfg_path = NULL,
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.data = { .bpf_syscall = true } },
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{ .name = "/proc/config.gz", .cfg_path = "/proc/config.gz",
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.data = { .bpf_syscall = true } },
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{ .name = "missing config", .fails = true,
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.cfg_path = "/proc/invalid-config.gz" },
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{
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.name = "custom values",
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.cfg = "CONFIG_BPF_SYSCALL=y\n"
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"CONFIG_TRISTATE=m\n"
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"CONFIG_BOOL=y\n"
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"CONFIG_CHAR=100\n"
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"CONFIG_USHORT=30000\n"
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"CONFIG_INT=123456\n"
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"CONFIG_ULONG=0xDEADBEEFC0DE\n"
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"CONFIG_STR=\"abracad\"\n"
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"CONFIG_MISSING=0",
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.data = {
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.bpf_syscall = true,
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.tristate_val = TRI_MODULE,
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.bool_val = true,
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.char_val = 100,
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.ushort_val = 30000,
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.int_val = 123456,
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.ulong_val = 0xDEADBEEFC0DE,
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.str_val = "abracad",
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},
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},
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/* TRISTATE */
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{ .name = "tristate (y)", .cfg = CFG"CONFIG_TRISTATE=y\n",
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.data = { .tristate_val = TRI_YES } },
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{ .name = "tristate (n)", .cfg = CFG"CONFIG_TRISTATE=n\n",
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.data = { .tristate_val = TRI_NO } },
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{ .name = "tristate (m)", .cfg = CFG"CONFIG_TRISTATE=m\n",
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.data = { .tristate_val = TRI_MODULE } },
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{ .name = "tristate (int)", .fails = 1, .cfg = CFG"CONFIG_TRISTATE=1" },
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{ .name = "tristate (bad)", .fails = 1, .cfg = CFG"CONFIG_TRISTATE=M" },
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/* BOOL */
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{ .name = "bool (y)", .cfg = CFG"CONFIG_BOOL=y\n",
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.data = { .bool_val = true } },
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{ .name = "bool (n)", .cfg = CFG"CONFIG_BOOL=n\n",
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.data = { .bool_val = false } },
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{ .name = "bool (tristate)", .fails = 1, .cfg = CFG"CONFIG_BOOL=m" },
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{ .name = "bool (int)", .fails = 1, .cfg = CFG"CONFIG_BOOL=1" },
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/* CHAR */
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{ .name = "char (tristate)", .cfg = CFG"CONFIG_CHAR=m\n",
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.data = { .char_val = 'm' } },
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{ .name = "char (bad)", .fails = 1, .cfg = CFG"CONFIG_CHAR=q\n" },
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{ .name = "char (empty)", .fails = 1, .cfg = CFG"CONFIG_CHAR=\n" },
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{ .name = "char (str)", .fails = 1, .cfg = CFG"CONFIG_CHAR=\"y\"\n" },
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/* STRING */
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{ .name = "str (empty)", .cfg = CFG"CONFIG_STR=\"\"\n",
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.data = { .str_val = "\0\0\0\0\0\0\0" } },
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{ .name = "str (padded)", .cfg = CFG"CONFIG_STR=\"abra\"\n",
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.data = { .str_val = "abra\0\0\0" } },
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{ .name = "str (too long)", .cfg = CFG"CONFIG_STR=\"abracada\"\n",
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.data = { .str_val = "abracad" } },
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{ .name = "str (no value)", .fails = 1, .cfg = CFG"CONFIG_STR=\n" },
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{ .name = "str (bad value)", .fails = 1, .cfg = CFG"CONFIG_STR=bla\n" },
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/* INTEGERS */
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{
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.name = "integer forms",
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.cfg = CFG
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"CONFIG_CHAR=0xA\n"
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"CONFIG_USHORT=0462\n"
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"CONFIG_INT=-100\n"
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"CONFIG_ULONG=+1000000000000",
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.data = {
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.char_val = 0xA,
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.ushort_val = 0462,
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.int_val = -100,
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.ulong_val = 1000000000000,
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},
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},
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{ .name = "int (bad)", .fails = 1, .cfg = CFG"CONFIG_INT=abc" },
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{ .name = "int (str)", .fails = 1, .cfg = CFG"CONFIG_INT=\"abc\"" },
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{ .name = "int (empty)", .fails = 1, .cfg = CFG"CONFIG_INT=" },
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{ .name = "int (mixed)", .fails = 1, .cfg = CFG"CONFIG_INT=123abc" },
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{ .name = "int (max)", .cfg = CFG"CONFIG_INT=2147483647",
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.data = { .int_val = 2147483647 } },
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{ .name = "int (min)", .cfg = CFG"CONFIG_INT=-2147483648",
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.data = { .int_val = -2147483648 } },
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{ .name = "int (max+1)", .fails = 1, .cfg = CFG"CONFIG_INT=2147483648" },
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{ .name = "int (min-1)", .fails = 1, .cfg = CFG"CONFIG_INT=-2147483649" },
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{ .name = "ushort (max)", .cfg = CFG"CONFIG_USHORT=65535",
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.data = { .ushort_val = 65535 } },
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{ .name = "ushort (min)", .cfg = CFG"CONFIG_USHORT=0",
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.data = { .ushort_val = 0 } },
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{ .name = "ushort (max+1)", .fails = 1, .cfg = CFG"CONFIG_USHORT=65536" },
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{ .name = "ushort (min-1)", .fails = 1, .cfg = CFG"CONFIG_USHORT=-1" },
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{ .name = "u64 (max)", .cfg = CFG"CONFIG_ULONG=0xffffffffffffffff",
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.data = { .ulong_val = 0xffffffffffffffff } },
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{ .name = "u64 (min)", .cfg = CFG"CONFIG_ULONG=0",
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.data = { .ulong_val = 0 } },
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{ .name = "u64 (max+1)", .fails = 1, .cfg = CFG"CONFIG_ULONG=0x10000000000000000" },
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};
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BPF_EMBED_OBJ(core_extern, "test_core_extern.o");
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void test_core_extern(void)
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{
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const uint32_t kern_ver = get_kernel_version();
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int err, duration = 0, i, j;
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struct test_core_extern *skel = NULL;
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uint64_t *got, *exp;
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int n = sizeof(*skel->data) / sizeof(uint64_t);
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for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
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char tmp_cfg_path[] = "/tmp/test_core_extern_cfg.XXXXXX";
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struct test_case *t = &test_cases[i];
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DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
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.kconfig_path = t->cfg_path,
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);
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if (!test__start_subtest(t->name))
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continue;
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if (t->cfg) {
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size_t n = strlen(t->cfg) + 1;
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int fd = mkstemp(tmp_cfg_path);
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int written;
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if (CHECK(fd < 0, "mkstemp", "errno: %d\n", errno))
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continue;
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printf("using '%s' as config file\n", tmp_cfg_path);
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written = write(fd, t->cfg, n);
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close(fd);
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if (CHECK_FAIL(written != n))
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goto cleanup;
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opts.kconfig_path = tmp_cfg_path;
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}
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skel = test_core_extern__open_opts(&core_extern_embed, &opts);
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if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
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goto cleanup;
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err = test_core_extern__load(skel);
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if (t->fails) {
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CHECK(!err, "skel_load",
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"shouldn't succeed open/load of skeleton\n");
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goto cleanup;
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} else if (CHECK(err, "skel_load",
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"failed to open/load skeleton\n")) {
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goto cleanup;
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}
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err = test_core_extern__attach(skel);
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if (CHECK(err, "attach_raw_tp", "failed attach: %d\n", err))
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goto cleanup;
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usleep(1);
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t->data.kern_ver = kern_ver;
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t->data.missing_val = 0xDEADC0DE;
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got = (uint64_t *)skel->data;
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exp = (uint64_t *)&t->data;
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for (j = 0; j < n; j++) {
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CHECK(got[j] != exp[j], "check_res",
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"result #%d: expected %lx, but got %lx\n",
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j, exp[j], got[j]);
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}
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cleanup:
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if (t->cfg)
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unlink(tmp_cfg_path);
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test_core_extern__destroy(skel);
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skel = NULL;
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}
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}
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@ -17,11 +17,21 @@ void test_skeleton(void)
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int duration = 0, err;
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struct test_skeleton* skel;
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struct test_skeleton__bss *bss;
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struct test_skeleton__externs *exts;
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skel = test_skeleton__open_and_load(&skeleton_embed);
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skel = test_skeleton__open(&skeleton_embed);
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if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
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return;
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printf("EXTERNS BEFORE: %p\n", skel->externs);
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if (CHECK(skel->externs, "skel_externs", "externs are mmaped()!\n"))
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goto cleanup;
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err = test_skeleton__load(skel);
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if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err))
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goto cleanup;
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printf("EXTERNS AFTER: %p\n", skel->externs);
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bss = skel->bss;
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bss->in1 = 1;
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bss->in2 = 2;
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@ -29,6 +39,7 @@ void test_skeleton(void)
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bss->in4 = 4;
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bss->in5.a = 5;
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bss->in5.b = 6;
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exts = skel->externs;
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err = test_skeleton__attach(skel);
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if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
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@ -46,6 +57,11 @@ void test_skeleton(void)
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CHECK(bss->handler_out5.b != 6, "res6", "got %lld != exp %d\n",
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bss->handler_out5.b, 6);
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CHECK(bss->bpf_syscall != exts->CONFIG_BPF_SYSCALL, "ext1",
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"got %d != exp %d\n", bss->bpf_syscall, exts->CONFIG_BPF_SYSCALL);
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CHECK(bss->kern_ver != exts->LINUX_KERNEL_VERSION, "ext2",
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"got %d != exp %d\n", bss->kern_ver, exts->LINUX_KERNEL_VERSION);
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cleanup:
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test_skeleton__destroy(skel);
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}
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62
tools/testing/selftests/bpf/progs/test_core_extern.c
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62
tools/testing/selftests/bpf/progs/test_core_extern.c
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@ -0,0 +1,62 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <stdint.h>
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#include <stdbool.h>
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#include <linux/ptrace.h>
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#include <linux/bpf.h>
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#include "bpf_helpers.h"
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/* non-existing BPF helper, to test dead code elimination */
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static int (*bpf_missing_helper)(const void *arg1, int arg2) = (void *) 999;
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extern int LINUX_KERNEL_VERSION;
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extern bool CONFIG_BPF_SYSCALL; /* strong */
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extern enum libbpf_tristate CONFIG_TRISTATE __weak;
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extern bool CONFIG_BOOL __weak;
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extern char CONFIG_CHAR __weak;
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extern uint16_t CONFIG_USHORT __weak;
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extern int CONFIG_INT __weak;
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extern uint64_t CONFIG_ULONG __weak;
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extern const char CONFIG_STR[8] __weak;
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extern uint64_t CONFIG_MISSING __weak;
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uint64_t kern_ver = -1;
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uint64_t bpf_syscall = -1;
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uint64_t tristate_val = -1;
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uint64_t bool_val = -1;
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uint64_t char_val = -1;
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uint64_t ushort_val = -1;
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uint64_t int_val = -1;
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uint64_t ulong_val = -1;
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char str_val[8] = {-1, -1, -1, -1, -1, -1, -1, -1};
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uint64_t missing_val = -1;
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SEC("raw_tp/sys_enter")
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int handle_sys_enter(struct pt_regs *ctx)
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{
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int i;
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kern_ver = LINUX_KERNEL_VERSION;
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bpf_syscall = CONFIG_BPF_SYSCALL;
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tristate_val = CONFIG_TRISTATE;
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bool_val = CONFIG_BOOL;
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char_val = CONFIG_CHAR;
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ushort_val = CONFIG_USHORT;
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int_val = CONFIG_INT;
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ulong_val = CONFIG_ULONG;
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for (i = 0; i < sizeof(CONFIG_STR); i++) {
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str_val[i] = CONFIG_STR[i];
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}
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if (CONFIG_MISSING)
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/* invalid, but dead code - never executed */
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missing_val = bpf_missing_helper(ctx, 123);
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else
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missing_val = 0xDEADC0DE;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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@ -1,6 +1,7 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <stdbool.h>
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#include <linux/bpf.h>
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#include "bpf_helpers.h"
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@ -20,6 +21,10 @@ char out3 = 0;
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long long out4 = 0;
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int out1 = 0;
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extern bool CONFIG_BPF_SYSCALL;
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extern int LINUX_KERNEL_VERSION;
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bool bpf_syscall = 0;
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int kern_ver = 0;
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SEC("raw_tp/sys_enter")
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int handler(const void *ctx)
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@ -31,6 +36,10 @@ int handler(const void *ctx)
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out3 = in3;
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out4 = in4;
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out5 = in5;
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bpf_syscall = CONFIG_BPF_SYSCALL;
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kern_ver = LINUX_KERNEL_VERSION;
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return 0;
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}
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