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Subject[PATCH v7 bpf-next 4/8] selftests/bpf: add bpf_snprintf_btf helper tests
Date
Tests verifying snprintf()ing of various data structures,
flags combinations using a tp_btf program. Tests are skipped
if __builtin_btf_type_id is not available to retrieve BTF
type ids.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
.../selftests/bpf/prog_tests/snprintf_btf.c | 60 +++++
.../selftests/bpf/progs/netif_receive_skb.c | 249 +++++++++++++++++++++
2 files changed, 309 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf_btf.c
create mode 100644 tools/testing/selftests/bpf/progs/netif_receive_skb.c

diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf_btf.c b/tools/testing/selftests/bpf/prog_tests/snprintf_btf.c
new file mode 100644
index 0000000..3a8ecf8
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/snprintf_btf.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <linux/btf.h>
+#include "netif_receive_skb.skel.h"
+
+/* Demonstrate that bpf_snprintf_btf succeeds and that various data types
+ * are formatted correctly.
+ */
+void test_snprintf_btf(void)
+{
+ struct netif_receive_skb *skel;
+ struct netif_receive_skb__bss *bss;
+ int err, duration = 0;
+
+ skel = netif_receive_skb__open();
+ if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+ return;
+
+ err = netif_receive_skb__load(skel);
+ if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err))
+ goto cleanup;
+
+ bss = skel->bss;
+
+ err = netif_receive_skb__attach(skel);
+ if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+ goto cleanup;
+
+ /* generate receive event */
+ system("ping -c 1 127.0.0.1 > /dev/null");
+
+ if (bss->skip) {
+ printf("%s:SKIP:no __builtin_btf_type_id\n", __func__);
+ test__skip();
+ goto cleanup;
+ }
+
+ /*
+ * Make sure netif_receive_skb program was triggered
+ * and it set expected return values from bpf_trace_printk()s
+ * and all tests ran.
+ */
+ if (CHECK(bss->ret <= 0,
+ "bpf_snprintf_btf: got return value",
+ "ret <= 0 %ld test %d\n", bss->ret, bss->ran_subtests))
+ goto cleanup;
+
+ if (CHECK(bss->ran_subtests == 0, "check if subtests ran",
+ "no subtests ran, did BPF program run?"))
+ goto cleanup;
+
+ if (CHECK(bss->num_subtests != bss->ran_subtests,
+ "check all subtests ran",
+ "only ran %d of %d tests\n", bss->num_subtests,
+ bss->ran_subtests))
+ goto cleanup;
+
+cleanup:
+ netif_receive_skb__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/netif_receive_skb.c b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
new file mode 100644
index 0000000..b873d80
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020, Oracle and/or its affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+#include <errno.h>
+
+long ret = 0;
+int num_subtests = 0;
+int ran_subtests = 0;
+bool skip = false;
+
+#define STRSIZE 2048
+#define EXPECTED_STRSIZE 256
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, char[STRSIZE]);
+} strdata SEC(".maps");
+
+static int __strncmp(const void *m1, const void *m2, size_t len)
+{
+ const unsigned char *s1 = m1;
+ const unsigned char *s2 = m2;
+ int i, delta = 0;
+
+ for (i = 0; i < len; i++) {
+ delta = s1[i] - s2[i];
+ if (delta || s1[i] == 0 || s2[i] == 0)
+ break;
+ }
+ return delta;
+}
+
+#if __has_builtin(__builtin_btf_type_id)
+#define TEST_BTF(_str, _type, _flags, _expected, ...) \
+ do { \
+ static const char _expectedval[EXPECTED_STRSIZE] = \
+ _expected; \
+ static const char _ptrtype[64] = #_type; \
+ __u64 _hflags = _flags | BTF_F_COMPACT; \
+ static _type _ptrdata = __VA_ARGS__; \
+ static struct btf_ptr _ptr = { }; \
+ int _cmp; \
+ \
+ ++num_subtests; \
+ if (ret < 0) \
+ break; \
+ ++ran_subtests; \
+ _ptr.ptr = &_ptrdata; \
+ _ptr.type_id = bpf_core_type_id_kernel(_type); \
+ if (_ptr.type_id <= 0) { \
+ ret = -EINVAL; \
+ break; \
+ } \
+ ret = bpf_snprintf_btf(_str, STRSIZE, \
+ &_ptr, sizeof(_ptr), _hflags); \
+ if (ret) \
+ break; \
+ _cmp = __strncmp(_str, _expectedval, EXPECTED_STRSIZE); \
+ if (_cmp != 0) { \
+ bpf_printk("(%d) got %s", _cmp, _str); \
+ bpf_printk("(%d) expected %s", _cmp, \
+ _expectedval); \
+ ret = -EBADMSG; \
+ break; \
+ } \
+ } while (0)
+#endif
+
+/* Use where expected data string matches its stringified declaration */
+#define TEST_BTF_C(_str, _type, _flags, ...) \
+ TEST_BTF(_str, _type, _flags, "(" #_type ")" #__VA_ARGS__, \
+ __VA_ARGS__)
+
+/* TRACE_EVENT(netif_receive_skb,
+ * TP_PROTO(struct sk_buff *skb),
+ */
+SEC("tp_btf/netif_receive_skb")
+int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
+{
+ static __u64 flags[] = { 0, BTF_F_COMPACT, BTF_F_ZERO, BTF_F_PTR_RAW,
+ BTF_F_NONAME, BTF_F_COMPACT | BTF_F_ZERO |
+ BTF_F_PTR_RAW | BTF_F_NONAME };
+ static struct btf_ptr p = { };
+ __u32 key = 0;
+ int i, __ret;
+ char *str;
+
+#if __has_builtin(__builtin_btf_type_id)
+ str = bpf_map_lookup_elem(&strdata, &key);
+ if (!str)
+ return 0;
+
+ /* Ensure we can write skb string representation */
+ p.type_id = bpf_core_type_id_kernel(struct sk_buff);
+ p.ptr = skb;
+ for (i = 0; i < ARRAY_SIZE(flags); i++) {
+ ++num_subtests;
+ ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
+ if (ret < 0)
+ bpf_printk("returned %d when writing skb", ret);
+ ++ran_subtests;
+ }
+
+ /* Check invalid ptr value */
+ p.ptr = 0;
+ __ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
+ if (__ret >= 0) {
+ bpf_printk("printing NULL should generate error, got (%d)",
+ __ret);
+ ret = -ERANGE;
+ }
+
+ /* Verify type display for various types. */
+
+ /* simple int */
+ TEST_BTF_C(str, int, 0, 1234);
+ TEST_BTF(str, int, BTF_F_NONAME, "1234", 1234);
+ /* zero value should be printed at toplevel */
+ TEST_BTF(str, int, 0, "(int)0", 0);
+ TEST_BTF(str, int, BTF_F_NONAME, "0", 0);
+ TEST_BTF(str, int, BTF_F_ZERO, "(int)0", 0);
+ TEST_BTF(str, int, BTF_F_NONAME | BTF_F_ZERO, "0", 0);
+ TEST_BTF_C(str, int, 0, -4567);
+ TEST_BTF(str, int, BTF_F_NONAME, "-4567", -4567);
+
+ /* simple char */
+ TEST_BTF_C(str, char, 0, 100);
+ TEST_BTF(str, char, BTF_F_NONAME, "100", 100);
+ /* zero value should be printed at toplevel */
+ TEST_BTF(str, char, 0, "(char)0", 0);
+ TEST_BTF(str, char, BTF_F_NONAME, "0", 0);
+ TEST_BTF(str, char, BTF_F_ZERO, "(char)0", 0);
+ TEST_BTF(str, char, BTF_F_NONAME | BTF_F_ZERO, "0", 0);
+
+ /* simple typedef */
+ TEST_BTF_C(str, uint64_t, 0, 100);
+ TEST_BTF(str, u64, BTF_F_NONAME, "1", 1);
+ /* zero value should be printed at toplevel */
+ TEST_BTF(str, u64, 0, "(u64)0", 0);
+ TEST_BTF(str, u64, BTF_F_NONAME, "0", 0);
+ TEST_BTF(str, u64, BTF_F_ZERO, "(u64)0", 0);
+ TEST_BTF(str, u64, BTF_F_NONAME|BTF_F_ZERO, "0", 0);
+
+ /* typedef struct */
+ TEST_BTF_C(str, atomic_t, 0, {.counter = (int)1,});
+ TEST_BTF(str, atomic_t, BTF_F_NONAME, "{1,}", {.counter = 1,});
+ /* typedef with 0 value should be printed at toplevel */
+ TEST_BTF(str, atomic_t, 0, "(atomic_t){}", {.counter = 0,});
+ TEST_BTF(str, atomic_t, BTF_F_NONAME, "{}", {.counter = 0,});
+ TEST_BTF(str, atomic_t, BTF_F_ZERO, "(atomic_t){.counter = (int)0,}",
+ {.counter = 0,});
+ TEST_BTF(str, atomic_t, BTF_F_NONAME|BTF_F_ZERO,
+ "{0,}", {.counter = 0,});
+
+ /* enum where enum value does (and does not) exist */
+ TEST_BTF_C(str, enum bpf_cmd, 0, BPF_MAP_CREATE);
+ TEST_BTF(str, enum bpf_cmd, 0, "(enum bpf_cmd)BPF_MAP_CREATE", 0);
+ TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "BPF_MAP_CREATE",
+ BPF_MAP_CREATE);
+ TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
+ "BPF_MAP_CREATE", 0);
+
+ TEST_BTF(str, enum bpf_cmd, BTF_F_ZERO, "(enum bpf_cmd)BPF_MAP_CREATE",
+ BPF_MAP_CREATE);
+ TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
+ "BPF_MAP_CREATE", BPF_MAP_CREATE);
+ TEST_BTF_C(str, enum bpf_cmd, 0, 2000);
+ TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "2000", 2000);
+
+ /* simple struct */
+ TEST_BTF_C(str, struct btf_enum, 0,
+ {.name_off = (__u32)3,.val = (__s32)-1,});
+ TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{3,-1,}",
+ { .name_off = 3, .val = -1,});
+ TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{-1,}",
+ { .name_off = 0, .val = -1,});
+ TEST_BTF(str, struct btf_enum, BTF_F_NONAME|BTF_F_ZERO, "{0,-1,}",
+ { .name_off = 0, .val = -1,});
+ /* empty struct should be printed */
+ TEST_BTF(str, struct btf_enum, 0, "(struct btf_enum){}",
+ { .name_off = 0, .val = 0,});
+ TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{}",
+ { .name_off = 0, .val = 0,});
+ TEST_BTF(str, struct btf_enum, BTF_F_ZERO,
+ "(struct btf_enum){.name_off = (__u32)0,.val = (__s32)0,}",
+ { .name_off = 0, .val = 0,});
+
+ /* struct with pointers */
+ TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
+ "(struct list_head){.next = (struct list_head *)0x0000000000000001,}",
+ { .next = (struct list_head *)1 });
+ /* NULL pointer should not be displayed */
+ TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
+ "(struct list_head){}",
+ { .next = (struct list_head *)0 });
+
+ /* struct with char array */
+ TEST_BTF(str, struct bpf_prog_info, 0,
+ "(struct bpf_prog_info){.name = (char[])['f','o','o',],}",
+ { .name = "foo",});
+ TEST_BTF(str, struct bpf_prog_info, BTF_F_NONAME,
+ "{['f','o','o',],}",
+ {.name = "foo",});
+ /* leading null char means do not display string */
+ TEST_BTF(str, struct bpf_prog_info, 0,
+ "(struct bpf_prog_info){}",
+ {.name = {'\0', 'f', 'o', 'o'}});
+ /* handle non-printable characters */
+ TEST_BTF(str, struct bpf_prog_info, 0,
+ "(struct bpf_prog_info){.name = (char[])[1,2,3,],}",
+ { .name = {1, 2, 3, 0}});
+
+ /* struct with non-char array */
+ TEST_BTF(str, struct __sk_buff, 0,
+ "(struct __sk_buff){.cb = (__u32[])[1,2,3,4,5,],}",
+ { .cb = {1, 2, 3, 4, 5,},});
+ TEST_BTF(str, struct __sk_buff, BTF_F_NONAME,
+ "{[1,2,3,4,5,],}",
+ { .cb = { 1, 2, 3, 4, 5},});
+ /* For non-char, arrays, show non-zero values only */
+ TEST_BTF(str, struct __sk_buff, 0,
+ "(struct __sk_buff){.cb = (__u32[])[1,],}",
+ { .cb = { 0, 0, 1, 0, 0},});
+
+ /* struct with bitfields */
+ TEST_BTF_C(str, struct bpf_insn, 0,
+ {.code = (__u8)1,.dst_reg = (__u8)0x2,.src_reg = (__u8)0x3,.off = (__s16)4,.imm = (__s32)5,});
+ TEST_BTF(str, struct bpf_insn, BTF_F_NONAME, "{1,0x2,0x3,4,5,}",
+ {.code = 1, .dst_reg = 0x2, .src_reg = 0x3, .off = 4,
+ .imm = 5,});
+#else
+ skip = true;
+#endif
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
1.8.3.1
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