1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020, Oracle and/or its affiliates. */
3 
4 #include "btf_ptr.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7 #include <bpf/bpf_core_read.h>
8 
9 #include <errno.h>
10 
11 long ret = 0;
12 int num_subtests = 0;
13 int ran_subtests = 0;
14 bool skip = false;
15 
16 #define STRSIZE			2048
17 #define EXPECTED_STRSIZE	256
18 
19 #if defined(bpf_target_s390)
20 /* NULL points to a readable struct lowcore on s390, so take the last page */
21 #define BADPTR			((void *)0xFFFFFFFFFFFFF000ULL)
22 #else
23 #define BADPTR			0
24 #endif
25 
26 #ifndef ARRAY_SIZE
27 #define ARRAY_SIZE(x)	(sizeof(x) / sizeof((x)[0]))
28 #endif
29 
30 struct {
31 	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
32 	__uint(max_entries, 1);
33 	__type(key, __u32);
34 	__type(value, char[STRSIZE]);
35 } strdata SEC(".maps");
36 
__strncmp(const void * m1,const void * m2,size_t len)37 static int __strncmp(const void *m1, const void *m2, size_t len)
38 {
39 	const unsigned char *s1 = m1;
40 	const unsigned char *s2 = m2;
41 	int i, delta = 0;
42 
43 	for (i = 0; i < len; i++) {
44 		delta = s1[i] - s2[i];
45 		if (delta || s1[i] == 0 || s2[i] == 0)
46 			break;
47 	}
48 	return delta;
49 }
50 
51 #if __has_builtin(__builtin_btf_type_id)
52 #define	TEST_BTF(_str, _type, _flags, _expected, ...)			\
53 	do {								\
54 		static const char _expectedval[EXPECTED_STRSIZE] =	\
55 							_expected;	\
56 		__u64 _hflags = _flags | BTF_F_COMPACT;			\
57 		static _type _ptrdata = __VA_ARGS__;			\
58 		static struct btf_ptr _ptr = { };			\
59 		int _cmp;						\
60 									\
61 		++num_subtests;						\
62 		if (ret < 0)						\
63 			break;						\
64 		++ran_subtests;						\
65 		_ptr.ptr = &_ptrdata;					\
66 		_ptr.type_id = bpf_core_type_id_kernel(_type);		\
67 		if (_ptr.type_id <= 0) {				\
68 			ret = -EINVAL;					\
69 			break;						\
70 		}							\
71 		ret = bpf_snprintf_btf(_str, STRSIZE,			\
72 				       &_ptr, sizeof(_ptr), _hflags);	\
73 		if (ret)						\
74 			break;						\
75 		_cmp = __strncmp(_str, _expectedval, EXPECTED_STRSIZE);	\
76 		if (_cmp != 0) {					\
77 			bpf_printk("(%d) got %s", _cmp, _str);		\
78 			bpf_printk("(%d) expected %s", _cmp,		\
79 				   _expectedval);			\
80 			ret = -EBADMSG;					\
81 			break;						\
82 		}							\
83 	} while (0)
84 #endif
85 
86 /* Use where expected data string matches its stringified declaration */
87 #define TEST_BTF_C(_str, _type, _flags, ...)				\
88 	TEST_BTF(_str, _type, _flags, "(" #_type ")" #__VA_ARGS__,	\
89 		 __VA_ARGS__)
90 
91 /* TRACE_EVENT(netif_receive_skb,
92  *	TP_PROTO(struct sk_buff *skb),
93  */
94 SEC("tp_btf/netif_receive_skb")
BPF_PROG(trace_netif_receive_skb,struct sk_buff * skb)95 int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
96 {
97 	static __u64 flags[] = { 0, BTF_F_COMPACT, BTF_F_ZERO, BTF_F_PTR_RAW,
98 				 BTF_F_NONAME, BTF_F_COMPACT | BTF_F_ZERO |
99 				 BTF_F_PTR_RAW | BTF_F_NONAME };
100 	static struct btf_ptr p = { };
101 	__u32 key = 0;
102 	int i, __ret;
103 	char *str;
104 
105 #if __has_builtin(__builtin_btf_type_id)
106 	str = bpf_map_lookup_elem(&strdata, &key);
107 	if (!str)
108 		return 0;
109 
110 	/* Ensure we can write skb string representation */
111 	p.type_id = bpf_core_type_id_kernel(struct sk_buff);
112 	p.ptr = skb;
113 	for (i = 0; i < ARRAY_SIZE(flags); i++) {
114 		++num_subtests;
115 		ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
116 		if (ret < 0)
117 			bpf_printk("returned %d when writing skb", ret);
118 		++ran_subtests;
119 	}
120 
121 	/* Check invalid ptr value */
122 	p.ptr = BADPTR;
123 	__ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0);
124 	if (__ret >= 0) {
125 		bpf_printk("printing %llx should generate error, got (%d)",
126 			   (unsigned long long)BADPTR, __ret);
127 		ret = -ERANGE;
128 	}
129 
130 	/* Verify type display for various types. */
131 
132 	/* simple int */
133 	TEST_BTF_C(str, int, 0, 1234);
134 	TEST_BTF(str, int, BTF_F_NONAME, "1234", 1234);
135 	/* zero value should be printed at toplevel */
136 	TEST_BTF(str, int, 0, "(int)0", 0);
137 	TEST_BTF(str, int, BTF_F_NONAME, "0", 0);
138 	TEST_BTF(str, int, BTF_F_ZERO, "(int)0", 0);
139 	TEST_BTF(str, int, BTF_F_NONAME | BTF_F_ZERO, "0", 0);
140 	TEST_BTF_C(str, int, 0, -4567);
141 	TEST_BTF(str, int, BTF_F_NONAME, "-4567", -4567);
142 
143 	/* simple char */
144 	TEST_BTF_C(str, char, 0, 100);
145 	TEST_BTF(str, char, BTF_F_NONAME, "100", 100);
146 	/* zero value should be printed at toplevel */
147 	TEST_BTF(str, char, 0, "(char)0", 0);
148 	TEST_BTF(str, char, BTF_F_NONAME, "0", 0);
149 	TEST_BTF(str, char, BTF_F_ZERO, "(char)0", 0);
150 	TEST_BTF(str, char, BTF_F_NONAME | BTF_F_ZERO, "0", 0);
151 
152 	/* simple typedef */
153 	TEST_BTF_C(str, uint64_t, 0, 100);
154 	TEST_BTF(str, u64, BTF_F_NONAME, "1", 1);
155 	/* zero value should be printed at toplevel */
156 	TEST_BTF(str, u64, 0, "(u64)0", 0);
157 	TEST_BTF(str, u64, BTF_F_NONAME, "0", 0);
158 	TEST_BTF(str, u64, BTF_F_ZERO, "(u64)0", 0);
159 	TEST_BTF(str, u64, BTF_F_NONAME|BTF_F_ZERO, "0", 0);
160 
161 	/* typedef struct */
162 	TEST_BTF_C(str, atomic_t, 0, {.counter = (int)1,});
163 	TEST_BTF(str, atomic_t, BTF_F_NONAME, "{1,}", {.counter = 1,});
164 	/* typedef with 0 value should be printed at toplevel */
165 	TEST_BTF(str, atomic_t, 0, "(atomic_t){}", {.counter = 0,});
166 	TEST_BTF(str, atomic_t, BTF_F_NONAME, "{}", {.counter = 0,});
167 	TEST_BTF(str, atomic_t, BTF_F_ZERO, "(atomic_t){.counter = (int)0,}",
168 		 {.counter = 0,});
169 	TEST_BTF(str, atomic_t, BTF_F_NONAME|BTF_F_ZERO,
170 		 "{0,}", {.counter = 0,});
171 
172 	/* enum where enum value does (and does not) exist */
173 	TEST_BTF_C(str, enum bpf_cmd, 0, BPF_MAP_CREATE);
174 	TEST_BTF(str, enum bpf_cmd, 0, "(enum bpf_cmd)BPF_MAP_CREATE", 0);
175 	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "BPF_MAP_CREATE",
176 		 BPF_MAP_CREATE);
177 	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
178 		 "BPF_MAP_CREATE", 0);
179 
180 	TEST_BTF(str, enum bpf_cmd, BTF_F_ZERO, "(enum bpf_cmd)BPF_MAP_CREATE",
181 		 BPF_MAP_CREATE);
182 	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME|BTF_F_ZERO,
183 		 "BPF_MAP_CREATE", BPF_MAP_CREATE);
184 	TEST_BTF_C(str, enum bpf_cmd, 0, 2000);
185 	TEST_BTF(str, enum bpf_cmd, BTF_F_NONAME, "2000", 2000);
186 
187 	/* simple struct */
188 	TEST_BTF_C(str, struct btf_enum, 0,
189 		   {.name_off = (__u32)3,.val = (__s32)-1,});
190 	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{3,-1,}",
191 		 { .name_off = 3, .val = -1,});
192 	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{-1,}",
193 		 { .name_off = 0, .val = -1,});
194 	TEST_BTF(str, struct btf_enum, BTF_F_NONAME|BTF_F_ZERO, "{0,-1,}",
195 		 { .name_off = 0, .val = -1,});
196 	/* empty struct should be printed */
197 	TEST_BTF(str, struct btf_enum, 0, "(struct btf_enum){}",
198 		 { .name_off = 0, .val = 0,});
199 	TEST_BTF(str, struct btf_enum, BTF_F_NONAME, "{}",
200 		 { .name_off = 0, .val = 0,});
201 	TEST_BTF(str, struct btf_enum, BTF_F_ZERO,
202 		 "(struct btf_enum){.name_off = (__u32)0,.val = (__s32)0,}",
203 		 { .name_off = 0, .val = 0,});
204 
205 	/* struct with pointers */
206 	TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
207 		 "(struct list_head){.next = (struct list_head *)0x0000000000000001,}",
208 		 { .next = (struct list_head *)1 });
209 	/* NULL pointer should not be displayed */
210 	TEST_BTF(str, struct list_head, BTF_F_PTR_RAW,
211 		 "(struct list_head){}",
212 		 { .next = (struct list_head *)0 });
213 
214 	/* struct with char array */
215 	TEST_BTF(str, struct bpf_prog_info, 0,
216 		 "(struct bpf_prog_info){.name = (char[])['f','o','o',],}",
217 		 { .name = "foo",});
218 	TEST_BTF(str, struct bpf_prog_info, BTF_F_NONAME,
219 		 "{['f','o','o',],}",
220 		 {.name = "foo",});
221 	/* leading null char means do not display string */
222 	TEST_BTF(str, struct bpf_prog_info, 0,
223 		 "(struct bpf_prog_info){}",
224 		 {.name = {'\0', 'f', 'o', 'o'}});
225 	/* handle non-printable characters */
226 	TEST_BTF(str, struct bpf_prog_info, 0,
227 		 "(struct bpf_prog_info){.name = (char[])[1,2,3,],}",
228 		 { .name = {1, 2, 3, 0}});
229 
230 	/* struct with non-char array */
231 	TEST_BTF(str, struct __sk_buff, 0,
232 		 "(struct __sk_buff){.cb = (__u32[])[1,2,3,4,5,],}",
233 		 { .cb = {1, 2, 3, 4, 5,},});
234 	TEST_BTF(str, struct __sk_buff, BTF_F_NONAME,
235 		 "{[1,2,3,4,5,],}",
236 		 { .cb = { 1, 2, 3, 4, 5},});
237 	/* For non-char, arrays, show non-zero values only */
238 	TEST_BTF(str, struct __sk_buff, 0,
239 		 "(struct __sk_buff){.cb = (__u32[])[1,],}",
240 		 { .cb = { 0, 0, 1, 0, 0},});
241 
242 	/* struct with bitfields */
243 	TEST_BTF_C(str, struct bpf_insn, 0,
244 		   {.code = (__u8)1,.dst_reg = (__u8)0x2,.src_reg = (__u8)0x3,.off = (__s16)4,.imm = (__s32)5,});
245 	TEST_BTF(str, struct bpf_insn, BTF_F_NONAME, "{1,0x2,0x3,4,5,}",
246 		 {.code = 1, .dst_reg = 0x2, .src_reg = 0x3, .off = 4,
247 		  .imm = 5,});
248 #else
249 	skip = true;
250 #endif
251 
252 	return 0;
253 }
254 
255 char _license[] SEC("license") = "GPL";
256