test_core_autosize.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2020 Facebook */
  3
  4#include <linux/bpf.h>
  5#include <stdint.h>
  6#include <bpf/bpf_helpers.h>
  7#include <bpf/bpf_core_read.h>
  8
  9char _license[] SEC("license") = "GPL";
 10
 11/* fields of exactly the same size */
 12struct test_struct___samesize {
 13	void *ptr;
 14	unsigned long long val1;
 15	unsigned int val2;
 16	unsigned short val3;
 17	unsigned char val4;
 18} __attribute((preserve_access_index));
 19
 20/* unsigned fields that have to be downsized by libbpf */
 21struct test_struct___downsize {
 22	void *ptr;
 23	unsigned long val1;
 24	unsigned long val2;
 25	unsigned long val3;
 26	unsigned long val4;
 27	/* total sz: 40 */
 28} __attribute__((preserve_access_index));
 29
 30/* fields with signed integers of wrong size, should be rejected */
 31struct test_struct___signed {
 32	void *ptr;
 33	long val1;
 34	long val2;
 35	long val3;
 36	long val4;
 37} __attribute((preserve_access_index));
 38
 39/* real layout and sizes according to test's (32-bit) BTF */
 40struct test_struct___real {
 41	unsigned int ptr; /* can't use `void *`, it is always 8 byte in BPF target */
 42	unsigned int val2;
 43	unsigned long long val1;
 44	unsigned short val3;
 45	unsigned char val4;
 46	unsigned char _pad;
 47	/* total sz: 20 */
 48};
 49
 50struct test_struct___real input = {
 51	.ptr = 0x01020304,
 52	.val1 = 0x1020304050607080,
 53	.val2 = 0x0a0b0c0d,
 54	.val3 = 0xfeed,
 55	.val4 = 0xb9,
 56	._pad = 0xff, /* make sure no accidental zeros are present */
 57};
 58
 59unsigned long long ptr_samesized = 0;
 60unsigned long long val1_samesized = 0;
 61unsigned long long val2_samesized = 0;
 62unsigned long long val3_samesized = 0;
 63unsigned long long val4_samesized = 0;
 64struct test_struct___real output_samesized = {};
 65
 66unsigned long long ptr_downsized = 0;
 67unsigned long long val1_downsized = 0;
 68unsigned long long val2_downsized = 0;
 69unsigned long long val3_downsized = 0;
 70unsigned long long val4_downsized = 0;
 71struct test_struct___real output_downsized = {};
 72
 73unsigned long long ptr_probed = 0;
 74unsigned long long val1_probed = 0;
 75unsigned long long val2_probed = 0;
 76unsigned long long val3_probed = 0;
 77unsigned long long val4_probed = 0;
 78
 79unsigned long long ptr_signed = 0;
 80unsigned long long val1_signed = 0;
 81unsigned long long val2_signed = 0;
 82unsigned long long val3_signed = 0;
 83unsigned long long val4_signed = 0;
 84struct test_struct___real output_signed = {};
 85
 86SEC("raw_tp/sys_exit")
 87int handle_samesize(void *ctx)
 88{
 89	struct test_struct___samesize *in = (void *)&input;
 90	struct test_struct___samesize *out = (void *)&output_samesized;
 91
 92	ptr_samesized = (unsigned long long)in->ptr;
 93	val1_samesized = in->val1;
 94	val2_samesized = in->val2;
 95	val3_samesized = in->val3;
 96	val4_samesized = in->val4;
 97
 98	out->ptr = in->ptr;
 99	out->val1 = in->val1;
100	out->val2 = in->val2;
101	out->val3 = in->val3;
102	out->val4 = in->val4;
103
104	return 0;
105}
106
107SEC("raw_tp/sys_exit")
108int handle_downsize(void *ctx)
109{
110	struct test_struct___downsize *in = (void *)&input;
111	struct test_struct___downsize *out = (void *)&output_downsized;
112
113	ptr_downsized = (unsigned long long)in->ptr;
114	val1_downsized = in->val1;
115	val2_downsized = in->val2;
116	val3_downsized = in->val3;
117	val4_downsized = in->val4;
118
119	out->ptr = in->ptr;
120	out->val1 = in->val1;
121	out->val2 = in->val2;
122	out->val3 = in->val3;
123	out->val4 = in->val4;
124
125	return 0;
126}
127
128#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
129#define bpf_core_read_int bpf_core_read
130#else
131#define bpf_core_read_int(dst, sz, src) ({ \
132	/* Prevent "subtraction from stack pointer prohibited" */ \
133	volatile long __off = sizeof(*dst) - (sz); \
134	bpf_core_read((char *)(dst) + __off, sz, src); \
135})
136#endif
137
138SEC("raw_tp/sys_enter")
139int handle_probed(void *ctx)
140{
141	struct test_struct___downsize *in = (void *)&input;
142	__u64 tmp;
143
144	tmp = 0;
145	bpf_core_read_int(&tmp, bpf_core_field_size(in->ptr), &in->ptr);
146	ptr_probed = tmp;
147
148	tmp = 0;
149	bpf_core_read_int(&tmp, bpf_core_field_size(in->val1), &in->val1);
150	val1_probed = tmp;
151
152	tmp = 0;
153	bpf_core_read_int(&tmp, bpf_core_field_size(in->val2), &in->val2);
154	val2_probed = tmp;
155
156	tmp = 0;
157	bpf_core_read_int(&tmp, bpf_core_field_size(in->val3), &in->val3);
158	val3_probed = tmp;
159
160	tmp = 0;
161	bpf_core_read_int(&tmp, bpf_core_field_size(in->val4), &in->val4);
162	val4_probed = tmp;
163
164	return 0;
165}
166
167SEC("raw_tp/sys_enter")
168int handle_signed(void *ctx)
169{
170	struct test_struct___signed *in = (void *)&input;
171	struct test_struct___signed *out = (void *)&output_signed;
172
173	val2_signed = in->val2;
174	val3_signed = in->val3;
175	val4_signed = in->val4;
176
177	out->val2= in->val2;
178	out->val3= in->val3;
179	out->val4= in->val4;
180
181	return 0;
182}