1 KCOV: code coverage for fuzzing !! 1 kcov: code coverage for fuzzing
2 =============================== 2 ===============================
3 3
4 KCOV collects and exposes kernel code coverage !! 4 kcov exposes kernel code coverage information in a form suitable for coverage-
5 for coverage-guided fuzzing. Coverage data of !! 5 guided fuzzing (randomized testing). Coverage data of a running kernel is
6 the ``kcov`` debugfs file. Coverage collection !! 6 exported via the "kcov" debugfs file. Coverage collection is enabled on a task
7 thus KCOV can capture precise coverage of a si !! 7 basis, and thus it can capture precise coverage of a single system call.
8 !! 8
9 Note that KCOV does not aim to collect as much !! 9 Note that kcov does not aim to collect as much coverage as possible. It aims
10 to collect more or less stable coverage that i !! 10 to collect more or less stable coverage that is function of syscall inputs.
11 To achieve this goal, it does not collect cove !! 11 To achieve this goal it does not collect coverage in soft/hard interrupts
12 (unless remove coverage collection is enabled, !! 12 and instrumentation of some inherently non-deterministic parts of kernel is
13 inherently non-deterministic parts of the kern !! 13 disabled (e.g. scheduler, locking).
14 !! 14
15 Besides collecting code coverage, KCOV can als !! 15 kcov is also able to collect comparison operands from the instrumented code
16 See the "Comparison operands collection" secti !! 16 (this feature currently requires that the kernel is compiled with clang).
17 <<
18 Besides collecting coverage data from syscall <<
19 coverage for annotated parts of the kernel exe <<
20 tasks or soft interrupts. See the "Remote cove <<
21 details. <<
22 17
23 Prerequisites 18 Prerequisites
24 ------------- 19 -------------
25 20
26 KCOV relies on compiler instrumentation and re !! 21 Configure the kernel with::
27 or any Clang version supported by the kernel. <<
28 <<
29 Collecting comparison operands is supported wi <<
30 <<
31 To enable KCOV, configure the kernel with:: <<
32 22
33 CONFIG_KCOV=y 23 CONFIG_KCOV=y
34 24
35 To enable comparison operands collection, set: !! 25 CONFIG_KCOV requires gcc 6.1.0 or later.
>> 26
>> 27 If the comparison operands need to be collected, set::
36 28
37 CONFIG_KCOV_ENABLE_COMPARISONS=y 29 CONFIG_KCOV_ENABLE_COMPARISONS=y
38 30
39 Coverage data only becomes accessible once deb !! 31 Profiling data will only become accessible once debugfs has been mounted::
40 32
41 mount -t debugfs none /sys/kernel/debu 33 mount -t debugfs none /sys/kernel/debug
42 34
43 Coverage collection 35 Coverage collection
44 ------------------- 36 -------------------
45 37
46 The following program demonstrates how to use !! 38 The following program demonstrates coverage collection from within a test
47 single syscall from within a test program: !! 39 program using kcov:
48 40
49 .. code-block:: c 41 .. code-block:: c
50 42
51 #include <stdio.h> 43 #include <stdio.h>
52 #include <stddef.h> 44 #include <stddef.h>
53 #include <stdint.h> 45 #include <stdint.h>
54 #include <stdlib.h> 46 #include <stdlib.h>
55 #include <sys/types.h> 47 #include <sys/types.h>
56 #include <sys/stat.h> 48 #include <sys/stat.h>
57 #include <sys/ioctl.h> 49 #include <sys/ioctl.h>
58 #include <sys/mman.h> 50 #include <sys/mman.h>
59 #include <unistd.h> 51 #include <unistd.h>
60 #include <fcntl.h> 52 #include <fcntl.h>
61 #include <linux/types.h> <<
62 53
63 #define KCOV_INIT_TRACE 54 #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
64 #define KCOV_ENABLE _IO('c 55 #define KCOV_ENABLE _IO('c', 100)
65 #define KCOV_DISABLE 56 #define KCOV_DISABLE _IO('c', 101)
66 #define COVER_SIZE (64<<1 57 #define COVER_SIZE (64<<10)
67 58
68 #define KCOV_TRACE_PC 0 59 #define KCOV_TRACE_PC 0
69 #define KCOV_TRACE_CMP 1 60 #define KCOV_TRACE_CMP 1
70 61
71 int main(int argc, char **argv) 62 int main(int argc, char **argv)
72 { 63 {
73 int fd; 64 int fd;
74 unsigned long *cover, n, i; 65 unsigned long *cover, n, i;
75 66
76 /* A single fd descriptor allows cover 67 /* A single fd descriptor allows coverage collection on a single
77 * thread. 68 * thread.
78 */ 69 */
79 fd = open("/sys/kernel/debug/kcov", O_ 70 fd = open("/sys/kernel/debug/kcov", O_RDWR);
80 if (fd == -1) 71 if (fd == -1)
81 perror("open"), exit(1); 72 perror("open"), exit(1);
82 /* Setup trace mode and trace size. */ 73 /* Setup trace mode and trace size. */
83 if (ioctl(fd, KCOV_INIT_TRACE, COVER_S 74 if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE))
84 perror("ioctl"), exit(1); 75 perror("ioctl"), exit(1);
85 /* Mmap buffer shared between kernel- 76 /* Mmap buffer shared between kernel- and user-space. */
86 cover = (unsigned long*)mmap(NULL, COV 77 cover = (unsigned long*)mmap(NULL, COVER_SIZE * sizeof(unsigned long),
87 PROT_READ 78 PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
88 if ((void*)cover == MAP_FAILED) 79 if ((void*)cover == MAP_FAILED)
89 perror("mmap"), exit(1); 80 perror("mmap"), exit(1);
90 /* Enable coverage collection on the c 81 /* Enable coverage collection on the current thread. */
91 if (ioctl(fd, KCOV_ENABLE, KCOV_TRACE_ 82 if (ioctl(fd, KCOV_ENABLE, KCOV_TRACE_PC))
92 perror("ioctl"), exit(1); 83 perror("ioctl"), exit(1);
93 /* Reset coverage from the tail of the 84 /* Reset coverage from the tail of the ioctl() call. */
94 __atomic_store_n(&cover[0], 0, __ATOMI 85 __atomic_store_n(&cover[0], 0, __ATOMIC_RELAXED);
95 /* Call the target syscall call. */ !! 86 /* That's the target syscal call. */
96 read(-1, NULL, 0); 87 read(-1, NULL, 0);
97 /* Read number of PCs collected. */ 88 /* Read number of PCs collected. */
98 n = __atomic_load_n(&cover[0], __ATOMI 89 n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);
99 for (i = 0; i < n; i++) 90 for (i = 0; i < n; i++)
100 printf("0x%lx\n", cover[i + 1] 91 printf("0x%lx\n", cover[i + 1]);
101 /* Disable coverage collection for the 92 /* Disable coverage collection for the current thread. After this call
102 * coverage can be enabled for a diffe 93 * coverage can be enabled for a different thread.
103 */ 94 */
104 if (ioctl(fd, KCOV_DISABLE, 0)) 95 if (ioctl(fd, KCOV_DISABLE, 0))
105 perror("ioctl"), exit(1); 96 perror("ioctl"), exit(1);
106 /* Free resources. */ 97 /* Free resources. */
107 if (munmap(cover, COVER_SIZE * sizeof( 98 if (munmap(cover, COVER_SIZE * sizeof(unsigned long)))
108 perror("munmap"), exit(1); 99 perror("munmap"), exit(1);
109 if (close(fd)) 100 if (close(fd))
110 perror("close"), exit(1); 101 perror("close"), exit(1);
111 return 0; 102 return 0;
112 } 103 }
113 104
114 After piping through ``addr2line`` the output !! 105 After piping through addr2line output of the program looks as follows::
115 106
116 SyS_read 107 SyS_read
117 fs/read_write.c:562 108 fs/read_write.c:562
118 __fdget_pos 109 __fdget_pos
119 fs/file.c:774 110 fs/file.c:774
120 __fget_light 111 __fget_light
121 fs/file.c:746 112 fs/file.c:746
122 __fget_light 113 __fget_light
123 fs/file.c:750 114 fs/file.c:750
124 __fget_light 115 __fget_light
125 fs/file.c:760 116 fs/file.c:760
126 __fdget_pos 117 __fdget_pos
127 fs/file.c:784 118 fs/file.c:784
128 SyS_read 119 SyS_read
129 fs/read_write.c:562 120 fs/read_write.c:562
130 121
131 If a program needs to collect coverage from se 122 If a program needs to collect coverage from several threads (independently),
132 it needs to open ``/sys/kernel/debug/kcov`` in !! 123 it needs to open /sys/kernel/debug/kcov in each thread separately.
133 124
134 The interface is fine-grained to allow efficie 125 The interface is fine-grained to allow efficient forking of test processes.
135 That is, a parent process opens ``/sys/kernel/ !! 126 That is, a parent process opens /sys/kernel/debug/kcov, enables trace mode,
136 mmaps coverage buffer, and then forks child pr !! 127 mmaps coverage buffer and then forks child processes in a loop. Child processes
137 processes only need to enable coverage (it get !! 128 only need to enable coverage (disable happens automatically on thread end).
138 a thread exits). <<
139 129
140 Comparison operands collection 130 Comparison operands collection
141 ------------------------------ 131 ------------------------------
142 132
143 Comparison operands collection is similar to c 133 Comparison operands collection is similar to coverage collection:
144 134
145 .. code-block:: c 135 .. code-block:: c
146 136
147 /* Same includes and defines as above. */ 137 /* Same includes and defines as above. */
148 138
149 /* Number of 64-bit words per record. */ 139 /* Number of 64-bit words per record. */
150 #define KCOV_WORDS_PER_CMP 4 140 #define KCOV_WORDS_PER_CMP 4
151 141
152 /* 142 /*
153 * The format for the types of collected c 143 * The format for the types of collected comparisons.
154 * 144 *
155 * Bit 0 shows whether one of the argument 145 * Bit 0 shows whether one of the arguments is a compile-time constant.
156 * Bits 1 & 2 contain log2 of the argument 146 * Bits 1 & 2 contain log2 of the argument size, up to 8 bytes.
157 */ 147 */
158 148
159 #define KCOV_CMP_CONST (1 << 0) 149 #define KCOV_CMP_CONST (1 << 0)
160 #define KCOV_CMP_SIZE(n) ((n) << 1) 150 #define KCOV_CMP_SIZE(n) ((n) << 1)
161 #define KCOV_CMP_MASK KCOV_CMP_S 151 #define KCOV_CMP_MASK KCOV_CMP_SIZE(3)
162 152
163 int main(int argc, char **argv) 153 int main(int argc, char **argv)
164 { 154 {
165 int fd; 155 int fd;
166 uint64_t *cover, type, arg1, arg2, is_ 156 uint64_t *cover, type, arg1, arg2, is_const, size;
167 unsigned long n, i; 157 unsigned long n, i;
168 158
169 fd = open("/sys/kernel/debug/kcov", O_ 159 fd = open("/sys/kernel/debug/kcov", O_RDWR);
170 if (fd == -1) 160 if (fd == -1)
171 perror("open"), exit(1); 161 perror("open"), exit(1);
172 if (ioctl(fd, KCOV_INIT_TRACE, COVER_S 162 if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE))
173 perror("ioctl"), exit(1); 163 perror("ioctl"), exit(1);
174 /* 164 /*
175 * Note that the buffer pointer is of t 165 * Note that the buffer pointer is of type uint64_t*, because all
176 * the comparison operands are promoted 166 * the comparison operands are promoted to uint64_t.
177 */ 167 */
178 cover = (uint64_t *)mmap(NULL, COVER_S 168 cover = (uint64_t *)mmap(NULL, COVER_SIZE * sizeof(unsigned long),
179 PROT_READ 169 PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
180 if ((void*)cover == MAP_FAILED) 170 if ((void*)cover == MAP_FAILED)
181 perror("mmap"), exit(1); 171 perror("mmap"), exit(1);
182 /* Note KCOV_TRACE_CMP instead of KCOV 172 /* Note KCOV_TRACE_CMP instead of KCOV_TRACE_PC. */
183 if (ioctl(fd, KCOV_ENABLE, KCOV_TRACE_ 173 if (ioctl(fd, KCOV_ENABLE, KCOV_TRACE_CMP))
184 perror("ioctl"), exit(1); 174 perror("ioctl"), exit(1);
185 __atomic_store_n(&cover[0], 0, __ATOMI 175 __atomic_store_n(&cover[0], 0, __ATOMIC_RELAXED);
186 read(-1, NULL, 0); 176 read(-1, NULL, 0);
187 /* Read number of comparisons collecte 177 /* Read number of comparisons collected. */
188 n = __atomic_load_n(&cover[0], __ATOMI 178 n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);
189 for (i = 0; i < n; i++) { 179 for (i = 0; i < n; i++) {
190 uint64_t ip; <<
191 <<
192 type = cover[i * KCOV_WORDS_PE 180 type = cover[i * KCOV_WORDS_PER_CMP + 1];
193 /* arg1 and arg2 - operands of 181 /* arg1 and arg2 - operands of the comparison. */
194 arg1 = cover[i * KCOV_WORDS_PE 182 arg1 = cover[i * KCOV_WORDS_PER_CMP + 2];
195 arg2 = cover[i * KCOV_WORDS_PE 183 arg2 = cover[i * KCOV_WORDS_PER_CMP + 3];
196 /* ip - caller address. */ 184 /* ip - caller address. */
197 ip = cover[i * KCOV_WORDS_PER_ 185 ip = cover[i * KCOV_WORDS_PER_CMP + 4];
198 /* size of the operands. */ 186 /* size of the operands. */
199 size = 1 << ((type & KCOV_CMP_ 187 size = 1 << ((type & KCOV_CMP_MASK) >> 1);
200 /* is_const - true if either o 188 /* is_const - true if either operand is a compile-time constant.*/
201 is_const = type & KCOV_CMP_CON 189 is_const = type & KCOV_CMP_CONST;
202 printf("ip: 0x%lx type: 0x%lx, 190 printf("ip: 0x%lx type: 0x%lx, arg1: 0x%lx, arg2: 0x%lx, "
203 "size: %lu, %s\n", 191 "size: %lu, %s\n",
204 ip, type, arg1, arg2, 192 ip, type, arg1, arg2, size,
205 is_const ? "const" : "non-cons 193 is_const ? "const" : "non-const");
206 } 194 }
207 if (ioctl(fd, KCOV_DISABLE, 0)) 195 if (ioctl(fd, KCOV_DISABLE, 0))
208 perror("ioctl"), exit(1); 196 perror("ioctl"), exit(1);
209 /* Free resources. */ 197 /* Free resources. */
210 if (munmap(cover, COVER_SIZE * sizeof( 198 if (munmap(cover, COVER_SIZE * sizeof(unsigned long)))
211 perror("munmap"), exit(1); 199 perror("munmap"), exit(1);
212 if (close(fd)) 200 if (close(fd))
213 perror("close"), exit(1); 201 perror("close"), exit(1);
214 return 0; 202 return 0;
215 } 203 }
216 204
217 Note that the KCOV modes (collection of code c !! 205 Note that the kcov modes (coverage collection or comparison operands) are
218 are mutually exclusive. !! 206 mutually exclusive.
219 207
220 Remote coverage collection 208 Remote coverage collection
221 -------------------------- 209 --------------------------
222 210
223 Besides collecting coverage data from handlers !! 211 With KCOV_ENABLE coverage is collected only for syscalls that are issued
224 userspace process, KCOV can also collect cover !! 212 from the current process. With KCOV_REMOTE_ENABLE it's possible to collect
225 executing in other contexts - so-called "remot !! 213 coverage for arbitrary parts of the kernel code, provided that those parts
226 !! 214 are annotated with kcov_remote_start()/kcov_remote_stop().
227 Using KCOV to collect remote coverage requires !! 215
228 !! 216 This allows to collect coverage from two types of kernel background
229 1. Modifying kernel code to annotate the code !! 217 threads: the global ones, that are spawned during kernel boot in a limited
230 should be collected with ``kcov_remote_star !! 218 number of instances (e.g. one USB hub_event() worker thread is spawned per
231 !! 219 USB HCD); and the local ones, that are spawned when a user interacts with
232 2. Using ``KCOV_REMOTE_ENABLE`` instead of ``K !! 220 some kernel interface (e.g. vhost workers); as well as from soft
233 process that collects coverage. !! 221 interrupts.
234 !! 222
235 Both ``kcov_remote_start`` and ``kcov_remote_s !! 223 To enable collecting coverage from a global background thread or from a
236 ``KCOV_REMOTE_ENABLE`` ioctl accept handles th !! 224 softirq, a unique global handle must be assigned and passed to the
237 collection sections. The way a handle is used !! 225 corresponding kcov_remote_start() call. Then a userspace process can pass
238 matching code section executes. !! 226 a list of such handles to the KCOV_REMOTE_ENABLE ioctl in the handles
239 !! 227 array field of the kcov_remote_arg struct. This will attach the used kcov
240 KCOV supports collecting remote coverage from !! 228 device to the code sections, that are referenced by those handles.
241 !! 229
242 1. Global kernel background tasks. These are t !! 230 Since there might be many local background threads spawned from different
243 kernel boot in a limited number of instance !! 231 userspace processes, we can't use a single global handle per annotation.
244 worker is spawned per one USB HCD). !! 232 Instead, the userspace process passes a non-zero handle through the
245 !! 233 common_handle field of the kcov_remote_arg struct. This common handle gets
246 2. Local kernel background tasks. These are sp !! 234 saved to the kcov_handle field in the current task_struct and needs to be
247 interacts with some kernel interface and ar !! 235 passed to the newly spawned threads via custom annotations. Those threads
248 exits (e.g. vhost workers). !! 236 should in turn be annotated with kcov_remote_start()/kcov_remote_stop().
249 !! 237
250 3. Soft interrupts. !! 238 Internally kcov stores handles as u64 integers. The top byte of a handle
251 !! 239 is used to denote the id of a subsystem that this handle belongs to, and
252 For #1 and #3, a unique global handle must be !! 240 the lower 4 bytes are used to denote the id of a thread instance within
253 corresponding ``kcov_remote_start`` call. Then !! 241 that subsystem. A reserved value 0 is used as a subsystem id for common
254 this handle to ``KCOV_REMOTE_ENABLE`` in the ` !! 242 handles as they don't belong to a particular subsystem. The bytes 4-7 are
255 ``kcov_remote_arg`` struct. This will attach t !! 243 currently reserved and must be zero. In the future the number of bytes
256 section referenced by this handle. Multiple gl !! 244 used for the subsystem or handle ids might be increased.
257 different code sections can be passed at once. !! 245
258 !! 246 When a particular userspace proccess collects coverage via a common
259 For #2, the userspace process instead must pas !! 247 handle, kcov will collect coverage for each code section that is annotated
260 ``common_handle`` field of the ``kcov_remote_a !! 248 to use the common handle obtained as kcov_handle from the current
261 gets saved to the ``kcov_handle`` field in the !! 249 task_struct. However non common handles allow to collect coverage
262 needs to be passed to the newly spawned local !! 250 selectively from different subsystems.
263 modifications. Those tasks should in turn use <<
264 ``kcov_remote_start`` and ``kcov_remote_stop`` <<
265 <<
266 KCOV follows a predefined format for both glob <<
267 handle is a ``u64`` integer. Currently, only t <<
268 are used. Bytes 4-7 are reserved and must be z <<
269 <<
270 For global handles, the top byte of the handle <<
271 this handle belongs to. For example, KCOV uses <<
272 The lower 4 bytes of a global handle denote th <<
273 that subsystem. For example, each ``hub_event` <<
274 as the task instance id. <<
275 <<
276 For common handles, a reserved value ``0`` is <<
277 handles don't belong to a particular subsystem <<
278 handle identify a collective instance of all l <<
279 userspace process that passed a common handle <<
280 <<
281 In practice, any value can be used for common <<
282 is only collected from a single userspace proc <<
283 common handles are used by multiple processes, <<
284 used for each process. One option is to use th <<
285 handle instance id. <<
286 <<
287 The following program demonstrates using KCOV <<
288 local tasks spawned by the process and the glo <<
289 251
290 .. code-block:: c 252 .. code-block:: c
291 <<
292 /* Same includes and defines as above. */ <<
293 253
294 struct kcov_remote_arg { 254 struct kcov_remote_arg {
295 __u32 trace_mode; 255 __u32 trace_mode;
296 __u32 area_size; 256 __u32 area_size;
297 __u32 num_handles; 257 __u32 num_handles;
298 __aligned_u64 common_handle; 258 __aligned_u64 common_handle;
299 __aligned_u64 handles[0]; 259 __aligned_u64 handles[0];
300 }; 260 };
301 261
302 #define KCOV_INIT_TRACE 262 #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
303 #define KCOV_DISABLE 263 #define KCOV_DISABLE _IO('c', 101)
304 #define KCOV_REMOTE_ENABLE _IOW(' 264 #define KCOV_REMOTE_ENABLE _IOW('c', 102, struct kcov_remote_arg)
305 265
306 #define COVER_SIZE (64 << 10) 266 #define COVER_SIZE (64 << 10)
307 267
308 #define KCOV_TRACE_PC 0 268 #define KCOV_TRACE_PC 0
309 269
310 #define KCOV_SUBSYSTEM_COMMON (0x00u 270 #define KCOV_SUBSYSTEM_COMMON (0x00ull << 56)
311 #define KCOV_SUBSYSTEM_USB (0x01ull << 56 271 #define KCOV_SUBSYSTEM_USB (0x01ull << 56)
312 272
313 #define KCOV_SUBSYSTEM_MASK (0xffull << 56 273 #define KCOV_SUBSYSTEM_MASK (0xffull << 56)
314 #define KCOV_INSTANCE_MASK (0xffffffffull 274 #define KCOV_INSTANCE_MASK (0xffffffffull)
315 275
316 static inline __u64 kcov_remote_handle(__u 276 static inline __u64 kcov_remote_handle(__u64 subsys, __u64 inst)
317 { 277 {
318 if (subsys & ~KCOV_SUBSYSTEM_MASK || i 278 if (subsys & ~KCOV_SUBSYSTEM_MASK || inst & ~KCOV_INSTANCE_MASK)
319 return 0; 279 return 0;
320 return subsys | inst; 280 return subsys | inst;
321 } 281 }
322 282
323 #define KCOV_COMMON_ID 0x42 283 #define KCOV_COMMON_ID 0x42
324 #define KCOV_USB_BUS_NUM 1 284 #define KCOV_USB_BUS_NUM 1
325 285
326 int main(int argc, char **argv) 286 int main(int argc, char **argv)
327 { 287 {
328 int fd; 288 int fd;
329 unsigned long *cover, n, i; 289 unsigned long *cover, n, i;
330 struct kcov_remote_arg *arg; 290 struct kcov_remote_arg *arg;
331 291
332 fd = open("/sys/kernel/debug/kcov", O_ 292 fd = open("/sys/kernel/debug/kcov", O_RDWR);
333 if (fd == -1) 293 if (fd == -1)
334 perror("open"), exit(1); 294 perror("open"), exit(1);
335 if (ioctl(fd, KCOV_INIT_TRACE, COVER_S 295 if (ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE))
336 perror("ioctl"), exit(1); 296 perror("ioctl"), exit(1);
337 cover = (unsigned long*)mmap(NULL, COV 297 cover = (unsigned long*)mmap(NULL, COVER_SIZE * sizeof(unsigned long),
338 PROT_READ 298 PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
339 if ((void*)cover == MAP_FAILED) 299 if ((void*)cover == MAP_FAILED)
340 perror("mmap"), exit(1); 300 perror("mmap"), exit(1);
341 301
342 /* Enable coverage collection via comm 302 /* Enable coverage collection via common handle and from USB bus #1. */
343 arg = calloc(1, sizeof(*arg) + sizeof( 303 arg = calloc(1, sizeof(*arg) + sizeof(uint64_t));
344 if (!arg) 304 if (!arg)
345 perror("calloc"), exit(1); 305 perror("calloc"), exit(1);
346 arg->trace_mode = KCOV_TRACE_PC; 306 arg->trace_mode = KCOV_TRACE_PC;
347 arg->area_size = COVER_SIZE; 307 arg->area_size = COVER_SIZE;
348 arg->num_handles = 1; 308 arg->num_handles = 1;
349 arg->common_handle = kcov_remote_handl 309 arg->common_handle = kcov_remote_handle(KCOV_SUBSYSTEM_COMMON,
350 310 KCOV_COMMON_ID);
351 arg->handles[0] = kcov_remote_handle(K 311 arg->handles[0] = kcov_remote_handle(KCOV_SUBSYSTEM_USB,
352 312 KCOV_USB_BUS_NUM);
353 if (ioctl(fd, KCOV_REMOTE_ENABLE, arg) 313 if (ioctl(fd, KCOV_REMOTE_ENABLE, arg))
354 perror("ioctl"), free(arg), ex 314 perror("ioctl"), free(arg), exit(1);
355 free(arg); 315 free(arg);
356 316
357 /* 317 /*
358 * Here the user needs to trigger exec 318 * Here the user needs to trigger execution of a kernel code section
359 * that is either annotated with the c 319 * that is either annotated with the common handle, or to trigger some
360 * activity on USB bus #1. 320 * activity on USB bus #1.
361 */ 321 */
362 sleep(2); 322 sleep(2);
363 323
364 n = __atomic_load_n(&cover[0], __ATOMI 324 n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);
365 for (i = 0; i < n; i++) 325 for (i = 0; i < n; i++)
366 printf("0x%lx\n", cover[i + 1] 326 printf("0x%lx\n", cover[i + 1]);
367 if (ioctl(fd, KCOV_DISABLE, 0)) 327 if (ioctl(fd, KCOV_DISABLE, 0))
368 perror("ioctl"), exit(1); 328 perror("ioctl"), exit(1);
369 if (munmap(cover, COVER_SIZE * sizeof( 329 if (munmap(cover, COVER_SIZE * sizeof(unsigned long)))
370 perror("munmap"), exit(1); 330 perror("munmap"), exit(1);
371 if (close(fd)) 331 if (close(fd))
372 perror("close"), exit(1); 332 perror("close"), exit(1);
373 return 0; 333 return 0;
374 } 334 }
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