Linux Perf
bp_signal.c
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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Inspired by breakpoint overflow test done by
4  * Vince Weaver <vincent.weaver@maine.edu> for perf_event_tests
5  * (git://github.com/deater/perf_event_tests)
6  */
7 
8 /*
9  * Powerpc needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
10  * 'int-ll64.h' and avoid compile warnings when printing __u64 with %llu.
11  */
12 #define __SANE_USERSPACE_TYPES__
13 
14 #include <stdlib.h>
15 #include <stdio.h>
16 #include <unistd.h>
17 #include <string.h>
18 #include <sys/ioctl.h>
19 #include <time.h>
20 #include <fcntl.h>
21 #include <signal.h>
22 #include <sys/mman.h>
23 #include <linux/compiler.h>
24 #include <linux/hw_breakpoint.h>
25 
26 #include "tests.h"
27 #include "debug.h"
28 #include "perf.h"
29 #include "cloexec.h"
30 
31 static int fd1;
32 static int fd2;
33 static int fd3;
34 static int overflows;
35 static int overflows_2;
36 
37 volatile long the_var;
38 
39 
40 /*
41  * Use ASM to ensure watchpoint and breakpoint can be triggered
42  * at one instruction.
43  */
44 #if defined (__x86_64__)
45 extern void __test_function(volatile long *ptr);
46 asm (
47  ".globl __test_function\n"
48  "__test_function:\n"
49  "incq (%rdi)\n"
50  "ret\n");
51 #elif defined (__aarch64__)
52 extern void __test_function(volatile long *ptr);
53 asm (
54  ".globl __test_function\n"
55  "__test_function:\n"
56  "str x30, [x0]\n"
57  "ret\n");
58 
59 #else
60 static void __test_function(volatile long *ptr)
61 {
62  *ptr = 0x1234;
63 }
64 #endif
65 
66 static noinline int test_function(void)
67 {
69  the_var++;
70  return time(NULL);
71 }
72 
73 static void sig_handler_2(int signum __maybe_unused,
74  siginfo_t *oh __maybe_unused,
75  void *uc __maybe_unused)
76 {
77  overflows_2++;
78  if (overflows_2 > 10) {
79  ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
80  ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
81  ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
82  }
83 }
84 
85 static void sig_handler(int signum __maybe_unused,
86  siginfo_t *oh __maybe_unused,
87  void *uc __maybe_unused)
88 {
89  overflows++;
90 
91  if (overflows > 10) {
92  /*
93  * This should be executed only once during
94  * this test, if we are here for the 10th
95  * time, consider this the recursive issue.
96  *
97  * We can get out of here by disable events,
98  * so no new SIGIO is delivered.
99  */
100  ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
101  ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
102  ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
103  }
104 }
105 
106 static int __event(bool is_x, void *addr, int sig)
107 {
108  struct perf_event_attr pe;
109  int fd;
110 
111  memset(&pe, 0, sizeof(struct perf_event_attr));
112  pe.type = PERF_TYPE_BREAKPOINT;
113  pe.size = sizeof(struct perf_event_attr);
114 
115  pe.config = 0;
116  pe.bp_type = is_x ? HW_BREAKPOINT_X : HW_BREAKPOINT_W;
117  pe.bp_addr = (unsigned long) addr;
118  pe.bp_len = sizeof(long);
119 
120  pe.sample_period = 1;
121  pe.sample_type = PERF_SAMPLE_IP;
122  pe.wakeup_events = 1;
123 
124  pe.disabled = 1;
125  pe.exclude_kernel = 1;
126  pe.exclude_hv = 1;
127 
128  fd = sys_perf_event_open(&pe, 0, -1, -1,
130  if (fd < 0) {
131  pr_debug("failed opening event %llx\n", pe.config);
132  return TEST_FAIL;
133  }
134 
135  fcntl(fd, F_SETFL, O_RDWR|O_NONBLOCK|O_ASYNC);
136  fcntl(fd, F_SETSIG, sig);
137  fcntl(fd, F_SETOWN, getpid());
138 
139  ioctl(fd, PERF_EVENT_IOC_RESET, 0);
140 
141  return fd;
142 }
143 
144 static int bp_event(void *addr, int sig)
145 {
146  return __event(true, addr, sig);
147 }
148 
149 static int wp_event(void *addr, int sig)
150 {
151  return __event(false, addr, sig);
152 }
153 
154 static long long bp_count(int fd)
155 {
156  long long count;
157  int ret;
158 
159  ret = read(fd, &count, sizeof(long long));
160  if (ret != sizeof(long long)) {
161  pr_debug("failed to read: %d\n", ret);
162  return TEST_FAIL;
163  }
164 
165  return count;
166 }
167 
168 int test__bp_signal(struct test *test __maybe_unused, int subtest __maybe_unused)
169 {
170  struct sigaction sa;
171  long long count1, count2, count3;
172 
173  /* setup SIGIO signal handler */
174  memset(&sa, 0, sizeof(struct sigaction));
175  sa.sa_sigaction = (void *) sig_handler;
176  sa.sa_flags = SA_SIGINFO;
177 
178  if (sigaction(SIGIO, &sa, NULL) < 0) {
179  pr_debug("failed setting up signal handler\n");
180  return TEST_FAIL;
181  }
182 
183  sa.sa_sigaction = (void *) sig_handler_2;
184  if (sigaction(SIGUSR1, &sa, NULL) < 0) {
185  pr_debug("failed setting up signal handler 2\n");
186  return TEST_FAIL;
187  }
188 
189  /*
190  * We create following events:
191  *
192  * fd1 - breakpoint event on __test_function with SIGIO
193  * signal configured. We should get signal
194  * notification each time the breakpoint is hit
195  *
196  * fd2 - breakpoint event on sig_handler with SIGUSR1
197  * configured. We should get SIGUSR1 each time when
198  * breakpoint is hit
199  *
200  * fd3 - watchpoint event on __test_function with SIGIO
201  * configured.
202  *
203  * Following processing should happen:
204  * Exec: Action: Result:
205  * incq (%rdi) - fd1 event breakpoint hit -> count1 == 1
206  * - SIGIO is delivered
207  * sig_handler - fd2 event breakpoint hit -> count2 == 1
208  * - SIGUSR1 is delivered
209  * sig_handler_2 -> overflows_2 == 1 (nested signal)
210  * sys_rt_sigreturn - return from sig_handler_2
211  * overflows++ -> overflows = 1
212  * sys_rt_sigreturn - return from sig_handler
213  * incq (%rdi) - fd3 event watchpoint hit -> count3 == 1 (wp and bp in one insn)
214  * - SIGIO is delivered
215  * sig_handler - fd2 event breakpoint hit -> count2 == 2
216  * - SIGUSR1 is delivered
217  * sig_handler_2 -> overflows_2 == 2 (nested signal)
218  * sys_rt_sigreturn - return from sig_handler_2
219  * overflows++ -> overflows = 2
220  * sys_rt_sigreturn - return from sig_handler
221  * the_var++ - fd3 event watchpoint hit -> count3 == 2 (standalone watchpoint)
222  * - SIGIO is delivered
223  * sig_handler - fd2 event breakpoint hit -> count2 == 3
224  * - SIGUSR1 is delivered
225  * sig_handler_2 -> overflows_2 == 3 (nested signal)
226  * sys_rt_sigreturn - return from sig_handler_2
227  * overflows++ -> overflows == 3
228  * sys_rt_sigreturn - return from sig_handler
229  *
230  * The test case check following error conditions:
231  * - we get stuck in signal handler because of debug
232  * exception being triggered receursively due to
233  * the wrong RF EFLAG management
234  *
235  * - we never trigger the sig_handler breakpoint due
236  * to the rong RF EFLAG management
237  *
238  */
239 
240  fd1 = bp_event(__test_function, SIGIO);
241  fd2 = bp_event(sig_handler, SIGUSR1);
242  fd3 = wp_event((void *)&the_var, SIGIO);
243 
244  ioctl(fd1, PERF_EVENT_IOC_ENABLE, 0);
245  ioctl(fd2, PERF_EVENT_IOC_ENABLE, 0);
246  ioctl(fd3, PERF_EVENT_IOC_ENABLE, 0);
247 
248  /*
249  * Kick off the test by trigering 'fd1'
250  * breakpoint.
251  */
252  test_function();
253 
254  ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0);
255  ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0);
256  ioctl(fd3, PERF_EVENT_IOC_DISABLE, 0);
257 
258  count1 = bp_count(fd1);
259  count2 = bp_count(fd2);
260  count3 = bp_count(fd3);
261 
262  close(fd1);
263  close(fd2);
264  close(fd3);
265 
266  pr_debug("count1 %lld, count2 %lld, count3 %lld, overflow %d, overflows_2 %d\n",
267  count1, count2, count3, overflows, overflows_2);
268 
269  if (count1 != 1) {
270  if (count1 == 11)
271  pr_debug("failed: RF EFLAG recursion issue detected\n");
272  else
273  pr_debug("failed: wrong count for bp1%lld\n", count1);
274  }
275 
276  if (overflows != 3)
277  pr_debug("failed: wrong overflow hit\n");
278 
279  if (overflows_2 != 3)
280  pr_debug("failed: wrong overflow_2 hit\n");
281 
282  if (count2 != 3)
283  pr_debug("failed: wrong count for bp2\n");
284 
285  if (count3 != 2)
286  pr_debug("failed: wrong count for bp3\n");
287 
288  return count1 == 1 && overflows == 3 && count2 == 3 && overflows_2 == 3 && count3 == 2 ?
289  TEST_OK : TEST_FAIL;
290 }
291 
293 {
294 /*
295  * The powerpc so far does not have support to even create
296  * instruction breakpoint using the perf event interface.
297  * Once it's there we can release this.
298  */
299 #if defined(__powerpc__) || defined(__s390x__)
300  return false;
301 #else
302  return true;
303 #endif
304 }
bool test__bp_signal_is_supported(void)
Definition: bp_signal.c:292
static long long bp_count(int fd)
Definition: bp_signal.c:154
static int fd3
Definition: bp_signal.c:33
int test__bp_signal(struct test *test __maybe_unused, int subtest __maybe_unused)
Definition: bp_signal.c:168
static void sig_handler_2(int signum __maybe_unused, siginfo_t *oh __maybe_unused, void *uc __maybe_unused)
Definition: bp_signal.c:73
static void __test_function(volatile long *ptr)
Definition: bp_signal.c:60
static int sys_perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu, int group_fd, unsigned long flags)
Definition: perf-sys.h:58
static int bp_event(void *addr, int sig)
Definition: bp_signal.c:144
x86 movsq based memset() in arch/x86/lib/memset_64.S") MEMSET_FN(memset_erms
#define pr_debug(fmt,...)
Definition: json.h:27
static int fd1
Definition: bp_signal.c:31
static int overflows
Definition: bp_signal.c:34
static int wp_event(void *addr, int sig)
Definition: bp_signal.c:149
static int overflows_2
Definition: bp_signal.c:35
unsigned long perf_event_open_cloexec_flag(void)
Definition: cloexec.c:93
static void sig_handler(int signum __maybe_unused, siginfo_t *oh __maybe_unused, void *uc __maybe_unused)
Definition: bp_signal.c:85
Definition: tests.h:30
volatile long the_var
Definition: bp_signal.c:37
static noinline int test_function(void)
Definition: bp_signal.c:66
static int fd2
Definition: bp_signal.c:32
static int __event(bool is_x, void *addr, int sig)
Definition: bp_signal.c:106
Definition: tests.h:25