tools/perf/tests/bp_account.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Powerpc needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
   4  * 'int-ll64.h' and avoid compile warnings when printing __u64 with %llu.
   5  */
   6 #define __SANE_USERSPACE_TYPES__
   7
   8 #include <stdlib.h>
   9 #include <stdio.h>
  10 #include <unistd.h>
  11 #include <string.h>
  12 #include <sys/ioctl.h>
  13 #include <fcntl.h>
  14 #include <linux/hw_breakpoint.h>
  15
  16 #include "tests.h"
  17 #include "debug.h"
  18 #include "event.h"
  19 #include "../perf-sys.h"
  20 #include "cloexec.h"
  21
  22 static volatile long the_var;
  23
  24 static noinline int test_function(void)
  25 {
  26         return 0;
  27 }
  28
  29 static int __event(bool is_x, void *addr, struct perf_event_attr *attr)
  30 {
  31         int fd;
  32
  33         memset(attr, 0, sizeof(struct perf_event_attr));
  34         attr->type = PERF_TYPE_BREAKPOINT;
  35         attr->size = sizeof(struct perf_event_attr);
  36
  37         attr->config = 0;
  38         attr->bp_type = is_x ? HW_BREAKPOINT_X : HW_BREAKPOINT_W;
  39         attr->bp_addr = (unsigned long) addr;
  40         attr->bp_len = sizeof(long);
  41
  42         attr->sample_period = 1;
  43         attr->sample_type = PERF_SAMPLE_IP;
  44
  45         attr->exclude_kernel = 1;
  46         attr->exclude_hv = 1;
  47
  48         fd = sys_perf_event_open(attr, -1, 0, -1,
  49                                  perf_event_open_cloexec_flag());
  50         if (fd < 0) {
  51                 pr_debug("failed opening event %llx\n", attr->config);
  52                 return TEST_FAIL;
  53         }
  54
  55         return fd;
  56 }
  57
  58 static int wp_event(void *addr, struct perf_event_attr *attr)
  59 {
  60         return __event(false, addr, attr);
  61 }
  62
  63 static int bp_event(void *addr, struct perf_event_attr *attr)
  64 {
  65         return __event(true, addr, attr);
  66 }
  67
  68 static int bp_accounting(int wp_cnt, int share)
  69 {
  70         struct perf_event_attr attr, attr_mod, attr_new;
  71         int i, fd[wp_cnt], fd_wp, ret;
  72
  73         for (i = 0; i < wp_cnt; i++) {
  74                 fd[i] = wp_event((void *)&the_var, &attr);
  75                 TEST_ASSERT_VAL("failed to create wp\n", fd[i] != -1);
  76                 pr_debug("wp %d created\n", i);
  77         }
  78
  79         attr_mod = attr;
  80         attr_mod.bp_type = HW_BREAKPOINT_X;
  81         attr_mod.bp_addr = (unsigned long) test_function;
  82
  83         ret = ioctl(fd[0], PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &attr_mod);
  84         TEST_ASSERT_VAL("failed to modify wp\n", ret == 0);
  85
  86         pr_debug("wp 0 modified to bp\n");
  87
  88         if (!share) {
  89                 fd_wp = wp_event((void *)&the_var, &attr_new);
  90                 TEST_ASSERT_VAL("failed to create max wp\n", fd_wp != -1);
  91                 pr_debug("wp max created\n");
  92         }
  93
  94         for (i = 0; i < wp_cnt; i++)
  95                 close(fd[i]);
  96
  97         return 0;
  98 }
  99
 100 static int detect_cnt(bool is_x)
 101 {
 102         struct perf_event_attr attr;
 103         void *addr = is_x ? (void *)test_function : (void *)&the_var;
 104         int fd[100], cnt = 0, i;
 105
 106         while (1) {
 107                 if (cnt == 100) {
 108                         pr_debug("way too many debug registers, fix the test\n");
 109                         return 0;
 110                 }
 111                 fd[cnt] = __event(is_x, addr, &attr);
 112
 113                 if (fd[cnt] < 0)
 114                         break;
 115                 cnt++;
 116         }
 117
 118         for (i = 0; i < cnt; i++)
 119                 close(fd[i]);
 120
 121         return cnt;
 122 }
 123
 124 static int detect_ioctl(void)
 125 {
 126         struct perf_event_attr attr;
 127         int fd, ret = 1;
 128
 129         fd = wp_event((void *) &the_var, &attr);
 130         if (fd > 0) {
 131                 ret = ioctl(fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &attr);
 132                 close(fd);
 133         }
 134
 135         return ret ? 0 : 1;
 136 }
 137
 138 static int detect_share(int wp_cnt, int bp_cnt)
 139 {
 140         struct perf_event_attr attr;
 141         int i, fd[wp_cnt + bp_cnt], ret;
 142
 143         for (i = 0; i < wp_cnt; i++) {
 144                 fd[i] = wp_event((void *)&the_var, &attr);
 145                 TEST_ASSERT_VAL("failed to create wp\n", fd[i] != -1);
 146         }
 147
 148         for (; i < (bp_cnt + wp_cnt); i++) {
 149                 fd[i] = bp_event((void *)test_function, &attr);
 150                 if (fd[i] == -1)
 151                         break;
 152         }
 153
 154         ret = i != (bp_cnt + wp_cnt);
 155
 156         while (i--)
 157                 close(fd[i]);
 158
 159         return ret;
 160 }
 161
 162 /*
 163  * This test does following:
 164  *   - detects the number of watch/break-points,
 165  *     skip test if any is missing
 166  *   - detects PERF_EVENT_IOC_MODIFY_ATTRIBUTES ioctl,
 167  *     skip test if it's missing
 168  *   - detects if watchpoints and breakpoints share
 169  *     same slots
 170  *   - create all possible watchpoints on cpu 0
 171  *   - change one of it to breakpoint
 172  *   - in case wp and bp do not share slots,
 173  *     we create another watchpoint to ensure
 174  *     the slot accounting is correct
 175  */
 176 int test__bp_accounting(struct test *test __maybe_unused, int subtest __maybe_unused)
 177 {
 178         int has_ioctl = detect_ioctl();
 179         int wp_cnt = detect_cnt(false);
 180         int bp_cnt = detect_cnt(true);
 181         int share  = detect_share(wp_cnt, bp_cnt);
 182
 183         pr_debug("watchpoints count %d, breakpoints count %d, has_ioctl %d, share %d\n",
 184                  wp_cnt, bp_cnt, has_ioctl, share);
 185
 186         if (!wp_cnt || !bp_cnt || !has_ioctl)
 187                 return TEST_SKIP;
 188
 189         return bp_accounting(wp_cnt, share);
 190 }
 191
 192 bool test__bp_account_is_supported(void)
 193 {
 194         /*
 195          * PowerPC and S390 do not support creation of instruction
 196          * breakpoints using the perf_event interface.
 197          *
 198          * Just disable the test for these architectures until these
 199          * issues are resolved.
 200          */
 201 #if defined(__powerpc__) || defined(__s390x__)
 202         return false;
 203 #else
 204         return true;
 205 #endif
 206 }