tools/perf/tests/dwarf-unwind.c

   1 #include <linux/compiler.h>
   2 #include <linux/types.h>
   3 #include <unistd.h>
   4 #include "tests.h"
   5 #include "debug.h"
   6 #include "machine.h"
   7 #include "event.h"
   8 #include "unwind.h"
   9 #include "perf_regs.h"
  10 #include "map.h"
  11 #include "thread.h"
  12 #include "callchain.h"
  13
  14 /* For bsearch. We try to unwind functions in shared object. */
  15 #include <stdlib.h>
  16
  17 static int mmap_handler(struct perf_tool *tool __maybe_unused,
  18                         union perf_event *event,
  19                         struct perf_sample *sample __maybe_unused,
  20                         struct machine *machine)
  21 {
  22         return machine__process_mmap2_event(machine, event, NULL);
  23 }
  24
  25 static int init_live_machine(struct machine *machine)
  26 {
  27         union perf_event event;
  28         pid_t pid = getpid();
  29
  30         return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
  31                                                   mmap_handler, machine, true);
  32 }
  33
  34 #define MAX_STACK 8
  35
  36 static int unwind_entry(struct unwind_entry *entry, void *arg)
  37 {
  38         unsigned long *cnt = (unsigned long *) arg;
  39         char *symbol = entry->sym ? entry->sym->name : NULL;
  40         static const char *funcs[MAX_STACK] = {
  41                 "test__arch_unwind_sample",
  42                 "unwind_thread",
  43                 "compare",
  44                 "bsearch",
  45                 "krava_3",
  46                 "krava_2",
  47                 "krava_1",
  48                 "test__dwarf_unwind"
  49         };
  50
  51         if (*cnt >= MAX_STACK) {
  52                 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
  53                 return -1;
  54         }
  55
  56         if (!symbol) {
  57                 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
  58                          entry->ip);
  59                 return -1;
  60         }
  61
  62         pr_debug("got: %s 0x%" PRIx64 "\n", symbol, entry->ip);
  63         return strcmp((const char *) symbol, funcs[(*cnt)++]);
  64 }
  65
  66 __attribute__ ((noinline))
  67 static int unwind_thread(struct thread *thread)
  68 {
  69         struct perf_sample sample;
  70         unsigned long cnt = 0;
  71         int err = -1;
  72
  73         memset(&sample, 0, sizeof(sample));
  74
  75         if (test__arch_unwind_sample(&sample, thread)) {
  76                 pr_debug("failed to get unwind sample\n");
  77                 goto out;
  78         }
  79
  80         err = unwind__get_entries(unwind_entry, &cnt, thread,
  81                                   &sample, MAX_STACK);
  82         if (err)
  83                 pr_debug("unwind failed\n");
  84         else if (cnt != MAX_STACK) {
  85                 pr_debug("got wrong number of stack entries %lu != %d\n",
  86                          cnt, MAX_STACK);
  87                 err = -1;
  88         }
  89
  90  out:
  91         free(sample.user_stack.data);
  92         free(sample.user_regs.regs);
  93         return err;
  94 }
  95
  96 static int global_unwind_retval = -INT_MAX;
  97
  98 __attribute__ ((noinline))
  99 static int compare(void *p1, void *p2)
 100 {
 101         /* Any possible value should be 'thread' */
 102         struct thread *thread = *(struct thread **)p1;
 103
 104         if (global_unwind_retval == -INT_MAX)
 105                 global_unwind_retval = unwind_thread(thread);
 106
 107         return p1 - p2;
 108 }
 109
 110 __attribute__ ((noinline))
 111 static int krava_3(struct thread *thread)
 112 {
 113         struct thread *array[2] = {thread, thread};
 114         void *fp = &bsearch;
 115         /*
 116          * make _bsearch a volatile function pointer to
 117          * prevent potential optimization, which may expand
 118          * bsearch and call compare directly from this function,
 119          * instead of libc shared object.
 120          */
 121         void *(*volatile _bsearch)(void *, void *, size_t,
 122                         size_t, int (*)(void *, void *));
 123
 124         _bsearch = fp;
 125         _bsearch(array, &thread, 2, sizeof(struct thread **), compare);
 126         return global_unwind_retval;
 127 }
 128
 129 __attribute__ ((noinline))
 130 static int krava_2(struct thread *thread)
 131 {
 132         return krava_3(thread);
 133 }
 134
 135 __attribute__ ((noinline))
 136 static int krava_1(struct thread *thread)
 137 {
 138         return krava_2(thread);
 139 }
 140
 141 int test__dwarf_unwind(void)
 142 {
 143         struct machines machines;
 144         struct machine *machine;
 145         struct thread *thread;
 146         int err = -1;
 147
 148         machines__init(&machines);
 149
 150         machine = machines__find(&machines, HOST_KERNEL_ID);
 151         if (!machine) {
 152                 pr_err("Could not get machine\n");
 153                 return -1;
 154         }
 155
 156         callchain_param.record_mode = CALLCHAIN_DWARF;
 157
 158         if (init_live_machine(machine)) {
 159                 pr_err("Could not init machine\n");
 160                 goto out;
 161         }
 162
 163         if (verbose > 1)
 164                 machine__fprintf(machine, stderr);
 165
 166         thread = machine__find_thread(machine, getpid(), getpid());
 167         if (!thread) {
 168                 pr_err("Could not get thread\n");
 169                 goto out;
 170         }
 171
 172         err = krava_1(thread);
 173
 174  out:
 175         machine__delete_threads(machine);
 176         machine__exit(machine);
 177         machines__exit(&machines);
 178         return err;
 179 }