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 #if defined (__x86_64__) || defined (__i386__)
  15 #include "arch-tests.h"
  16 #endif
  17
  18 /* For bsearch. We try to unwind functions in shared object. */
  19 #include <stdlib.h>
  20
  21 static int mmap_handler(struct perf_tool *tool __maybe_unused,
  22                         union perf_event *event,
  23                         struct perf_sample *sample __maybe_unused,
  24                         struct machine *machine)
  25 {
  26         return machine__process_mmap2_event(machine, event, NULL);
  27 }
  28
  29 static int init_live_machine(struct machine *machine)
  30 {
  31         union perf_event event;
  32         pid_t pid = getpid();
  33
  34         return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
  35                                                   mmap_handler, machine, true, 500);
  36 }
  37
  38 #define MAX_STACK 8
  39
  40 static int unwind_entry(struct unwind_entry *entry, void *arg)
  41 {
  42         unsigned long *cnt = (unsigned long *) arg;
  43         char *symbol = entry->sym ? entry->sym->name : NULL;
  44         static const char *funcs[MAX_STACK] = {
  45                 "test__arch_unwind_sample",
  46                 "unwind_thread",
  47                 "compare",
  48                 "bsearch",
  49                 "krava_3",
  50                 "krava_2",
  51                 "krava_1",
  52                 "test__dwarf_unwind"
  53         };
  54
  55         if (*cnt >= MAX_STACK) {
  56                 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
  57                 return -1;
  58         }
  59
  60         if (!symbol) {
  61                 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
  62                          entry->ip);
  63                 return -1;
  64         }
  65
  66         pr_debug("got: %s 0x%" PRIx64 "\n", symbol, entry->ip);
  67         return strcmp((const char *) symbol, funcs[(*cnt)++]);
  68 }
  69
  70 __attribute__ ((noinline))
  71 static int unwind_thread(struct thread *thread)
  72 {
  73         struct perf_sample sample;
  74         unsigned long cnt = 0;
  75         int err = -1;
  76
  77         memset(&sample, 0, sizeof(sample));
  78
  79         if (test__arch_unwind_sample(&sample, thread)) {
  80                 pr_debug("failed to get unwind sample\n");
  81                 goto out;
  82         }
  83
  84         err = unwind__get_entries(unwind_entry, &cnt, thread,
  85                                   &sample, MAX_STACK);
  86         if (err)
  87                 pr_debug("unwind failed\n");
  88         else if (cnt != MAX_STACK) {
  89                 pr_debug("got wrong number of stack entries %lu != %d\n",
  90                          cnt, MAX_STACK);
  91                 err = -1;
  92         }
  93
  94  out:
  95         free(sample.user_stack.data);
  96         free(sample.user_regs.regs);
  97         return err;
  98 }
  99
 100 static int global_unwind_retval = -INT_MAX;
 101
 102 __attribute__ ((noinline))
 103 static int compare(void *p1, void *p2)
 104 {
 105         /* Any possible value should be 'thread' */
 106         struct thread *thread = *(struct thread **)p1;
 107
 108         if (global_unwind_retval == -INT_MAX)
 109                 global_unwind_retval = unwind_thread(thread);
 110
 111         return p1 - p2;
 112 }
 113
 114 __attribute__ ((noinline))
 115 static int krava_3(struct thread *thread)
 116 {
 117         struct thread *array[2] = {thread, thread};
 118         void *fp = &bsearch;
 119         /*
 120          * make _bsearch a volatile function pointer to
 121          * prevent potential optimization, which may expand
 122          * bsearch and call compare directly from this function,
 123          * instead of libc shared object.
 124          */
 125         void *(*volatile _bsearch)(void *, void *, size_t,
 126                         size_t, int (*)(void *, void *));
 127
 128         _bsearch = fp;
 129         _bsearch(array, &thread, 2, sizeof(struct thread **), compare);
 130         return global_unwind_retval;
 131 }
 132
 133 __attribute__ ((noinline))
 134 static int krava_2(struct thread *thread)
 135 {
 136         return krava_3(thread);
 137 }
 138
 139 __attribute__ ((noinline))
 140 static int krava_1(struct thread *thread)
 141 {
 142         return krava_2(thread);
 143 }
 144
 145 int test__dwarf_unwind(void)
 146 {
 147         struct machines machines;
 148         struct machine *machine;
 149         struct thread *thread;
 150         int err = -1;
 151
 152         machines__init(&machines);
 153
 154         machine = machines__find(&machines, HOST_KERNEL_ID);
 155         if (!machine) {
 156                 pr_err("Could not get machine\n");
 157                 return -1;
 158         }
 159
 160         callchain_param.record_mode = CALLCHAIN_DWARF;
 161
 162         if (init_live_machine(machine)) {
 163                 pr_err("Could not init machine\n");
 164                 goto out;
 165         }
 166
 167         if (verbose > 1)
 168                 machine__fprintf(machine, stderr);
 169
 170         thread = machine__find_thread(machine, getpid(), getpid());
 171         if (!thread) {
 172                 pr_err("Could not get thread\n");
 173                 goto out;
 174         }
 175
 176         err = krava_1(thread);
 177         thread__put(thread);
 178
 179  out:
 180         machine__delete_threads(machine);
 181         machine__exit(machine);
 182         machines__exit(&machines);
 183         return err;
 184 }