tools/perf/tests/dwarf-unwind.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/compiler.h>
   3 #include <linux/types.h>
   4 #include <inttypes.h>
   5 #include <unistd.h>
   6 #include "tests.h"
   7 #include "debug.h"
   8 #include "machine.h"
   9 #include "event.h"
  10 #include "../util/unwind.h"
  11 #include "perf_regs.h"
  12 #include "map.h"
  13 #include "thread.h"
  14 #include "callchain.h"
  15
  16 #if defined (__x86_64__) || defined (__i386__) || defined (__powerpc__)
  17 #include "arch-tests.h"
  18 #endif
  19
  20 /* For bsearch. We try to unwind functions in shared object. */
  21 #include <stdlib.h>
  22
  23 static int mmap_handler(struct perf_tool *tool __maybe_unused,
  24                         union perf_event *event,
  25                         struct perf_sample *sample,
  26                         struct machine *machine)
  27 {
  28         return machine__process_mmap2_event(machine, event, sample);
  29 }
  30
  31 static int init_live_machine(struct machine *machine)
  32 {
  33         union perf_event event;
  34         pid_t pid = getpid();
  35
  36         return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
  37                                                   mmap_handler, machine, true, 500);
  38 }
  39
  40 #define MAX_STACK 8
  41
  42 static int unwind_entry(struct unwind_entry *entry, void *arg)
  43 {
  44         unsigned long *cnt = (unsigned long *) arg;
  45         char *symbol = entry->sym ? entry->sym->name : NULL;
  46         static const char *funcs[MAX_STACK] = {
  47                 "test__arch_unwind_sample",
  48                 "unwind_thread",
  49                 "compare",
  50                 "bsearch",
  51                 "krava_3",
  52                 "krava_2",
  53                 "krava_1",
  54                 "test__dwarf_unwind"
  55         };
  56         /*
  57          * The funcs[MAX_STACK] array index, based on the
  58          * callchain order setup.
  59          */
  60         int idx = callchain_param.order == ORDER_CALLER ?
  61                   MAX_STACK - *cnt - 1 : *cnt;
  62
  63         if (*cnt >= MAX_STACK) {
  64                 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
  65                 return -1;
  66         }
  67
  68         if (!symbol) {
  69                 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
  70                          entry->ip);
  71                 return -1;
  72         }
  73
  74         (*cnt)++;
  75         pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n",
  76                  symbol, entry->ip, funcs[idx]);
  77         return strcmp((const char *) symbol, funcs[idx]);
  78 }
  79
  80 static noinline int unwind_thread(struct thread *thread)
  81 {
  82         struct perf_sample sample;
  83         unsigned long cnt = 0;
  84         int err = -1;
  85
  86         memset(&sample, 0, sizeof(sample));
  87
  88         if (test__arch_unwind_sample(&sample, thread)) {
  89                 pr_debug("failed to get unwind sample\n");
  90                 goto out;
  91         }
  92
  93         err = unwind__get_entries(unwind_entry, &cnt, thread,
  94                                   &sample, MAX_STACK);
  95         if (err)
  96                 pr_debug("unwind failed\n");
  97         else if (cnt != MAX_STACK) {
  98                 pr_debug("got wrong number of stack entries %lu != %d\n",
  99                          cnt, MAX_STACK);
 100                 err = -1;
 101         }
 102
 103  out:
 104         free(sample.user_stack.data);
 105         free(sample.user_regs.regs);
 106         return err;
 107 }
 108
 109 static int global_unwind_retval = -INT_MAX;
 110
 111 static noinline int compare(void *p1, void *p2)
 112 {
 113         /* Any possible value should be 'thread' */
 114         struct thread *thread = *(struct thread **)p1;
 115
 116         if (global_unwind_retval == -INT_MAX) {
 117                 /* Call unwinder twice for both callchain orders. */
 118                 callchain_param.order = ORDER_CALLER;
 119
 120                 global_unwind_retval = unwind_thread(thread);
 121                 if (!global_unwind_retval) {
 122                         callchain_param.order = ORDER_CALLEE;
 123                         global_unwind_retval = unwind_thread(thread);
 124                 }
 125         }
 126
 127         return p1 - p2;
 128 }
 129
 130 static noinline int krava_3(struct thread *thread)
 131 {
 132         struct thread *array[2] = {thread, thread};
 133         void *fp = &bsearch;
 134         /*
 135          * make _bsearch a volatile function pointer to
 136          * prevent potential optimization, which may expand
 137          * bsearch and call compare directly from this function,
 138          * instead of libc shared object.
 139          */
 140         void *(*volatile _bsearch)(void *, void *, size_t,
 141                         size_t, int (*)(void *, void *));
 142
 143         _bsearch = fp;
 144         _bsearch(array, &thread, 2, sizeof(struct thread **), compare);
 145         return global_unwind_retval;
 146 }
 147
 148 static noinline int krava_2(struct thread *thread)
 149 {
 150         return krava_3(thread);
 151 }
 152
 153 static noinline int krava_1(struct thread *thread)
 154 {
 155         return krava_2(thread);
 156 }
 157
 158 int test__dwarf_unwind(struct test *test __maybe_unused, int subtest __maybe_unused)
 159 {
 160         struct machine *machine;
 161         struct thread *thread;
 162         int err = -1;
 163
 164         machine = machine__new_host();
 165         if (!machine) {
 166                 pr_err("Could not get machine\n");
 167                 return -1;
 168         }
 169
 170         if (machine__create_kernel_maps(machine)) {
 171                 pr_err("Failed to create kernel maps\n");
 172                 return -1;
 173         }
 174
 175         callchain_param.record_mode = CALLCHAIN_DWARF;
 176         dwarf_callchain_users = true;
 177
 178         if (init_live_machine(machine)) {
 179                 pr_err("Could not init machine\n");
 180                 goto out;
 181         }
 182
 183         if (verbose > 1)
 184                 machine__fprintf(machine, stderr);
 185
 186         thread = machine__find_thread(machine, getpid(), getpid());
 187         if (!thread) {
 188                 pr_err("Could not get thread\n");
 189                 goto out;
 190         }
 191
 192         err = krava_1(thread);
 193         thread__put(thread);
 194
 195  out:
 196         machine__delete_threads(machine);
 197         machine__delete(machine);
 198         return err;
 199 }