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 <linux/zalloc.h>
   5 #include <inttypes.h>
   6 #include <limits.h>
   7 #include <unistd.h>
   8 #include "tests.h"
   9 #include "debug.h"
  10 #include "machine.h"
  11 #include "event.h"
  12 #include "../util/unwind.h"
  13 #include "perf_regs.h"
  14 #include "map.h"
  15 #include "symbol.h"
  16 #include "thread.h"
  17 #include "callchain.h"
  18 #include "util/synthetic-events.h"
  19
  20 #if defined (__x86_64__) || defined (__i386__) || defined (__powerpc__)
  21 #include "arch-tests.h"
  22 #endif
  23
  24 /* For bsearch. We try to unwind functions in shared object. */
  25 #include <stdlib.h>
  26
  27 static int mmap_handler(struct perf_tool *tool __maybe_unused,
  28                         union perf_event *event,
  29                         struct perf_sample *sample,
  30                         struct machine *machine)
  31 {
  32         return machine__process_mmap2_event(machine, event, sample);
  33 }
  34
  35 static int init_live_machine(struct machine *machine)
  36 {
  37         union perf_event event;
  38         pid_t pid = getpid();
  39
  40         memset(&event, 0, sizeof(event));
  41         return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
  42                                                   mmap_handler, machine, true);
  43 }
  44
  45 /*
  46  * We need to keep these functions global, despite the
  47  * fact that they are used only locally in this object,
  48  * in order to keep them around even if the binary is
  49  * stripped. If they are gone, the unwind check for
  50  * symbol fails.
  51  */
  52 int test_dwarf_unwind__thread(struct thread *thread);
  53 int test_dwarf_unwind__compare(void *p1, void *p2);
  54 int test_dwarf_unwind__krava_3(struct thread *thread);
  55 int test_dwarf_unwind__krava_2(struct thread *thread);
  56 int test_dwarf_unwind__krava_1(struct thread *thread);
  57
  58 #define MAX_STACK 8
  59
  60 static int unwind_entry(struct unwind_entry *entry, void *arg)
  61 {
  62         unsigned long *cnt = (unsigned long *) arg;
  63         char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL;
  64         static const char *funcs[MAX_STACK] = {
  65                 "test__arch_unwind_sample",
  66                 "test_dwarf_unwind__thread",
  67                 "test_dwarf_unwind__compare",
  68                 "bsearch",
  69                 "test_dwarf_unwind__krava_3",
  70                 "test_dwarf_unwind__krava_2",
  71                 "test_dwarf_unwind__krava_1",
  72                 "test__dwarf_unwind"
  73         };
  74         /*
  75          * The funcs[MAX_STACK] array index, based on the
  76          * callchain order setup.
  77          */
  78         int idx = callchain_param.order == ORDER_CALLER ?
  79                   MAX_STACK - *cnt - 1 : *cnt;
  80
  81         if (*cnt >= MAX_STACK) {
  82                 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
  83                 return -1;
  84         }
  85
  86         if (!symbol) {
  87                 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
  88                          entry->ip);
  89                 return -1;
  90         }
  91
  92         (*cnt)++;
  93         pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n",
  94                  symbol, entry->ip, funcs[idx]);
  95         return strcmp((const char *) symbol, funcs[idx]);
  96 }
  97
  98 __no_tail_call noinline int test_dwarf_unwind__thread(struct thread *thread)
  99 {
 100         struct perf_sample sample;
 101         unsigned long cnt = 0;
 102         int err = -1;
 103
 104         memset(&sample, 0, sizeof(sample));
 105
 106         if (test__arch_unwind_sample(&sample, thread)) {
 107                 pr_debug("failed to get unwind sample\n");
 108                 goto out;
 109         }
 110
 111         err = unwind__get_entries(unwind_entry, &cnt, thread,
 112                                   &sample, MAX_STACK);
 113         if (err)
 114                 pr_debug("unwind failed\n");
 115         else if (cnt != MAX_STACK) {
 116                 pr_debug("got wrong number of stack entries %lu != %d\n",
 117                          cnt, MAX_STACK);
 118                 err = -1;
 119         }
 120
 121  out:
 122         zfree(&sample.user_stack.data);
 123         zfree(&sample.user_regs.regs);
 124         return err;
 125 }
 126
 127 static int global_unwind_retval = -INT_MAX;
 128
 129 __no_tail_call noinline int test_dwarf_unwind__compare(void *p1, void *p2)
 130 {
 131         /* Any possible value should be 'thread' */
 132         struct thread *thread = *(struct thread **)p1;
 133
 134         if (global_unwind_retval == -INT_MAX) {
 135                 /* Call unwinder twice for both callchain orders. */
 136                 callchain_param.order = ORDER_CALLER;
 137
 138                 global_unwind_retval = test_dwarf_unwind__thread(thread);
 139                 if (!global_unwind_retval) {
 140                         callchain_param.order = ORDER_CALLEE;
 141                         global_unwind_retval = test_dwarf_unwind__thread(thread);
 142                 }
 143         }
 144
 145         return p1 - p2;
 146 }
 147
 148 __no_tail_call noinline int test_dwarf_unwind__krava_3(struct thread *thread)
 149 {
 150         struct thread *array[2] = {thread, thread};
 151         void *fp = &bsearch;
 152         /*
 153          * make _bsearch a volatile function pointer to
 154          * prevent potential optimization, which may expand
 155          * bsearch and call compare directly from this function,
 156          * instead of libc shared object.
 157          */
 158         void *(*volatile _bsearch)(void *, void *, size_t,
 159                         size_t, int (*)(void *, void *));
 160
 161         _bsearch = fp;
 162         _bsearch(array, &thread, 2, sizeof(struct thread **),
 163                  test_dwarf_unwind__compare);
 164         return global_unwind_retval;
 165 }
 166
 167 __no_tail_call noinline int test_dwarf_unwind__krava_2(struct thread *thread)
 168 {
 169         return test_dwarf_unwind__krava_3(thread);
 170 }
 171
 172 __no_tail_call noinline int test_dwarf_unwind__krava_1(struct thread *thread)
 173 {
 174         return test_dwarf_unwind__krava_2(thread);
 175 }
 176
 177 int test__dwarf_unwind(struct test *test __maybe_unused, int subtest __maybe_unused)
 178 {
 179         struct machine *machine;
 180         struct thread *thread;
 181         int err = -1;
 182
 183         machine = machine__new_host();
 184         if (!machine) {
 185                 pr_err("Could not get machine\n");
 186                 return -1;
 187         }
 188
 189         if (machine__create_kernel_maps(machine)) {
 190                 pr_err("Failed to create kernel maps\n");
 191                 return -1;
 192         }
 193
 194         callchain_param.record_mode = CALLCHAIN_DWARF;
 195         dwarf_callchain_users = true;
 196
 197         if (init_live_machine(machine)) {
 198                 pr_err("Could not init machine\n");
 199                 goto out;
 200         }
 201
 202         if (verbose > 1)
 203                 machine__fprintf(machine, stderr);
 204
 205         thread = machine__find_thread(machine, getpid(), getpid());
 206         if (!thread) {
 207                 pr_err("Could not get thread\n");
 208                 goto out;
 209         }
 210
 211         err = test_dwarf_unwind__krava_1(thread);
 212         thread__put(thread);
 213
 214  out:
 215         machine__delete_threads(machine);
 216         machine__delete(machine);
 217         return err;
 218 }