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