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