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