LXR linux/tools/perf/tests/dwarf-unwind.c

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