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Linux/tools/perf/tests/dwarf-unwind.c

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  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 #if defined (__x86_64__) || defined (__i386__)
 15 #include "arch-tests.h"
 16 #endif
 17 
 18 /* For bsearch. We try to unwind functions in shared object. */
 19 #include <stdlib.h>
 20 
 21 static int mmap_handler(struct perf_tool *tool __maybe_unused,
 22                         union perf_event *event,
 23                         struct perf_sample *sample __maybe_unused,
 24                         struct machine *machine)
 25 {
 26         return machine__process_mmap2_event(machine, event, NULL);
 27 }
 28 
 29 static int init_live_machine(struct machine *machine)
 30 {
 31         union perf_event event;
 32         pid_t pid = getpid();
 33 
 34         return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,
 35                                                   mmap_handler, machine, true, 500);
 36 }
 37 
 38 #define MAX_STACK 8
 39 
 40 static int unwind_entry(struct unwind_entry *entry, void *arg)
 41 {
 42         unsigned long *cnt = (unsigned long *) arg;
 43         char *symbol = entry->sym ? entry->sym->name : NULL;
 44         static const char *funcs[MAX_STACK] = {
 45                 "test__arch_unwind_sample",
 46                 "unwind_thread",
 47                 "compare",
 48                 "bsearch",
 49                 "krava_3",
 50                 "krava_2",
 51                 "krava_1",
 52                 "test__dwarf_unwind"
 53         };
 54 
 55         if (*cnt >= MAX_STACK) {
 56                 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);
 57                 return -1;
 58         }
 59 
 60         if (!symbol) {
 61                 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",
 62                          entry->ip);
 63                 return -1;
 64         }
 65 
 66         pr_debug("got: %s 0x%" PRIx64 "\n", symbol, entry->ip);
 67         return strcmp((const char *) symbol, funcs[(*cnt)++]);
 68 }
 69 
 70 __attribute__ ((noinline))
 71 static int unwind_thread(struct thread *thread)
 72 {
 73         struct perf_sample sample;
 74         unsigned long cnt = 0;
 75         int err = -1;
 76 
 77         memset(&sample, 0, sizeof(sample));
 78 
 79         if (test__arch_unwind_sample(&sample, thread)) {
 80                 pr_debug("failed to get unwind sample\n");
 81                 goto out;
 82         }
 83 
 84         err = unwind__get_entries(unwind_entry, &cnt, thread,
 85                                   &sample, MAX_STACK);
 86         if (err)
 87                 pr_debug("unwind failed\n");
 88         else if (cnt != MAX_STACK) {
 89                 pr_debug("got wrong number of stack entries %lu != %d\n",
 90                          cnt, MAX_STACK);
 91                 err = -1;
 92         }
 93 
 94  out:
 95         free(sample.user_stack.data);
 96         free(sample.user_regs.regs);
 97         return err;
 98 }
 99 
100 static int global_unwind_retval = -INT_MAX;
101 
102 __attribute__ ((noinline))
103 static int compare(void *p1, void *p2)
104 {
105         /* Any possible value should be 'thread' */
106         struct thread *thread = *(struct thread **)p1;
107 
108         if (global_unwind_retval == -INT_MAX)
109                 global_unwind_retval = unwind_thread(thread);
110 
111         return p1 - p2;
112 }
113 
114 __attribute__ ((noinline))
115 static int krava_3(struct thread *thread)
116 {
117         struct thread *array[2] = {thread, thread};
118         void *fp = &bsearch;
119         /*
120          * make _bsearch a volatile function pointer to
121          * prevent potential optimization, which may expand
122          * bsearch and call compare directly from this function,
123          * instead of libc shared object.
124          */
125         void *(*volatile _bsearch)(void *, void *, size_t,
126                         size_t, int (*)(void *, void *));
127 
128         _bsearch = fp;
129         _bsearch(array, &thread, 2, sizeof(struct thread **), compare);
130         return global_unwind_retval;
131 }
132 
133 __attribute__ ((noinline))
134 static int krava_2(struct thread *thread)
135 {
136         return krava_3(thread);
137 }
138 
139 __attribute__ ((noinline))
140 static int krava_1(struct thread *thread)
141 {
142         return krava_2(thread);
143 }
144 
145 int test__dwarf_unwind(void)
146 {
147         struct machines machines;
148         struct machine *machine;
149         struct thread *thread;
150         int err = -1;
151 
152         machines__init(&machines);
153 
154         machine = machines__find(&machines, HOST_KERNEL_ID);
155         if (!machine) {
156                 pr_err("Could not get machine\n");
157                 return -1;
158         }
159 
160         callchain_param.record_mode = CALLCHAIN_DWARF;
161 
162         if (init_live_machine(machine)) {
163                 pr_err("Could not init machine\n");
164                 goto out;
165         }
166 
167         if (verbose > 1)
168                 machine__fprintf(machine, stderr);
169 
170         thread = machine__find_thread(machine, getpid(), getpid());
171         if (!thread) {
172                 pr_err("Could not get thread\n");
173                 goto out;
174         }
175 
176         err = krava_1(thread);
177         thread__put(thread);
178 
179  out:
180         machine__delete_threads(machine);
181         machine__exit(machine);
182         machines__exit(&machines);
183         return err;
184 }
185 

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