tools/perf/util/unwind-libdw.c

   1 #include <linux/compiler.h>
   2 #include <elfutils/libdw.h>
   3 #include <elfutils/libdwfl.h>
   4 #include <inttypes.h>
   5 #include <errno.h>
   6 #include "debug.h"
   7 #include "unwind.h"
   8 #include "unwind-libdw.h"
   9 #include "machine.h"
  10 #include "thread.h"
  11 #include <linux/types.h>
  12 #include "event.h"
  13 #include "perf_regs.h"
  14 #include "callchain.h"
  15
  16 static char *debuginfo_path;
  17
  18 static const Dwfl_Callbacks offline_callbacks = {
  19         .find_debuginfo         = dwfl_standard_find_debuginfo,
  20         .debuginfo_path         = &debuginfo_path,
  21         .section_address        = dwfl_offline_section_address,
  22 };
  23
  24 static int __report_module(struct addr_location *al, u64 ip,
  25                             struct unwind_info *ui)
  26 {
  27         Dwfl_Module *mod;
  28         struct dso *dso = NULL;
  29
  30         thread__find_addr_location(ui->thread,
  31                                    PERF_RECORD_MISC_USER,
  32                                    MAP__FUNCTION, ip, al);
  33
  34         if (al->map)
  35                 dso = al->map->dso;
  36
  37         if (!dso)
  38                 return 0;
  39
  40         mod = dwfl_addrmodule(ui->dwfl, ip);
  41         if (!mod)
  42                 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
  43                                       dso->long_name, -1, al->map->start,
  44                                       false);
  45
  46         return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
  47 }
  48
  49 static int report_module(u64 ip, struct unwind_info *ui)
  50 {
  51         struct addr_location al;
  52
  53         return __report_module(&al, ip, ui);
  54 }
  55
  56 /*
  57  * Store all entries within entries array,
  58  * we will process it after we finish unwind.
  59  */
  60 static int entry(u64 ip, struct unwind_info *ui)
  61
  62 {
  63         struct unwind_entry *e = &ui->entries[ui->idx++];
  64         struct addr_location al;
  65
  66         if (__report_module(&al, ip, ui))
  67                 return -1;
  68
  69         e->ip  = ip;
  70         e->map = al.map;
  71         e->sym = al.sym;
  72
  73         pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
  74                  al.sym ? al.sym->name : "''",
  75                  ip,
  76                  al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
  77         return 0;
  78 }
  79
  80 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
  81 {
  82         /* We want only single thread to be processed. */
  83         if (*thread_argp != NULL)
  84                 return 0;
  85
  86         *thread_argp = arg;
  87         return dwfl_pid(dwfl);
  88 }
  89
  90 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
  91                           Dwarf_Word *data)
  92 {
  93         struct addr_location al;
  94         ssize_t size;
  95
  96         thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
  97                               MAP__FUNCTION, addr, &al);
  98         if (!al.map) {
  99                 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
 100                 return -1;
 101         }
 102
 103         if (!al.map->dso)
 104                 return -1;
 105
 106         size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
 107                                    addr, (u8 *) data, sizeof(*data));
 108
 109         return !(size == sizeof(*data));
 110 }
 111
 112 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
 113                         void *arg)
 114 {
 115         struct unwind_info *ui = arg;
 116         struct stack_dump *stack = &ui->sample->user_stack;
 117         u64 start, end;
 118         int offset;
 119         int ret;
 120
 121         ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
 122         if (ret)
 123                 return false;
 124
 125         end = start + stack->size;
 126
 127         /* Check overflow. */
 128         if (addr + sizeof(Dwarf_Word) < addr)
 129                 return false;
 130
 131         if (addr < start || addr + sizeof(Dwarf_Word) > end) {
 132                 ret = access_dso_mem(ui, addr, result);
 133                 if (ret) {
 134                         pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
 135                                  " 0x%" PRIx64 "-0x%" PRIx64 "\n",
 136                                 addr, start, end);
 137                         return false;
 138                 }
 139                 return true;
 140         }
 141
 142         offset  = addr - start;
 143         *result = *(Dwarf_Word *)&stack->data[offset];
 144         pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
 145                  addr, (unsigned long)*result, offset);
 146         return true;
 147 }
 148
 149 static const Dwfl_Thread_Callbacks callbacks = {
 150         .next_thread            = next_thread,
 151         .memory_read            = memory_read,
 152         .set_initial_registers  = libdw__arch_set_initial_registers,
 153 };
 154
 155 static int
 156 frame_callback(Dwfl_Frame *state, void *arg)
 157 {
 158         struct unwind_info *ui = arg;
 159         Dwarf_Addr pc;
 160
 161         if (!dwfl_frame_pc(state, &pc, NULL)) {
 162                 pr_err("%s", dwfl_errmsg(-1));
 163                 return DWARF_CB_ABORT;
 164         }
 165
 166         return entry(pc, ui) || !(--ui->max_stack) ?
 167                DWARF_CB_ABORT : DWARF_CB_OK;
 168 }
 169
 170 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
 171                         struct thread *thread,
 172                         struct perf_sample *data,
 173                         int max_stack)
 174 {
 175         struct unwind_info *ui, ui_buf = {
 176                 .sample         = data,
 177                 .thread         = thread,
 178                 .machine        = thread->mg->machine,
 179                 .cb             = cb,
 180                 .arg            = arg,
 181                 .max_stack      = max_stack,
 182         };
 183         Dwarf_Word ip;
 184         int err = -EINVAL, i;
 185
 186         if (!data->user_regs.regs)
 187                 return -EINVAL;
 188
 189         ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
 190         if (!ui)
 191                 return -ENOMEM;
 192
 193         *ui = ui_buf;
 194
 195         ui->dwfl = dwfl_begin(&offline_callbacks);
 196         if (!ui->dwfl)
 197                 goto out;
 198
 199         err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
 200         if (err)
 201                 goto out;
 202
 203         err = report_module(ip, ui);
 204         if (err)
 205                 goto out;
 206
 207         if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui))
 208                 goto out;
 209
 210         err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
 211
 212         if (err && !ui->max_stack)
 213                 err = 0;
 214
 215         /*
 216          * Display what we got based on the order setup.
 217          */
 218         for (i = 0; i < ui->idx && !err; i++) {
 219                 int j = i;
 220
 221                 if (callchain_param.order == ORDER_CALLER)
 222                         j = ui->idx - i - 1;
 223
 224                 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
 225         }
 226
 227  out:
 228         if (err)
 229                 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
 230
 231         dwfl_end(ui->dwfl);
 232         free(ui);
 233         return 0;
 234 }