src/journal/stacktrace.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2014 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <dwarf.h>
  23 #include <elfutils/libdwfl.h>
  24
  25 #include "util.h"
  26 #include "macro.h"
  27 #include "stacktrace.h"
  28
  29 #define FRAMES_MAX 64
  30 #define THREADS_MAX 64
  31
  32 struct stack_context {
  33         FILE *f;
  34         Dwfl *dwfl;
  35         Elf *elf;
  36         unsigned n_thread;
  37         unsigned n_frame;
  38 };
  39
  40 static int frame_callback(Dwfl_Frame *frame, void *userdata) {
  41         struct stack_context *c = userdata;
  42         Dwarf_Addr pc, pc_adjusted, bias = 0;
  43         _cleanup_free_ Dwarf_Die *scopes = NULL;
  44         const char *fname = NULL, *symbol = NULL;
  45         Dwfl_Module *module;
  46         bool is_activation;
  47
  48         assert(frame);
  49         assert(c);
  50
  51         if (c->n_frame >= FRAMES_MAX)
  52                 return DWARF_CB_ABORT;
  53
  54         if (!dwfl_frame_pc(frame, &pc, &is_activation))
  55                 return DWARF_CB_ABORT;
  56
  57         pc_adjusted = pc - (is_activation ? 0 : 1);
  58
  59         module = dwfl_addrmodule(c->dwfl, pc_adjusted);
  60         if (module) {
  61                 Dwarf_Die *s, *cudie;
  62                 int n;
  63
  64                 cudie = dwfl_module_addrdie(module, pc_adjusted, &bias);
  65                 if (cudie) {
  66                         n = dwarf_getscopes(cudie, pc_adjusted - bias, &scopes);
  67                         for (s = scopes; s < scopes + n; s++) {
  68                                 if (IN_SET(dwarf_tag(s), DW_TAG_subprogram, DW_TAG_inlined_subroutine, DW_TAG_entry_point)) {
  69                                         Dwarf_Attribute *a, space;
  70
  71                                         a = dwarf_attr_integrate(s, DW_AT_MIPS_linkage_name, &space);
  72                                         if (!a)
  73                                                 a = dwarf_attr_integrate(s, DW_AT_linkage_name, &space);
  74                                         if (a)
  75                                                 symbol = dwarf_formstring(a);
  76                                         if (!symbol)
  77                                                 symbol = dwarf_diename(s);
  78
  79                                         if (symbol)
  80                                                 break;
  81                                 }
  82                         }
  83                 }
  84
  85                 if (!symbol)
  86                         symbol = dwfl_module_addrname(module, pc_adjusted);
  87
  88                 fname = dwfl_module_info(module, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
  89         }
  90
  91         fprintf(c->f, "#%-2u 0x%016" PRIx64 " %s (%s)\n", c->n_frame, (uint64_t) pc, strna(symbol), strna(fname));
  92         c->n_frame ++;
  93
  94         return DWARF_CB_OK;
  95 }
  96
  97 static int thread_callback(Dwfl_Thread *thread, void *userdata) {
  98         struct stack_context *c = userdata;
  99         pid_t tid;
 100
 101         assert(thread);
 102         assert(c);
 103
 104         if (c->n_thread >= THREADS_MAX)
 105                 return DWARF_CB_ABORT;
 106
 107         if (c->n_thread != 0)
 108                 fputc('\n', c->f);
 109
 110         c->n_frame = 0;
 111
 112         tid = dwfl_thread_tid(thread);
 113         fprintf(c->f, "Stack trace of thread " PID_FMT ":\n", tid);
 114
 115         if (dwfl_thread_getframes(thread, frame_callback, c) < 0)
 116                 return DWARF_CB_ABORT;
 117
 118         c->n_thread ++;
 119
 120         return DWARF_CB_OK;
 121 }
 122
 123 int coredump_make_stack_trace(int fd, const char *executable, char **ret) {
 124
 125         static const Dwfl_Callbacks callbacks = {
 126                 .find_elf = dwfl_build_id_find_elf,
 127                 .find_debuginfo = dwfl_standard_find_debuginfo,
 128         };
 129
 130         struct stack_context c = {};
 131         char *buf = NULL;
 132         size_t sz = 0;
 133         int r;
 134
 135         assert(fd >= 0);
 136         assert(ret);
 137
 138         if (lseek(fd, 0, SEEK_SET) == (off_t) -1)
 139                 return -errno;
 140
 141         c.f = open_memstream(&buf, &sz);
 142         if (!c.f)
 143                 return -ENOMEM;
 144
 145         elf_version(EV_CURRENT);
 146
 147         c.elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
 148         if (!c.elf) {
 149                 r = -EINVAL;
 150                 goto finish;
 151         }
 152
 153         c.dwfl = dwfl_begin(&callbacks);
 154         if (!c.dwfl) {
 155                 r = -EINVAL;
 156                 goto finish;
 157         }
 158
 159         if (dwfl_core_file_report(c.dwfl, c.elf, executable) < 0) {
 160                 r = -EINVAL;
 161                 goto finish;
 162         }
 163
 164         if (dwfl_report_end(c.dwfl, NULL, NULL) != 0) {
 165                 r = -EINVAL;
 166                 goto finish;
 167         }
 168
 169         if (dwfl_core_file_attach(c.dwfl, c.elf) < 0) {
 170                 r = -EINVAL;
 171                 goto finish;
 172         }
 173
 174         if (dwfl_getthreads(c.dwfl, thread_callback, &c) < 0) {
 175                 r = -EINVAL;
 176                 goto finish;
 177         }
 178
 179         fclose(c.f);
 180         c.f = NULL;
 181
 182         *ret = buf;
 183         buf = NULL;
 184
 185         r = 0;
 186
 187 finish:
 188         if (c.dwfl)
 189                 dwfl_end(c.dwfl);
 190
 191         if (c.elf)
 192                 elf_end(c.elf);
 193
 194         if (c.f)
 195                 fclose(c.f);
 196
 197         free(buf);
 198
 199         return r;
 200 }