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 "alloc-util.h"
  26 #include "fd-util.h"
  27 #include "formats-util.h"
  28 #include "macro.h"
  29 #include "stacktrace.h"
  30 #include "string-util.h"
  31 #include "util.h"
  32
  33 #define FRAMES_MAX 64
  34 #define THREADS_MAX 64
  35
  36 struct stack_context {
  37         FILE *f;
  38         Dwfl *dwfl;
  39         Elf *elf;
  40         unsigned n_thread;
  41         unsigned n_frame;
  42 };
  43
  44 static int frame_callback(Dwfl_Frame *frame, void *userdata) {
  45         struct stack_context *c = userdata;
  46         Dwarf_Addr pc, pc_adjusted, bias = 0;
  47         _cleanup_free_ Dwarf_Die *scopes = NULL;
  48         const char *fname = NULL, *symbol = NULL;
  49         Dwfl_Module *module;
  50         bool is_activation;
  51
  52         assert(frame);
  53         assert(c);
  54
  55         if (c->n_frame >= FRAMES_MAX)
  56                 return DWARF_CB_ABORT;
  57
  58         if (!dwfl_frame_pc(frame, &pc, &is_activation))
  59                 return DWARF_CB_ABORT;
  60
  61         pc_adjusted = pc - (is_activation ? 0 : 1);
  62
  63         module = dwfl_addrmodule(c->dwfl, pc_adjusted);
  64         if (module) {
  65                 Dwarf_Die *s, *cudie;
  66                 int n;
  67
  68                 cudie = dwfl_module_addrdie(module, pc_adjusted, &bias);
  69                 if (cudie) {
  70                         n = dwarf_getscopes(cudie, pc_adjusted - bias, &scopes);
  71                         for (s = scopes; s < scopes + n; s++) {
  72                                 if (IN_SET(dwarf_tag(s), DW_TAG_subprogram, DW_TAG_inlined_subroutine, DW_TAG_entry_point)) {
  73                                         Dwarf_Attribute *a, space;
  74
  75                                         a = dwarf_attr_integrate(s, DW_AT_MIPS_linkage_name, &space);
  76                                         if (!a)
  77                                                 a = dwarf_attr_integrate(s, DW_AT_linkage_name, &space);
  78                                         if (a)
  79                                                 symbol = dwarf_formstring(a);
  80                                         if (!symbol)
  81                                                 symbol = dwarf_diename(s);
  82
  83                                         if (symbol)
  84                                                 break;
  85                                 }
  86                         }
  87                 }
  88
  89                 if (!symbol)
  90                         symbol = dwfl_module_addrname(module, pc_adjusted);
  91
  92                 fname = dwfl_module_info(module, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
  93         }
  94
  95         fprintf(c->f, "#%-2u 0x%016" PRIx64 " %s (%s)\n", c->n_frame, (uint64_t) pc, strna(symbol), strna(fname));
  96         c->n_frame ++;
  97
  98         return DWARF_CB_OK;
  99 }
 100
 101 static int thread_callback(Dwfl_Thread *thread, void *userdata) {
 102         struct stack_context *c = userdata;
 103         pid_t tid;
 104
 105         assert(thread);
 106         assert(c);
 107
 108         if (c->n_thread >= THREADS_MAX)
 109                 return DWARF_CB_ABORT;
 110
 111         if (c->n_thread != 0)
 112                 fputc('\n', c->f);
 113
 114         c->n_frame = 0;
 115
 116         tid = dwfl_thread_tid(thread);
 117         fprintf(c->f, "Stack trace of thread " PID_FMT ":\n", tid);
 118
 119         if (dwfl_thread_getframes(thread, frame_callback, c) < 0)
 120                 return DWARF_CB_ABORT;
 121
 122         c->n_thread ++;
 123
 124         return DWARF_CB_OK;
 125 }
 126
 127 int coredump_make_stack_trace(int fd, const char *executable, char **ret) {
 128
 129         static const Dwfl_Callbacks callbacks = {
 130                 .find_elf = dwfl_build_id_find_elf,
 131                 .find_debuginfo = dwfl_standard_find_debuginfo,
 132         };
 133
 134         struct stack_context c = {};
 135         char *buf = NULL;
 136         size_t sz = 0;
 137         int r;
 138
 139         assert(fd >= 0);
 140         assert(ret);
 141
 142         if (lseek(fd, 0, SEEK_SET) == (off_t) -1)
 143                 return -errno;
 144
 145         c.f = open_memstream(&buf, &sz);
 146         if (!c.f)
 147                 return -ENOMEM;
 148
 149         elf_version(EV_CURRENT);
 150
 151         c.elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
 152         if (!c.elf) {
 153                 r = -EINVAL;
 154                 goto finish;
 155         }
 156
 157         c.dwfl = dwfl_begin(&callbacks);
 158         if (!c.dwfl) {
 159                 r = -EINVAL;
 160                 goto finish;
 161         }
 162
 163         if (dwfl_core_file_report(c.dwfl, c.elf, executable) < 0) {
 164                 r = -EINVAL;
 165                 goto finish;
 166         }
 167
 168         if (dwfl_report_end(c.dwfl, NULL, NULL) != 0) {
 169                 r = -EINVAL;
 170                 goto finish;
 171         }
 172
 173         if (dwfl_core_file_attach(c.dwfl, c.elf) < 0) {
 174                 r = -EINVAL;
 175                 goto finish;
 176         }
 177
 178         if (dwfl_getthreads(c.dwfl, thread_callback, &c) < 0) {
 179                 r = -EINVAL;
 180                 goto finish;
 181         }
 182
 183         c.f = safe_fclose(c.f);
 184
 185         *ret = buf;
 186         buf = NULL;
 187
 188         r = 0;
 189
 190 finish:
 191         if (c.dwfl)
 192                 dwfl_end(c.dwfl);
 193
 194         if (c.elf)
 195                 elf_end(c.elf);
 196
 197         safe_fclose(c.f);
 198
 199         free(buf);
 200
 201         return r;
 202 }