libunwind/src/Unwind_AIXExtras.cpp

   1 //===--------------------- Unwind_AIXExtras.cpp -------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 // This file is only used for AIX.
  11 #if defined(_AIX)
  12
  13 #include "config.h"
  14 #include "libunwind_ext.h"
  15 #include <sys/debug.h>
  16
  17 namespace libunwind {
  18 // getFuncNameFromTBTable
  19 // Get the function name from its traceback table.
  20 char *getFuncNameFromTBTable(uintptr_t Pc, uint16_t &NameLen,
  21                              unw_word_t *Offset) {
  22   uint32_t *p = reinterpret_cast<uint32_t *>(Pc);
  23   *Offset = 0;
  24
  25   // Keep looking forward until a word of 0 is found. The traceback
  26   // table starts at the following word.
  27   while (*p)
  28     p++;
  29   tbtable *TBTable = reinterpret_cast<tbtable *>(p + 1);
  30
  31   if (!TBTable->tb.name_present)
  32     return NULL;
  33
  34   // Get to the name of the function.
  35   p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);
  36
  37   // Skip field parminfo if it exists.
  38   if (TBTable->tb.fixedparms || TBTable->tb.floatparms)
  39     p++;
  40
  41   // If the tb_offset field exists, get the offset from the start of
  42   // the function to pc. Skip the field.
  43   if (TBTable->tb.has_tboff) {
  44     unw_word_t StartIp =
  45         reinterpret_cast<uintptr_t>(TBTable) - *p - sizeof(uint32_t);
  46     *Offset = Pc - StartIp;
  47     p++;
  48   }
  49
  50   // Skip field hand_mask if it exists.
  51   if (TBTable->tb.int_hndl)
  52     p++;
  53
  54   // Skip fields ctl_info and ctl_info_disp if they exist.
  55   if (TBTable->tb.has_ctl) {
  56     p += 1 + *p;
  57   }
  58
  59   NameLen = *(reinterpret_cast<uint16_t *>(p));
  60   return reinterpret_cast<char *>(p) + sizeof(uint16_t);
  61 }
  62 } // namespace libunwind
  63 #endif // defined(_AIX)