src/libs/libunwind/setjmp/siglongjmp.c

   1 /* libunwind - a platform-independent unwind library
   2    Copyright (C) 2003-2005 Hewlett-Packard Co
   3         Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
   4
   5 This file is part of libunwind.
   6
   7 Permission is hereby granted, free of charge, to any person obtaining
   8 a copy of this software and associated documentation files (the
   9 "Software"), to deal in the Software without restriction, including
  10 without limitation the rights to use, copy, modify, merge, publish,
  11 distribute, sublicense, and/or sell copies of the Software, and to
  12 permit persons to whom the Software is furnished to do so, subject to
  13 the following conditions:
  14
  15 The above copyright notice and this permission notice shall be
  16 included in all copies or substantial portions of the Software.
  17
  18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
  25
  26 #define UNW_LOCAL_ONLY
  27
  28 #include <setjmp.h>
  29
  30 #include "libunwind_i.h"
  31 #include "jmpbuf.h"
  32 #include "setjmp_i.h"
  33
  34 #if !defined(_NSIG) && defined(_SIG_MAXSIG)
  35 # define _NSIG (_SIG_MAXSIG - 1)
  36 #endif
  37
  38 #if defined(__GLIBC__)
  39 #if __GLIBC_PREREQ(2, 4)
  40
  41 /* Starting with glibc-2.4, {sig,}setjmp in GLIBC obfuscates the
  42    register values in jmp_buf by XORing them with a "random"
  43    canary value.
  44
  45    This makes it impossible to implement longjmp, as we
  46    can never match wp[JB_SP], unless we decode the canary first.
  47
  48    Doing so is possible, but doesn't appear to be worth the trouble,
  49    so we simply defer to glibc siglongjmp here.  */
  50
  51 #define siglongjmp __nonworking_siglongjmp
  52 static void siglongjmp (sigjmp_buf env, int val) UNUSED;
  53 #endif
  54 #endif /* __GLIBC_PREREQ */
  55
  56 void
  57 siglongjmp (sigjmp_buf env, int val)
  58 {
  59   unw_word_t *wp = (unw_word_t *) env;
  60   extern int _UI_siglongjmp_cont;
  61   extern int _UI_longjmp_cont;
  62   unw_context_t uc;
  63   unw_cursor_t c;
  64   unw_word_t sp;
  65   int *cont;
  66
  67   if (unw_getcontext (&uc) < 0 || unw_init_local (&c, &uc) < 0)
  68     abort ();
  69
  70   do
  71     {
  72       if (unw_get_reg (&c, UNW_REG_SP, &sp) < 0)
  73         abort ();
  74 #ifdef __FreeBSD__
  75       if (sp != wp[JB_SP] + sizeof(unw_word_t))
  76 #else
  77       if (sp != wp[JB_SP])
  78 #endif
  79         continue;
  80
  81       if (!bsp_match (&c, wp))
  82         continue;
  83
  84       /* found the right frame: */
  85
  86       /* default to resuming without restoring signal-mask */
  87       cont = &_UI_longjmp_cont;
  88
  89       /* Order of evaluation is important here: if unw_resume()
  90          restores signal mask, we must set it up appropriately, even
  91          if wp[JB_MASK_SAVED] is FALSE.  */
  92       if (!resume_restores_sigmask (&c, wp) && wp[JB_MASK_SAVED])
  93         {
  94           /* sigmask was saved */
  95 #if defined(__linux__)
  96           if (UNW_NUM_EH_REGS < 4 || _NSIG > 16 * sizeof (unw_word_t))
  97             /* signal mask doesn't fit into EH arguments and we can't
  98                put it on the stack without overwriting something
  99                else... */
 100             abort ();
 101           else
 102             if (unw_set_reg (&c, UNW_REG_EH + 2, wp[JB_MASK]) < 0
 103                 || (_NSIG > 8 * sizeof (unw_word_t)
 104                     && unw_set_reg (&c, UNW_REG_EH + 3, wp[JB_MASK + 1]) < 0))
 105               abort ();
 106 #elif defined(__FreeBSD__)
 107           if (unw_set_reg (&c, UNW_REG_EH + 2, &wp[JB_MASK]) < 0)
 108               abort();
 109 #else
 110 #error Port me
 111 #endif
 112           cont = &_UI_siglongjmp_cont;
 113         }
 114
 115       if (unw_set_reg (&c, UNW_REG_EH + 0, wp[JB_RP]) < 0
 116           || unw_set_reg (&c, UNW_REG_EH + 1, val) < 0
 117           || unw_set_reg (&c, UNW_REG_IP, (unw_word_t) (uintptr_t) cont))
 118         abort ();
 119
 120       unw_resume (&c);
 121
 122       abort ();
 123     }
 124   while (unw_step (&c) > 0);
 125
 126   abort ();
 127 }