sysdeps/unix/sysv/linux/arm/nptl/unwind-forcedunwind.c

   1 /* Copyright (C) 2003, 2005, 2007, 2009, 2010 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <dlfcn.h>
  20 #include <stdio.h>
  21 #include <unwind.h>
  22 #include <pthreadP.h>
  23
  24 static void *libgcc_s_handle;
  25 static void (*libgcc_s_resume) (struct _Unwind_Exception *exc);
  26 static _Unwind_Reason_Code (*libgcc_s_personality)
  27   (_Unwind_State, struct _Unwind_Exception *, struct _Unwind_Context *);
  28 static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
  29   (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
  30 static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
  31
  32 void
  33 __attribute_noinline__
  34 pthread_cancel_init (void)
  35 {
  36   void *resume, *personality, *forcedunwind, *getcfa;
  37   void *handle;
  38
  39   if (__builtin_expect (libgcc_s_handle != NULL, 1))
  40     {
  41       /* Force gcc to reload all values.  */
  42       asm volatile ("" ::: "memory");
  43       return;
  44     }
  45
  46   handle = __libc_dlopen ("libgcc_s.so.1");
  47
  48   if (handle == NULL
  49       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
  50       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
  51       || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
  52          == NULL
  53       || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
  54 #ifdef ARCH_CANCEL_INIT
  55       || ARCH_CANCEL_INIT (handle)
  56 #endif
  57       )
  58     __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
  59
  60   libgcc_s_resume = resume;
  61   libgcc_s_personality = personality;
  62   libgcc_s_forcedunwind = forcedunwind;
  63   libgcc_s_getcfa = getcfa;
  64   /* Make sure libgcc_s_getcfa is written last.  Otherwise,
  65      pthread_cancel_init might return early even when the pointer the
  66      caller is interested in is not initialized yet.  */
  67   atomic_write_barrier ();
  68   libgcc_s_handle = handle;
  69 }
  70
  71 void
  72 __libc_freeres_fn_section
  73 __unwind_freeres (void)
  74 {
  75   void *handle = libgcc_s_handle;
  76   if (handle != NULL)
  77     {
  78       libgcc_s_handle = NULL;
  79       __libc_dlclose (handle);
  80     }
  81 }
  82
  83 /* It's vitally important that _Unwind_Resume not have a stack frame; the
  84    ARM unwinder relies on register state at entrance.  So we write this in
  85    assembly.  */
  86
  87 asm (
  88 "       .globl  _Unwind_Resume\n"
  89 "       .type   _Unwind_Resume, %function\n"
  90 "_Unwind_Resume:\n"
  91 "       .cfi_sections .debug_frame\n"
  92 "       " CFI_STARTPROC "\n"
  93 "       stmfd   sp!, {r4, r5, r6, lr}\n"
  94 "       " CFI_ADJUST_CFA_OFFSET (16)" \n"
  95 "       " CFI_REL_OFFSET (r4, 0) "\n"
  96 "       " CFI_REL_OFFSET (r5, 4) "\n"
  97 "       " CFI_REL_OFFSET (r6, 8) "\n"
  98 "       " CFI_REL_OFFSET (lr, 12) "\n"
  99 "       " CFI_REMEMBER_STATE "\n"
 100 "       ldr     r4, 1f\n"
 101 "       ldr     r5, 2f\n"
 102 "3:     add     r4, pc, r4\n"
 103 "       ldr     r3, [r4, r5]\n"
 104 "       mov     r6, r0\n"
 105 "       cmp     r3, #0\n"
 106 "       beq     4f\n"
 107 "5:     mov     r0, r6\n"
 108 "       ldmfd   sp!, {r4, r5, r6, lr}\n"
 109 "       " CFI_ADJUST_CFA_OFFSET (-16) "\n"
 110 "       " CFI_RESTORE (r4) "\n"
 111 "       " CFI_RESTORE (r5) "\n"
 112 "       " CFI_RESTORE (r6) "\n"
 113 "       " CFI_RESTORE (lr) "\n"
 114 "       bx      r3\n"
 115 "       " CFI_RESTORE_STATE "\n"
 116 "4:     bl      pthread_cancel_init\n"
 117 "       ldr     r3, [r4, r5]\n"
 118 "       b       5b\n"
 119 "       " CFI_ENDPROC "\n"
 120 "       .align 2\n"
 121 #ifdef __thumb2__
 122 "1:     .word   _GLOBAL_OFFSET_TABLE_ - 3b - 4\n"
 123 #else
 124 "1:     .word   _GLOBAL_OFFSET_TABLE_ - 3b - 8\n"
 125 #endif
 126 "2:     .word   libgcc_s_resume(GOTOFF)\n"
 127 "       .size   _Unwind_Resume, .-_Unwind_Resume\n"
 128 );
 129
 130 _Unwind_Reason_Code
 131 __gcc_personality_v0 (_Unwind_State state,
 132                       struct _Unwind_Exception *ue_header,
 133                       struct _Unwind_Context *context)
 134 {
 135   if (__builtin_expect (libgcc_s_personality == NULL, 0))
 136     pthread_cancel_init ();
 137
 138   return libgcc_s_personality (state, ue_header, context);
 139 }
 140
 141 _Unwind_Reason_Code
 142 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
 143                       void *stop_argument)
 144 {
 145   if (__builtin_expect (libgcc_s_forcedunwind == NULL, 0))
 146     pthread_cancel_init ();
 147
 148   return libgcc_s_forcedunwind (exc, stop, stop_argument);
 149 }
 150
 151 _Unwind_Word
 152 _Unwind_GetCFA (struct _Unwind_Context *context)
 153 {
 154   if (__builtin_expect (libgcc_s_getcfa == NULL, 0))
 155     pthread_cancel_init ();
 156
 157   return libgcc_s_getcfa (context);
 158 }