sysdeps/unix/sysv/linux/arm/unwind-resume.c

   1 /* Copyright (C) 2003-2015 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
  23 static void (*libgcc_s_resume) (struct _Unwind_Exception *exc)
  24   __attribute_used__;
  25 static _Unwind_Reason_Code (*libgcc_s_personality)
  26   (_Unwind_State, struct _Unwind_Exception *, struct _Unwind_Context *);
  27
  28 static void init (void) __attribute_used__;
  29
  30 static void
  31 init (void)
  32 {
  33   void *resume, *personality;
  34   void *handle;
  35
  36   handle = __libc_dlopen ("libgcc_s.so.1");
  37
  38   if (handle == NULL
  39       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
  40       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL)
  41     __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
  42
  43   libgcc_s_resume = resume;
  44   libgcc_s_personality = personality;
  45 }
  46
  47 /* It's vitally important that _Unwind_Resume not have a stack frame; the
  48    ARM unwinder relies on register state at entrance.  So we write this in
  49    assembly.  */
  50
  51 #define STR1(S) #S
  52 #define STR(S)  STR1(S)
  53
  54 asm (
  55 "       .globl  _Unwind_Resume\n"
  56 "       .type   _Unwind_Resume, %function\n"
  57 "_Unwind_Resume:\n"
  58 "       .cfi_sections .debug_frame\n"
  59 "       " CFI_STARTPROC "\n"
  60 "       push    {r4, r5, r6, lr}\n"
  61 "       " CFI_ADJUST_CFA_OFFSET (16)" \n"
  62 "       " CFI_REL_OFFSET (r4, 0) "\n"
  63 "       " CFI_REL_OFFSET (r5, 4) "\n"
  64 "       " CFI_REL_OFFSET (r6, 8) "\n"
  65 "       " CFI_REL_OFFSET (lr, 12) "\n"
  66 "       " CFI_REMEMBER_STATE "\n"
  67 "       ldr     r4, 1f\n"
  68 "       ldr     r5, 2f\n"
  69 "3:     add     r4, pc, r4\n"
  70 "       ldr     r3, [r4, r5]\n"
  71 "       mov     r6, r0\n"
  72 "       cmp     r3, #0\n"
  73 "       beq     4f\n"
  74 "5:     mov     r0, r6\n"
  75 "       pop     {r4, r5, r6, lr}\n"
  76 "       " CFI_ADJUST_CFA_OFFSET (-16) "\n"
  77 "       " CFI_RESTORE (r4) "\n"
  78 "       " CFI_RESTORE (r5) "\n"
  79 "       " CFI_RESTORE (r6) "\n"
  80 "       " CFI_RESTORE (lr) "\n"
  81 "       bx      r3\n"
  82 "       " CFI_RESTORE_STATE "\n"
  83 "4:     bl      init\n"
  84 "       ldr     r3, [r4, r5]\n"
  85 "       b       5b\n"
  86 "       " CFI_ENDPROC "\n"
  87 "       .align 2\n"
  88 "1:     .word   _GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
  89 "2:     .word   libgcc_s_resume(GOTOFF)\n"
  90 "       .size   _Unwind_Resume, .-_Unwind_Resume\n"
  91 );
  92
  93 _Unwind_Reason_Code
  94 __gcc_personality_v0 (_Unwind_State state,
  95                       struct _Unwind_Exception *ue_header,
  96                       struct _Unwind_Context *context)
  97 {
  98   if (__builtin_expect (libgcc_s_personality == NULL, 0))
  99     init ();
 100   return libgcc_s_personality (state, ue_header, context);
 101 }