1  /* Dynamic loading of the libgcc unwinder.  Generic version.
       2     Copyright (C) 2021-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       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
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the 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     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _UNWIND_LINK_H
      20  #define _UNWIND_LINK_H
      21  
      22  #include <unwind.h>
      23  #include <unwind-arch.h>
      24  
      25  #if !UNWIND_LINK_FRAME_ADJUSTMENT
      26  static inline void *
      27  unwind_arch_adjustment (void *prev, void *addr)
      28  {
      29    return addr;
      30  }
      31  #endif
      32  
      33  #ifdef SHARED
      34  # include <pointer_guard.h>
      35  # include <unwind-resume.h>
      36  
      37  # if UNWIND_LINK_FRAME_STATE_FOR
      38  struct frame_state;
      39  # endif
      40  
      41  struct unwind_link
      42  {
      43    __typeof (_Unwind_Backtrace) *ptr__Unwind_Backtrace;
      44    __typeof (_Unwind_ForcedUnwind) *ptr__Unwind_ForcedUnwind;
      45    __typeof (_Unwind_GetCFA) *ptr__Unwind_GetCFA;
      46  # if UNWIND_LINK_GETIP
      47    __typeof (_Unwind_GetIP) *ptr__Unwind_GetIP;
      48  # endif
      49    __typeof (_Unwind_Resume) *ptr__Unwind_Resume;
      50  #if UNWIND_LINK_FRAME_STATE_FOR
      51    struct frame_state *(*ptr___frame_state_for) (void *, struct frame_state *);
      52  #endif
      53    _Unwind_Reason_Code (*ptr_personality) PERSONALITY_PROTO;
      54    UNWIND_LINK_EXTRA_FIELDS
      55  };
      56  
      57  /* Return a pointer to the implementation, or NULL on failure.  */
      58  struct unwind_link *__libc_unwind_link_get (void);
      59  libc_hidden_proto (__libc_unwind_link_get)
      60  
      61  /* UNWIND_LINK_PTR returns the stored function pointer NAME from the
      62     cached unwind link OBJ (which was previously returned by
      63     __libc_unwind_link_get).  */
      64  # define UNWIND_LINK_PTR(obj, name, ...)                             \
      65    ({                                                                \
      66      __typeof ((obj)->ptr_##name) __unwind_fptr = (obj)->ptr_##name; \
      67      PTR_DEMANGLE (__unwind_fptr);                                   \
      68      __unwind_fptr;                                                  \
      69    })
      70  
      71  /* Called from fork, in the new subprocess.  */
      72  void __libc_unwind_link_after_fork (void);
      73  
      74  /* Called from __libc_freeres.  */
      75  void __libc_unwind_link_freeres (void) attribute_hidden;
      76  
      77  #else /* !SHARED */
      78  
      79  /* Dummy implementation so that the code can be shared with the SHARED
      80     version.  */
      81  struct unwind_link;
      82  static inline struct unwind_link *
      83  __libc_unwind_link_get (void)
      84  {
      85    /* Return something that is not a null pointer, so that error checks
      86       succeed.  */
      87    return (struct unwind_link *) 1;
      88  }
      89  
      90  /* Directly call the static implementation.  */
      91  # define UNWIND_LINK_PTR(obj, name, ...) \
      92    ((void) (obj), &name)
      93  
      94  static inline void
      95  __libc_unwind_link_after_fork (void)
      96  {
      97    /* No need to clean up if the unwinder is statically linked.  */
      98  }
      99  
     100  #endif /* !SHARED */
     101  
     102  #endif /* _UNWIND_LINK_H */