libgcc/config/ia64/fde-glibc.c

   1 /* Copyright (C) 2000-2024 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@cygnus.com>.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 /* Locate the FDE entry for a given address, using glibc ld.so routines
  26    to avoid register/deregister calls at DSO load/unload.  */
  27
  28 #ifndef _GNU_SOURCE
  29 #define _GNU_SOURCE 1
  30 #endif
  31 #include "config.h"
  32 #ifndef inhibit_libc
  33 #include <stddef.h>
  34 #include <stdlib.h>
  35 #include <link.h>
  36 #include "unwind-ia64.h"
  37
  38 #if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
  39     || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
  40 # error You need GLIBC 2.2.4 or later on IA-64 Linux
  41 #endif
  42
  43 struct unw_ia64_callback_data
  44 {
  45   Elf64_Addr pc;
  46   unsigned long *segment_base;
  47   unsigned long *gp;
  48   struct unw_table_entry *ret;
  49 };
  50
  51 static int
  52 _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
  53 {
  54   struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
  55   const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
  56   long n, match;
  57   Elf64_Addr load_base, seg_base;
  58   struct unw_table_entry *f_base, *f;
  59   size_t lo, hi;
  60
  61   /* Make sure struct dl_phdr_info is at least as big as we need.  */
  62   if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
  63              + sizeof (info->dlpi_phnum))
  64     return -1;
  65
  66   match = 0;
  67   phdr = info->dlpi_phdr;
  68   load_base = info->dlpi_addr;
  69   p_unwind = NULL;
  70   p_dynamic = NULL;
  71   seg_base = ~(Elf64_Addr) 0;
  72
  73   /* See if PC falls into one of the loaded segments.  Find the unwind
  74      segment at the same time.  */
  75   for (n = info->dlpi_phnum; --n >= 0; phdr++)
  76     {
  77       if (phdr->p_type == PT_LOAD)
  78         {
  79           Elf64_Addr vaddr = phdr->p_vaddr + load_base;
  80           if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
  81             match = 1;
  82           if (vaddr < seg_base)
  83             seg_base = vaddr;
  84         }
  85       else if (phdr->p_type == PT_IA_64_UNWIND)
  86         p_unwind = phdr;
  87       else if (phdr->p_type == PT_DYNAMIC)
  88         p_dynamic = phdr;
  89     }
  90   if (!match || !p_unwind)
  91     return 0;
  92
  93   /* Search for the FDE within the unwind segment.  */
  94
  95   f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
  96   lo = 0;
  97   hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);
  98
  99   while (lo < hi)
 100     {
 101       size_t mid = (lo + hi) / 2;
 102
 103       f = f_base + mid;
 104       if (data->pc < f->start_offset + seg_base)
 105         hi = mid;
 106       else if (data->pc >= f->end_offset + seg_base)
 107         lo = mid + 1;
 108       else
 109         goto found;
 110     }
 111   /* No need to search for further libraries when we know pc is contained
 112      in this library.  */
 113   return 1;
 114
 115  found:
 116   *data->segment_base = seg_base;
 117   *data->gp = 0;
 118   data->ret = f;
 119
 120   if (p_dynamic)
 121     {
 122       /* For dynamically linked executables and shared libraries,
 123          DT_PLTGOT is the gp value for that object.  */
 124       Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
 125       for (; dyn->d_tag != DT_NULL ; dyn++)
 126         if (dyn->d_tag == DT_PLTGOT)
 127           {
 128             /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it.  */
 129             *data->gp = dyn->d_un.d_ptr;
 130             break;
 131           }
 132     }
 133   else
 134     {
 135       /* Otherwise this is a static executable with no _DYNAMIC.
 136          The gp is constant program-wide.  */
 137       register unsigned long gp __asm__("gp");
 138       *data->gp = gp;
 139     }
 140
 141   return 1;
 142 }
 143
 144 /* Return a pointer to the unwind table entry for the function
 145    containing PC.  */
 146
 147 struct unw_table_entry *
 148 _Unwind_FindTableEntry (void *pc, unw_word *segment_base, unw_word *gp,
 149                         struct unw_table_entry *ent ATTRIBUTE_UNUSED)
 150 {
 151   struct unw_ia64_callback_data data;
 152
 153   data.pc = (Elf64_Addr) pc;
 154   data.segment_base = segment_base;
 155   data.gp = gp;
 156   data.ret = NULL;
 157
 158   if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
 159     return NULL;
 160
 161   return data.ret;
 162 }
 163 #endif