libgcc/config/ia64/fde-glibc.c

   1 /* Copyright (C) 2000-2021 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 #include <stddef.h>
  33 #include <stdlib.h>
  34 #include <link.h>
  35 #include "unwind-ia64.h"
  36
  37 #if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
  38     || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
  39 # error You need GLIBC 2.2.4 or later on IA-64 Linux
  40 #endif
  41
  42 struct unw_ia64_callback_data
  43 {
  44   Elf64_Addr pc;
  45   unsigned long *segment_base;
  46   unsigned long *gp;
  47   struct unw_table_entry *ret;
  48 };
  49
  50 static int
  51 _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
  52 {
  53   struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
  54   const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
  55   long n, match;
  56   Elf64_Addr load_base, seg_base;
  57   struct unw_table_entry *f_base, *f;
  58   size_t lo, hi;
  59
  60   /* Make sure struct dl_phdr_info is at least as big as we need.  */
  61   if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
  62              + sizeof (info->dlpi_phnum))
  63     return -1;
  64
  65   match = 0;
  66   phdr = info->dlpi_phdr;
  67   load_base = info->dlpi_addr;
  68   p_unwind = NULL;
  69   p_dynamic = NULL;
  70   seg_base = ~(Elf64_Addr) 0;
  71
  72   /* See if PC falls into one of the loaded segments.  Find the unwind
  73      segment at the same time.  */
  74   for (n = info->dlpi_phnum; --n >= 0; phdr++)
  75     {
  76       if (phdr->p_type == PT_LOAD)
  77         {
  78           Elf64_Addr vaddr = phdr->p_vaddr + load_base;
  79           if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
  80             match = 1;
  81           if (vaddr < seg_base)
  82             seg_base = vaddr;
  83         }
  84       else if (phdr->p_type == PT_IA_64_UNWIND)
  85         p_unwind = phdr;
  86       else if (phdr->p_type == PT_DYNAMIC)
  87         p_dynamic = phdr;
  88     }
  89   if (!match || !p_unwind)
  90     return 0;
  91
  92   /* Search for the FDE within the unwind segment.  */
  93
  94   f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
  95   lo = 0;
  96   hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);
  97
  98   while (lo < hi)
  99     {
 100       size_t mid = (lo + hi) / 2;
 101
 102       f = f_base + mid;
 103       if (data->pc < f->start_offset + seg_base)
 104         hi = mid;
 105       else if (data->pc >= f->end_offset + seg_base)
 106         lo = mid + 1;
 107       else
 108         goto found;
 109     }
 110   /* No need to search for further libraries when we know pc is contained
 111      in this library.  */
 112   return 1;
 113
 114  found:
 115   *data->segment_base = seg_base;
 116   *data->gp = 0;
 117   data->ret = f;
 118
 119   if (p_dynamic)
 120     {
 121       /* For dynamically linked executables and shared libraries,
 122          DT_PLTGOT is the gp value for that object.  */
 123       Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
 124       for (; dyn->d_tag != DT_NULL ; dyn++)
 125         if (dyn->d_tag == DT_PLTGOT)
 126           {
 127             /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it.  */
 128             *data->gp = dyn->d_un.d_ptr;
 129             break;
 130           }
 131     }
 132   else
 133     {
 134       /* Otherwise this is a static executable with no _DYNAMIC.
 135          The gp is constant program-wide.  */
 136       register unsigned long gp __asm__("gp");
 137       *data->gp = gp;
 138     }
 139
 140   return 1;
 141 }
 142
 143 /* Return a pointer to the unwind table entry for the function
 144    containing PC.  */
 145
 146 struct unw_table_entry *
 147 _Unwind_FindTableEntry (void *pc, unw_word *segment_base, unw_word *gp,
 148                         struct unw_table_entry *ent ATTRIBUTE_UNUSED)
 149 {
 150   struct unw_ia64_callback_data data;
 151
 152   data.pc = (Elf64_Addr) pc;
 153   data.segment_base = segment_base;
 154   data.gp = gp;
 155   data.ret = NULL;
 156
 157   if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
 158     return NULL;
 159
 160   return data.ret;
 161 }