ldso/ldso/xtensa/dl-sysdep.h

   1 /* Machine-dependent ELF dynamic relocation.
   2    Parts copied from glibc/sysdeps/xtensa/dl-machine.h
   3    Copyright (C) 2001, 2007 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library 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 GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 /* Define this if the system uses RELOCA.  */
  21 #define ELF_USES_RELOCA
  22 #include <elf.h>
  23 #include <link.h>
  24
  25 /* Translate a processor specific dynamic tag to the index
  26    in l_info array.  */
  27 #define DT_XTENSA(x) (DT_XTENSA_##x - DT_LOPROC + DT_NUM + OS_NUM)
  28
  29 typedef struct xtensa_got_location_struct {
  30   Elf32_Off offset;
  31   Elf32_Word length;
  32 } xtensa_got_location;
  33
  34 /* Initialization sequence for the GOT.  */
  35 #define INIT_GOT(GOT_BASE, MODULE) \
  36   do {                                                                        \
  37     xtensa_got_location *got_loc;                                             \
  38     Elf32_Addr l_addr = MODULE->loadaddr;                                     \
  39     Elf32_Addr prev_got_start = 0, prev_got_end = 0;                          \
  40     int x;                                                                    \
  41                                                                               \
  42     got_loc = (xtensa_got_location *)                                         \
  43       (MODULE->dynamic_info[DT_XTENSA (GOT_LOC_OFF)] + l_addr);               \
  44                                                                               \
  45     for (x = 0; x < MODULE->dynamic_info[DT_XTENSA (GOT_LOC_SZ)]; x++)        \
  46       {                                                                       \
  47         Elf32_Addr got_start, got_end;                                        \
  48         got_start = got_loc[x].offset & ~(PAGE_SIZE - 1);                     \
  49         got_end = ((got_loc[x].offset + got_loc[x].length + PAGE_SIZE - 1)    \
  50                    & ~(PAGE_SIZE - 1));                                       \
  51         if (got_end >= prev_got_start && got_start <= prev_got_end)           \
  52           {                                                                   \
  53             if (got_end > prev_got_end)                                       \
  54                 prev_got_end = got_end;                                       \
  55             if (got_start < prev_got_start)                                   \
  56                 prev_got_start = got_start;                                   \
  57             continue;                                                         \
  58           }                                                                   \
  59         else if (prev_got_start != prev_got_end)                              \
  60           {                                                                   \
  61             _dl_mprotect ((void *)(prev_got_start + l_addr),                  \
  62                           prev_got_end - prev_got_start,                      \
  63                           PROT_READ | PROT_WRITE | PROT_EXEC);                \
  64           }                                                                   \
  65         prev_got_start = got_start;                                           \
  66         prev_got_end = got_end;                                               \
  67       }                                                                       \
  68                                                                               \
  69     if (prev_got_start != prev_got_end)                                       \
  70       {                                                                       \
  71         _dl_mprotect ((void *)(prev_got_start + l_addr),                      \
  72                       prev_got_end - prev_got_start,                          \
  73                       PROT_READ | PROT_WRITE | PROT_EXEC);                    \
  74       }                                                                       \
  75                                                                               \
  76     /* Fill in first GOT entry according to the ABI.  */                      \
  77     GOT_BASE[0] = (unsigned long) _dl_linux_resolve;                          \
  78   } while (0)
  79
  80 /* Parse dynamic info */
  81 #define ARCH_NUM 2
  82 #define ARCH_DYNAMIC_INFO(dpnt, dynamic, debug_addr) \
  83   do {                                                                  \
  84     if (dpnt->d_tag == DT_XTENSA_GOT_LOC_OFF)                           \
  85       dynamic[DT_XTENSA (GOT_LOC_OFF)] = dpnt->d_un.d_ptr;              \
  86     else if (dpnt->d_tag == DT_XTENSA_GOT_LOC_SZ)                       \
  87       dynamic[DT_XTENSA (GOT_LOC_SZ)] = dpnt->d_un.d_val;               \
  88   } while (0)
  89
  90 /* Here we define the magic numbers that this dynamic loader should accept. */
  91 #define MAGIC1 EM_XTENSA
  92 #undef  MAGIC2
  93
  94 /* Used for error messages. */
  95 #define ELF_TARGET "Xtensa"
  96
  97 struct elf_resolve;
  98 extern unsigned long _dl_linux_resolver (struct elf_resolve *, int);
  99
 100 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 101    TLS variable, so undefined references should not be allowed to define
 102    the value.  */
 103 #define elf_machine_type_class(type) \
 104   (((type) == R_XTENSA_JMP_SLOT || (type) == R_XTENSA_TLS_TPOFF \
 105    || (type) == R_XTENSA_TLSDESC_FN || (type) == R_XTENSA_TLSDESC_ARG) \
 106    * ELF_RTYPE_CLASS_PLT)
 107
 108 /* Return the link-time address of _DYNAMIC.  */
 109 static __always_inline Elf32_Addr
 110 elf_machine_dynamic (void)
 111 {
 112   /* This function is only used while bootstrapping the runtime linker.
 113      The "_DYNAMIC" symbol is always local so its GOT entry will initially
 114      contain the link-time address.  */
 115   return (Elf32_Addr) &_DYNAMIC;
 116 }
 117
 118 /* Return the run-time load address of the shared object.  */
 119 static __always_inline Elf32_Addr
 120 elf_machine_load_address (void)
 121 {
 122   Elf32_Addr addr, tmp;
 123
 124   /* At this point, the runtime linker is being bootstrapped and the GOT
 125      entry used for ".Lhere" will contain the link address.  The CALL0 will
 126      produce the dynamic address of ".Lhere" + 3.  Thus, the end result is
 127      equal to "dynamic_address(.Lhere) - link_address(.Lhere)".  */
 128   __asm__ ("\
 129         movi    %0, .Lhere\n\
 130         mov     %1, a0\n\
 131 .Lhere: _call0  0f\n\
 132         .align  4\n\
 133 0:      sub     %0, a0, %0\n\
 134         mov     a0, %1"
 135            : "=a" (addr), "=a" (tmp));
 136
 137   return addr - 3;
 138 }
 139
 140 static __always_inline void
 141 elf_machine_relative (Elf32_Addr load_off, const Elf32_Addr rel_addr,
 142                       Elf32_Word relative_count)
 143 {
 144   Elf32_Rela *rpnt = (Elf32_Rela *) rel_addr;
 145   while (relative_count--)
 146     {
 147       Elf32_Addr *const reloc_addr = (Elf32_Addr *) (load_off + rpnt->r_offset);
 148       *reloc_addr += load_off + rpnt->r_addend;
 149       rpnt++;
 150     }
 151 }