/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "linker.h"
#include "linker_debug.h"
#include "linker_relocs.h"
#include "linker_reloc_iterators.h"
#include "linker_leb128.h"
template bool soinfo::relocate<plain_reloc_iterator>(plain_reloc_iterator&& rel_iterator,
const soinfo_list_t& global_group,
const soinfo_list_t& local_group);
template bool soinfo::relocate<packed_reloc_iterator<sleb128_decoder>>(
packed_reloc_iterator<sleb128_decoder>&& rel_iterator,
const soinfo_list_t& global_group,
const soinfo_list_t& local_group);
template bool soinfo::relocate<packed_reloc_iterator<leb128_decoder>>(
packed_reloc_iterator<leb128_decoder>&& rel_iterator,
const soinfo_list_t& global_group,
const soinfo_list_t& local_group);
template <typename ElfRelIteratorT>
bool soinfo::relocate(ElfRelIteratorT&& rel_iterator,
const soinfo_list_t& global_group,
const soinfo_list_t& local_group) {
for (size_t idx = 0; rel_iterator.has_next(); ++idx) {
const auto rel = rel_iterator.next();
if (rel == nullptr) {
return false;
}
ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias);
ElfW(Addr) sym_addr = 0;
const char* sym_name = nullptr;
DEBUG("Processing '%s' relocation at index %zd", this->name, idx);
if (type == R_GENERIC_NONE) {
continue;
}
ElfW(Sym)* s = nullptr;
soinfo* lsi = nullptr;
if (sym != 0) {
sym_name = get_string(symtab_[sym].st_name);
s = soinfo_do_lookup(this, sym_name, &lsi, global_group,local_group);
if (s == nullptr) {
// mips does not support relocation with weak-undefined symbols
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, name);
return false;
} else {
// We got a definition.
sym_addr = lsi->resolve_symbol_address(s);
}
count_relocation(kRelocSymbol);
}
switch (type) {
case R_MIPS_REL32:
#if defined(__LP64__)
// MIPS Elf64_Rel entries contain compound relocations
// We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case
if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 ||
ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) {
DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)",
type, static_cast<unsigned>(ELF64_R_TYPE2(rel->r_info)),
static_cast<unsigned>(ELF64_R_TYPE3(rel->r_info)), rel, idx);
return false;
}
#endif
count_relocation(s == nullptr ? kRelocAbsolute : kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*");
if (s != nullptr) {
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
} else {
*reinterpret_cast<ElfW(Addr)*>(reloc) += base;
}
break;
default:
DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx);
return false;
}
}
return true;
}
bool soinfo::mips_relocate_got(const soinfo_list_t& global_group,
const soinfo_list_t& local_group) {
ElfW(Addr)** got = plt_got_;
if (got == nullptr) {
return true;
}
// got[0] is the address of the lazy resolver function.
// got[1] may be used for a GNU extension.
// Set it to a recognizable address in case someone calls it (should be _rtld_bind_start).
// FIXME: maybe this should be in a separate routine?
if ((flags_ & FLAG_LINKER) == 0) {
size_t g = 0;
got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef);
if (reinterpret_cast<intptr_t>(got[g]) < 0) {
got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed);
}
// Relocate the local GOT entries.
for (; g < mips_local_gotno_; g++) {
got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + load_bias);
}
}
// Now for the global GOT entries...
ElfW(Sym)* sym = symtab_ + mips_gotsym_;
got = plt_got_ + mips_local_gotno_;
for (size_t g = mips_gotsym_; g < mips_symtabno_; g++, sym++, got++) {
// This is an undefined reference... try to locate it.
const char* sym_name = get_string(sym->st_name);
soinfo* lsi = nullptr;
ElfW(Sym)* s = soinfo_do_lookup(this, sym_name, &lsi, global_group, local_group);
if (s == nullptr) {
// We only allow an undefined symbol if this is a weak reference.
s = &symtab_[g];
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
DL_ERR("cannot locate \"%s\"...", sym_name);
return false;
}
*got = 0;
} else {
// FIXME: is this sufficient?
// For reference see NetBSD link loader
// http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup
*got = reinterpret_cast<ElfW(Addr)*>(lsi->resolve_symbol_address(s));
}
}
return true;
}