333 lines
13 KiB
C++
333 lines
13 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if !defined(__LP64__) && __mips_isa_rev >= 5
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#include <sys/prctl.h>
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#endif
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#include "linker.h"
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#include "linker_debug.h"
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#include "linker_globals.h"
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#include "linker_phdr.h"
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#include "linker_relocs.h"
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#include "linker_reloc_iterators.h"
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#include "linker_sleb128.h"
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#include "linker_soinfo.h"
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template bool soinfo::relocate<plain_reloc_iterator>(const VersionTracker& version_tracker,
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plain_reloc_iterator&& rel_iterator,
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const soinfo_list_t& global_group,
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const soinfo_list_t& local_group);
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template bool soinfo::relocate<packed_reloc_iterator<sleb128_decoder>>(
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const VersionTracker& version_tracker,
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packed_reloc_iterator<sleb128_decoder>&& rel_iterator,
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const soinfo_list_t& global_group,
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const soinfo_list_t& local_group);
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template <typename ElfRelIteratorT>
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bool soinfo::relocate(const VersionTracker& version_tracker,
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ElfRelIteratorT&& rel_iterator,
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const soinfo_list_t& global_group,
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const soinfo_list_t& local_group) {
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for (size_t idx = 0; rel_iterator.has_next(); ++idx) {
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const auto rel = rel_iterator.next();
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if (rel == nullptr) {
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return false;
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}
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ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
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ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
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ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias);
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ElfW(Addr) sym_addr = 0;
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const char* sym_name = nullptr;
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DEBUG("Processing \"%s\" relocation at index %zd", get_realpath(), idx);
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if (type == R_GENERIC_NONE) {
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continue;
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}
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const ElfW(Sym)* s = nullptr;
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soinfo* lsi = nullptr;
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if (sym != 0) {
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sym_name = get_string(symtab_[sym].st_name);
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const version_info* vi = nullptr;
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if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) {
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return false;
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}
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if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) {
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return false;
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}
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if (s == nullptr) {
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// mips does not support relocation with weak-undefined symbols
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DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...",
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sym_name, get_realpath());
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return false;
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} else {
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// We got a definition.
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sym_addr = lsi->resolve_symbol_address(s);
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}
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count_relocation(kRelocSymbol);
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}
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switch (type) {
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case R_MIPS_REL32:
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#if defined(__LP64__)
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// MIPS Elf64_Rel entries contain compound relocations
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// We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case
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if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 ||
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ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) {
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DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)",
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type, static_cast<unsigned>(ELF64_R_TYPE2(rel->r_info)),
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static_cast<unsigned>(ELF64_R_TYPE3(rel->r_info)), rel, idx);
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return false;
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}
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#endif
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count_relocation(s == nullptr ? kRelocAbsolute : kRelocRelative);
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MARK(rel->r_offset);
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TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc),
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static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*");
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if (s != nullptr) {
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*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
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} else {
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*reinterpret_cast<ElfW(Addr)*>(reloc) += load_bias;
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}
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break;
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default:
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DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx);
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return false;
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}
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}
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return true;
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}
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bool soinfo::mips_relocate_got(const VersionTracker& version_tracker,
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const soinfo_list_t& global_group,
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const soinfo_list_t& local_group) {
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ElfW(Addr)** got = plt_got_;
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if (got == nullptr) {
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return true;
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}
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// got[0] is the address of the lazy resolver function.
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// got[1] may be used for a GNU extension.
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// Set it to a recognizable address in case someone calls it (should be _rtld_bind_start).
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// FIXME: maybe this should be in a separate routine?
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if ((flags_ & FLAG_LINKER) == 0) {
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size_t g = 0;
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got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef);
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if (reinterpret_cast<intptr_t>(got[g]) < 0) {
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got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed);
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}
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// Relocate the local GOT entries.
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for (; g < mips_local_gotno_; g++) {
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got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + load_bias);
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}
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}
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// Now for the global GOT entries...
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got = plt_got_ + mips_local_gotno_;
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for (ElfW(Word) sym = mips_gotsym_; sym < mips_symtabno_; sym++, got++) {
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// This is an undefined reference... try to locate it.
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const ElfW(Sym)* local_sym = symtab_ + sym;
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const char* sym_name = get_string(local_sym->st_name);
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soinfo* lsi = nullptr;
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const ElfW(Sym)* s = nullptr;
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ElfW(Word) st_visibility = (local_sym->st_other & 0x3);
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if (st_visibility == STV_DEFAULT) {
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const version_info* vi = nullptr;
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if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) {
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return false;
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}
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if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) {
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return false;
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}
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} else if (st_visibility == STV_PROTECTED) {
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if (local_sym->st_value == 0) {
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DL_ERR("%s: invalid symbol \"%s\" (PROTECTED/UNDEFINED) ",
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get_realpath(), sym_name);
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return false;
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}
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s = local_sym;
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lsi = this;
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} else {
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DL_ERR("%s: invalid symbol \"%s\" visibility: 0x%x",
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get_realpath(), sym_name, st_visibility);
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return false;
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}
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if (s == nullptr) {
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// We only allow an undefined symbol if this is a weak reference.
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if (ELF_ST_BIND(local_sym->st_info) != STB_WEAK) {
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DL_ERR("%s: cannot locate \"%s\"...", get_realpath(), sym_name);
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return false;
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}
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*got = 0;
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} else {
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// FIXME: is this sufficient?
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// For reference see NetBSD link loader
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// 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
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*got = reinterpret_cast<ElfW(Addr)*>(lsi->resolve_symbol_address(s));
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}
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}
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return true;
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}
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#if !defined(__LP64__)
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// Checks for mips32's various floating point abis.
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// (Mips64 Android has a single floating point abi and doesn't need any checks)
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// Linux kernel has declarations similar to the following
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// in <linux>/arch/mips/include/asm/elf.h,
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// but that non-uapi internal header file will never be imported
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// into bionic's kernel headers.
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#define PT_MIPS_ABIFLAGS 0x70000003 // is .MIPS.abiflags segment
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struct mips_elf_abiflags_v0 {
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uint16_t version; // version of this structure
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uint8_t isa_level, isa_rev, gpr_size, cpr1_size, cpr2_size;
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uint8_t fp_abi; // mips32 ABI variants for floating point
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uint32_t isa_ext, ases, flags1, flags2;
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};
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// Bits of flags1:
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#define MIPS_AFL_FLAGS1_ODDSPREG 1 // Uses odd-numbered single-prec fp regs
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// Some values of fp_abi: via compiler flag:
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#define MIPS_ABI_FP_DOUBLE 1 // -mdouble-float
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#define MIPS_ABI_FP_XX 5 // -mfpxx
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#define MIPS_ABI_FP_64A 7 // -mips32r* -mfp64 -mno-odd-spreg
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#if __mips_isa_rev >= 5
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static bool mips_fre_mode_on = false; // have set FRE=1 mode for process
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#endif
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bool soinfo::mips_check_and_adjust_fp_modes() {
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mips_elf_abiflags_v0* abiflags = nullptr;
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int mips_fpabi;
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// Find soinfo's optional .MIPS.abiflags segment
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for (size_t i = 0; i<phnum; ++i) {
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const ElfW(Phdr)& ph = phdr[i];
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if (ph.p_type == PT_MIPS_ABIFLAGS) {
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if (ph.p_filesz < sizeof (mips_elf_abiflags_v0)) {
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DL_ERR("Corrupt PT_MIPS_ABIFLAGS header found \"%s\"", get_realpath());
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return false;
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}
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abiflags = reinterpret_cast<mips_elf_abiflags_v0*>(ph.p_vaddr + load_bias);
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break;
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}
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}
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// FP ABI-variant compatibility checks for MIPS o32 ABI
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if (abiflags == nullptr) {
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// Old compilers lack the new abiflags section.
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// These compilers used -mfp32 -mdouble-float -modd-spreg defaults,
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// ie FP32 aka DOUBLE, using odd-numbered single-prec regs
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mips_fpabi = MIPS_ABI_FP_DOUBLE;
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} else {
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mips_fpabi = abiflags->fp_abi;
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if ( (abiflags->flags1 & MIPS_AFL_FLAGS1_ODDSPREG)
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&& (mips_fpabi == MIPS_ABI_FP_XX ||
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mips_fpabi == MIPS_ABI_FP_64A ) ) {
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// Android supports fewer cases than Linux
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DL_ERR("Unsupported odd-single-prec FloatPt reg uses in \"%s\"",
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get_realpath());
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return false;
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}
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}
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if (!(mips_fpabi == MIPS_ABI_FP_DOUBLE ||
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#if __mips_isa_rev >= 5
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mips_fpabi == MIPS_ABI_FP_64A ||
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#endif
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mips_fpabi == MIPS_ABI_FP_XX )) {
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DL_ERR("Unsupported MIPS32 FloatPt ABI %d found in \"%s\"",
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mips_fpabi, get_realpath());
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return false;
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}
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#if __mips_isa_rev >= 5
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// Adjust process's FR Emulation mode, if needed
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//
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// On Mips R5 & R6, Android runs continuously in FR=1 64bit-fpreg mode.
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// NDK mips32 apps compiled with old compilers generate FP32 code
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// which expects FR=0 32-bit fp registers.
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// NDK mips32 apps compiled with newer compilers generate modeless
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// FPXX code which runs on both FR=0 and FR=1 modes.
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// Android itself is compiled in FP64A which requires FR=1 mode.
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// FP32, FPXX, and FP64A all interlink okay, without dynamic FR mode
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// changes during calls. For details, see
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// http://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
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// Processes containing FR32 FR=0 code are run via kernel software assist,
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// which maps all odd-numbered single-precision reg refs onto the
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// upper half of the paired even-numbered double-precision reg.
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// FRE=1 triggers traps to the kernel's emulator on every single-precision
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// fp op (for both odd and even-numbered registers).
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// Turning on FRE=1 traps is done at most once per process, simultanously
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// for all threads of that process, when dlopen discovers FP32 code.
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// The kernel repacks threads' registers when FRE mode is turn on or off.
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// These asynchronous adjustments are wrong if any thread was executing
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// FPXX code using odd-numbered single-precision regs.
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// Current Android compilers default to the -mno-oddspreg option,
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// and this requirement is checked by Android's dlopen.
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// So FRE can always be safely turned on for FP32, anytime.
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// Deferred enhancement: Allow loading of odd-spreg FPXX modules.
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if (mips_fpabi == MIPS_ABI_FP_DOUBLE && !mips_fre_mode_on) {
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// Turn on FRE mode, which emulates mode-sensitive FR=0 code on FR=1
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// register files, by trapping to kernel on refs to single-precision regs
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if (prctl(PR_SET_FP_MODE, PR_FP_MODE_FR|PR_FP_MODE_FRE)) {
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DL_ERR("Kernel or cpu failed to set FRE mode required for running \"%s\"",
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get_realpath());
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return false;
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}
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DL_WARN("Using FRE=1 mode to run \"%s\"", get_realpath());
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mips_fre_mode_on = true; // Avoid future redundant mode-switch calls
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// FRE mode is never turned back off.
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// Deferred enhancement:
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// Reset FRE mode when dlclose() removes all FP32 modules
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}
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#else
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// Android runs continuously in FR=0 32bit-fpreg mode.
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#endif // __mips_isa_rev
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return true;
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}
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#endif // __LP64___
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