Add support for packed relocations.
Change-Id: I796a4ce86d3fccb8361c19889419c96147ee3c9f
diff --git a/linker/linker.cpp b/linker/linker.cpp
index ae9df52..87fce95 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -53,6 +53,7 @@
#include "linker_allocator.h"
#include "linker_debug.h"
#include "linker_environ.h"
+#include "linker_leb128.h"
#include "linker_phdr.h"
#include "linker_relocs.h"
#include "linker_reloc_iterators.h"
@@ -1302,6 +1303,10 @@
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);
@@ -1407,16 +1412,16 @@
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO RELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
- reinterpret_cast<void*>(base + addend));
- *reinterpret_cast<ElfW(Addr)*>(reloc) = (base + addend);
+ reinterpret_cast<void*>(load_bias + addend));
+ *reinterpret_cast<ElfW(Addr)*>(reloc) = (load_bias + addend);
break;
case R_GENERIC_IRELATIVE:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO IRELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
- reinterpret_cast<void*>(base + addend));
- *reinterpret_cast<ElfW(Addr)*>(reloc) = call_ifunc_resolver(base + addend);
+ reinterpret_cast<void*>(load_bias + addend));
+ *reinterpret_cast<ElfW(Addr)*>(reloc) = call_ifunc_resolver(load_bias + addend);
break;
#if defined(__aarch64__)
@@ -2053,6 +2058,22 @@
rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
break;
+ case DT_ANDROID_RELA:
+ android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
+ break;
+
+ case DT_ANDROID_RELASZ:
+ android_relocs_size_ = d->d_un.d_val;
+ break;
+
+ case DT_ANDROID_REL:
+ DL_ERR("unsupported DT_ANDROID_REL in \"%s\"", name);
+ return false;
+
+ case DT_ANDROID_RELSZ:
+ DL_ERR("unsupported DT_ANDROID_RELSZ in \"%s\"", name);
+ return false;
+
case DT_RELAENT:
if (d->d_un.d_val != sizeof(ElfW(Rela))) {
DL_ERR("invalid DT_RELAENT: %zd", static_cast<size_t>(d->d_un.d_val));
@@ -2071,6 +2092,7 @@
case DT_RELSZ:
DL_ERR("unsupported DT_RELSZ in \"%s\"", name);
return false;
+
#else
case DT_REL:
rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
@@ -2087,6 +2109,22 @@
}
break;
+ case DT_ANDROID_REL:
+ android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
+ break;
+
+ case DT_ANDROID_RELSZ:
+ android_relocs_size_ = d->d_un.d_val;
+ break;
+
+ case DT_ANDROID_RELA:
+ DL_ERR("unsupported DT_ANDROID_RELA in \"%s\"", name);
+ return false;
+
+ case DT_ANDROID_RELASZ:
+ DL_ERR("unsupported DT_ANDROID_RELASZ in \"%s\"", name);
+ return false;
+
// "Indicates that all RELATIVE relocations have been concatenated together,
// and specifies the RELATIVE relocation count."
//
@@ -2094,9 +2132,15 @@
// Not currently used by bionic linker - ignored.
case DT_RELCOUNT:
break;
+
case DT_RELA:
DL_ERR("unsupported DT_RELA in \"%s\"", name);
return false;
+
+ case DT_RELASZ:
+ DL_ERR("unsupported DT_RELASZ in \"%s\"", name);
+ return false;
+
#endif
case DT_INIT:
init_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
@@ -2251,7 +2295,8 @@
return true;
}
-bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group, const android_dlextinfo* extinfo) {
+bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group,
+ const android_dlextinfo* extinfo) {
local_group_root_ = local_group.front();
if (local_group_root_ == nullptr) {
@@ -2272,6 +2317,40 @@
}
#endif
+ if (android_relocs_ != nullptr) {
+ // check signature
+ if (android_relocs_size_ > 3 &&
+ android_relocs_[0] == 'A' &&
+ android_relocs_[1] == 'P' &&
+ (android_relocs_[2] == 'U' || android_relocs_[2] == 'S') &&
+ android_relocs_[3] == '2') {
+ DEBUG("[ android relocating %s ]", name);
+
+ bool relocated = false;
+ const uint8_t* packed_relocs = android_relocs_ + 4;
+ const size_t packed_relocs_size = android_relocs_size_ - 4;
+
+ if (android_relocs_[2] == 'U') {
+ relocated = relocate(
+ packed_reloc_iterator<leb128_decoder>(
+ leb128_decoder(packed_relocs, packed_relocs_size)),
+ global_group, local_group);
+ } else { // android_relocs_[2] == 'S'
+ relocated = relocate(
+ packed_reloc_iterator<sleb128_decoder>(
+ sleb128_decoder(packed_relocs, packed_relocs_size)),
+ global_group, local_group);
+ }
+
+ if (!relocated) {
+ return false;
+ }
+ } else {
+ DL_ERR("bad android relocation header.");
+ return false;
+ }
+ }
+
#if defined(USE_RELA)
if (rela_ != nullptr) {
DEBUG("[ relocating %s ]", name);
diff --git a/linker/linker.h b/linker/linker.h
index 222ddbf..f8640a0 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -315,6 +315,9 @@
soinfo* local_group_root_;
+ uint8_t* android_relocs_;
+ size_t android_relocs_size_;
+
friend soinfo* get_libdl_info();
};
diff --git a/linker/linker_leb128.h b/linker/linker_leb128.h
new file mode 100644
index 0000000..d5c6488
--- /dev/null
+++ b/linker/linker_leb128.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _LINKER_LEB128_H
+#define _LINKER_LEB128_H
+
+#include <stdint.h>
+
+// Helper classes for decoding LEB128, used in packed relocation data.
+// http://en.wikipedia.org/wiki/LEB128
+
+class leb128_decoder {
+ public:
+ leb128_decoder(const uint8_t* buffer, size_t count)
+ : current_(buffer), end_(buffer + count) { }
+
+ size_t pop_front() {
+ size_t value = 0;
+
+ size_t shift = 0;
+ uint8_t byte;
+
+ do {
+ if (current_ >= end_) {
+ __libc_fatal("leb128_decoder ran out of bounds");
+ }
+ byte = *current_++;
+ value |= static_cast<size_t>(byte & 127) << shift;
+ shift += 7;
+ } while (byte & 128);
+
+ return value;
+ }
+
+ private:
+ const uint8_t* current_;
+ const uint8_t* const end_;
+};
+
+class sleb128_decoder {
+ public:
+ sleb128_decoder(const uint8_t* buffer, size_t count)
+ : current_(buffer), end_(buffer+count) { }
+
+ size_t pop_front() {
+ size_t value = 0;
+ static const size_t size = CHAR_BIT * sizeof(value);
+
+ size_t shift = 0;
+ uint8_t byte;
+
+ do {
+ if (current_ >= end_) {
+ __libc_fatal("leb128_decoder ran out of bounds");
+ }
+ byte = *current_++;
+ value |= (static_cast<size_t>(byte & 127) << shift);
+ shift += 7;
+ } while (byte & 128);
+
+ if (shift < size && (byte & 64)) {
+ value |= -(static_cast<size_t>(1) << shift);
+ }
+
+ return value;
+ }
+
+ private:
+ const uint8_t* current_;
+ const uint8_t* const end_;
+};
+
+#endif // __LINKER_LEB128_H
+
diff --git a/linker/linker_mips.cpp b/linker/linker_mips.cpp
index d71659e..f0bde55 100644
--- a/linker/linker_mips.cpp
+++ b/linker/linker_mips.cpp
@@ -30,14 +30,31 @@
#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<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);
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 91a2fb8..38e6262 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -332,7 +332,7 @@
return false;
}
int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
- start = mmap(addr, load_size_, PROT_NONE, mmap_flags, -1, 0);
+ start = mmap(nullptr, load_size_, PROT_NONE, mmap_flags, -1, 0);
if (start == MAP_FAILED) {
DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_);
return false;
diff --git a/linker/linker_reloc_iterators.h b/linker/linker_reloc_iterators.h
index 6388bb0..5db31f9 100644
--- a/linker/linker_reloc_iterators.h
+++ b/linker/linker_reloc_iterators.h
@@ -19,6 +19,18 @@
#include "linker.h"
+#include <string.h>
+
+#define RELOCATION_GROUPED_BY_INFO_FLAG 1
+#define RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG 2
+#define RELOCATION_GROUPED_BY_ADDEND_FLAG 4
+#define RELOCATION_GROUP_HAS_ADDEND_FLAG 8
+
+#define RELOCATION_GROUPED_BY_INFO(flags) (((flags) & RELOCATION_GROUPED_BY_INFO_FLAG) != 0)
+#define RELOCATION_GROUPED_BY_OFFSET_DELTA(flags) (((flags) & RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG) != 0)
+#define RELOCATION_GROUPED_BY_ADDEND(flags) (((flags) & RELOCATION_GROUPED_BY_ADDEND_FLAG) != 0)
+#define RELOCATION_GROUP_HAS_ADDEND(flags) (((flags) & RELOCATION_GROUP_HAS_ADDEND_FLAG) != 0)
+
class plain_reloc_iterator {
#if defined(USE_RELA)
typedef ElfW(Rela) rel_t;
@@ -44,4 +56,97 @@
DISALLOW_COPY_AND_ASSIGN(plain_reloc_iterator);
};
+template <typename decoder_t>
+class packed_reloc_iterator {
+#if defined(USE_RELA)
+ typedef ElfW(Rela) rel_t;
+#else
+ typedef ElfW(Rel) rel_t;
+#endif
+ public:
+ explicit packed_reloc_iterator(decoder_t&& decoder)
+ : decoder_(decoder) {
+ // initialize fields
+ memset(&reloc_, 0, sizeof(reloc_));
+ relocation_count_ = decoder_.pop_front();
+ reloc_.r_offset = decoder_.pop_front();
+ relocation_index_ = 0;
+ relocation_group_index_ = 0;
+ group_size_ = 0;
+ }
+
+ bool has_next() const {
+ return relocation_index_ < relocation_count_;
+ }
+
+ rel_t* next() {
+ if (relocation_group_index_ == group_size_) {
+ if (!read_group_fields()) {
+ // Iterator is inconsistent state; it should not be called again
+ // but in case it is let's make sure has_next() returns false.
+ relocation_index_ = relocation_count_ = 0;
+ return nullptr;
+ }
+ }
+
+ if (RELOCATION_GROUPED_BY_OFFSET_DELTA(group_flags_)) {
+ reloc_.r_offset += group_r_offset_delta_;
+ } else {
+ reloc_.r_offset += decoder_.pop_front();
+ }
+
+ if (!RELOCATION_GROUPED_BY_INFO(group_flags_)) {
+ reloc_.r_info = decoder_.pop_front();
+ }
+
+#if defined(USE_RELA)
+ if (RELOCATION_GROUP_HAS_ADDEND(group_flags_) && !RELOCATION_GROUPED_BY_ADDEND(group_flags_)) {
+ reloc_.r_addend += decoder_.pop_front();
+ }
+#endif
+
+ relocation_index_++;
+ relocation_group_index_++;
+
+ return &reloc_;
+ }
+ private:
+ bool read_group_fields() {
+ group_size_ = decoder_.pop_front();
+ group_flags_ = decoder_.pop_front();
+
+ if (RELOCATION_GROUPED_BY_OFFSET_DELTA(group_flags_)) {
+ group_r_offset_delta_ = decoder_.pop_front();
+ }
+
+ if (RELOCATION_GROUPED_BY_INFO(group_flags_)) {
+ reloc_.r_info = decoder_.pop_front();
+ }
+
+ if (RELOCATION_GROUP_HAS_ADDEND(group_flags_) && RELOCATION_GROUPED_BY_ADDEND(group_flags_)) {
+#if !defined(USE_RELA)
+ // This platform does not support rela, and yet we have it encoded in android_rel section.
+ DL_ERR("unexpected r_addend in android.rel section");
+ return false;
+#else
+ reloc_.r_addend += decoder_.pop_front();
+ } else if (!RELOCATION_GROUP_HAS_ADDEND(group_flags_)) {
+ reloc_.r_addend = 0;
+#endif
+ }
+
+ relocation_group_index_ = 0;
+ return true;
+ }
+
+ decoder_t decoder_;
+ size_t relocation_count_;
+ size_t group_size_;
+ size_t group_flags_;
+ size_t group_r_offset_delta_;
+ size_t relocation_index_;
+ size_t relocation_group_index_;
+ rel_t reloc_;
+};
+
#endif // __LINKER_RELOC_ITERATORS_H