Add support for .bss section in oat files.
Change-Id: I779b80b8139d9afdc28373f8c68edff5df7726ce
diff --git a/compiler/common_compiler_test.cc b/compiler/common_compiler_test.cc
index e8354b2..09be437 100644
--- a/compiler/common_compiler_test.cc
+++ b/compiler/common_compiler_test.cc
@@ -253,6 +253,7 @@
(size_t)100 * 1024 * 1024, // 100MB
PROT_NONE,
false /* no need for 4gb flag with fixed mmap*/,
+ false /* not reusing existing reservation */,
&error_msg));
CHECK(image_reservation_.get() != nullptr) << error_msg;
}
diff --git a/compiler/elf_builder.h b/compiler/elf_builder.h
index 94268de..9ab3602 100644
--- a/compiler/elf_builder.h
+++ b/compiler/elf_builder.h
@@ -538,6 +538,8 @@
Elf_Word rodata_size,
Elf_Word text_relative_offset,
Elf_Word text_size,
+ Elf_Word bss_relative_offset,
+ Elf_Word bss_size,
const bool add_symbols,
bool debug = false)
: oat_writer_(oat_writer),
@@ -547,6 +549,7 @@
text_builder_(".text", text_size, text_relative_offset, SHT_PROGBITS,
SHF_ALLOC | SHF_EXECINSTR),
rodata_builder_(".rodata", rodata_size, rodata_relative_offset, SHT_PROGBITS, SHF_ALLOC),
+ bss_builder_(".bss", bss_size, bss_relative_offset, SHT_NOBITS, SHF_ALLOC),
dynsym_builder_(".dynsym", SHT_DYNSYM, ".dynstr", SHT_STRTAB, true),
symtab_builder_(".symtab", SHT_SYMTAB, ".strtab", SHT_STRTAB, false),
hash_builder_(".hash", SHT_HASH, SHF_ALLOC, &dynsym_builder_, 0, sizeof(Elf_Word),
@@ -569,6 +572,11 @@
}
bool Init() {
+ // Since the .text section of an oat file contains relative references to .rodata
+ // and (optionally) .bss, we keep these 2 or 3 sections together. This creates
+ // a non-traditional layout where the .bss section is mapped independently of the
+ // .dynamic section and needs its own program header with LOAD RW.
+ //
// The basic layout of the elf file. Order may be different in final output.
// +-------------------------+
// | Elf_Ehdr |
@@ -576,6 +584,7 @@
// | Elf_Phdr PHDR |
// | Elf_Phdr LOAD R | .dynsym .dynstr .hash .rodata
// | Elf_Phdr LOAD R X | .text
+ // | Elf_Phdr LOAD RW | .bss (Optional)
// | Elf_Phdr LOAD RW | .dynamic
// | Elf_Phdr DYNAMIC | .dynamic
// +-------------------------+
@@ -584,6 +593,8 @@
// | Elf_Sym oatdata |
// | Elf_Sym oatexec |
// | Elf_Sym oatlastword |
+ // | Elf_Sym oatbss | (Optional)
+ // | Elf_Sym oatbsslastword | (Optional)
// +-------------------------+
// | .dynstr |
// | \0 |
@@ -631,6 +642,7 @@
// | .hash\0 |
// | .rodata\0 |
// | .text\0 |
+ // | .bss\0 | (Optional)
// | .shstrtab\0 |
// | .symtab\0 | (Optional)
// | .strtab\0 | (Optional)
@@ -654,8 +666,9 @@
// | Elf_Shdr .dynsym |
// | Elf_Shdr .dynstr |
// | Elf_Shdr .hash |
- // | Elf_Shdr .text |
// | Elf_Shdr .rodata |
+ // | Elf_Shdr .text |
+ // | Elf_Shdr .bss | (Optional)
// | Elf_Shdr .dynamic |
// | Elf_Shdr .shstrtab |
// | Elf_Shdr .debug_info | (Optional)
@@ -694,8 +707,11 @@
program_headers_[PH_LOAD_R_X].p_type = PT_LOAD;
program_headers_[PH_LOAD_R_X].p_flags = PF_R | PF_X;
- program_headers_[PH_LOAD_RW_].p_type = PT_LOAD;
- program_headers_[PH_LOAD_RW_].p_flags = PF_R | PF_W;
+ program_headers_[PH_LOAD_RW_BSS].p_type = PT_LOAD;
+ program_headers_[PH_LOAD_RW_BSS].p_flags = PF_R | PF_W;
+
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_type = PT_LOAD;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_flags = PF_R | PF_W;
program_headers_[PH_DYNAMIC].p_type = PT_DYNAMIC;
program_headers_[PH_DYNAMIC].p_flags = PF_R | PF_W;
@@ -760,6 +776,14 @@
text_builder_.SetSectionIndex(section_index_);
section_index_++;
+ // Setup .bss
+ if (bss_builder_.GetSize() != 0u) {
+ section_ptrs_.push_back(bss_builder_.GetSection());
+ AssignSectionStr(&bss_builder_, &shstrtab_);
+ bss_builder_.SetSectionIndex(section_index_);
+ section_index_++;
+ }
+
// Setup .dynamic
section_ptrs_.push_back(dynamic_builder_.GetSection());
AssignSectionStr(&dynamic_builder_, &shstrtab_);
@@ -820,10 +844,20 @@
CHECK_ALIGNED(rodata_builder_.GetSection()->sh_offset +
rodata_builder_.GetSection()->sh_size, kPageSize);
+ // Get the layout of the .bss section.
+ bss_builder_.GetSection()->sh_offset =
+ NextOffset<Elf_Word, Elf_Shdr>(*bss_builder_.GetSection(),
+ *text_builder_.GetSection());
+ bss_builder_.GetSection()->sh_addr = bss_builder_.GetSection()->sh_offset;
+ bss_builder_.GetSection()->sh_size = bss_builder_.GetSize();
+ bss_builder_.GetSection()->sh_link = bss_builder_.GetLink();
+
// Get the layout of the dynamic section.
- dynamic_builder_.GetSection()->sh_offset =
- NextOffset<Elf_Word, Elf_Shdr>(*dynamic_builder_.GetSection(), *text_builder_.GetSection());
- dynamic_builder_.GetSection()->sh_addr = dynamic_builder_.GetSection()->sh_offset;
+ CHECK(IsAlignedParam(bss_builder_.GetSection()->sh_offset,
+ dynamic_builder_.GetSection()->sh_addralign));
+ dynamic_builder_.GetSection()->sh_offset = bss_builder_.GetSection()->sh_offset;
+ dynamic_builder_.GetSection()->sh_addr =
+ NextOffset<Elf_Word, Elf_Shdr>(*dynamic_builder_.GetSection(), *bss_builder_.GetSection());
dynamic_builder_.GetSection()->sh_size = dynamic_builder_.GetSize() * sizeof(Elf_Dyn);
dynamic_builder_.GetSection()->sh_link = dynamic_builder_.GetLink();
@@ -987,16 +1021,23 @@
program_headers_[PH_LOAD_R_X].p_memsz = load_rx_size;
program_headers_[PH_LOAD_R_X].p_align = text_builder_.GetSection()->sh_addralign;
- program_headers_[PH_LOAD_RW_].p_offset = dynamic_builder_.GetSection()->sh_offset;
- program_headers_[PH_LOAD_RW_].p_vaddr = dynamic_builder_.GetSection()->sh_offset;
- program_headers_[PH_LOAD_RW_].p_paddr = dynamic_builder_.GetSection()->sh_offset;
- program_headers_[PH_LOAD_RW_].p_filesz = dynamic_builder_.GetSection()->sh_size;
- program_headers_[PH_LOAD_RW_].p_memsz = dynamic_builder_.GetSection()->sh_size;
- program_headers_[PH_LOAD_RW_].p_align = dynamic_builder_.GetSection()->sh_addralign;
+ program_headers_[PH_LOAD_RW_BSS].p_offset = bss_builder_.GetSection()->sh_offset;
+ program_headers_[PH_LOAD_RW_BSS].p_vaddr = bss_builder_.GetSection()->sh_offset;
+ program_headers_[PH_LOAD_RW_BSS].p_paddr = bss_builder_.GetSection()->sh_offset;
+ program_headers_[PH_LOAD_RW_BSS].p_filesz = 0;
+ program_headers_[PH_LOAD_RW_BSS].p_memsz = bss_builder_.GetSection()->sh_size;
+ program_headers_[PH_LOAD_RW_BSS].p_align = bss_builder_.GetSection()->sh_addralign;
+
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_offset = dynamic_builder_.GetSection()->sh_offset;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_vaddr = dynamic_builder_.GetSection()->sh_addr;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_paddr = dynamic_builder_.GetSection()->sh_addr;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_filesz = dynamic_builder_.GetSection()->sh_size;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_memsz = dynamic_builder_.GetSection()->sh_size;
+ program_headers_[PH_LOAD_RW_DYNAMIC].p_align = dynamic_builder_.GetSection()->sh_addralign;
program_headers_[PH_DYNAMIC].p_offset = dynamic_builder_.GetSection()->sh_offset;
- program_headers_[PH_DYNAMIC].p_vaddr = dynamic_builder_.GetSection()->sh_offset;
- program_headers_[PH_DYNAMIC].p_paddr = dynamic_builder_.GetSection()->sh_offset;
+ program_headers_[PH_DYNAMIC].p_vaddr = dynamic_builder_.GetSection()->sh_addr;
+ program_headers_[PH_DYNAMIC].p_paddr = dynamic_builder_.GetSection()->sh_addr;
program_headers_[PH_DYNAMIC].p_filesz = dynamic_builder_.GetSection()->sh_size;
program_headers_[PH_DYNAMIC].p_memsz = dynamic_builder_.GetSection()->sh_size;
program_headers_[PH_DYNAMIC].p_align = dynamic_builder_.GetSection()->sh_addralign;
@@ -1004,15 +1045,29 @@
// Finish setup of the Ehdr values.
elf_header_.e_phoff = PHDR_OFFSET;
elf_header_.e_shoff = sections_offset;
- elf_header_.e_phnum = PH_NUM;
+ elf_header_.e_phnum = (bss_builder_.GetSection()->sh_size != 0u) ? PH_NUM : PH_NUM - 1;
elf_header_.e_shnum = section_ptrs_.size();
elf_header_.e_shstrndx = shstrtab_builder_.GetSectionIndex();
// Add the rest of the pieces to the list.
pieces.push_back(new ElfFileMemoryPiece<Elf_Word>("Elf Header", 0, &elf_header_,
sizeof(elf_header_)));
- pieces.push_back(new ElfFileMemoryPiece<Elf_Word>("Program headers", PHDR_OFFSET,
- &program_headers_, sizeof(program_headers_)));
+ if (bss_builder_.GetSection()->sh_size != 0u) {
+ pieces.push_back(new ElfFileMemoryPiece<Elf_Word>("Program headers", PHDR_OFFSET,
+ &program_headers_[0],
+ elf_header_.e_phnum * sizeof(Elf_Phdr)));
+ } else {
+ // Skip PH_LOAD_RW_BSS.
+ Elf_Word part1_size = PH_LOAD_RW_BSS * sizeof(Elf_Phdr);
+ Elf_Word part2_size = (PH_NUM - PH_LOAD_RW_BSS - 1) * sizeof(Elf_Phdr);
+ CHECK_EQ(part1_size + part2_size, elf_header_.e_phnum * sizeof(Elf_Phdr));
+ pieces.push_back(new ElfFileMemoryPiece<Elf_Word>("Program headers", PHDR_OFFSET,
+ &program_headers_[0], part1_size));
+ pieces.push_back(new ElfFileMemoryPiece<Elf_Word>("Program headers part 2",
+ PHDR_OFFSET + part1_size,
+ &program_headers_[PH_LOAD_RW_BSS + 1],
+ part2_size));
+ }
pieces.push_back(new ElfFileMemoryPiece<Elf_Word>(".dynamic",
dynamic_builder_.GetSection()->sh_offset,
dynamic.data(),
@@ -1175,6 +1230,12 @@
text_builder_.GetSize(), STB_GLOBAL, STT_OBJECT);
dynsym_builder_.AddSymbol("oatlastword", &text_builder_, text_builder_.GetSize() - 4,
true, 4, STB_GLOBAL, STT_OBJECT);
+ if (bss_builder_.GetSize() != 0u) {
+ dynsym_builder_.AddSymbol("oatbss", &bss_builder_, 0, true,
+ bss_builder_.GetSize(), STB_GLOBAL, STT_OBJECT);
+ dynsym_builder_.AddSymbol("oatbsslastword", &bss_builder_, bss_builder_.GetSize() - 4,
+ true, 4, STB_GLOBAL, STT_OBJECT);
+ }
}
void AssignSectionStr(ElfSectionBuilder<Elf_Word, Elf_Sword, Elf_Shdr>* builder,
@@ -1213,12 +1274,13 @@
// What phdr is.
static const uint32_t PHDR_OFFSET = sizeof(Elf_Ehdr);
enum : uint8_t {
- PH_PHDR = 0,
- PH_LOAD_R__ = 1,
- PH_LOAD_R_X = 2,
- PH_LOAD_RW_ = 3,
- PH_DYNAMIC = 4,
- PH_NUM = 5,
+ PH_PHDR = 0,
+ PH_LOAD_R__ = 1,
+ PH_LOAD_R_X = 2,
+ PH_LOAD_RW_BSS = 3,
+ PH_LOAD_RW_DYNAMIC = 4,
+ PH_DYNAMIC = 5,
+ PH_NUM = 6,
};
static const uint32_t PHDR_SIZE = sizeof(Elf_Phdr) * PH_NUM;
Elf_Phdr program_headers_[PH_NUM];
@@ -1236,6 +1298,7 @@
ElfOatSectionBuilder<Elf_Word, Elf_Sword, Elf_Shdr> text_builder_;
ElfOatSectionBuilder<Elf_Word, Elf_Sword, Elf_Shdr> rodata_builder_;
+ ElfOatSectionBuilder<Elf_Word, Elf_Sword, Elf_Shdr> bss_builder_;
ElfSymtabBuilder<Elf_Word, Elf_Sword, Elf_Addr, Elf_Sym, Elf_Shdr> dynsym_builder_;
ElfSymtabBuilder<Elf_Word, Elf_Sword, Elf_Addr, Elf_Sym, Elf_Shdr> symtab_builder_;
ElfSectionBuilder<Elf_Word, Elf_Sword, Elf_Shdr> hash_builder_;
diff --git a/compiler/elf_writer_quick.cc b/compiler/elf_writer_quick.cc
index 401d5a9..a822b24 100644
--- a/compiler/elf_writer_quick.cc
+++ b/compiler/elf_writer_quick.cc
@@ -229,6 +229,7 @@
const OatHeader& oat_header = oat_writer->GetOatHeader();
Elf_Word oat_data_size = oat_header.GetExecutableOffset();
uint32_t oat_exec_size = oat_writer->GetSize() - oat_data_size;
+ uint32_t oat_bss_size = oat_writer->GetBssSize();
OatWriterWrapper wrapper(oat_writer);
@@ -243,6 +244,8 @@
oat_data_size,
oat_data_size,
oat_exec_size,
+ RoundUp(oat_data_size + oat_exec_size, kPageSize),
+ oat_bss_size,
compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols(),
debug));
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index c588e1a..f5f9320 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -408,8 +408,8 @@
bool ImageWriter::AllocMemory() {
size_t length = RoundUp(Runtime::Current()->GetHeap()->GetTotalMemory(), kPageSize);
std::string error_msg;
- image_.reset(MemMap::MapAnonymous("image writer image", NULL, length, PROT_READ | PROT_WRITE,
- false, &error_msg));
+ image_.reset(MemMap::MapAnonymous("image writer image", nullptr, length, PROT_READ | PROT_WRITE,
+ false, false, &error_msg));
if (UNLIKELY(image_.get() == nullptr)) {
LOG(ERROR) << "Failed to allocate memory for image file generation: " << error_msg;
return false;
diff --git a/compiler/oat_writer.cc b/compiler/oat_writer.cc
index 8411091..c32a992 100644
--- a/compiler/oat_writer.cc
+++ b/compiler/oat_writer.cc
@@ -403,6 +403,7 @@
image_writer_(image_writer),
dex_files_(&dex_files),
size_(0u),
+ bss_size_(0u),
oat_data_offset_(0u),
image_file_location_oat_checksum_(image_file_location_oat_checksum),
image_file_location_oat_begin_(image_file_location_oat_begin),
diff --git a/compiler/oat_writer.h b/compiler/oat_writer.h
index 980611f..fd2ccae 100644
--- a/compiler/oat_writer.h
+++ b/compiler/oat_writer.h
@@ -96,6 +96,10 @@
return size_;
}
+ size_t GetBssSize() const {
+ return bss_size_;
+ }
+
const std::vector<uintptr_t>& GetAbsolutePatchLocations() const {
return absolute_patch_locations_;
}
@@ -266,6 +270,9 @@
// Size required for Oat data structures.
size_t size_;
+ // The size of the required .bss section holding the DexCache data.
+ size_t bss_size_;
+
// Offset of the oat data from the start of the mmapped region of the elf file.
size_t oat_data_offset_;