[lld] r218007 - [PECOFF] Support TLS callbacks.
Rui Ueyama
ruiu at google.com
Wed Sep 17 19:02:53 PDT 2014
Author: ruiu
Date: Wed Sep 17 21:02:52 2014
New Revision: 218007
URL: http://llvm.org/viewvc/llvm-project?rev=218007&view=rev
Log:
[PECOFF] Support TLS callbacks.
The contents from section .CRT$XLA to .CRT$XLZ is an array of function
pointers. They are called by the runtime when a new thread is created
or (gracefully) terminated.
You can make your own initialization function to be called by that
mechanism. All you have to do is:
- Define a pointer to a function in a .CRT$XL* section using pragma
- Make an external reference to "__tls_used" symbol
That technique is used in many projects. This patch is to support that.
What this patch does is to set the relative virtual address of
"__tls_used" to the PECOFF directory table. __tls_used is actually a
struct containing pointers to a symbol in .CRT$XLA and another symbol
in .CRT$XLZ. The runtime looks at the directory table, gets the address
of the struct, and call the function pointers between XLA and XLZ.
Added:
lld/trunk/test/pecoff/Inputs/tlsused.obj.yaml
lld/trunk/test/pecoff/tls.test
Modified:
lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
Modified: lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp?rev=218007&r1=218006&r2=218007&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp (original)
+++ lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp Wed Sep 17 21:02:52 2014
@@ -885,6 +885,9 @@ private:
// The size of the image on disk. This is basically the sum of all chunks in
// the output file with paddings between them.
uint32_t _imageSizeOnDisk;
+
+ // The map from atom to its relative virtual address.
+ std::map<const Atom *, uint64_t> _atomRva;
};
StringRef customSectionName(const DefinedAtom *atom) {
@@ -933,6 +936,13 @@ void groupAtoms(const PECOFFLinkingConte
}
}
+static const DefinedAtom *findTLSUsedSymbol(const File &file) {
+ for (const DefinedAtom *atom : file.defined())
+ if (atom->name() == "__tls_used")
+ return atom;
+ return nullptr;
+}
+
// Create all chunks that consist of the output file.
template <class PEHeader>
void PECOFFWriter::build(const File &linkedFile) {
@@ -949,6 +959,7 @@ void PECOFFWriter::build(const File &lin
addChunk(dataDirectory);
addChunk(sectionTable);
+ // Create sections and add the atoms to them.
for (auto i : atoms) {
StringRef sectionName = i.first;
std::vector<const DefinedAtom *> &contents = i.second;
@@ -957,9 +968,14 @@ void PECOFFWriter::build(const File &lin
addSectionChunk(section, sectionTable);
}
- // Now that we know the addresses of all defined atoms that needs to be
- // relocated. So we can create the ".reloc" section which contains all the
- // relocation sites.
+ // Build atom to its RVA map.
+ for (std::unique_ptr<Chunk> &cp : _chunks)
+ if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp))
+ chunk->buildAtomRvaMap(_atomRva);
+
+ // We know the addresses of all defined atoms that needs to be
+ // relocated. So we can create the ".reloc" section which contains
+ // all the relocation sites.
if (_ctx.getBaseRelocationEnabled()) {
BaseRelocChunk *baseReloc = new BaseRelocChunk(_chunks, _ctx);
if (baseReloc->size()) {
@@ -1014,6 +1030,11 @@ void PECOFFWriter::build(const File &lin
section->getVirtualAddress(), section->size());
}
+ if (const DefinedAtom *atom = findTLSUsedSymbol(linkedFile)) {
+ dataDirectory->setField(DataDirectoryIndex::TLS_TABLE,
+ _atomRva[atom], 0x18);
+ }
+
// Now that we know the size and file offset of sections. Set the file
// header accordingly.
peHeader->setSizeOfCode(calcSizeOfCode());
@@ -1057,27 +1078,20 @@ std::error_code PECOFFWriter::writeFile(
/// address. In the second pass, we visit all relocation references to fix
/// up addresses in the buffer.
void PECOFFWriter::applyAllRelocations(uint8_t *bufferStart) {
- std::map<const Atom *, uint64_t> atomRva;
+ // Create the list of section start addresses. It's needed for
+ // relocations of SECREL type.
std::vector<uint64_t> sectionRva;
-
- // Create the list of section start addresses.
for (auto &cp : _chunks)
if (SectionChunk *section = dyn_cast<SectionChunk>(&*cp))
sectionRva.push_back(section->getVirtualAddress());
- // Pass 1
- for (auto &cp : _chunks)
- if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp))
- chunk->buildAtomRvaMap(atomRva);
-
- // Pass 2
uint64_t base = _ctx.getBaseAddress();
for (auto &cp : _chunks) {
if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp)) {
if (_ctx.is64Bit()) {
- chunk->applyRelocations64(bufferStart, atomRva, sectionRva, base);
+ chunk->applyRelocations64(bufferStart, _atomRva, sectionRva, base);
} else {
- chunk->applyRelocations32(bufferStart, atomRva, sectionRva, base);
+ chunk->applyRelocations32(bufferStart, _atomRva, sectionRva, base);
}
}
}
Added: lld/trunk/test/pecoff/Inputs/tlsused.obj.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/pecoff/Inputs/tlsused.obj.yaml?rev=218007&view=auto
==============================================================================
--- lld/trunk/test/pecoff/Inputs/tlsused.obj.yaml (added)
+++ lld/trunk/test/pecoff/Inputs/tlsused.obj.yaml Wed Sep 17 21:02:52 2014
@@ -0,0 +1,29 @@
+---
+header:
+ Machine: IMAGE_FILE_MACHINE_I386
+ Characteristics: []
+sections:
+ - Name: .data
+ Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+ Alignment: 4
+ SectionData: "0000000000000000"
+symbols:
+ - Name: .data
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ SectionDefinition:
+ Length: 8
+ NumberOfRelocations: 0
+ NumberOfLinenumbers: 0
+ CheckSum: 0
+ Number: 0
+ - Name: __tls_used
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
Added: lld/trunk/test/pecoff/tls.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/pecoff/tls.test?rev=218007&view=auto
==============================================================================
--- lld/trunk/test/pecoff/tls.test (added)
+++ lld/trunk/test/pecoff/tls.test Wed Sep 17 21:02:52 2014
@@ -0,0 +1,14 @@
+# RUN: yaml2obj %p/Inputs/hello.obj.yaml > %t1.obj
+# RUN: yaml2obj %p/Inputs/tlsused.obj.yaml > %t2.obj
+
+# RUN: lld -flavor link /out:%t1.exe /subsystem:console /force -- %t1.obj
+# RUN: llvm-readobj -file-headers %t1.exe | FileCheck -check-prefix=NOTLS %s
+
+# RUN: lld -flavor link /out:%t2.exe /subsystem:console /force -- %t1.obj %t2.obj
+# RUN: llvm-readobj -file-headers %t2.exe | FileCheck -check-prefix=TLS %s
+
+NOTLS: TLSTableRVA: 0x0
+NOTLS: TLSTableSize: 0x0
+
+TLS: TLSTableRVA: 0x1014
+TLS: TLSTableSize: 0x18
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