1 files changed, 462 insertions, 0 deletions
diff --git a/lld/lib/ReaderWriter/ELF/SegmentChunks.cpp b/lld/lib/ReaderWriter/ELF/SegmentChunks.cpp
new file mode 100644
index 00000000000..237ef059ebf
--- /dev/null
+++ b/lld/lib/ReaderWriter/ELF/SegmentChunks.cpp
@@ -0,0 +1,462 @@
+//===- lib/ReaderWriter/ELF/SegmentChunks.h -------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SegmentChunks.h"
+#include "TargetLayout.h"
+
+namespace lld {
+namespace elf {
+
+template <class ELFT>
+bool SegmentSlice<ELFT>::compare_slices(SegmentSlice<ELFT> *a,
+                                        SegmentSlice<ELFT> *b) {
+  return a->startSection() < b->startSection();
+}
+
+template <class ELFT>
+Segment<ELFT>::Segment(const ELFLinkingContext &ctx, StringRef name,
+                       const typename TargetLayout<ELFT>::SegmentType type)
+    : Chunk<ELFT>(name, Chunk<ELFT>::Kind::ELFSegment, ctx), _segmentType(type),
+      _flags(0), _atomflags(0) {
+  this->_alignment = 1;
+  this->_fsize = 0;
+  _outputMagic = ctx.getOutputMagic();
+}
+
+// This function actually is used, but not in all instantiations of Segment.
+LLVM_ATTRIBUTE_UNUSED
+static DefinedAtom::ContentPermissions toAtomPerms(uint64_t flags) {
+  switch (flags & (SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR)) {
+  case SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR:
+    return DefinedAtom::permRWX;
+  case SHF_ALLOC | SHF_EXECINSTR:
+    return DefinedAtom::permR_X;
+  case SHF_ALLOC:
+    return DefinedAtom::permR__;
+  case SHF_ALLOC | SHF_WRITE:
+    return DefinedAtom::permRW_;
+  default:
+    return DefinedAtom::permUnknown;
+  }
+}
+
+template <class ELFT> void Segment<ELFT>::append(Chunk<ELFT> *chunk) {
+  _sections.push_back(chunk);
+  Section<ELFT> *section = dyn_cast<Section<ELFT>>(chunk);
+  if (!section)
+    return;
+  if (_flags < section->getFlags())
+    _flags |= section->getFlags();
+  if (_atomflags < toAtomPerms(_flags))
+    _atomflags = toAtomPerms(_flags);
+  if (this->_alignment < section->alignment())
+    this->_alignment = section->alignment();
+}
+
+template <class ELFT>
+bool Segment<ELFT>::compareSegments(Segment<ELFT> *sega, Segment<ELFT> *segb) {
+  int64_t type1 = sega->segmentType();
+  int64_t type2 = segb->segmentType();
+
+  if (type1 == type2)
+    return sega->atomflags() < segb->atomflags();
+
+  // The single PT_PHDR segment is required to precede any loadable
+  // segment.  We simply make it always first.
+  if (type1 == llvm::ELF::PT_PHDR)
+    return true;
+  if (type2 == llvm::ELF::PT_PHDR)
+    return false;
+
+  // The single PT_INTERP segment is required to precede any loadable
+  // segment.  We simply make it always second.
+  if (type1 == llvm::ELF::PT_INTERP)
+    return true;
+  if (type2 == llvm::ELF::PT_INTERP)
+    return false;
+
+  // We then put PT_LOAD segments before any other segments.
+  if (type1 == llvm::ELF::PT_LOAD)
+    return true;
+  if (type2 == llvm::ELF::PT_LOAD)
+    return false;
+
+  // We put the PT_GNU_RELRO segment last, because that is where the
+  // dynamic linker expects to find it
+  if (type1 == llvm::ELF::PT_GNU_RELRO)
+    return false;
+  if (type2 == llvm::ELF::PT_GNU_RELRO)
+    return true;
+
+  // We put the PT_TLS segment last except for the PT_GNU_RELRO
+  // segment, because that is where the dynamic linker expects to find
+  if (type1 == llvm::ELF::PT_TLS)
+    return false;
+  if (type2 == llvm::ELF::PT_TLS)
+    return true;
+
+  // Otherwise compare the types to establish an arbitrary ordering.
+  // FIXME: Should figure out if we should just make all other types compare
+  // equal, but if so, we should probably do the same for atom flags and change
+  // users of this to use stable_sort.
+  return type1 < type2;
+}
+
+template <class ELFT>
+void Segment<ELFT>::assignFileOffsets(uint64_t startOffset) {
+  uint64_t fileOffset = startOffset;
+  uint64_t curSliceFileOffset = fileOffset;
+  bool isDataPageAlignedForNMagic = false;
+  bool alignSegments = this->_ctx.alignSegments();
+  uint64_t p_align = this->_ctx.getPageSize();
+  uint64_t lastVirtualAddress = 0;
+
+  this->setFileOffset(startOffset);
+  for (auto &slice : slices()) {
+    bool isFirstSection = true;
+    for (auto section : slice->sections()) {
+      // Handle linker script expressions, which may change the offset
+      if (!isFirstSection)
+        if (auto expr = dyn_cast<ExpressionChunk<ELFT>>(section))
+          fileOffset += expr->virtualAddr() - lastVirtualAddress;
+      // Align fileoffset to the alignment of the section.
+      fileOffset = llvm::RoundUpToAlignment(fileOffset, section->alignment());
+      // If the linker outputmagic is set to OutputMagic::NMAGIC, align the Data
+      // to a page boundary
+      if (isFirstSection &&
+          _outputMagic != ELFLinkingContext::OutputMagic::NMAGIC &&
+          _outputMagic != ELFLinkingContext::OutputMagic::OMAGIC) {
+        // Align to a page only if the output is not
+        // OutputMagic::NMAGIC/OutputMagic::OMAGIC
+        if (alignSegments)
+          fileOffset = llvm::RoundUpToAlignment(fileOffset, p_align);
+        else {
+          // Align according to ELF spec.
+          // in p75, http://www.sco.com/developers/devspecs/gabi41.pdf
+          uint64_t virtualAddress = slice->virtualAddr();
+          Section<ELFT> *sect = dyn_cast<Section<ELFT>>(section);
+          if (sect && sect->isLoadableSection() &&
+              ((virtualAddress & (p_align - 1)) !=
+               (fileOffset & (p_align - 1))))
+            fileOffset = llvm::RoundUpToAlignment(fileOffset, p_align) +
+                         (virtualAddress % p_align);
+        }
+      } else if (!isDataPageAlignedForNMagic && needAlign(section)) {
+        fileOffset =
+            llvm::RoundUpToAlignment(fileOffset, this->_ctx.getPageSize());
+        isDataPageAlignedForNMagic = true;
+      }
+      if (isFirstSection) {
+        slice->setFileOffset(fileOffset);
+        isFirstSection = false;
+        curSliceFileOffset = fileOffset;
+      }
+      section->setFileOffset(fileOffset);
+      fileOffset += section->fileSize();
+      lastVirtualAddress = section->virtualAddr() + section->memSize();
+    }
+    slice->setFileSize(fileOffset - curSliceFileOffset);
+  }
+  this->setFileSize(fileOffset - startOffset);
+}
+
+/// \brief Assign virtual addresses to the slices
+template <class ELFT> void Segment<ELFT>::assignVirtualAddress(uint64_t addr) {
+  int startSection = 0;
+  int currSection = 0;
+  SectionIter startSectionIter;
+
+  // slice align is set to the max alignment of the chunks that are
+  // contained in the slice
+  uint64_t sliceAlign = 0;
+  // Current slice size
+  uint64_t curSliceSize = 0;
+  // Current Slice File Offset
+  uint64_t curSliceAddress = 0;
+
+  startSectionIter = _sections.begin();
+  startSection = 0;
+  bool isFirstSection = true;
+  bool isDataPageAlignedForNMagic = false;
+  uint64_t startAddr = addr;
+  SegmentSlice<ELFT> *slice = nullptr;
+  uint64_t tlsStartAddr = 0;
+  bool alignSegments = this->_ctx.alignSegments();
+  StringRef prevOutputSectionName = StringRef();
+
+  for (auto si = _sections.begin(); si != _sections.end(); ++si) {
+    // If this is first section in the segment, page align the section start
+    // address. The linker needs to align the data section to a page boundary
+    // only if NMAGIC is set.
+    if (isFirstSection) {
+      isFirstSection = false;
+      if (alignSegments &&
+          _outputMagic != ELFLinkingContext::OutputMagic::NMAGIC &&
+          _outputMagic != ELFLinkingContext::OutputMagic::OMAGIC)
+        // Align to a page only if the output is not
+        // OutputMagic::NMAGIC/OutputMagic::OMAGIC
+        startAddr =
+            llvm::RoundUpToAlignment(startAddr, this->_ctx.getPageSize());
+      else if (!isDataPageAlignedForNMagic && needAlign(*si)) {
+        // If the linker outputmagic is set to OutputMagic::NMAGIC, align the
+        // Data to a page boundary.
+        startAddr =
+            llvm::RoundUpToAlignment(startAddr, this->_ctx.getPageSize());
+        isDataPageAlignedForNMagic = true;
+      }
+      // align the startOffset to the section alignment
+      uint64_t newAddr =
+          llvm::RoundUpToAlignment(startAddr, (*si)->alignment());
+      // Handle linker script expressions, which *may update newAddr* if the
+      // expression assigns to "."
+      if (auto expr = dyn_cast<ExpressionChunk<ELFT>>(*si))
+        expr->evalExpr(newAddr);
+      curSliceAddress = newAddr;
+      sliceAlign = (*si)->alignment();
+      (*si)->setVirtualAddr(curSliceAddress);
+
+      // Handle TLS.
+      if (auto section = dyn_cast<Section<ELFT>>(*si)) {
+        if (section->getSegmentType() == llvm::ELF::PT_TLS) {
+          tlsStartAddr =
+              llvm::RoundUpToAlignment(tlsStartAddr, (*si)->alignment());
+          section->assignVirtualAddress(tlsStartAddr);
+          tlsStartAddr += (*si)->memSize();
+        } else {
+          section->assignVirtualAddress(newAddr);
+        }
+      }
+      // TBSS section is special in that it doesn't contribute to memory of any
+      // segment. If we see a tbss section, don't add memory size to addr The
+      // fileOffset is automatically taken care of since TBSS section does not
+      // end up using file size
+      if ((*si)->order() != TargetLayout<ELFT>::ORDER_TBSS)
+        curSliceSize = (*si)->memSize();
+    } else {
+      uint64_t curAddr = curSliceAddress + curSliceSize;
+      if (!isDataPageAlignedForNMagic && needAlign(*si)) {
+        // If the linker outputmagic is set to OutputMagic::NMAGIC, align the
+        // Data
+        // to a page boundary
+        curAddr = llvm::RoundUpToAlignment(curAddr, this->_ctx.getPageSize());
+        isDataPageAlignedForNMagic = true;
+      }
+      uint64_t newAddr = llvm::RoundUpToAlignment(curAddr, (*si)->alignment());
+      // Handle linker script expressions, which *may update newAddr* if the
+      // expression assigns to "."
+      if (auto expr = dyn_cast<ExpressionChunk<ELFT>>(*si))
+        expr->evalExpr(newAddr);
+      Section<ELFT> *sec = dyn_cast<Section<ELFT>>(*si);
+      StringRef curOutputSectionName;
+      if (sec)
+        curOutputSectionName = sec->outputSectionName();
+      else {
+        // If this is a linker script expression, propagate the name of the
+        // previous section instead
+        if (isa<ExpressionChunk<ELFT>>(*si))
+          curOutputSectionName = prevOutputSectionName;
+        else
+          curOutputSectionName = (*si)->name();
+      }
+      bool autoCreateSlice = true;
+      if (curOutputSectionName == prevOutputSectionName)
+        autoCreateSlice = false;
+      // If the newAddress computed is more than a page away, let's create
+      // a separate segment, so that memory is not used up while running.
+      // Dont create a slice, if the new section falls in the same output
+      // section as the previous section.
+      if (autoCreateSlice && ((newAddr - curAddr) > this->_ctx.getPageSize()) &&
+          (_outputMagic != ELFLinkingContext::OutputMagic::NMAGIC &&
+           _outputMagic != ELFLinkingContext::OutputMagic::OMAGIC)) {
+        auto sliceIter =
+            std::find_if(_segmentSlices.begin(), _segmentSlices.end(),
+                         [startSection](SegmentSlice<ELFT> *s) -> bool {
+                           return s->startSection() == startSection;
+                         });
+        if (sliceIter == _segmentSlices.end()) {
+          slice = new (_segmentAllocate.Allocate<SegmentSlice<ELFT>>())
+              SegmentSlice<ELFT>();
+          _segmentSlices.push_back(slice);
+        } else {
+          slice = (*sliceIter);
+        }
+        slice->setStart(startSection);
+        slice->setSections(make_range(startSectionIter, si));
+        slice->setMemSize(curSliceSize);
+        slice->setAlign(sliceAlign);
+        slice->setVirtualAddr(curSliceAddress);
+        // Start new slice
+        curSliceAddress = newAddr;
+        (*si)->setVirtualAddr(curSliceAddress);
+        startSectionIter = si;
+        startSection = currSection;
+        if (auto section = dyn_cast<Section<ELFT>>(*si))
+          section->assignVirtualAddress(newAddr);
+        curSliceSize = newAddr - curSliceAddress + (*si)->memSize();
+        sliceAlign = (*si)->alignment();
+      } else {
+        if (sliceAlign < (*si)->alignment())
+          sliceAlign = (*si)->alignment();
+        (*si)->setVirtualAddr(newAddr);
+        // Handle TLS.
+        if (auto section = dyn_cast<Section<ELFT>>(*si)) {
+          if (section->getSegmentType() == llvm::ELF::PT_TLS) {
+            tlsStartAddr =
+                llvm::RoundUpToAlignment(tlsStartAddr, (*si)->alignment());
+            section->assignVirtualAddress(tlsStartAddr);
+            tlsStartAddr += (*si)->memSize();
+          } else {
+            section->assignVirtualAddress(newAddr);
+          }
+        }
+        // TBSS section is special in that it doesn't contribute to memory of
+        // any segment. If we see a tbss section, don't add memory size to addr
+        // The fileOffset is automatically taken care of since TBSS section does
+        // not end up using file size.
+        if ((*si)->order() != TargetLayout<ELFT>::ORDER_TBSS)
+          curSliceSize = newAddr - curSliceAddress + (*si)->memSize();
+        else
+          curSliceSize = newAddr - curSliceAddress;
+      }
+      prevOutputSectionName = curOutputSectionName;
+    }
+    currSection++;
+  }
+  auto sliceIter = std::find_if(_segmentSlices.begin(), _segmentSlices.end(),
+                                [startSection](SegmentSlice<ELFT> *s) -> bool {
+                                  return s->startSection() == startSection;
+                                });
+  if (sliceIter == _segmentSlices.end()) {
+    slice = new (_segmentAllocate.Allocate<SegmentSlice<ELFT>>())
+        SegmentSlice<ELFT>();
+    _segmentSlices.push_back(slice);
+  } else {
+    slice = (*sliceIter);
+  }
+  slice->setStart(startSection);
+  slice->setVirtualAddr(curSliceAddress);
+  slice->setMemSize(curSliceSize);
+  slice->setSections(make_range(startSectionIter, _sections.end()));
+  slice->setAlign(sliceAlign);
+
+  // Set the segment memory size and the virtual address.
+  this->setMemSize(curSliceAddress - startAddr + curSliceSize);
+  this->setVirtualAddr(curSliceAddress);
+  std::stable_sort(_segmentSlices.begin(), _segmentSlices.end(),
+                   SegmentSlice<ELFT>::compare_slices);
+}
+
+// Write the Segment
+template <class ELFT>
+void Segment<ELFT>::write(ELFWriter *writer, TargetLayout<ELFT> &layout,
+                          llvm::FileOutputBuffer &buffer) {
+  for (auto slice : slices())
+    for (auto section : slice->sections())
+      section->write(writer, layout, buffer);
+}
+
+template <class ELFT> int64_t Segment<ELFT>::flags() const {
+  int64_t fl = 0;
+  if (_flags & llvm::ELF::SHF_ALLOC)
+    fl |= llvm::ELF::PF_R;
+  if (_flags & llvm::ELF::SHF_WRITE)
+    fl |= llvm::ELF::PF_W;
+  if (_flags & llvm::ELF::SHF_EXECINSTR)
+    fl |= llvm::ELF::PF_X;
+  return fl;
+}
+
+template <class ELFT> void Segment<ELFT>::finalize() {
+  // We want to finalize the segment values for now only for non loadable
+  // segments, since those values are not set in the Layout
+  if (_segmentType == llvm::ELF::PT_LOAD)
+    return;
+  // The size is the difference of the
+  // last section to the first section, especially for TLS because
+  // the TLS segment contains both .tdata/.tbss
+  this->setFileOffset(_sections.front()->fileOffset());
+  this->setVirtualAddr(_sections.front()->virtualAddr());
+  size_t startFileOffset = _sections.front()->fileOffset();
+  size_t startAddr = _sections.front()->virtualAddr();
+  for (auto ai : _sections) {
+    this->_fsize = ai->fileOffset() + ai->fileSize() - startFileOffset;
+    this->_msize = ai->virtualAddr() + ai->memSize() - startAddr;
+  }
+}
+
+template <class ELFT> int Segment<ELFT>::getContentType() const {
+  int64_t fl = flags();
+  switch (_segmentType) {
+  case llvm::ELF::PT_LOAD: {
+    if (fl && llvm::ELF::PF_X)
+      return Chunk<ELFT>::ContentType::Code;
+    if (fl && llvm::ELF::PF_W)
+      return Chunk<ELFT>::ContentType::Data;
+  }
+  case llvm::ELF::PT_TLS:
+    return Chunk<ELFT>::ContentType::TLS;
+  case llvm::ELF::PT_NOTE:
+    return Chunk<ELFT>::ContentType::Note;
+  default:
+    return Chunk<ELFT>::ContentType::Unknown;
+  }
+}
+
+template <class ELFT> int64_t Segment<ELFT>::atomflags() const {
+  switch (_atomflags) {
+  case DefinedAtom::permUnknown:
+    return permUnknown;
+  case DefinedAtom::permRWX:
+    return permRWX;
+  case DefinedAtom::permR_X:
+    return permRX;
+  case DefinedAtom::permR__:
+    return permR;
+  case DefinedAtom::permRW_L:
+    return permRWL;
+  case DefinedAtom::permRW_:
+    return permRW;
+  case DefinedAtom::perm___:
+  default:
+    return permNonAccess;
+  }
+}
+
+/// \brief Check if the chunk needs to be aligned
+template <class ELFT> bool Segment<ELFT>::needAlign(Chunk<ELFT> *chunk) const {
+  if (chunk->getContentType() == Chunk<ELFT>::ContentType::Data &&
+      _outputMagic == ELFLinkingContext::OutputMagic::NMAGIC)
+    return true;
+  return false;
+}
+
+template <class ELFT> void ProgramHeaderSegment<ELFT>::finalize() {
+  // If the segment is of type Program Header, then the values fileOffset
+  // and the fileSize need to be picked up from the last section, the first
+  // section points to the ELF header and the second chunk points to the
+  // actual program headers
+  this->setFileOffset(this->_sections.back()->fileOffset());
+  this->setVirtualAddr(this->_sections.back()->virtualAddr());
+  this->_fsize = this->_sections.back()->fileSize();
+  this->_msize = this->_sections.back()->memSize();
+}
+
+#define INSTANTIATE(klass)        \
+  template class klass<ELF32LE>;  \
+  template class klass<ELF32BE>;  \
+  template class klass<ELF64LE>;  \
+  template class klass<ELF64BE>;
+
+INSTANTIATE(ExpressionChunk);
+INSTANTIATE(ProgramHeaderSegment);
+INSTANTIATE(Segment);
+INSTANTIATE(SegmentSlice);
+
+} // end namespace elf
+} // end namespace lld