PR gold/12571

	* options.h (class General_options): Add
	--ld-generated-unwind-info.
	* ehframe.cc (Fde::write): Add address parameter.  Change all
	callers.  If associated with PLT, fill in address and size.
	(Cie::set_output_offset): Only add merge mapping if there is an
	object.
	(Cie::write): Add address parameter.  Change all callers.
	(Eh_frame::add_ehframe_for_plt): New function.
	* ehframe.h (class Fde): Update declarations.  Move shndx_ and
	input_offset_ fields into union u_, with new plt field.
	(Fde::Fde): Adjust for new union field.
	(Fde::Fde) [Output_data version]: New constructor.
	(Fde::add_mapping): Only add merge mapping if there is an object.
	(class Cie): Update declarations.
	(class Eh_frame): Declare add_ehframe_for_plt.
	* layout.cc (Layout::layout_eh_frame): Break out code into
	make_eh_frame_section, and call it.
	(Layout::make_eh_frame_section): New function.
	(Layout::add_eh_frame_for_plt): New function.
	* layout.h (class Layout): Update declarations.
	* merge.cc (Merge_map::add_mapping): Add assertion.
	* i386.cc: Include "dwarf.h".
	(class Output_data_plt_i386): Make first_plt_entry,
	dyn_first_plt_entry, exec_plt_entry, and dyn_plt_entry const.  Add
	plt_eh_frame_cie_size, plt_eh_frame_fde_size, plt_eh_frame_cie,
	and plt_eh_frame_fde.
	(Output_data_plt_i386::Output_data_plt_i386): Align to 16-byte
	boundary.  Call add_eh_frame_for_plt if appropriate.
	* x86_64.cc: Include "dwarf.h".
	(class Output_data_plt_x86_64): Align to 16-byte boundary.  Make
	first_plt_entry, plt_entry and tlsdesc_plt_entry const.  Add
	plt_eh_frame_cie_size, plt_eh_frame_fde_size, plt_eh_frame_cie,
	and plt_eh_frame_fde.
	(Output_data_plt_x86_64::init): Call add_eh_frame_for_plt if
	appropriate.

1 files changed, 63 insertions, 25 deletions

diff --git a/gold/ehframe.h b/gold/ehframe.h
index f626b1f..c3f82e9 100644
--- a/gold/ehframe.h
+++ b/gold/ehframe.h
@@ -1,6 +1,6 @@
 // ehframe.h -- handle exception frame sections for gold  -*- C++ -*-
 
-// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
@@ -45,10 +45,6 @@ class Eh_frame;
 // time and when a shared object is loaded, and the time required to
 // deregister the exception handlers when a shared object is unloaded.
 
-// FIXME: gcc supports using storing a sorted lookup table for the
-// FDEs in the PT_GNU_EH_FRAME segment, but we do not yet generate
-// that.
-
 class Eh_frame_hdr : public Output_section_data
 {
  public:
@@ -170,9 +166,18 @@ class Fde
  public:
   Fde(Relobj* object, unsigned int shndx, section_offset_type input_offset,
       const unsigned char* contents, size_t length)
-    : object_(object), shndx_(shndx), input_offset_(input_offset),
+    : object_(object),
       contents_(reinterpret_cast<const char*>(contents), length)
-  { }
+  {
+    this->u_.from_object.shndx = shndx;
+    this->u_.from_object.input_offset = input_offset;
+  }
+
+  // Create an FDE associated with a PLT.
+  Fde(Output_data* plt, const unsigned char* contents, size_t length)
+    : object_(NULL),
+      contents_(reinterpret_cast<const char*>(contents), length)
+  { this->u_.from_linker.plt = plt; }
 
   // Return the length of this FDE.  Add 4 for the length and 4 for
   // the offset to the CIE.
@@ -180,32 +185,52 @@ class Fde
   length() const
   { return this->contents_.length() + 8; }
 
-  // Add a mapping for this FDE to MERGE_MAP.
+  // Add a mapping for this FDE to MERGE_MAP, so that relocations
+  // against the FDE are applied to right part of the output file.
   void
   add_mapping(section_offset_type output_offset, Merge_map* merge_map) const
   {
-    merge_map->add_mapping(this->object_, this->shndx_,
-			   this->input_offset_, this->length(),
-			   output_offset);
+    if (this->object_ != NULL)
+      merge_map->add_mapping(this->object_, this->u_.from_object.shndx,
+			     this->u_.from_object.input_offset, this->length(),
+			     output_offset);
   }
 
   // Write the FDE to OVIEW starting at OFFSET.  FDE_ENCODING is the
   // encoding, from the CIE.  Round up the bytes to ADDRALIGN if
-  // necessary.  Record the FDE in EH_FRAME_HDR.  Return the new
-  // offset.
+  // necessary.  ADDRESS is the virtual address of OVIEW.  Record the
+  // FDE in EH_FRAME_HDR.  Return the new offset.
   template<int size, bool big_endian>
   section_offset_type
   write(unsigned char* oview, section_offset_type offset,
-	unsigned int addralign, section_offset_type cie_offset,
-        unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr);
+	uint64_t address, unsigned int addralign,
+	section_offset_type cie_offset, unsigned char fde_encoding,
+	Eh_frame_hdr* eh_frame_hdr);
 
  private:
-  // The object in which this FDE was seen.
+  // The object in which this FDE was seen.  This will be NULL for a
+  // linker generated FDE.
   Relobj* object_;
-  // Input section index for this FDE.
-  unsigned int shndx_;
-  // Offset within the input section for this FDE.
-  section_offset_type input_offset_;
+  union
+  {
+    // These fields are used if the FDE is from an input object (the
+    // object_ field is not NULL).
+    struct
+    {
+      // Input section index for this FDE.
+      unsigned int shndx;
+      // Offset within the input section for this FDE.
+      section_offset_type input_offset;
+    } from_object;
+    // This field is used if the FDE is generated by the linker (the
+    // object_ field is NULL).
+    struct
+    {
+      // The only linker generated FDEs are for PLT sections, and this
+      // points to the PLT section.
+      Output_data* plt;
+    } from_linker;
+  } u_;
   // FDE data.
   std::string contents_;
 };
@@ -261,10 +286,11 @@ class Cie
 
   // Write the CIE to OVIEW starting at OFFSET.  EH_FRAME_HDR is the
   // exception frame header for FDE recording.  Round up the bytes to
-  // ADDRALIGN.  Return the new offset.
+  // ADDRALIGN.  ADDRESS is the virtual address of OVIEW.  Return the
+  // new offset.
   template<int size, bool big_endian>
   section_offset_type
-  write(unsigned char* oview, section_offset_type offset,
+  write(unsigned char* oview, section_offset_type offset, uint64_t address,
 	unsigned int addralign, Eh_frame_hdr* eh_frame_hdr);
 
   friend bool operator<(const Cie&, const Cie&);
@@ -274,11 +300,14 @@ class Cie
   // The class is not assignable.
   Cie& operator=(const Cie&);
 
-  // The object in which this CIE was first seen.
+  // The object in which this CIE was first seen.  This will be NULL
+  // for a linker generated CIE.
   Relobj* object_;
-  // Input section index for this CIE.
+  // Input section index for this CIE.  This will be 0 for a linker
+  // generated CIE.
   unsigned int shndx_;
-  // Offset within the input section for this CIE.
+  // Offset within the input section for this CIE.  This will be 0 for
+  // a linker generated CIE.
   section_offset_type input_offset_;
   // The encoding of the FDE.  This is a DW_EH_PE code.
   unsigned char fde_encoding_;
@@ -324,6 +353,15 @@ class Eh_frame : public Output_section_data
 			    unsigned int shndx, unsigned int reloc_shndx,
 			    unsigned int reloc_type);
 
+  // Add a CIE and an FDE for a PLT section, to permit unwinding
+  // through a PLT.  The FDE data should start with 8 bytes of zero,
+  // which will be replaced by a 4 byte PC relative reference to the
+  // address of PLT and a 4 byte size of PLT.
+  void
+  add_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data,
+		      size_t cie_length, const unsigned char* fde_data,
+		      size_t fde_length);
+
   // Return the number of FDEs.
   unsigned int
   fde_count() const;