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, 68 insertions, 8 deletions

diff --git a/gold/x86_64.cc b/gold/x86_64.cc
index de39cb42887..12a5467f3f5 100644
--- a/gold/x86_64.cc
+++ b/gold/x86_64.cc
@@ -25,6 +25,7 @@
 #include <cstring>
 
 #include "elfcpp.h"
+#include "dwarf.h"
 #include "parameters.h"
 #include "reloc.h"
 #include "x86_64.h"
@@ -56,7 +57,7 @@ class Output_data_plt_x86_64 : public Output_section_data
   Output_data_plt_x86_64(Symbol_table* symtab, Layout* layout,
 			 Output_data_got<64, false>* got,
 			 Output_data_space* got_plt)
-    : Output_section_data(8), tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt),
+    : Output_section_data(16), tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt),
       count_(0), tlsdesc_got_offset_(-1U), free_list_()
   { this->init(symtab, layout); }
 
@@ -64,7 +65,7 @@ class Output_data_plt_x86_64 : public Output_section_data
 			 Output_data_got<64, false>* got,
 			 Output_data_space* got_plt,
 			 unsigned int plt_count)
-    : Output_section_data((plt_count + 1) * plt_entry_size, 8, false),
+    : Output_section_data((plt_count + 1) * plt_entry_size, 16, false),
       tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt),
       count_(plt_count), tlsdesc_got_offset_(-1U), free_list_()
   {
@@ -160,13 +161,19 @@ class Output_data_plt_x86_64 : public Output_section_data
   // The first entry in the PLT.
   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
   // procedure linkage table for both programs and shared objects."
-  static unsigned char first_plt_entry[plt_entry_size];
+  static const unsigned char first_plt_entry[plt_entry_size];
 
   // Other entries in the PLT for an executable.
-  static unsigned char plt_entry[plt_entry_size];
+  static const unsigned char plt_entry[plt_entry_size];
 
   // The reserved TLSDESC entry in the PLT for an executable.
-  static unsigned char tlsdesc_plt_entry[plt_entry_size];
+  static const unsigned char tlsdesc_plt_entry[plt_entry_size];
+
+  // The .eh_frame unwind information for the PLT.
+  static const int plt_eh_frame_cie_size = 16;
+  static const int plt_eh_frame_fde_size = 32;
+  static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size];
+  static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
 
   // Set the final size.
   void
@@ -871,6 +878,11 @@ Output_data_plt_x86_64::init(Symbol_table* symtab, Layout* layout)
 				    elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN,
 				    0, true, true);
     }
+
+  // Add unwind information if requested.
+  if (parameters->options().ld_generated_unwind_info())
+    layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
+				 plt_eh_frame_fde, plt_eh_frame_fde_size);
 }
 
 void
@@ -1004,7 +1016,7 @@ Output_data_plt_x86_64::set_final_data_size()
 
 // The first entry in the PLT for an executable.
 
-unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
+const unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 {
   // From AMD64 ABI Draft 0.98, page 76
   0xff, 0x35,	// pushq contents of memory address
@@ -1016,7 +1028,7 @@ unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 
 // Subsequent entries in the PLT for an executable.
 
-unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
+const unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 {
   // From AMD64 ABI Draft 0.98, page 76
   0xff, 0x25,	// jmpq indirect
@@ -1029,7 +1041,7 @@ unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 
 // The reserved TLSDESC entry in the PLT for an executable.
 
-unsigned char Output_data_plt_x86_64::tlsdesc_plt_entry[plt_entry_size] =
+const unsigned char Output_data_plt_x86_64::tlsdesc_plt_entry[plt_entry_size] =
 {
   // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32
   // and AMD64/EM64T", Version 0.9.4 (2005-10-10).
@@ -1041,6 +1053,54 @@ unsigned char Output_data_plt_x86_64::tlsdesc_plt_entry[plt_entry_size] =
   0x40, 0
 };
 
+// The .eh_frame unwind information for the PLT.
+
+const unsigned char 
+Output_data_plt_x86_64::plt_eh_frame_cie[plt_eh_frame_cie_size] =
+{
+  1,				// CIE version.
+  'z',				// Augmentation: augmentation size included.
+  'R',				// Augmentation: FDE encoding included.
+  '\0',				// End of augmentation string.
+  1,				// Code alignment factor.
+  0x78,				// Data alignment factor.
+  16,				// Return address column.
+  1,				// Augmentation size.
+  (elfcpp::DW_EH_PE_pcrel	// FDE encoding.
+   | elfcpp::DW_EH_PE_sdata4),
+  elfcpp::DW_CFA_def_cfa, 7, 8,	// DW_CFA_def_cfa: r7 (rsp) ofs 8.
+  elfcpp::DW_CFA_offset + 16, 1,// DW_CFA_offset: r16 (rip) at cfa-8.
+  elfcpp::DW_CFA_nop,		// Align to 16 bytes.
+  elfcpp::DW_CFA_nop
+};
+
+const unsigned char
+Output_data_plt_x86_64::plt_eh_frame_fde[plt_eh_frame_fde_size] =
+{
+  0, 0, 0, 0,				// Replaced with offset to .plt.
+  0, 0, 0, 0,				// Replaced with size of .plt.
+  0,					// Augmentation size.
+  elfcpp::DW_CFA_def_cfa_offset, 16,	// DW_CFA_def_cfa_offset: 16.
+  elfcpp::DW_CFA_advance_loc + 6,	// Advance 6 to __PLT__ + 6.
+  elfcpp::DW_CFA_def_cfa_offset, 24,	// DW_CFA_def_cfa_offset: 24.
+  elfcpp::DW_CFA_advance_loc + 10,	// Advance 10 to __PLT__ + 16.
+  elfcpp::DW_CFA_def_cfa_expression,	// DW_CFA_def_cfa_expression.
+  11,					// Block length.
+  elfcpp::DW_OP_breg7, 8,		// Push %rsp + 8.
+  elfcpp::DW_OP_breg16, 0,		// Push %rip.
+  elfcpp::DW_OP_lit15,			// Push 0xf.
+  elfcpp::DW_OP_and,			// & (%rip & 0xf).
+  elfcpp::DW_OP_lit11,			// Push 0xb.
+  elfcpp::DW_OP_ge,			// >= ((%rip & 0xf) >= 0xb)
+  elfcpp::DW_OP_lit3,			// Push 3.
+  elfcpp::DW_OP_shl,			// << (((%rip & 0xf) >= 0xb) << 3)
+  elfcpp::DW_OP_plus,			// + ((((%rip&0xf)>=0xb)<<3)+%rsp+8
+  elfcpp::DW_CFA_nop,			// Align to 32 bytes.
+  elfcpp::DW_CFA_nop,
+  elfcpp::DW_CFA_nop,
+  elfcpp::DW_CFA_nop
+};
+
 // Write out the PLT.  This uses the hand-coded instructions above,
 // and adjusts them as needed.  This is specified by the AMD64 ABI.