Don't check assertions until symbols are finalized. Create an output

section if the script uses a data statement with no input sections. Don't create a loadable segment for the headers if there is no room.
2024-11-21 01:12:32 +08:00 · 2008-02-28 04:45:47 +00:00 · 2008-02-28 04:45:47 +00:00 · 919ed24cbc
commit 919ed24cbc
parent 15cf077ef4
8 changed files with 166 additions and 58 deletions
--- a/gold/expression.cc
+++ b/gold/expression.cc
@ -54,6 +54,8 @@ struct Expression::Expression_eval_info
  const Symbol_table* symtab;
  // The layout--we use this to get section information.
  const Layout* layout;
+  // Whether to check assertions.
+  bool check_assertions;
  // Whether expressions can refer to the dot symbol.  The dot symbol
  // is only available within a SECTIONS clause.
  bool is_dot_available;
@ -69,21 +71,24 @@ struct Expression::Expression_eval_info
 // Evaluate an expression.

 uint64_t
-Expression::eval(const Symbol_table* symtab, const Layout* layout)
+Expression::eval(const Symbol_table* symtab, const Layout* layout,
+		 bool check_assertions)
 {
  Output_section* dummy;
-  return this->eval_maybe_dot(symtab, layout, false, 0, NULL, &dummy);
+  return this->eval_maybe_dot(symtab, layout, check_assertions,
+			      false, 0, NULL, &dummy);
 }

 // Evaluate an expression which may refer to the dot symbol.

 uint64_t
 Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout,
-			  uint64_t dot_value, Output_section* dot_section,
+			  bool check_assertions, uint64_t dot_value,
+			  Output_section* dot_section,
 			  Output_section** result_section_pointer)
 {
-  return this->eval_maybe_dot(symtab, layout, true, dot_value, dot_section,
-			      result_section_pointer);
+  return this->eval_maybe_dot(symtab, layout, check_assertions, true,
+			      dot_value, dot_section, result_section_pointer);
 }

 // Evaluate an expression which may or may not refer to the dot
@ -91,13 +96,14 @@ Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout,

 uint64_t
 Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout,
-			   bool is_dot_available, uint64_t dot_value,
-			   Output_section* dot_section,
+			   bool check_assertions, bool is_dot_available,
+			   uint64_t dot_value, Output_section* dot_section,
 			   Output_section** result_section_pointer)
 {
  Expression_eval_info eei;
  eei.symtab = symtab;
  eei.layout = layout;
+  eei.check_assertions = check_assertions;
  eei.is_dot_available = is_dot_available;
  eei.dot_value = dot_value;
  eei.dot_section = dot_section;
@ -237,6 +243,7 @@ class Unary_expression : public Expression
 	    Output_section** arg_section_pointer) const
  {
    return this->arg_->eval_maybe_dot(eei->symtab, eei->layout,
+				      eei->check_assertions,
 				      eei->is_dot_available,
 				      eei->dot_value,
 				      eei->dot_section,
@ -313,6 +320,7 @@ class Binary_expression : public Expression
 	     Output_section** section_pointer) const
  {
    return this->left_->eval_maybe_dot(eei->symtab, eei->layout,
+				       eei->check_assertions,
 				       eei->is_dot_available,
 				       eei->dot_value,
 				       eei->dot_section,
@ -324,6 +332,7 @@ class Binary_expression : public Expression
 	      Output_section** section_pointer) const
  {
    return this->right_->eval_maybe_dot(eei->symtab, eei->layout,
+					eei->check_assertions,
 					eei->is_dot_available,
 					eei->dot_value,
 					eei->dot_section,
@ -456,6 +465,7 @@ class Trinary_expression : public Expression
 	     Output_section** section_pointer) const
  {
    return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
+				       eei->check_assertions,
 				       eei->is_dot_available,
 				       eei->dot_value,
 				       eei->dot_section,
@ -467,6 +477,7 @@ class Trinary_expression : public Expression
 	     Output_section** section_pointer) const
  {
    return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
+				       eei->check_assertions,
 				       eei->is_dot_available,
 				       eei->dot_value,
 				       eei->dot_section,
@ -478,6 +489,7 @@ class Trinary_expression : public Expression
 	     Output_section** section_pointer) const
  {
    return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
+				       eei->check_assertions,
 				       eei->is_dot_available,
 				       eei->dot_value,
 				       eei->dot_section,
@ -738,7 +750,7 @@ class Assert_expression : public Unary_expression
  value(const Expression_eval_info* eei)
  {
    uint64_t value = this->arg_value(eei, eei->result_section_pointer);
-    if (!value)
+    if (!value && eei->check_assertions)
      gold_error("%s", this->message_.c_str());
    return value;
  }
--- a/gold/gold.cc
+++ b/gold/gold.cc
@ -202,6 +202,9 @@ queue_middle_tasks(const General_options& options,
  // TODO: if this is too slow, do this as a task, rather than inline.
  symtab->detect_odr_violations(task, options.output_file_name());

+  // Create any output sections required by any linker script.
+  layout->create_script_sections();
+
  // Define some sections and symbols needed for a dynamic link.  This
  // handles some cases we want to see before we read the relocs.
  layout->create_initial_dynamic_sections(symtab);
--- a/gold/layout.cc
+++ b/gold/layout.cc
@ -712,6 +712,18 @@ Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
  return os;
 }

+// Make an output section for a script.
+
+Output_section*
+Layout::make_output_section_for_script(const char* name)
+{
+  name = this->namepool_.add(name, false, NULL);
+  Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
+						 elfcpp::SHF_ALLOC);
+  os->set_found_in_sections_clause();
+  return os;
+}
+
 // Return the number of segments we expect to see.

 size_t
--- a/gold/layout.h
+++ b/gold/layout.h
@ -168,6 +168,11 @@ class Layout
  void
  define_section_symbols(Symbol_table*);

+  // Create sections for linker scripts.
+  void
+  create_script_sections()
+  { this->script_options_->create_script_sections(this); }
+
  // Define symbols from any linker script.
  void
  define_script_symbols(Symbol_table* symtab)
@ -314,6 +319,10 @@ class Layout
  void
  get_allocated_sections(Section_list*) const;

+  // Make a section for a linker script to hold data.
+  Output_section*
+  make_output_section_for_script(const char* name);
+
  // Make a segment.  This is used by the linker script code.
  Output_segment*
  make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags);
--- a/gold/script-sections.cc
+++ b/gold/script-sections.cc
@ -54,6 +54,12 @@ class Sections_element
  virtual ~Sections_element()
  { }

+  // Create any required output sections.  The only real
+  // implementation is in Output_section_definition.
+  virtual void
+  create_sections(Layout*)
+  { }
+
  // Add any symbol being defined to the symbol table.
  virtual void
  add_symbols_to_table(Symbol_table*)
@ -175,7 +181,7 @@ class Sections_element_dot_assignment : public Sections_element
    // output section definition the dot symbol is always considered
    // to be absolute.
    Output_section* dummy;
-    *dot_value = this->val_->eval_with_dot(symtab, layout, *dot_value,
+    *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
 					   NULL, &dummy);
  }

@ -185,7 +191,7 @@ class Sections_element_dot_assignment : public Sections_element
 			uint64_t* dot_value, uint64_t* load_address)
  {
    Output_section* dummy;
-    *dot_value = this->val_->eval_with_dot(symtab, layout, *dot_value,
+    *dot_value = this->val_->eval_with_dot(symtab, layout, false, *dot_value,
 					   NULL, &dummy);
    *load_address = *dot_value;
  }
@ -244,6 +250,11 @@ class Output_section_element
  virtual ~Output_section_element()
  { }

+  // Return whether this element requires an output section to exist.
+  virtual bool
+  needs_output_section() const
+  { return false; }
+
  // Add any symbol being defined to the symbol table.
  virtual void
  add_symbols_to_table(Symbol_table*)
@ -354,7 +365,7 @@ class Output_section_element_dot_assignment : public Output_section_element
  finalize_symbols(Symbol_table* symtab, const Layout* layout,
 		   uint64_t* dot_value, Output_section** dot_section)
  {
-    *dot_value = this->val_->eval_with_dot(symtab, layout, *dot_value,
+    *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
 					   *dot_section, dot_section);
  }

@ -390,8 +401,9 @@ Output_section_element_dot_assignment::set_section_addresses(
    std::string* fill,
    Input_section_list*)
 {
-  uint64_t next_dot = this->val_->eval_with_dot(symtab, layout, *dot_value,
-						*dot_section, dot_section);
+  uint64_t next_dot = this->val_->eval_with_dot(symtab, layout, false,
+						*dot_value, *dot_section,
+						dot_section);
  if (next_dot < *dot_value)
    gold_error(_("dot may not move backward"));
  if (next_dot > *dot_value && output_section != NULL)
@ -486,7 +498,7 @@ Output_data_expression::do_write_to_buffer(unsigned char* buf)
 {
  Output_section* dummy;
  uint64_t val = this->val_->eval_with_dot(this->symtab_, this->layout_,
-					   this->dot_value_,
+					   true, this->dot_value_,
 					   this->dot_section_, &dummy);

  if (parameters->target().is_big_endian())
@ -534,6 +546,11 @@ class Output_section_element_data : public Output_section_element
    : size_(size), is_signed_(is_signed), val_(val)
  { }

+  // If there is a data item, then we must create an output section.
+  bool
+  needs_output_section() const
+  { return true; }
+
  // Finalize symbols--we just need to update dot.
  void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value,
@ -631,7 +648,7 @@ class Output_section_element_fill : public Output_section_element
 			std::string* fill, Input_section_list*)
  {
    Output_section* fill_section;
-    uint64_t fill_val = this->val_->eval_with_dot(symtab, layout,
+    uint64_t fill_val = this->val_->eval_with_dot(symtab, layout, false,
 						  *dot_value, *dot_section,
 						  &fill_section);
    if (fill_section != NULL)
@ -1195,6 +1212,10 @@ class Output_section_definition : public Sections_element
  void
  add_input_section(const Input_section_spec* spec, bool keep);

+  // Create any required output sections.
+  void
+  create_sections(Layout*);
+
  // Add any symbols being defined to the symbol table.
  void
  add_symbols_to_table(Symbol_table* symtab);
@ -1365,6 +1386,27 @@ Output_section_definition::add_input_section(const Input_section_spec* spec,
  this->elements_.push_back(p);
 }

+// Create any required output sections.  We need an output section if
+// there is a data statement here.
+
+void
+Output_section_definition::create_sections(Layout* layout)
+{
+  if (this->output_section_ != NULL)
+    return;
+  for (Output_section_elements::const_iterator p = this->elements_.begin();
+       p != this->elements_.end();
+       ++p)
+    {
+      if ((*p)->needs_output_section())
+	{
+	  const char* name = this->name_.c_str();
+	  this->output_section_ = layout->make_output_section_for_script(name);
+	  return;
+	}
+    }
+}
+
 // Add any symbols being defined to the symbol table.

 void
@ -1391,14 +1433,14 @@ Output_section_definition::finalize_symbols(Symbol_table* symtab,
      if (this->address_ != NULL)
 	{
 	  Output_section* dummy;
-	  address = this->address_->eval_with_dot(symtab, layout,
+	  address = this->address_->eval_with_dot(symtab, layout, true,
 						  *dot_value, NULL,
 						  &dummy);
 	}
      if (this->align_ != NULL)
 	{
 	  Output_section* dummy;
-	  uint64_t align = this->align_->eval_with_dot(symtab, layout,
+	  uint64_t align = this->align_->eval_with_dot(symtab, layout, true,
 						       *dot_value,
 						       NULL,
 						       &dummy);
@ -1570,8 +1612,8 @@ Output_section_definition::set_section_addresses(Symbol_table* symtab,
  else
    {
      Output_section* dummy;
-      address = this->address_->eval_with_dot(symtab, layout, *dot_value,
-					      NULL, &dummy);
+      address = this->address_->eval_with_dot(symtab, layout, true,
+					      *dot_value, NULL, &dummy);
    }

  uint64_t align;
@ -1585,7 +1627,7 @@ Output_section_definition::set_section_addresses(Symbol_table* symtab,
  else
    {
      Output_section* align_section;
-      align = this->align_->eval_with_dot(symtab, layout, *dot_value,
+      align = this->align_->eval_with_dot(symtab, layout, true, *dot_value,
 					  NULL, &align_section);
      if (align_section != NULL)
 	gold_warning(_("alignment of section %s is not absolute"),
@ -1610,7 +1652,7 @@ Output_section_definition::set_section_addresses(Symbol_table* symtab,
    {
      Output_section* dummy;
      uint64_t load_address =
-	this->load_address_->eval_with_dot(symtab, layout, *dot_value,
+	this->load_address_->eval_with_dot(symtab, layout, true, *dot_value,
 					   this->output_section_, &dummy);
      this->output_section_->set_load_address(load_address);
    }
@ -1621,8 +1663,9 @@ Output_section_definition::set_section_addresses(Symbol_table* symtab,
  else
    {
      Output_section* subalign_section;
-      subalign = this->subalign_->eval_with_dot(symtab, layout, *dot_value,
-						NULL, &subalign_section);
+      subalign = this->subalign_->eval_with_dot(symtab, layout, true,
+						*dot_value, NULL,
+						&subalign_section);
      if (subalign_section != NULL)
 	gold_warning(_("subalign of section %s is not absolute"),
 		     this->name_.c_str());
@ -1634,7 +1677,7 @@ Output_section_definition::set_section_addresses(Symbol_table* symtab,
      // FIXME: The GNU linker supports fill values of arbitrary
      // length.
      Output_section* fill_section;
-      uint64_t fill_val = this->fill_->eval_with_dot(symtab, layout,
+      uint64_t fill_val = this->fill_->eval_with_dot(symtab, layout, true,
 						     *dot_value,
 						     NULL,
 						     &fill_section);
@ -2002,7 +2045,8 @@ class Phdrs_element
  eval_load_address(Symbol_table* symtab, Layout* layout)
  {
    if (this->load_address_ != NULL)
-      this->load_address_value_ = this->load_address_->eval(symtab, layout);
+      this->load_address_value_ = this->load_address_->eval(symtab, layout,
+							    true);
  }

  // Return the load address.
@ -2216,6 +2260,19 @@ Script_sections::add_input_section(const Input_section_spec* spec, bool keep)
  this->output_section_->add_input_section(spec, keep);
 }

+// Create any required sections.
+
+void
+Script_sections::create_sections(Layout* layout)
+{
+  if (!this->saw_sections_clause_)
+    return;
+  for (Sections_elements::iterator p = this->sections_elements_->begin();
+       p != this->sections_elements_->end();
+       ++p)
+    (*p)->create_sections(layout);
+}
+
 // Add any symbols we are defining to the symbol table.

 void
@ -2575,38 +2632,32 @@ Script_sections::create_segments(Layout* layout)
  // efficient in any case.  We try to use the first PT_LOAD segment
  // if we can, otherwise we make a new one.

+  if (first_seg == NULL)
+    return NULL;
+
  size_t sizeof_headers = this->total_header_size(layout);

-  if (first_seg != NULL
-      && (first_seg->paddr() & (abi_pagesize - 1)) >= sizeof_headers)
+  if ((first_seg->paddr() & (abi_pagesize - 1)) >= sizeof_headers)
    {
      first_seg->set_addresses(first_seg->vaddr() - sizeof_headers,
 			       first_seg->paddr() - sizeof_headers);
      return first_seg;
    }

+  uint64_t vma = first_seg->vaddr();
+  uint64_t lma = first_seg->paddr();
+
+  uint64_t subtract = this->header_size_adjustment(lma, sizeof_headers);
+
+  // If there is no room to squeeze in the headers, then punt.  The
+  // resulting executable probably won't run on GNU/Linux, but we
+  // trust that the user knows what they are doing.
+  if (lma < subtract || vma < subtract)
+    return NULL;
+
  Output_segment* load_seg = layout->make_output_segment(elfcpp::PT_LOAD,
 							 elfcpp::PF_R);
-  if (first_seg == NULL)
-    load_seg->set_addresses(0, 0);
-  else
-    {
-      uint64_t vma = first_seg->vaddr();
-      uint64_t lma = first_seg->paddr();
-
-      uint64_t subtract = this->header_size_adjustment(lma, sizeof_headers);
-      if (lma >= subtract && vma >= subtract)
-	load_seg->set_addresses(vma - subtract, lma - subtract);
-      else
-	{
-	  // We could handle this case by create the file header
-	  // outside of any PT_LOAD segment, and creating a new
-	  // PT_LOAD segment after the others to hold the segment
-	  // headers.
-	  gold_error(_("sections loaded on first page without room for "
-		       "file and program headers are not supported"));
-	}
-    }
+  load_seg->set_addresses(vma - subtract, lma - subtract);

  return load_seg;
 }
--- a/gold/script-sections.h
+++ b/gold/script-sections.h
@ -106,6 +106,10 @@ class Script_sections
  void
  add_input_section(const Input_section_spec* spec, bool keep);

+  // Create any required sections.
+  void
+  create_sections(Layout*);
+
  // Add any symbols we are defining to the symbol table.
  void
  add_symbols_to_table(Symbol_table*);
--- a/gold/script.cc
+++ b/gold/script.cc
@ -980,7 +980,7 @@ Symbol_assignment::sized_finalize(Symbol_table* symtab, const Layout* layout,
 				  Output_section* dot_section)
 {
  Output_section* section;
-  uint64_t final_val = this->val_->eval_maybe_dot(symtab, layout,
+  uint64_t final_val = this->val_->eval_maybe_dot(symtab, layout, true,
 						  is_dot_available,
 						  dot_value, dot_section,
 						  &section);
@ -1000,8 +1000,9 @@ Symbol_assignment::set_if_absolute(Symbol_table* symtab, const Layout* layout,
    return;

  Output_section* val_section;
-  uint64_t val = this->val_->eval_maybe_dot(symtab, layout, is_dot_available,
-					    dot_value, NULL, &val_section);
+  uint64_t val = this->val_->eval_maybe_dot(symtab, layout, false,
+					    is_dot_available, dot_value,
+					    NULL, &val_section);
  if (val_section != NULL)
    return;

@ -1055,7 +1056,7 @@ Symbol_assignment::print(FILE* f) const
 void
 Script_assertion::check(const Symbol_table* symtab, const Layout* layout)
 {
-  if (!this->check_->eval(symtab, layout))
+  if (!this->check_->eval(symtab, layout, true))
    gold_error("%s", this->message_.c_str());
 }

@ -1122,6 +1123,15 @@ Script_options::add_assertion(Expression* check, const char* message,
    }
 }

+// Create sections required by any linker scripts.
+
+void
+Script_options::create_script_sections(Layout* layout)
+{
+  if (this->saw_sections_clause())
+    this->script_sections_.create_sections(layout);
+}
+
 // Add any symbols we are defining to the symbol table.

 void
--- a/gold/script.h
+++ b/gold/script.h
@ -67,9 +67,10 @@ class Expression
  { }

  // Return the value of the expression which is not permitted to
-  // refer to the dot symbol.
+  // refer to the dot symbol.  CHECK_ASSERTIONS is true if we should
+  // check whether assertions are true.
  uint64_t
-  eval(const Symbol_table*, const Layout*);
+  eval(const Symbol_table*, const Layout*, bool check_assertions);

  // Return the value of an expression which is permitted to refer to
  // the dot symbol.  DOT_VALUE is the absolute value of the dot
@ -82,15 +83,17 @@ class Expression
  // value; to get a section relative value the caller must subtract
  // the section address.
  uint64_t
-  eval_with_dot(const Symbol_table*, const Layout*, uint64_t dot_value,
-		Output_section* dot_section, Output_section** result_section);
+  eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,
+		uint64_t dot_value, Output_section* dot_section,
+		Output_section** result_section);

  // Return the value of an expression which may or may not be
  // permitted to refer to the dot symbol, depending on
  // is_dot_available.
  uint64_t
-  eval_maybe_dot(const Symbol_table*, const Layout*, bool is_dot_available,
-		 uint64_t dot_value, Output_section* dot_section,
+  eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,
+		 bool is_dot_available, uint64_t dot_value,
+		 Output_section* dot_section,
 		 Output_section** result_section);

  // Print the expression to the FILE.  This is for debugging.
@ -219,7 +222,7 @@ class Symbol_assignment

  // Set the symbol value, but only if the value is absolute.  This is
  // used while processing a SECTIONS clause.  We assume that dot is
-  // an absolute value here.
+  // an absolute value here.  We do not check assertions.
  void
  set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,
 		  uint64_t dot_value);
@ -307,6 +310,10 @@ class Script_options
  bool
  define_symbol(const char* definition);

+  // Create sections required by any linker scripts.
+  void
+  create_script_sections(Layout*);
+
  // Add all symbol definitions to the symbol table.
  void
  add_symbols_to_table(Symbol_table*);