attributes_(attributes),
start_(start),
length_(length),
- current_vma_offset_(0),
- current_lma_offset_(0),
+ current_offset_(0),
vma_sections_(),
- lma_sections_()
+ lma_sections_(),
+ last_section_(NULL)
{ }
// Return the name of this region.
}
Expression*
- get_current_vma_address(void) const
+ get_current_address() const
{
return
script_exp_binary_add(this->start_,
- script_exp_integer(this->current_vma_offset_));
- }
-
- Expression*
- get_current_lma_address(void) const
- {
- return
- script_exp_binary_add(this->start_,
- script_exp_integer(this->current_lma_offset_));
+ script_exp_integer(this->current_offset_));
}
void
- increment_vma_offset(std::string section_name, uint64_t amount,
- const Symbol_table* symtab, const Layout* layout)
+ increment_offset(std::string section_name, uint64_t amount,
+ const Symbol_table* symtab, const Layout* layout)
{
- this->current_vma_offset_ += amount;
+ this->current_offset_ += amount;
- if (this->current_vma_offset_
+ if (this->current_offset_
> this->length_->eval(symtab, layout, false))
- gold_error (_("section %s overflows end of region %s"),
- section_name.c_str(), this->name_.c_str());
+ gold_error(_("section %s overflows end of region %s"),
+ section_name.c_str(), this->name_.c_str());
}
- void
- increment_lma_offset(std::string section_name, uint64_t amount,
- const Symbol_table* symtab, const Layout* layout)
+ // Returns true iff there is room left in this region
+ // for AMOUNT more bytes of data.
+ bool
+ has_room_for(const Symbol_table* symtab, const Layout* layout,
+ uint64_t amount) const
{
- this->current_lma_offset_ += amount;
-
- if (this->current_lma_offset_
- > this->length_->eval(symtab, layout, false))
- gold_error (_("section %s overflows end of region %s (based on load address)"),
- section_name.c_str(), this->name_.c_str());
+ return (this->current_offset_ + amount
+ < this->length_->eval(symtab, layout, false));
}
+ // Return true if the provided section flags
+ // are compatible with this region's attributes.
+ bool
+ attributes_compatible(elfcpp::Elf_Xword flags, elfcpp::Elf_Xword type) const;
+
void
add_section(Output_section_definition* sec, bool vma)
{
// Return the start of the list of sections
// whose VMAs are taken from this region.
Section_list::const_iterator
- get_vma_section_list_start(void) const
+ get_vma_section_list_start() const
{ return this->vma_sections_.begin(); }
// Return the start of the list of sections
// whose LMAs are taken from this region.
Section_list::const_iterator
- get_lma_section_list_start(void) const
+ get_lma_section_list_start() const
{ return this->lma_sections_.begin(); }
// Return the end of the list of sections
// whose VMAs are taken from this region.
Section_list::const_iterator
- get_vma_section_list_end(void) const
+ get_vma_section_list_end() const
{ return this->vma_sections_.end(); }
// Return the end of the list of sections
// whose LMAs are taken from this region.
Section_list::const_iterator
- get_lma_section_list_end(void) const
+ get_lma_section_list_end() const
{ return this->lma_sections_.end(); }
+ Output_section_definition*
+ get_last_section() const
+ { return this->last_section_; }
+
+ void
+ set_last_section(Output_section_definition* sec)
+ { this->last_section_ = sec; }
+
private:
std::string name_;
unsigned int attributes_;
Expression* start_;
Expression* length_;
- uint64_t current_vma_offset_;
- uint64_t current_lma_offset_;
+ // The offset to the next free byte in the region.
+ // Note - for compatibility with GNU LD we only maintain one offset
+ // regardless of whether the region is being used for VMA values,
+ // LMA values, or both.
+ uint64_t current_offset_;
// A list of sections whose VMAs are set inside this region.
Section_list vma_sections_;
// A list of sections whose LMAs are set inside this region.
Section_list lma_sections_;
+ // The latest section to make use of this region.
+ Output_section_definition* last_section_;
};
+// Return true if the provided section flags
+// are compatible with this region's attributes.
+
+bool
+Memory_region::attributes_compatible(elfcpp::Elf_Xword flags,
+ elfcpp::Elf_Xword type) const
+{
+ unsigned int attrs = this->attributes_;
+
+ // No attributes means that this region is not compatible with anything.
+ if (attrs == 0)
+ return false;
+
+ bool match = true;
+ do
+ {
+ switch (attrs & - attrs)
+ {
+ case MEM_EXECUTABLE:
+ if ((flags & elfcpp::SHF_EXECINSTR) == 0)
+ match = false;
+ break;
+
+ case MEM_WRITEABLE:
+ if ((flags & elfcpp::SHF_WRITE) == 0)
+ match = false;
+ break;
+
+ case MEM_READABLE:
+ // All sections are presumed readable.
+ break;
+
+ case MEM_ALLOCATABLE:
+ if ((flags & elfcpp::SHF_ALLOC) == 0)
+ match = false;
+ break;
+
+ case MEM_INITIALIZED:
+ if ((type & elfcpp::SHT_NOBITS) != 0)
+ match = false;
+ break;
+ }
+ attrs &= ~ (attrs & - attrs);
+ }
+ while (attrs != 0);
+
+ return match;
+}
+
// Print a memory region.
void
isi.set_section_name(relobj->section_name(shndx));
if (p->is_relaxed_input_section())
{
- // We use current data size because relxed section sizes may not
+ // We use current data size because relaxed section sizes may not
// have finalized yet.
isi.set_size(p->relaxed_input_section()->current_data_size());
isi.set_addralign(p->relaxed_input_section()->addralign());
set_section_lma(Expression* address)
{ this->load_address_ = address; }
- std::string
- get_section_name(void) const
+ const std::string&
+ get_section_name() const
{ return this->name_; }
private:
return NULL;
}
+// Return true if memory from START to START + LENGTH is contained
+// within a memory region.
+
+bool
+Script_sections::block_in_region(Symbol_table* symtab, Layout* layout,
+ uint64_t start, uint64_t length) const
+{
+ if (this->memory_regions_ == NULL)
+ return false;
+
+ for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
+ mr != this->memory_regions_->end();
+ ++mr)
+ {
+ uint64_t s = (*mr)->start_address()->eval(symtab, layout, false);
+ uint64_t l = (*mr)->length()->eval(symtab, layout, false);
+
+ if (s <= start
+ && (s + l) >= (start + length))
+ return true;
+ }
+
+ return false;
+}
+
+// Find a memory region that should be used by a given output SECTION.
+// If provided set PREVIOUS_SECTION_RETURN to point to the last section
+// that used the return memory region.
+
+Memory_region*
+Script_sections::find_memory_region(
+ Output_section_definition* section,
+ bool find_vma_region,
+ Output_section_definition** previous_section_return)
+{
+ if (previous_section_return != NULL)
+ * previous_section_return = NULL;
+
+ // Walk the memory regions specified in this script, if any.
+ if (this->memory_regions_ == NULL)
+ return NULL;
+
+ // The /DISCARD/ section never gets assigned to any region.
+ if (section->get_section_name() == "/DISCARD/")
+ return NULL;
+
+ Memory_region* first_match = NULL;
+
+ // First check to see if a region has been assigned to this section.
+ for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
+ mr != this->memory_regions_->end();
+ ++mr)
+ {
+ if (find_vma_region)
+ {
+ for (Memory_region::Section_list::const_iterator s =
+ (*mr)->get_vma_section_list_start();
+ s != (*mr)->get_vma_section_list_end();
+ ++s)
+ if ((*s) == section)
+ {
+ (*mr)->set_last_section(section);
+ return *mr;
+ }
+ }
+ else
+ {
+ for (Memory_region::Section_list::const_iterator s =
+ (*mr)->get_lma_section_list_start();
+ s != (*mr)->get_lma_section_list_end();
+ ++s)
+ if ((*s) == section)
+ {
+ (*mr)->set_last_section(section);
+ return *mr;
+ }
+ }
+
+ // Make a note of the first memory region whose attributes
+ // are compatible with the section. If we do not find an
+ // explicit region assignment, then we will return this region.
+ Output_section* out_sec = section->get_output_section();
+ if (first_match == NULL
+ && (*mr)->attributes_compatible(out_sec->flags(),
+ out_sec->type()))
+ first_match = *mr;
+ }
+
+ // With LMA computations, if an explicit region has not been specified then
+ // we will want to set the difference between the VMA and the LMA of the
+ // section were searching for to be the same as the difference between the
+ // VMA and LMA of the last section to be added to first matched region.
+ // Hence, if it was asked for, we return a pointer to the last section
+ // known to be used by the first matched region.
+ if (first_match != NULL
+ && previous_section_return != NULL)
+ *previous_section_return = first_match->get_last_section();
+
+ return first_match;
+}
+
// Set the section address. Note that the OUTPUT_SECTION_ field will
// be NULL if no input sections were mapped to this output section.
// We still have to adjust dot and process symbol assignments.
uint64_t* dot_alignment,
uint64_t* load_address)
{
+ Memory_region* vma_region = NULL;
+ Memory_region* lma_region = NULL;
+ Script_sections* script_sections =
+ layout->script_options()->script_sections();
uint64_t address;
uint64_t old_dot_value = *dot_value;
uint64_t old_load_address = *load_address;
- // Check for --section-start.
- bool is_address_set = false;
- if (this->output_section_ != NULL)
- is_address_set =
- parameters->options().section_start(this->output_section_->name(),
- &address);
- if (!is_address_set)
+ // Decide the start address for the section. The algorithm is:
+ // 1) If an address has been specified in a linker script, use that.
+ // 2) Otherwise if a memory region has been specified for the section,
+ // use the next free address in the region.
+ // 3) Otherwise if memory regions have been specified find the first
+ // region whose attributes are compatible with this section and
+ // install it into that region.
+ // 4) Otherwise use the current location counter.
+
+ if (this->output_section_ != NULL
+ // Check for --section-start.
+ && parameters->options().section_start(this->output_section_->name(),
+ &address))
+ ;
+ else if (this->address_ == NULL)
{
- if (this->address_ == NULL)
- address = *dot_value;
+ vma_region = script_sections->find_memory_region(this, true, NULL);
+
+ if (vma_region != NULL)
+ address = vma_region->get_current_address()->eval(symtab, layout,
+ false);
else
- {
- address = this->address_->eval_with_dot(symtab, layout, true,
- *dot_value, NULL, NULL,
- dot_alignment);
- }
+ address = *dot_value;
}
-
+ else
+ address = this->address_->eval_with_dot(symtab, layout, true,
+ *dot_value, NULL, NULL,
+ dot_alignment);
uint64_t align;
if (this->align_ == NULL)
{
this->evaluated_address_ = address;
this->evaluated_addralign_ = align;
+ uint64_t laddr;
+
if (this->load_address_ == NULL)
- this->evaluated_load_address_ = address;
+ {
+ Output_section_definition* previous_section;
+
+ // Determine if an LMA region has been set for this section.
+ lma_region = script_sections->find_memory_region(this, false,
+ &previous_section);
+
+ if (lma_region != NULL)
+ {
+ if (previous_section == NULL)
+ // The LMA address was explicitly set to the given region.
+ laddr = lma_region->get_current_address()->eval(symtab, layout,
+ false);
+ else
+ {
+ // We are not going to use the discovered lma_region, so
+ // make sure that we do not update it in the code below.
+ lma_region = NULL;
+
+ if (this->address_ != NULL || previous_section == this)
+ {
+ // Either an explicit VMA address has been set, or an
+ // explicit VMA region has been set, so set the LMA equal to
+ // the VMA.
+ laddr = address;
+ }
+ else
+ {
+ // The LMA address was not explicitly or implicitly set.
+ //
+ // We have been given the first memory region that is
+ // compatible with the current section and a pointer to the
+ // last section to use this region. Set the LMA of this
+ // section so that the difference between its' VMA and LMA
+ // is the same as the difference between the VMA and LMA of
+ // the last section in the given region.
+ laddr = address + (previous_section->evaluated_load_address_
+ - previous_section->evaluated_address_);
+ }
+ }
+
+ if (this->output_section_ != NULL)
+ this->output_section_->set_load_address(laddr);
+ }
+ else
+ {
+ // Do not set the load address of the output section, if one exists.
+ // This allows future sections to determine what the load address
+ // should be. If none is ever set, it will default to being the
+ // same as the vma address.
+ laddr = address;
+ }
+ }
else
{
- uint64_t laddr =
- this->load_address_->eval_with_dot(symtab, layout, true, *dot_value,
- this->output_section_, NULL, NULL);
+ laddr = this->load_address_->eval_with_dot(symtab, layout, true,
+ *dot_value,
+ this->output_section_,
+ NULL, NULL);
if (this->output_section_ != NULL)
this->output_section_->set_load_address(laddr);
- this->evaluated_load_address_ = laddr;
}
+ this->evaluated_load_address_ = laddr;
+
uint64_t subalign;
if (this->subalign_ == NULL)
subalign = 0;
gold_assert(input_sections.empty());
- if (this->load_address_ == NULL || this->output_section_ == NULL)
+ if (vma_region != NULL)
+ {
+ // Update the VMA region being used by the section now that we know how
+ // big it is. Use the current address in the region, rather than
+ // start_address because that might have been aligned upwards and we
+ // need to allow for the padding.
+ Expression* addr = vma_region->get_current_address();
+ uint64_t size = *dot_value - addr->eval(symtab, layout, false);
+
+ vma_region->increment_offset(this->get_section_name(), size,
+ symtab, layout);
+ }
+
+ // If the LMA region is different from the VMA region, then increment the
+ // offset there as well. Note that we use the same "dot_value -
+ // start_address" formula that is used in the load_address assignment below.
+ if (lma_region != NULL && lma_region != vma_region)
+ lma_region->increment_offset(this->get_section_name(),
+ *dot_value - start_address,
+ symtab, layout);
+
+ // Compute the load address for the following section.
+ if (this->output_section_ == NULL)
*load_address = *dot_value;
+ else if (this->load_address_ == NULL)
+ {
+ if (lma_region == NULL)
+ *load_address = *dot_value;
+ else
+ *load_address =
+ lma_region->get_current_address()->eval(symtab, layout, false);
+ }
else
*load_address = (this->output_section_->load_address()
+ (*dot_value - start_address));
this->memory_regions_ = new Memory_regions();
else if (this->find_memory_region(name, namelen))
{
- gold_error (_("region '%.*s' already defined"), static_cast<int>(namelen),
+ gold_error(_("region '%.*s' already defined"), static_cast<int>(namelen),
name);
// FIXME: Add a GOLD extension to allow multiple regions with the same
// name. This would amount to a single region covering disjoint blocks
Script_sections::set_section_addresses(Symbol_table* symtab, Layout* layout)
{
gold_assert(this->saw_sections_clause_);
-
- // Walk the memory regions specified in this script, if any.
- if (this->memory_regions_ != NULL)
- {
- for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
- mr != this->memory_regions_->end();
- ++mr)
- {
- // FIXME: What should we do with the attributes of the regions ?
-
- // For each region, set the VMA of the sections associated with it.
- for (Memory_region::Section_list::const_iterator s =
- (*mr)->get_vma_section_list_start();
- s != (*mr)->get_vma_section_list_end();
- ++s)
- {
- (*s)->set_section_vma((*mr)->get_current_vma_address());
- (*mr)->increment_vma_offset((*s)->get_section_name(),
- (*s)->get_output_section()->current_data_size(),
- symtab, layout);
- }
-
- // Similarly, set the LMA values.
- for (Memory_region::Section_list::const_iterator s =
- (*mr)->get_lma_section_list_start();
- s != (*mr)->get_lma_section_list_end();
- ++s)
- {
- (*s)->set_section_lma((*mr)->get_current_lma_address());
- (*mr)->increment_lma_offset((*s)->get_section_name(),
- (*s)->get_output_section()->current_data_size(),
- symtab, layout);
- }
- }
- }
// Implement ONLY_IF_RO/ONLY_IF_RW constraints. These are a pain
// for our representation.
if (lma < subtract || vma < subtract)
return NULL;
+ // If memory regions have been specified and the address range
+ // we are about to use is not contained within any region then
+ // issue a warning message about the segment we are going to
+ // create. It will be outside of any region and so possibly
+ // using non-existent or protected memory. We test LMA rather
+ // than VMA since we assume that the headers will never be
+ // relocated.
+ if (this->memory_regions_ != NULL
+ && !this->block_in_region (NULL, layout, lma - subtract, subtract))
+ gold_warning(_("creating a segment to contain the file and program"
+ " headers outside of any MEMORY region"));
+
Output_segment* load_seg = layout->make_output_segment(elfcpp::PT_LOAD,
elfcpp::PF_R);
load_seg->set_addresses(vma - subtract, lma - subtract);
@cindex address, section
@cindex section address
The @var{address} is an expression for the VMA (the virtual memory
-address) of the output section. If you do not provide @var{address},
-the linker will set it based on @var{region} if present, or otherwise
-based on the current value of the location counter.
-
-If you provide @var{address}, the address of the output section will be
-set to precisely that. If you provide neither @var{address} nor
-@var{region}, then the address of the output section will be set to the
-current value of the location counter aligned to the alignment
-requirements of the output section. The alignment requirement of the
-output section is the strictest alignment of any input section contained
-within the output section.
-
-For example,
+address) of the output section. This address is optional, but if it
+is provided then the output address will be set exactly as specified.
+
+If the output address is not specified then one will be chosen for the
+section, based on the heuristic below. This address will be adjusted
+to fit the alignment requirement of the output section. The
+alignment requirement is the strictest alignment of any input section
+contained within the output section.
+
+The output section address heuristic is as follows:
+
+@itemize @bullet
+@item
+If an output memory @var{region} is set for the section then it
+is added to this region and its address will be the next free address
+in that region.
+
+@item
+If the MEMORY command has been used to create a list of memory
+regions then the first region which has attributes compatible with the
+section is selected to contain it. The section's output address will
+be the next free address in that region; @ref{MEMORY}.
+
+@item
+If no memory regions were specified, or none match the section then
+the output address will be based on the current value of the location
+counter.
+@end itemize
+
+@noindent
+For example:
+
@smallexample
.text . : @{ *(.text) @}
@end smallexample
+
@noindent
and
+
@smallexample
.text : @{ *(.text) @}
@end smallexample
+
@noindent
are subtly different. The first will set the address of the
@samp{.text} output section to the current value of the location
counter. The second will set it to the current value of the location
-counter aligned to the strictest alignment of a @samp{.text} input
-section.
+counter aligned to the strictest alignment of any of the @samp{.text}
+input sections.
The @var{address} may be an arbitrary expression; @ref{Expressions}.
For example, if you want to align the section on a 0x10 byte boundary,
@cindex load address
@cindex section load address
Every section has a virtual address (VMA) and a load address (LMA); see
-@ref{Basic Script Concepts}. The address expression which may appear in
-an output section description sets the VMA (@pxref{Output Section
-Address}).
+@ref{Basic Script Concepts}. The virtual address is specified by the
+@pxref{Output Section Address} described earlier. The load address is
+specified by the @code{AT} or @code{AT>} keywords. Specifying a load
+address is optional.
-The expression @var{lma} that follows the @code{AT} keyword specifies
-the load address of the section.
-
-Alternatively, with @samp{AT>@var{lma_region}} expression, you may
-specify a memory region for the section's load address. @xref{MEMORY}.
-Note that if the section has not had a VMA assigned to it then the
-linker will use the @var{lma_region} as the VMA region as well.
+The @code{AT} keyword takes an expression as an argument. This
+specifies the exact load address of the section. The @code{AT>} keyword
+takes the name of a memory region as an argument. @xref{MEMORY}. The
+load address of the section is set to the next free address in the
+region, aligned to the section's alignment requirements.
If neither @code{AT} nor @code{AT>} is specified for an allocatable
-section, the linker will set the LMA such that the difference between
-VMA and LMA for the section is the same as the preceding output
-section in the same region. If there is no preceding output section
-or the section is not allocatable, the linker will set the LMA equal
-to the VMA.
-@xref{Output Section Region}.
+section, the linker will use the following heuristic to determine the
+load address:
+
+@itemize @bullet
+@item
+If the section has a specific VMA address, then this is used as
+the LMA address as well.
+
+@item
+If the section is not allocatable then its LMA is set to its VMA.
+
+@item
+Otherwise if a memory region can be found that is compatible
+with the current section, and this region contains at least one
+section, then the LMA is set so the difference between the
+VMA and LMA is the same as the difference between the VMA and LMA of
+the last section in the located region.
+
+@item
+If no memory regions have been declared then a default region
+that covers the entire address space is used in the previous step.
+
+@item
+If no suitable region could be found, or there was no previous
+section then the LMA is set equal to the VMA.
+@end itemize
@cindex ROM initialized data
@cindex initialized data in ROM
char *src = &_etext;
char *dst = &_data;
-/* ROM has data at end of text; copy it. */
-while (dst < &_edata) @{
+/* ROM has data at end of text; copy it. */
+while (dst < &_edata)
*dst++ = *src++;
-@}
-/* Zero bss */
+/* Zero bss. */
for (dst = &_bstart; dst< &_bend; dst++)
*dst = 0;
@end group
projects / deliverable / binutils-gdb.git / commitdiff
