791 lines
33 KiB
HTML
791 lines
33 KiB
HTML
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<title>Untitled Document: coff</title>
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<meta name="description" content="Untitled Document: coff">
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<link href="BFD-Index.html#BFD-Index" rel="index" title="BFD Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="coff"></a>
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<div class="header">
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<p>
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Next: <a href="elf.html#elf" accesskey="n" rel="next">elf</a>, Previous: <a href="aout.html#aout" accesskey="p" rel="prev">aout</a>, Up: <a href="BFD-back-ends.html#BFD-back-ends" accesskey="u" rel="up">BFD back ends</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="BFD-Index.html#BFD-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="coff-backends"></a>
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<h3 class="section">3.3 coff backends</h3>
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<p>BFD supports a number of different flavours of coff format.
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The major differences between formats are the sizes and
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alignments of fields in structures on disk, and the occasional
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extra field.
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</p>
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<p>Coff in all its varieties is implemented with a few common
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files and a number of implementation specific files. For
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example, The 88k bcs coff format is implemented in the file
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<samp>coff-m88k.c</samp>. This file <code>#include</code>s
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<samp>coff/m88k.h</samp> which defines the external structure of the
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coff format for the 88k, and <samp>coff/internal.h</samp> which
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defines the internal structure. <samp>coff-m88k.c</samp> also
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defines the relocations used by the 88k format
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See <a href="Relocations.html#Relocations">Relocations</a>.
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</p>
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<p>The Intel i960 processor version of coff is implemented in
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<samp>coff-i960.c</samp>. This file has the same structure as
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<samp>coff-m88k.c</samp>, except that it includes <samp>coff/i960.h</samp>
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rather than <samp>coff-m88k.h</samp>.
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</p>
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<a name="Porting-to-a-new-version-of-coff"></a>
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<h4 class="subsection">3.3.1 Porting to a new version of coff</h4>
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<p>The recommended method is to select from the existing
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implementations the version of coff which is most like the one
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you want to use. For example, we’ll say that i386 coff is
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the one you select, and that your coff flavour is called foo.
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Copy <samp>i386coff.c</samp> to <samp>foocoff.c</samp>, copy
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<samp>../include/coff/i386.h</samp> to <samp>../include/coff/foo.h</samp>,
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and add the lines to <samp>targets.c</samp> and <samp>Makefile.in</samp>
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so that your new back end is used. Alter the shapes of the
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structures in <samp>../include/coff/foo.h</samp> so that they match
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what you need. You will probably also have to add
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<code>#ifdef</code>s to the code in <samp>coff/internal.h</samp> and
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<samp>coffcode.h</samp> if your version of coff is too wild.
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</p>
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<p>You can verify that your new BFD backend works quite simply by
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building <samp>objdump</samp> from the <samp>binutils</samp> directory,
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and making sure that its version of what’s going on and your
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host system’s idea (assuming it has the pretty standard coff
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dump utility, usually called <code>att-dump</code> or just
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<code>dump</code>) are the same. Then clean up your code, and send
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what you’ve done to Cygnus. Then your stuff will be in the
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next release, and you won’t have to keep integrating it.
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</p>
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<a name="How-the-coff-backend-works"></a>
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<h4 class="subsection">3.3.2 How the coff backend works</h4>
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<a name="File-layout-1"></a>
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<h4 class="subsubsection">3.3.2.1 File layout</h4>
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<p>The Coff backend is split into generic routines that are
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applicable to any Coff target and routines that are specific
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to a particular target. The target-specific routines are
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further split into ones which are basically the same for all
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Coff targets except that they use the external symbol format
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or use different values for certain constants.
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</p>
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<p>The generic routines are in <samp>coffgen.c</samp>. These routines
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work for any Coff target. They use some hooks into the target
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specific code; the hooks are in a <code>bfd_coff_backend_data</code>
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structure, one of which exists for each target.
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</p>
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<p>The essentially similar target-specific routines are in
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<samp>coffcode.h</samp>. This header file includes executable C code.
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The various Coff targets first include the appropriate Coff
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header file, make any special defines that are needed, and
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then include <samp>coffcode.h</samp>.
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</p>
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<p>Some of the Coff targets then also have additional routines in
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the target source file itself.
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</p>
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<p>For example, <samp>coff-i960.c</samp> includes
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<samp>coff/internal.h</samp> and <samp>coff/i960.h</samp>. It then
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defines a few constants, such as <code>I960</code>, and includes
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<samp>coffcode.h</samp>. Since the i960 has complex relocation
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types, <samp>coff-i960.c</samp> also includes some code to
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manipulate the i960 relocs. This code is not in
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<samp>coffcode.h</samp> because it would not be used by any other
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target.
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</p>
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<a name="Coff-long-section-names"></a>
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<h4 class="subsubsection">3.3.2.2 Coff long section names</h4>
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<p>In the standard Coff object format, section names are limited to
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the eight bytes available in the <code>s_name</code> field of the
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<code>SCNHDR</code> section header structure. The format requires the
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field to be NUL-padded, but not necessarily NUL-terminated, so
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the longest section names permitted are a full eight characters.
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</p>
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<p>The Microsoft PE variants of the Coff object file format add
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an extension to support the use of long section names. This
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extension is defined in section 4 of the Microsoft PE/COFF
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specification (rev 8.1). If a section name is too long to fit
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into the section header’s <code>s_name</code> field, it is instead
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placed into the string table, and the <code>s_name</code> field is
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filled with a slash ("/") followed by the ASCII decimal
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representation of the offset of the full name relative to the
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string table base.
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</p>
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<p>Note that this implies that the extension can only be used in object
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files, as executables do not contain a string table. The standard
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specifies that long section names from objects emitted into executable
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images are to be truncated.
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</p>
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<p>However, as a GNU extension, BFD can generate executable images
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that contain a string table and long section names. This
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would appear to be technically valid, as the standard only says
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that Coff debugging information is deprecated, not forbidden,
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and in practice it works, although some tools that parse PE files
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expecting the MS standard format may become confused; <samp>PEview</samp> is
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one known example.
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</p>
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<p>The functionality is supported in BFD by code implemented under
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the control of the macro <code>COFF_LONG_SECTION_NAMES</code>. If not
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defined, the format does not support long section names in any way.
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If defined, it is used to initialise a flag,
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<code>_bfd_coff_long_section_names</code>, and a hook function pointer,
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<code>_bfd_coff_set_long_section_names</code>, in the Coff backend data
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structure. The flag controls the generation of long section names
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in output BFDs at runtime; if it is false, as it will be by default
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when generating an executable image, long section names are truncated;
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if true, the long section names extension is employed. The hook
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points to a function that allows the value of the flag to be altered
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at runtime, on formats that support long section names at all; on
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other formats it points to a stub that returns an error indication.
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</p>
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<p>With input BFDs, the flag is set according to whether any long section
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names are detected while reading the section headers. For a completely
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new BFD, the flag is set to the default for the target format. This
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information can be used by a client of the BFD library when deciding
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what output format to generate, and means that a BFD that is opened
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for read and subsequently converted to a writeable BFD and modified
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in-place will retain whatever format it had on input.
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</p>
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<p>If <code>COFF_LONG_SECTION_NAMES</code> is simply defined (blank), or is
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defined to the value "1", then long section names are enabled by
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default; if it is defined to the value zero, they are disabled by
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default (but still accepted in input BFDs). The header <samp>coffcode.h</samp>
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defines a macro, <code>COFF_DEFAULT_LONG_SECTION_NAMES</code>, which is
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used in the backends to initialise the backend data structure fields
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appropriately; see the comments for further detail.
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</p>
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<a name="Bit-twiddling"></a>
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<h4 class="subsubsection">3.3.2.3 Bit twiddling</h4>
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<p>Each flavour of coff supported in BFD has its own header file
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describing the external layout of the structures. There is also
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an internal description of the coff layout, in
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<samp>coff/internal.h</samp>. A major function of the
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coff backend is swapping the bytes and twiddling the bits to
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translate the external form of the structures into the normal
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internal form. This is all performed in the
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<code>bfd_swap</code>_<i>thing</i>_<i>direction</i> routines. Some
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elements are different sizes between different versions of
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coff; it is the duty of the coff version specific include file
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to override the definitions of various packing routines in
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<samp>coffcode.h</samp>. E.g., the size of line number entry in coff is
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sometimes 16 bits, and sometimes 32 bits. <code>#define</code>ing
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<code>PUT_LNSZ_LNNO</code> and <code>GET_LNSZ_LNNO</code> will select the
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correct one. No doubt, some day someone will find a version of
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coff which has a varying field size not catered to at the
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moment. To port BFD, that person will have to add more <code>#defines</code>.
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Three of the bit twiddling routines are exported to
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<code>gdb</code>; <code>coff_swap_aux_in</code>, <code>coff_swap_sym_in</code>
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and <code>coff_swap_lineno_in</code>. <code>GDB</code> reads the symbol
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table on its own, but uses BFD to fix things up. More of the
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bit twiddlers are exported for <code>gas</code>;
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<code>coff_swap_aux_out</code>, <code>coff_swap_sym_out</code>,
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<code>coff_swap_lineno_out</code>, <code>coff_swap_reloc_out</code>,
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<code>coff_swap_filehdr_out</code>, <code>coff_swap_aouthdr_out</code>,
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<code>coff_swap_scnhdr_out</code>. <code>Gas</code> currently keeps track
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of all the symbol table and reloc drudgery itself, thereby
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saving the internal BFD overhead, but uses BFD to swap things
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on the way out, making cross ports much safer. Doing so also
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allows BFD (and thus the linker) to use the same header files
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as <code>gas</code>, which makes one avenue to disaster disappear.
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</p>
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<a name="Symbol-reading"></a>
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<h4 class="subsubsection">3.3.2.4 Symbol reading</h4>
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<p>The simple canonical form for symbols used by BFD is not rich
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enough to keep all the information available in a coff symbol
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table. The back end gets around this problem by keeping the original
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symbol table around, "behind the scenes".
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</p>
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<p>When a symbol table is requested (through a call to
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<code>bfd_canonicalize_symtab</code>), a request gets through to
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<code>coff_get_normalized_symtab</code>. This reads the symbol table from
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the coff file and swaps all the structures inside into the
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internal form. It also fixes up all the pointers in the table
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(represented in the file by offsets from the first symbol in
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the table) into physical pointers to elements in the new
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internal table. This involves some work since the meanings of
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fields change depending upon context: a field that is a
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pointer to another structure in the symbol table at one moment
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may be the size in bytes of a structure at the next. Another
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pass is made over the table. All symbols which mark file names
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(<code>C_FILE</code> symbols) are modified so that the internal
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string points to the value in the auxent (the real filename)
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rather than the normal text associated with the symbol
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(<code>".file"</code>).
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</p>
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<p>At this time the symbol names are moved around. Coff stores
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all symbols less than nine characters long physically
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within the symbol table; longer strings are kept at the end of
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the file in the string table. This pass moves all strings
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into memory and replaces them with pointers to the strings.
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</p>
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<p>The symbol table is massaged once again, this time to create
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the canonical table used by the BFD application. Each symbol
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is inspected in turn, and a decision made (using the
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<code>sclass</code> field) about the various flags to set in the
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<code>asymbol</code>. See <a href="Symbols.html#Symbols">Symbols</a>. The generated canonical table
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shares strings with the hidden internal symbol table.
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</p>
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<p>Any linenumbers are read from the coff file too, and attached
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to the symbols which own the functions the linenumbers belong to.
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</p>
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<a name="Symbol-writing"></a>
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<h4 class="subsubsection">3.3.2.5 Symbol writing</h4>
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<p>Writing a symbol to a coff file which didn’t come from a coff
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file will lose any debugging information. The <code>asymbol</code>
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structure remembers the BFD from which the symbol was taken, and on
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output the back end makes sure that the same destination target as
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source target is present.
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</p>
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<p>When the symbols have come from a coff file then all the
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debugging information is preserved.
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</p>
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<p>Symbol tables are provided for writing to the back end in a
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vector of pointers to pointers. This allows applications like
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the linker to accumulate and output large symbol tables
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without having to do too much byte copying.
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</p>
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<p>This function runs through the provided symbol table and
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patches each symbol marked as a file place holder
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(<code>C_FILE</code>) to point to the next file place holder in the
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list. It also marks each <code>offset</code> field in the list with
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the offset from the first symbol of the current symbol.
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</p>
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<p>Another function of this procedure is to turn the canonical
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value form of BFD into the form used by coff. Internally, BFD
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expects symbol values to be offsets from a section base; so a
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symbol physically at 0x120, but in a section starting at
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0x100, would have the value 0x20. Coff expects symbols to
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contain their final value, so symbols have their values
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changed at this point to reflect their sum with their owning
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section. This transformation uses the
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<code>output_section</code> field of the <code>asymbol</code>’s
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<code>asection</code> See <a href="Sections.html#Sections">Sections</a>.
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</p>
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<ul>
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<li> <code>coff_mangle_symbols</code>
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</li></ul>
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<p>This routine runs though the provided symbol table and uses
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the offsets generated by the previous pass and the pointers
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generated when the symbol table was read in to create the
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structured hierarchy required by coff. It changes each pointer
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to a symbol into the index into the symbol table of the asymbol.
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</p>
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<ul>
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<li> <code>coff_write_symbols</code>
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</li></ul>
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<p>This routine runs through the symbol table and patches up the
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symbols from their internal form into the coff way, calls the
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bit twiddlers, and writes out the table to the file.
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</p>
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<a name="index-coff_005fsymbol_005ftype"></a>
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<a name="coff_005fsymbol_005ftype"></a>
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<h4 class="subsubsection">3.3.2.6 <code>coff_symbol_type</code></h4>
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<p><strong>Description</strong><br>
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The hidden information for an <code>asymbol</code> is described in a
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<code>combined_entry_type</code>:
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</p>
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<div class="example">
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<pre class="example">
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typedef struct coff_ptr_struct
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{
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/* Remembers the offset from the first symbol in the file for
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this symbol. Generated by coff_renumber_symbols. */
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unsigned int offset;
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/* Should the value of this symbol be renumbered. Used for
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XCOFF C_BSTAT symbols. Set by coff_slurp_symbol_table. */
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unsigned int fix_value : 1;
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/* Should the tag field of this symbol be renumbered.
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Created by coff_pointerize_aux. */
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unsigned int fix_tag : 1;
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/* Should the endidx field of this symbol be renumbered.
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Created by coff_pointerize_aux. */
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unsigned int fix_end : 1;
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/* Should the x_csect.x_scnlen field be renumbered.
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Created by coff_pointerize_aux. */
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unsigned int fix_scnlen : 1;
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/* Fix up an XCOFF C_BINCL/C_EINCL symbol. The value is the
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index into the line number entries. Set by coff_slurp_symbol_table. */
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unsigned int fix_line : 1;
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/* The container for the symbol structure as read and translated
|
|
from the file. */
|
|
union
|
|
{
|
|
union internal_auxent auxent;
|
|
struct internal_syment syment;
|
|
} u;
|
|
|
|
/* Selector for the union above. */
|
|
bfd_boolean is_sym;
|
|
} combined_entry_type;
|
|
|
|
|
|
/* Each canonical asymbol really looks like this: */
|
|
|
|
typedef struct coff_symbol_struct
|
|
{
|
|
/* The actual symbol which the rest of BFD works with */
|
|
asymbol symbol;
|
|
|
|
/* A pointer to the hidden information for this symbol */
|
|
combined_entry_type *native;
|
|
|
|
/* A pointer to the linenumber information for this symbol */
|
|
struct lineno_cache_entry *lineno;
|
|
|
|
/* Have the line numbers been relocated yet ? */
|
|
bfd_boolean done_lineno;
|
|
} coff_symbol_type;
|
|
</pre></div>
|
|
<a name="index-bfd_005fcoff_005fbackend_005fdata"></a>
|
|
<a name="bfd_005fcoff_005fbackend_005fdata"></a>
|
|
<h4 class="subsubsection">3.3.2.7 <code>bfd_coff_backend_data</code></h4>
|
|
|
|
<div class="example">
|
|
<pre class="example">/* COFF symbol classifications. */
|
|
|
|
enum coff_symbol_classification
|
|
{
|
|
/* Global symbol. */
|
|
COFF_SYMBOL_GLOBAL,
|
|
/* Common symbol. */
|
|
COFF_SYMBOL_COMMON,
|
|
/* Undefined symbol. */
|
|
COFF_SYMBOL_UNDEFINED,
|
|
/* Local symbol. */
|
|
COFF_SYMBOL_LOCAL,
|
|
/* PE section symbol. */
|
|
COFF_SYMBOL_PE_SECTION
|
|
};
|
|
|
|
typedef asection * (*coff_gc_mark_hook_fn)
|
|
(asection *, struct bfd_link_info *, struct internal_reloc *,
|
|
struct coff_link_hash_entry *, struct internal_syment *);
|
|
|
|
</pre></div>
|
|
<p>Special entry points for gdb to swap in coff symbol table parts:
|
|
</p><div class="example">
|
|
<pre class="example">typedef struct
|
|
{
|
|
void (*_bfd_coff_swap_aux_in)
|
|
(bfd *, void *, int, int, int, int, void *);
|
|
|
|
void (*_bfd_coff_swap_sym_in)
|
|
(bfd *, void *, void *);
|
|
|
|
void (*_bfd_coff_swap_lineno_in)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_aux_out)
|
|
(bfd *, void *, int, int, int, int, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_sym_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_lineno_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_reloc_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_filehdr_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_aouthdr_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int (*_bfd_coff_swap_scnhdr_out)
|
|
(bfd *, void *, void *);
|
|
|
|
unsigned int _bfd_filhsz;
|
|
unsigned int _bfd_aoutsz;
|
|
unsigned int _bfd_scnhsz;
|
|
unsigned int _bfd_symesz;
|
|
unsigned int _bfd_auxesz;
|
|
unsigned int _bfd_relsz;
|
|
unsigned int _bfd_linesz;
|
|
unsigned int _bfd_filnmlen;
|
|
bfd_boolean _bfd_coff_long_filenames;
|
|
|
|
bfd_boolean _bfd_coff_long_section_names;
|
|
bfd_boolean (*_bfd_coff_set_long_section_names)
|
|
(bfd *, int);
|
|
|
|
unsigned int _bfd_coff_default_section_alignment_power;
|
|
bfd_boolean _bfd_coff_force_symnames_in_strings;
|
|
unsigned int _bfd_coff_debug_string_prefix_length;
|
|
unsigned int _bfd_coff_max_nscns;
|
|
|
|
void (*_bfd_coff_swap_filehdr_in)
|
|
(bfd *, void *, void *);
|
|
|
|
void (*_bfd_coff_swap_aouthdr_in)
|
|
(bfd *, void *, void *);
|
|
|
|
void (*_bfd_coff_swap_scnhdr_in)
|
|
(bfd *, void *, void *);
|
|
|
|
void (*_bfd_coff_swap_reloc_in)
|
|
(bfd *abfd, void *, void *);
|
|
|
|
bfd_boolean (*_bfd_coff_bad_format_hook)
|
|
(bfd *, void *);
|
|
|
|
bfd_boolean (*_bfd_coff_set_arch_mach_hook)
|
|
(bfd *, void *);
|
|
|
|
void * (*_bfd_coff_mkobject_hook)
|
|
(bfd *, void *, void *);
|
|
|
|
bfd_boolean (*_bfd_styp_to_sec_flags_hook)
|
|
(bfd *, void *, const char *, asection *, flagword *);
|
|
|
|
void (*_bfd_set_alignment_hook)
|
|
(bfd *, asection *, void *);
|
|
|
|
bfd_boolean (*_bfd_coff_slurp_symbol_table)
|
|
(bfd *);
|
|
|
|
bfd_boolean (*_bfd_coff_symname_in_debug)
|
|
(bfd *, struct internal_syment *);
|
|
|
|
bfd_boolean (*_bfd_coff_pointerize_aux_hook)
|
|
(bfd *, combined_entry_type *, combined_entry_type *,
|
|
unsigned int, combined_entry_type *);
|
|
|
|
bfd_boolean (*_bfd_coff_print_aux)
|
|
(bfd *, FILE *, combined_entry_type *, combined_entry_type *,
|
|
combined_entry_type *, unsigned int);
|
|
|
|
void (*_bfd_coff_reloc16_extra_cases)
|
|
(bfd *, struct bfd_link_info *, struct bfd_link_order *, arelent *,
|
|
bfd_byte *, unsigned int *, unsigned int *);
|
|
|
|
int (*_bfd_coff_reloc16_estimate)
|
|
(bfd *, asection *, arelent *, unsigned int,
|
|
struct bfd_link_info *);
|
|
|
|
enum coff_symbol_classification (*_bfd_coff_classify_symbol)
|
|
(bfd *, struct internal_syment *);
|
|
|
|
bfd_boolean (*_bfd_coff_compute_section_file_positions)
|
|
(bfd *);
|
|
|
|
bfd_boolean (*_bfd_coff_start_final_link)
|
|
(bfd *, struct bfd_link_info *);
|
|
|
|
bfd_boolean (*_bfd_coff_relocate_section)
|
|
(bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
|
|
struct internal_reloc *, struct internal_syment *, asection **);
|
|
|
|
reloc_howto_type *(*_bfd_coff_rtype_to_howto)
|
|
(bfd *, asection *, struct internal_reloc *,
|
|
struct coff_link_hash_entry *, struct internal_syment *,
|
|
bfd_vma *);
|
|
|
|
bfd_boolean (*_bfd_coff_adjust_symndx)
|
|
(bfd *, struct bfd_link_info *, bfd *, asection *,
|
|
struct internal_reloc *, bfd_boolean *);
|
|
|
|
bfd_boolean (*_bfd_coff_link_add_one_symbol)
|
|
(struct bfd_link_info *, bfd *, const char *, flagword,
|
|
asection *, bfd_vma, const char *, bfd_boolean, bfd_boolean,
|
|
struct bfd_link_hash_entry **);
|
|
|
|
bfd_boolean (*_bfd_coff_link_output_has_begun)
|
|
(bfd *, struct coff_final_link_info *);
|
|
|
|
bfd_boolean (*_bfd_coff_final_link_postscript)
|
|
(bfd *, struct coff_final_link_info *);
|
|
|
|
bfd_boolean (*_bfd_coff_print_pdata)
|
|
(bfd *, void *);
|
|
|
|
} bfd_coff_backend_data;
|
|
|
|
#define coff_backend_info(abfd) \
|
|
((bfd_coff_backend_data *) (abfd)->xvec->backend_data)
|
|
|
|
#define bfd_coff_swap_aux_in(a,e,t,c,ind,num,i) \
|
|
((coff_backend_info (a)->_bfd_coff_swap_aux_in) (a,e,t,c,ind,num,i))
|
|
|
|
#define bfd_coff_swap_sym_in(a,e,i) \
|
|
((coff_backend_info (a)->_bfd_coff_swap_sym_in) (a,e,i))
|
|
|
|
#define bfd_coff_swap_lineno_in(a,e,i) \
|
|
((coff_backend_info ( a)->_bfd_coff_swap_lineno_in) (a,e,i))
|
|
|
|
#define bfd_coff_swap_reloc_out(abfd, i, o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_reloc_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_lineno_out(abfd, i, o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_lineno_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_aux_out(a,i,t,c,ind,num,o) \
|
|
((coff_backend_info (a)->_bfd_coff_swap_aux_out) (a,i,t,c,ind,num,o))
|
|
|
|
#define bfd_coff_swap_sym_out(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_sym_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_scnhdr_out(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_scnhdr_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_filehdr_out(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_aouthdr_out(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_aouthdr_out) (abfd, i, o))
|
|
|
|
#define bfd_coff_filhsz(abfd) (coff_backend_info (abfd)->_bfd_filhsz)
|
|
#define bfd_coff_aoutsz(abfd) (coff_backend_info (abfd)->_bfd_aoutsz)
|
|
#define bfd_coff_scnhsz(abfd) (coff_backend_info (abfd)->_bfd_scnhsz)
|
|
#define bfd_coff_symesz(abfd) (coff_backend_info (abfd)->_bfd_symesz)
|
|
#define bfd_coff_auxesz(abfd) (coff_backend_info (abfd)->_bfd_auxesz)
|
|
#define bfd_coff_relsz(abfd) (coff_backend_info (abfd)->_bfd_relsz)
|
|
#define bfd_coff_linesz(abfd) (coff_backend_info (abfd)->_bfd_linesz)
|
|
#define bfd_coff_filnmlen(abfd) (coff_backend_info (abfd)->_bfd_filnmlen)
|
|
#define bfd_coff_long_filenames(abfd) \
|
|
(coff_backend_info (abfd)->_bfd_coff_long_filenames)
|
|
#define bfd_coff_long_section_names(abfd) \
|
|
(coff_backend_info (abfd)->_bfd_coff_long_section_names)
|
|
#define bfd_coff_set_long_section_names(abfd, enable) \
|
|
((coff_backend_info (abfd)->_bfd_coff_set_long_section_names) (abfd, enable))
|
|
#define bfd_coff_default_section_alignment_power(abfd) \
|
|
(coff_backend_info (abfd)->_bfd_coff_default_section_alignment_power)
|
|
#define bfd_coff_max_nscns(abfd) \
|
|
(coff_backend_info (abfd)->_bfd_coff_max_nscns)
|
|
|
|
#define bfd_coff_swap_filehdr_in(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_in) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_aouthdr_in(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_aouthdr_in) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_scnhdr_in(abfd, i,o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_scnhdr_in) (abfd, i, o))
|
|
|
|
#define bfd_coff_swap_reloc_in(abfd, i, o) \
|
|
((coff_backend_info (abfd)->_bfd_coff_swap_reloc_in) (abfd, i, o))
|
|
|
|
#define bfd_coff_bad_format_hook(abfd, filehdr) \
|
|
((coff_backend_info (abfd)->_bfd_coff_bad_format_hook) (abfd, filehdr))
|
|
|
|
#define bfd_coff_set_arch_mach_hook(abfd, filehdr)\
|
|
((coff_backend_info (abfd)->_bfd_coff_set_arch_mach_hook) (abfd, filehdr))
|
|
#define bfd_coff_mkobject_hook(abfd, filehdr, aouthdr)\
|
|
((coff_backend_info (abfd)->_bfd_coff_mkobject_hook)\
|
|
(abfd, filehdr, aouthdr))
|
|
|
|
#define bfd_coff_styp_to_sec_flags_hook(abfd, scnhdr, name, section, flags_ptr)\
|
|
((coff_backend_info (abfd)->_bfd_styp_to_sec_flags_hook)\
|
|
(abfd, scnhdr, name, section, flags_ptr))
|
|
|
|
#define bfd_coff_set_alignment_hook(abfd, sec, scnhdr)\
|
|
((coff_backend_info (abfd)->_bfd_set_alignment_hook) (abfd, sec, scnhdr))
|
|
|
|
#define bfd_coff_slurp_symbol_table(abfd)\
|
|
((coff_backend_info (abfd)->_bfd_coff_slurp_symbol_table) (abfd))
|
|
|
|
#define bfd_coff_symname_in_debug(abfd, sym)\
|
|
((coff_backend_info (abfd)->_bfd_coff_symname_in_debug) (abfd, sym))
|
|
|
|
#define bfd_coff_force_symnames_in_strings(abfd)\
|
|
(coff_backend_info (abfd)->_bfd_coff_force_symnames_in_strings)
|
|
|
|
#define bfd_coff_debug_string_prefix_length(abfd)\
|
|
(coff_backend_info (abfd)->_bfd_coff_debug_string_prefix_length)
|
|
|
|
#define bfd_coff_print_aux(abfd, file, base, symbol, aux, indaux)\
|
|
((coff_backend_info (abfd)->_bfd_coff_print_aux)\
|
|
(abfd, file, base, symbol, aux, indaux))
|
|
|
|
#define bfd_coff_reloc16_extra_cases(abfd, link_info, link_order,\
|
|
reloc, data, src_ptr, dst_ptr)\
|
|
((coff_backend_info (abfd)->_bfd_coff_reloc16_extra_cases)\
|
|
(abfd, link_info, link_order, reloc, data, src_ptr, dst_ptr))
|
|
|
|
#define bfd_coff_reloc16_estimate(abfd, section, reloc, shrink, link_info)\
|
|
((coff_backend_info (abfd)->_bfd_coff_reloc16_estimate)\
|
|
(abfd, section, reloc, shrink, link_info))
|
|
|
|
#define bfd_coff_classify_symbol(abfd, sym)\
|
|
((coff_backend_info (abfd)->_bfd_coff_classify_symbol)\
|
|
(abfd, sym))
|
|
|
|
#define bfd_coff_compute_section_file_positions(abfd)\
|
|
((coff_backend_info (abfd)->_bfd_coff_compute_section_file_positions)\
|
|
(abfd))
|
|
|
|
#define bfd_coff_start_final_link(obfd, info)\
|
|
((coff_backend_info (obfd)->_bfd_coff_start_final_link)\
|
|
(obfd, info))
|
|
#define bfd_coff_relocate_section(obfd,info,ibfd,o,con,rel,isyms,secs)\
|
|
((coff_backend_info (ibfd)->_bfd_coff_relocate_section)\
|
|
(obfd, info, ibfd, o, con, rel, isyms, secs))
|
|
#define bfd_coff_rtype_to_howto(abfd, sec, rel, h, sym, addendp)\
|
|
((coff_backend_info (abfd)->_bfd_coff_rtype_to_howto)\
|
|
(abfd, sec, rel, h, sym, addendp))
|
|
#define bfd_coff_adjust_symndx(obfd, info, ibfd, sec, rel, adjustedp)\
|
|
((coff_backend_info (abfd)->_bfd_coff_adjust_symndx)\
|
|
(obfd, info, ibfd, sec, rel, adjustedp))
|
|
#define bfd_coff_link_add_one_symbol(info, abfd, name, flags, section,\
|
|
value, string, cp, coll, hashp)\
|
|
((coff_backend_info (abfd)->_bfd_coff_link_add_one_symbol)\
|
|
(info, abfd, name, flags, section, value, string, cp, coll, hashp))
|
|
|
|
#define bfd_coff_link_output_has_begun(a,p) \
|
|
((coff_backend_info (a)->_bfd_coff_link_output_has_begun) (a, p))
|
|
#define bfd_coff_final_link_postscript(a,p) \
|
|
((coff_backend_info (a)->_bfd_coff_final_link_postscript) (a, p))
|
|
|
|
#define bfd_coff_have_print_pdata(a) \
|
|
(coff_backend_info (a)->_bfd_coff_print_pdata)
|
|
#define bfd_coff_print_pdata(a,p) \
|
|
((coff_backend_info (a)->_bfd_coff_print_pdata) (a, p))
|
|
|
|
/* Macro: Returns true if the bfd is a PE executable as opposed to a
|
|
PE object file. */
|
|
#define bfd_pei_p(abfd) \
|
|
(CONST_STRNEQ ((abfd)->xvec->name, "pei-"))
|
|
</pre></div>
|
|
<a name="Writing-relocations"></a>
|
|
<h4 class="subsubsection">3.3.2.8 Writing relocations</h4>
|
|
<p>To write relocations, the back end steps though the
|
|
canonical relocation table and create an
|
|
<code>internal_reloc</code>. The symbol index to use is removed from
|
|
the <code>offset</code> field in the symbol table supplied. The
|
|
address comes directly from the sum of the section base
|
|
address and the relocation offset; the type is dug directly
|
|
from the howto field. Then the <code>internal_reloc</code> is
|
|
swapped into the shape of an <code>external_reloc</code> and written
|
|
out to disk.
|
|
</p>
|
|
<a name="Reading-linenumbers"></a>
|
|
<h4 class="subsubsection">3.3.2.9 Reading linenumbers</h4>
|
|
<p>Creating the linenumber table is done by reading in the entire
|
|
coff linenumber table, and creating another table for internal use.
|
|
</p>
|
|
<p>A coff linenumber table is structured so that each function
|
|
is marked as having a line number of 0. Each line within the
|
|
function is an offset from the first line in the function. The
|
|
base of the line number information for the table is stored in
|
|
the symbol associated with the function.
|
|
</p>
|
|
<p>Note: The PE format uses line number 0 for a flag indicating a
|
|
new source file.
|
|
</p>
|
|
<p>The information is copied from the external to the internal
|
|
table, and each symbol which marks a function is marked by
|
|
pointing its...
|
|
</p>
|
|
<p>How does this work ?
|
|
</p>
|
|
<a name="Reading-relocations"></a>
|
|
<h4 class="subsubsection">3.3.2.10 Reading relocations</h4>
|
|
<p>Coff relocations are easily transformed into the internal BFD form
|
|
(<code>arelent</code>).
|
|
</p>
|
|
<p>Reading a coff relocation table is done in the following stages:
|
|
</p>
|
|
<ul>
|
|
<li> Read the entire coff relocation table into memory.
|
|
|
|
</li><li> Process each relocation in turn; first swap it from the
|
|
external to the internal form.
|
|
|
|
</li><li> Turn the symbol referenced in the relocation’s symbol index
|
|
into a pointer into the canonical symbol table.
|
|
This table is the same as the one returned by a call to
|
|
<code>bfd_canonicalize_symtab</code>. The back end will call that
|
|
routine and save the result if a canonicalization hasn’t been done.
|
|
|
|
</li><li> The reloc index is turned into a pointer to a howto
|
|
structure, in a back end specific way. For instance, the 386
|
|
and 960 use the <code>r_type</code> to directly produce an index
|
|
into a howto table vector; the 88k subtracts a number from the
|
|
<code>r_type</code> field and creates an addend field.
|
|
</li></ul>
|
|
|
|
|
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<hr>
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