1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2021 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with the 8Invariant Sections being "Free Software" and "Free Software Needs 9Free Documentation", with the Front-Cover Texts being "A GNU Manual," 10and with the Back-Cover Texts as in (a) below. 11 12(a) The FSF's Back-Cover Text is: "You are free to copy and modify 13this GNU Manual. 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This ABI is described in <samp>jit-reader.h</samp>. 76</p> 77<p><samp>jit-reader.h</samp> defines the structures, macros and functions 78required to write a reader. It is installed (along with 79<small>GDB</small>), in <samp><var>includedir</var>/gdb</samp> where <var>includedir</var> is 80the system include directory. 81</p> 82<p>Readers need to be released under a GPL compatible license. A reader 83can be declared as released under such a license by placing the macro 84<code>GDB_DECLARE_GPL_COMPATIBLE_READER</code> in a source file. 85</p> 86<p>The entry point for readers is the symbol <code>gdb_init_reader</code>, 87which is expected to be a function with the prototype 88</p> 89<a name="index-gdb_005finit_005freader"></a> 90<div class="smallexample"> 91<pre class="smallexample">extern struct gdb_reader_funcs *gdb_init_reader (void); 92</pre></div> 93 94<a name="index-struct-gdb_005freader_005ffuncs"></a> 95 96<p><code>struct gdb_reader_funcs</code> contains a set of pointers to callback 97functions. These functions are executed to read the debug info 98generated by the JIT compiler (<code>read</code>), to unwind stack frames 99(<code>unwind</code>) and to create canonical frame IDs 100(<code>get_frame_id</code>). It also has a callback that is called when the 101reader is being unloaded (<code>destroy</code>). The struct looks like this 102</p> 103<div class="smallexample"> 104<pre class="smallexample">struct gdb_reader_funcs 105{ 106 /* Must be set to GDB_READER_INTERFACE_VERSION. */ 107 int reader_version; 108 109 /* For use by the reader. */ 110 void *priv_data; 111 112 gdb_read_debug_info *read; 113 gdb_unwind_frame *unwind; 114 gdb_get_frame_id *get_frame_id; 115 gdb_destroy_reader *destroy; 116}; 117</pre></div> 118 119<a name="index-struct-gdb_005fsymbol_005fcallbacks"></a> 120<a name="index-struct-gdb_005funwind_005fcallbacks"></a> 121 122<p>The callbacks are provided with another set of callbacks by 123<small>GDB</small> to do their job. For <code>read</code>, these callbacks are 124passed in a <code>struct gdb_symbol_callbacks</code> and for <code>unwind</code> 125and <code>get_frame_id</code>, in a <code>struct gdb_unwind_callbacks</code>. 126<code>struct gdb_symbol_callbacks</code> has callbacks to create new object 127files and new symbol tables inside those object files. <code>struct 128gdb_unwind_callbacks</code> has callbacks to read registers off the current 129frame and to write out the values of the registers in the previous 130frame. Both have a callback (<code>target_read</code>) to read bytes off the 131target’s address space. 132</p> 133<hr> 134<div class="header"> 135<p> 136Previous: <a href="Using-JIT-Debug-Info-Readers.html#Using-JIT-Debug-Info-Readers" accesskey="p" rel="previous">Using JIT Debug Info Readers</a>, Up: <a href="Custom-Debug-Info.html#Custom-Debug-Info" accesskey="u" rel="up">Custom Debug Info</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> 137</div> 138 139 140 141</body> 142</html> 143