add file documentation and copyright

Signed-off-by: Seth Jennings <sjenning@redhat.com>

scripts/kpatch-build

@@ -1,12 +1,17 @@
 #/bin/bash
 
-# kpatch build script
-#
+# kpatch build script for Fedora
+
 # This script takes a patch based on the version of the kernel
 # currently running and creates a kernel module that will
 # replace modified functions in the kernel such that the
 # patched code takes effect.
 
+# This script contains Fedora specific nuances and will probably
+# not work on other distributions; however, it does serve as a tutorial
+# on the various steps involved and should be adaptable to other
+# distributions.
+
 # This script:
 # - Installs the required yum/rpm tools
 # - Downloads the kernel src rpm for the currently running kernel

tools/add-patches-section.c

@@ -1,3 +1,21 @@
+/*
+ * tools/add-patches-section.c
+ *
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ *
+ * This tool takes an elf object, the output of create-diff-object
+ * and the base vmlinux as arguments and adds two new sections
+ * to the elf object; .patches and .rela.patches.
+ *
+ * These two sections allow the kpatch core modules to know which
+ * functions are overridden by the patch module.
+ *
+ * For each struct kpatch_patch entry in the .patches section, the core
+ * module will register the new function as an ftrace handler for the
+ * old function.  The new function will return to the caller of the old
+ * function, not the old function itself, bypassing the old function.
+ */
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>

tools/create-diff-object.c

@@ -1,3 +1,35 @@
+/*
+ * tools/create-diff-object.c
+ *
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ * Copyright (C) 2013 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
+ * This file contains the heart of the ELF object differencing engine.
+ *
+ * The tool takes two ELF objects from two versions of the same source
+ * file; a "base" object and a "patched" object.  These object need to have
+ * been compiled with the -ffunction-sections and -fdata-sections GCC options.
+ *
+ * The tool compares the objects at a section level to determine what
+ * sections have changed.  Once a list of changed sections has been generated,
+ * various rules are applied to determine any object local sections that
+ * are dependencies of the changed section and also need to be included in
+ * the output object.
+ *
+ * After all the sections for the output object have been selected, a
+ * reachability test is performed to ensure that every included section
+ * is reachable from a changed function symbol.  If there is a section that
+ * is not reachable from a changed function, this means that the source-level
+ * change can not be captured by employing ftrace and therefore can not be
+ * dynamically patched by kpatch.  Changes to static data structures are an
+ * example.
+ *
+ * If the reachability test succeeds
+ * - Changed text sections are copied into the output object
+ * - Changed rela sections have there symbol indexes fixed up
+ * - shstrtab, strtab, and symtab are all rebuilt from scratch
+ */
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>

tools/link-vmlinux-syms.c

@@ -1,3 +1,18 @@
+/*
+ * tools/link-vmlinux-syms.c
+ *
+ * Copyright (C) Seth Jennings <sjenning@redhat.com>
+ *
+ * This tools takes the nearly complete hotfix kernel module and
+ * the base vmlinux. It hardcodes the addresses of any global symbols
+ * that are referenced by the output object but are not exported by
+ * vmlinux into the symbol table of the kernel module.
+ *
+ * Global symbols that are exported by the base vmlinux can be
+ * resolved by the kernel module linker at load time and are
+ * left unmodified.
+ */
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>