kpatch-build: use original vmlinux

There's at least one case in the kernel (ddebug_proc_show) where the
compiled instructions are affected by the source file path given to gcc.
Which means that compiling the kernel with O= will result in many of the
function addresses changing.  This causes a mismatch between the locally
compiled vmlinux and the original vmlinux, which is very dangerous,
since we need the addresses to be correct.

The easy fix is just to use the original vmlinux for all the function
addresses.

Other potential ways to fix it which we might want to consider in the
future:

- use a combination of the old System.map and the new vmlinux to find
  the addresses.  The function ordering should be the same.  For
  non-duplicate symbols, use System.map.  For duplicate symbols, use
  vmlinux to find what order the symbol comes in.  e.g. the 2nd
  occurrence of foo() in System.map.  It adds a little complexity to the
  lookup code, but seems safe and wouldn't require the kernel debuginfo
  package.  However, this may not help us for patching modules.

- do something similar at runtime, i.e. use kallsyms_lookup_name for
  non-dups and kallsyms_on_each_symbol for dups, and look for the nth
  occurrence of the symbol (value of n is decided at build time).  This
  has the complexity of the previous option but it's done at runtime
  rather than build time, so... why?  Doing it at build time is better.

- compile the kernel in place.  This basically means no more caching
  because recompiling with --function-sections causes everything to be
  recompiled again.  This is bad for kpatch developers' SSDs...
dracut: fix core module path

Forgot to update this file when moving the core module to the extras
subdirectory with a6694ffffff879b1255332e3b03e00b61630fa52.
cleanup: remove unneeded patches variable

Signed-off-by: Seth Jennings <sjenning@redhat.com>
fix included syms pointing to non-included sections

Right now, there is a case where a symbol is included but not its
section.  This is the case when the symbol is a rela dependency of
another section by the symbol section (the object or function) has not
changed.  When we migrate the included symbols over to the output kelf
structure however, these symbols are still referencing their old
non-included section via their sec fields.  This is a bug.

This commit adds code to the symbol migration to test whether the
symbol's section was also included.  If so, it updates the symbol's
section index.  If not it sets the section index to UNDEF and its sec
field to NULL.

Signed-off-by: Seth Jennings <sjenning@redhat.com>
merge add-patches-section functionality into create-obj-diff

In preparation for dynamic symbol linking, the symbol lookup logic
is going to move into create-diff-obj anyway.  We might as well
minimize the code duplication and pull this into create-diff-obj.
This avoids having to re-parse the ELF file modify it in-place.

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

Conflicts:
	kpatch-build/kpatch-build
rename .patches section to .kpatch.patches

Adding .kpatch to the section name more clearly documents that these
are kpatch related sections.

Signed-off-by: Seth Jennings <sjenning@redhat.com>
dynrelas support, obsoleting link-vmlinux-syms

This adds dynamic linking support for the patch modules.  It is the
first step toward supporting patching module code and relocatable
kernels.

Rela entries that reference non-included local and non-exported global
symbols are converted to "dynrelas".  These dynrelas are relocations
that are done by the core module, not the kernel module linker.  This
allows the core module to apply offsets to the base addresses found
in the base vmlinux or module.

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

Conflicts:
	kpatch-build/kpatch-build
fix review comments

Signed-off-by: Seth Jennings <sjenning@redhat.com>
remove redundant rela buffer rebuild

We rebuild the rela section data buffer in kpatch_create_rela_section()
just to rebuild it again later in kpatch_rebuild_rela_section_data()
before writing the output ELF file.

This commit removes the redundant rebuild while retaining the update
for the section header data.

Signed-off-by: Seth Jennings <sjenning@redhat.com>
add teardown/free functions for kpatch_elf data structures

Because create-diff-object is a one-shot program (not a long lived
process) we haven't really bothered with cleaning up and freeing any
allocated memory.  However, freeing data when it passes out of the
logical scope does have debugging benefits.

This commit adds two new functions for tearing down and freeing the
primary struct kpatch_elf data structures.  The idea is the if a stale
pointer still references the old data structure that has passed out of
the logical scope, an issue will be more immediately apparent (i.e. NULL
references).

Signed-off-by: Seth Jennings <sjenning@redhat.com>
test: tell user to check test.log on error
kpatch: prevent installing a duplicate patch module
kpatch: uninstall should only look in user-installed dir
kpatch: get rid of system-installed modules

The user-installed vs system-installed dichotomy is confusing.  Let's
just have "installed".  RPM-installed modules can just call "kpatch
install" in their post-install step.
kpatch: change --kver to --kernel-version
kpatch-build: put cache in ~/.kpatch/src

Since we only ever have one cache at a time, move the kernel source from
~/.kpatch/$(uname -r)/src to ~/.kpatch/src.  This allows ccache to work
between kernel version changes, making it less painful to build for
multiple kernels.  The cache's kernel version is stored in
~/.kpatch/version.
delay element reindexing and symbol reordering

Right now, reindexing of the included sections and symbols is done
when they migrate to the output kpatch_elf structure.  However, due
to recently added features, the section and symbol list is not
final at this point, leading to constant tracking of the indexes for
addition sections and symbols added after this point.  Additionally,
symbols have to be in a particular order, adding to the complexity.

This commit delays the reindexing and symbol reordering until the
section and symbol lists are finalized, removing the need to
track indexes and placeholders in the symbol list.

Signed-off-by: Seth Jennings <sjenning@redhat.com>
kpatch: make kpatch load & unload work on more distros with less code ;-D
create-diff-object: fix symtab sh_info field

This fixes the weird ld errors we've been seeing lately.

According to the "ELF-64 Object File Format" spec, the symtab sh_info
field should contain "Index of first non-local symbol (i.e., number of
local symbols)".
fix symbol migration

kpatch_migrate_included_symbols() is called from
kpatch_reorder_symbols() now, not kpatch_migrate_included_elements().
The difference is the kpatch_reorder_symbols() is operating on the
output kpatch_elf structure, and thus all symbols are by definition
included.

Remove the check and rename the function since it is redundant.

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