livepatch/sample: Use the right type for the leaking data pointer

The "leak" pointer, in the sample of shadow variable API, is allocated
as sizeof(int). Let's help developers and static analyzers with
understanding the code by using the appropriate pointer type.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

livepatch: samples: non static warnings fix

Sparse reported warnings about non-static symbols. For the variables
a simple static attribute is fine - for the functions referenced by
livepatch via klp_func the symbol-names must be unmodified in the
symbol table and the patchable code has to be emitted. The resolution
is to attach __used attribute to the shared statically declared functions.

Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@osadl.org/
Suggested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

livepatch: check kzalloc return values

kzalloc() return should always be checked - notably in example code
where this may be seen as reference. On failure of allocation in
livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous
allocation is freed (thanks to Petr Mladek <pmladek@suse.com> for
catching this) and NULL returned.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API")
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

livepatch: introduce shadow variable API

Add exported API for livepatch modules:

klp_shadow_get()
klp_shadow_alloc()
klp_shadow_get_or_alloc()
klp_shadow_free()
klp_shadow_free_all()

that implement "shadow" variables, which allow callers to associate new
shadow fields to existing data structures. This is intended to be used
by livepatch modules seeking to emulate additions to data structure
definitions.

See Documentation/livepatch/shadow-vars.txt for a summary of the new
shadow variable API, including a few common use cases.

See samples/livepatch/livepatch-shadow-* for example modules that
demonstrate shadow variables.

[jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by
Josh]
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>