linux-toradex.git/Documentation/livepatch, branch v5.17-rc4

Documentation: livepatch: Add livepatch API page

2021-12-23T10:35:53+00:00

The livepatch subsystem has several exported functions and objects with
kerneldoc comments. Though the livepatch documentation contains handwritten
descriptions of all of these exported functions, they are currently not
pulled into the docs build using the kernel-doc directive.

In order to allow readers of the documentation to see the full kerneldoc
comments in the generated documentation files, this change adds a new
Documentation/livepatch/api.rst page which contains kernel-doc directives
to link the kerneldoc comments directly in the documentation.  With this,
all of the hand-written descriptions of the APIs now cross-reference the
kerneldoc comments on the new Livepatching APIs page, and running
./scripts/find-unused-docs.sh on kernel/livepatch no longer shows any files
as missing documentation.

Note that all of the handwritten API descriptions were left alone with the
exception of Documentation/livepatch/system-state.rst, which was updated to
allow the cross-referencing to work correctly. The file now follows the
cross-referencing formatting guidance specified in
Documentation/doc-guide/kernel-doc.rst. Furthermore, some comments around
klp_shadow_free_all() were updated to say <_, id> rather than <*, id> to
match the rest of the file, and to prevent the docs build from emitting an
"Inline emphasis start-string without end string" error.

Signed-off-by: David Vernet 
Reviewed-by: Petr Mladek 
Acked-by: Miroslav Benes 
Signed-off-by: Petr Mladek 
Link: https://lore.kernel.org/r/20211221145743.4098360-1-void@manifault.com

docs: livepatch: Fix a typo and remove the unnecessary gaps in a sentence

2021-03-09T00:25:16+00:00

s/varibles/variables/

...and remove leading spaces from a sentence.

Signed-off-by: Bhaskar Chowdhury 
Acked-by: Joe Lawrence 
Acked-by: Petr Mladek 
Link: https://lore.kernel.org/r/20210305100923.3731-1-unixbhaskar@gmail.com
[jc: performed suggested prepositional tweak]
Signed-off-by: Jonathan Corbet

Documentation: livepatch: document reliable stacktrace

2021-01-26T10:50:00+00:00

Add documentation for reliable stacktrace. This is intended to describe
the semantics and to be an aid for implementing architecture support for
HAVE_RELIABLE_STACKTRACE.

Unwinding is a subtle area, and architectures vary greatly in both
implementation and the set of concerns that affect them, so I've tried
to avoid making this too specific to any given architecture. I've used
examples from both x86_64 and arm64 to explain corner cases in more
detail, but I've tried to keep the descriptions sufficient for those who
are unfamiliar with the particular architecture.

This document aims to give rationale for all the recommendations and
requirements, since that makes it easier to spot nearby issues, or when
a check happens to catch a few things at once.

Signed-off-by: Mark Rutland 
[Updates following review -- broonie]
Acked-by: Josh Poimboeuf 
Reviewed-by: Randy Dunlap 
Signed-off-by: Mark Brown 
Signed-off-by: Jiri Kosina

Documentation: livepatch: Convert to automatically generated contents

2021-01-26T10:50:00+00:00

Automatically generate the tables of contents for livepatch documentation
files that have tables of contents rather than open coding them so things
are a little easier to maintain.

Signed-off-by: Mark Brown 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: Remove .klp.arch

2020-05-07T22:12:42+00:00

After the previous patch, vmlinux-specific KLP relocations are now
applied early during KLP module load.  This means that .klp.arch
sections are no longer needed for *vmlinux-specific* KLP relocations.

One might think they're still needed for *module-specific* KLP
relocations.  If a to-be-patched module is loaded *after* its
corresponding KLP module is loaded, any corresponding KLP relocations
will be delayed until the to-be-patched module is loaded.  If any
special sections (.parainstructions, for example) rely on those
relocations, their initializations (apply_paravirt) need to be done
afterwards.  Thus the apparent need for arch_klp_init_object_loaded()
and its corresponding .klp.arch sections -- it allows some of the
special section initializations to be done at a later time.

But... if you look closer, that dependency between the special sections
and the module-specific KLP relocations doesn't actually exist in
reality.  Looking at the contents of the .altinstructions and
.parainstructions sections, there's not a realistic scenario in which a
KLP module's .altinstructions or .parainstructions section needs to
access a symbol in a to-be-patched module.  It might need to access a
local symbol or even a vmlinux symbol; but not another module's symbol.
When a special section needs to reference a local or vmlinux symbol, a
normal rela can be used instead of a KLP rela.

Since the special section initializations don't actually have any real
dependency on module-specific KLP relocations, .klp.arch and
arch_klp_init_object_loaded() no longer have a reason to exist.  So
remove them.

As Peter said much more succinctly:

  So the reason for .klp.arch was that .klp.rela.* stuff would overwrite
  paravirt instructions. If that happens you're doing it wrong. Those
  RELAs are core kernel, not module, and thus should've happened in
  .rela.* sections at patch-module loading time.

  Reverting this removes the two apply_{paravirt,alternatives}() calls
  from the late patching path, and means we don't have to worry about
  them when removing module_disable_ro().

[ jpoimboe: Rewrote patch description.  Tweaked klp_init_object_loaded()
	    error path. ]

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Josh Poimboeuf 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Joe Lawrence 
Acked-by: Miroslav Benes 
Signed-off-by: Jiri Kosina

livepatch: Documentation of the new API for tracking system state changes

2019-11-01T12:08:24+00:00

Documentation explaining the motivation, capabilities, and usage
of the new API for tracking system state changes.

Link: http://lkml.kernel.org/r/20191030154313.13263-5-pmladek@suse.com
To: Jiri Kosina 
Cc: Kamalesh Babulal 
Cc: Nicolai Stange 
Cc: live-patching@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Miroslav Benes 
Acked-by: Joe Lawrence 
Acked-by: Josh Poimboeuf 
Signed-off-by: Petr Mladek

docs: add some directories to the main documentation index

2019-07-15T14:03:03+00:00

The contents of those directories were orphaned at the documentation
body.

While those directories could likely be moved to be inside some guide,
I'm opting to just adding their indexes to the main one, removing the
:orphan: and adding the SPDX header.

For the drivers, the rationale is that the documentation contains
a mix of Kernelspace, uAPI and admin-guide. So, better to keep them on
separate directories, as we've be doing with similar subsystem-specific
docs that were not split yet.

For the others, well... I'm too lazy to do the move. Also, it
seems to make sense to keep at least some of those at the main
dir (like kbuild, for example). In any case, a latter patch
could do the move.

Signed-off-by: Mauro Carvalho Chehab 
Acked-by: Bartlomiej Zolnierkiewicz

docs/livepatch: Unify style of livepatch documentation in the ReST format

2019-05-07T22:06:28+00:00

Make the structure of "Livepatch module Elf format" document similar
to the main "Livepatch" document.

Also make the structure of "(Un)patching Callbacks" document similar
to the "Shadow Variables" document.

It fixes the most visible inconsistencies of the documentation
generated from the ReST format.

Signed-off-by: Petr Mladek 
Acked-by: Joe Lawrence 
Acked-by: Josh Poimboeuf 
Acked-by: Miroslav Benes 
Reviewed-by: Mauro Carvalho Chehab 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Jonathan Corbet

docs: livepatch: convert docs to ReST and rename to *.rst

2019-05-07T22:05:49+00:00

Convert livepatch documentation to ReST format. The changes
are mostly trivial, as the documents are already on a good
shape. Just a few markup changes are needed for Sphinx to
properly parse the docs.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - The in-file TOC becomes a comment, in order to skip it from the
    output, as Sphinx already generates an index there.
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Petr Mladek 
Acked-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Acked-by: Joe Lawrence 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Jonathan Corbet

livepatch: Remove signal sysfs attribute

2019-01-16T21:09:33+00:00

The fake signal is send automatically now. We can rely on it completely
and remove the sysfs attribute.

Signed-off-by: Miroslav Benes 
Signed-off-by: Jiri Kosina