user/sven/linux.git/Documentation/livepatch, branch v5.10.32

livepatch: Remove .klp.arch

2020-05-07T22:12:42Z

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

2019-11-01T12:08:24Z

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

2019-07-15T14:03:03Z

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

2019-05-07T22:06:28Z

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

2019-05-07T22:05:49Z

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

2019-01-16T21:09:33Z

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

livepatch: Send a fake signal periodically

2019-01-16T21:09:09Z

An administrator may send a fake signal to all remaining blocking tasks of a running transition by writing to /sys/kernel/livepatch//signal attribute. Let's do it automatically after 15 seconds. The timeout is chosen deliberately. It gives the tasks enough time to transition themselves. Theoretically, sending it once should be more than enough. However, every task must get outside of a patched function to be successfully transitioned. It could prove not to be simple and resending could be helpful in that case. A new workqueue job could be a cleaner solution to achieve it, but it could also introduce deadlocks and cause more headaches with synchronization and cancelling. [jkosina@suse.cz: removed added newline] Signed-off-by: Miroslav Benes Signed-off-by: Jiri Kosina

selftests/livepatch: introduce tests

2019-01-11T19:51:24Z

Add a few livepatch modules and simple target modules that the included regression suite can run tests against: - basic livepatching (multiple patches, atomic replace) - pre/post (un)patch callbacks - shadow variable API Signed-off-by: Joe Lawrence Signed-off-by: Petr Mladek Tested-by: Miroslav Benes Tested-by: Alice Ferrazzi Acked-by: Joe Lawrence Acked-by: Josh Poimboeuf Signed-off-by: Jiri Kosina

livepatch: Remove ordering (stacking) of the livepatches

2019-01-11T19:51:24Z

The atomic replace and cumulative patches were introduced as a more secure way to handle dependent patches. They simplify the logic: + Any new cumulative patch is supposed to take over shadow variables and changes made by callbacks from previous livepatches. + All replaced patches are discarded and the modules can be unloaded. As a result, there is only one scenario when a cumulative livepatch gets disabled. The different handling of "normal" and cumulative patches might cause confusion. It would make sense to keep only one mode. On the other hand, it would be rude to enforce using the cumulative livepatches even for trivial and independent (hot) fixes. However, the stack of patches is not really necessary any longer. The patch ordering was never clearly visible via the sysfs interface. Also the "normal" patches need a lot of caution anyway. Note that the list of enabled patches is still necessary but the ordering is not longer enforced. Otherwise, the code is ready to disable livepatches in an random order. Namely, klp_check_stack_func() always looks for the function from the livepatch that is being disabled. klp_func structures are just removed from the related func_stack. Finally, the ftrace handlers is removed only when the func_stack becomes empty. Signed-off-by: Petr Mladek Acked-by: Miroslav Benes Acked-by: Josh Poimboeuf Signed-off-by: Jiri Kosina

livepatch: Atomic replace and cumulative patches documentation

2019-01-11T19:51:24Z

User documentation for the atomic replace feature. It makes it easier to maintain livepatches using so-called cumulative patches. Signed-off-by: Petr Mladek Acked-by: Miroslav Benes Acked-by: Joe Lawrence Acked-by: Josh Poimboeuf Signed-off-by: Jiri Kosina