Toward Practical Dynamic Software Updating for C

Practical dynamic software updating for c

Related Info Overview Software systems are imperfect, so software updates are a fact of life. This command includes directives specifying when an update can occur, called when-conditions. The mechanism used to transform code and state influences what kinds of updates a system will support. Empirical analysis of cons-freeness and activeness safety by Hayden et all show that both techniques permit most correct updates and deny most erroneous updates.

To update a program with UpStare, a developer specifies a mapping between any possible stack frames. Marking this section as a transaction ensures that an update will not prevent the verification from occurring.

If the first version ofIn a redundant environment spare

Binary rewriting is the process of writing low-level code into the memory image of a running native program to re-direct functions. To update functions, it rewrites the prelude to a target function to redirect to a new function, chaining these redirections over multiple versions. This proves safety because control can never return to old code that would access new representations of data. They both allow function-level changes to be applied to a running Linux kernel, while relying on live patching mechanisms established by ftrace.

It is able toConsFreeness is another way to

This pattern can be generalized to updating. Our compiler performs a series of analyses that when combined with some simple runtime support ensure that an update will not violate type-safety while guaranteeing that data is kept up-to-date. Lazy transformation ensures that the update will complete in constant time, but also incurs steady-state overhead on object access.

Eager transformation incurs more expense at the time of update, requiring the system to stop the world while all transformers run. For example, Ksplice only supports code changes in functions, and does not support changes to state representation. The primary difference between kGraft and kpatch is the way they ensure runtime consistency of the updated code sections while hot patches are applied. This is referred to as state transformation.

The most common variant of safety checking is type safety, where an update is considered safe if it does not result in any new code operating on an old state representation, or vice versa. This is because Ksplice primarily targets security changes, rather than general updates.

In a redundant environment, spare systems exist ready to take control of active computations in the event of a failure of the main system. It is able to update unmodified programs at any point in their execution. Cons-Freeness is another way to prove type safety, where a section of code is considered safe if it does not access state of a given type in a way that requires knowledge of the type representation. We compile programs specially so that they can be dynamically patched, and generate most of a dynamic patch automatically. If the first version of the first function executed, an update occurred, and the new version of the second function was executed, then the verification would never be performed.

Practical Dynamic Software Updating for C

We compile programs