Red Hat Summit8.4. The process of live patching kernels
The kpatch kernel patching solution uses the livepatch kernel subsystem to redirect outdated functions to updated ones. Applying a live kernel patch to a system triggers the following processes:
-
The kernel patch module is copied to the
/var/lib/kpatch/directory and registered for re-application to the kernel bysystemdon next boot. -
The
kpatchmodule loads into the running kernel and the new functions are registered to theftracemechanism with a pointer to the location in memory of the new code.
When the kernel accesses the patched function, the ftrace mechanism redirects it, bypassing the original functions and leading the kernel to the patched version of the function.
図8.1 How kernel live patching works
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