> On May 20, 2024, at 14:46, Miroslav Benes <mbenes@xxxxxxx> wrote: > > Hi, > > On Mon, 20 May 2024, Wardenjohn wrote: > >> Livepatch module usually used to modify kernel functions. >> If the patched function have bug, it may cause serious result >> such as kernel crash. >> >> This is a kobject attribute of klp_func. Sysfs interface named >> "called" is introduced to livepatch which will be set as true >> if the patched function is called. >> >> /sys/kernel/livepatch/<patch>/<object>/<function,sympos>/called >> >> This value "called" is quite necessary for kernel stability >> assurance for livepatching module of a running system. >> Testing process is important before a livepatch module apply to >> a production system. With this interface, testing process can >> easily find out which function is successfully called. >> Any testing process can make sure they have successfully cover >> all the patched function that changed with the help of this interface. > > Even easier is to use the existing tracing infrastructure in the kernel > (ftrace for example) to track the new function. You can obtain much more > information with that than the new attribute provides. > > Regards, > Miroslav Hi Miroslav First, in most cases, testing process is should be automated, which make using existing tracing infrastructure inconvenient. Second, livepatch is already use ftrace for functional replacement, I don’t think it is a good choice of using kernel tracing tool to trace a patched function. At last, this attribute can be thought of as a state of a livepatch function. It is a state, like the "patched" "transition" state of a klp_patch. Adding this state will not break the state consistency of livepatch. Regards, Wardenjohn
