Messages in this thread | | | Date | Fri, 21 Nov 2008 21:34:43 +0530 | From | Balbir Singh <> | Subject | Re: [RFC] kreplace: Rebootless kernel updates |
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Ananth N Mavinakayanahalli wrote: > On Fri, Nov 21, 2008 at 05:20:25PM +0530, Nikanth Karthikesan wrote: >> This RFC patch adds support for limited form of rebootless kernel patching >> even without building the entire kernel. >> >> When looking for a shortcut to avoid the rebuild/reboot cycle when hacking the >> kernel - the ksplice[1] was posted. This patch extends kprobes to do something >> similar, which would require even lesser time to _experiment_ with the running >> kernel. > > There have been other implementations of this feature, I am sure quite a > few people would have objections to having this as part of the kernel :-) >
I had a patch for x86 a long time ago in 2005, but I never posted it :(
>> This small patch extends jprobes so that the jprobe's handler is executed but >> skips executing the actual function. But this has its own limitations such as >> Cannot access symbols not exported for modules (ofcourse hacks like >> pointers[2] can be used.), problems related to return values[3], etc... This >> is currently a x86_64 only _hack_. > > There are many other issues too... How do you enforce correct usage of this > infrastrucutre? What prevents people from overriding core-kernel > functions with their own? >
Yes and we need to be careful about licensing, tainting the kernel with such an implementation.
> Kprobes themselves provide enough ammunition to users to shoot themselves > in the foot, but this is way more dangerous than that. > ... >
Undoubtedly, but a good warning is the best way to keep people warned about running such code :) It is a useful thing to have and to run, but running it would take more guts than anything else.
-- Balbir
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