Messages in this thread | | | Subject | Re: [PATCH -tip v2 3/9] ftrace/x86: Support SAVE_REGS feature on i386 | From | Steven Rostedt <> | Date | Tue, 05 Jun 2012 19:37:50 -0400 |
| |
On Tue, 2012-06-05 at 17:24 -0400, Frank Ch. Eigler wrote: > Hi - > > On Tue, Jun 05, 2012 at 04:37:46PM -0400, Steven Rostedt wrote: > > [...] > > I'm not sure we really need to restore all the regs. I'll keep this for > > now, but for an optimization, we can just restore the ones that mcount > > mcount needs to. > > > > Or do you expect kprobes to change any of theses? > > That would be the way for a kprobe to modify variables/values that > happen to be in the registers. In systemtap, for example: > > # stap -g -e 'probe kernel.function("foo") { $bar = 1 }' >
And why would we want to allow this?
Modifying variables with probes is another way to lead to disaster. If the system did not intend for a variable to be a certain value, why let someone change it?
What real world example leads to external sources modifying internal core variables? With the obvious exception of rootkits.
-- Steve
| |