Hi, On 10.05.2018 13:14, Peter Zijlstra wrote: > On Thu, May 10, 2018 at 12:42:38PM +0300, Alexey Budankov wrote: >>> The Changelog needs to state that user_regs->bp is in fact valid and >> >> That actually was tested on binaries compiled without and with BP exposed >> and in the latter case proved the value of that change. > > Mostly works is not the same as 'always initialized', if there are entry > paths that do not store that register, then using the value might leak > values from the kernel stack, which would be bad.
Yep, absolutely agree. Extra care needs to be taken here. > > But like said, I think much of the kernel entry code was sanitized with > the PTI effort and I suspect things are in fact fine now, but lets wait > for Andy to confirm. > Thanks, Alexey
