Re: [v2, 2/2] powerpc/vdso: Avoid link stack corruption in __get_datapage()

2015-10-02 Thread Benjamin Herrenschmidt
On Fri, 2015-10-02 at 17:47 +1000, Michael Ellerman wrote: > On Fri, 2015-25-09 at 04:01:40 UTC, Michael Neuling wrote: > > powerpc has a link register (lr) used for calling functions. We "bl > > " to call a function, and "blr" to return back to the call > > site. > > >

Re: [v2, 2/2] powerpc/vdso: Avoid link stack corruption in __get_datapage()

2015-10-02 Thread Michael Ellerman
On Fri, 2015-25-09 at 04:01:40 UTC, Michael Neuling wrote: > powerpc has a link register (lr) used for calling functions. We "bl > " to call a function, and "blr" to return back to the call site. > For the benchmark in

[PATCH v2 2/2] powerpc/vdso: Avoid link stack corruption in __get_datapage()

2015-09-24 Thread Michael Neuling
powerpc has a link register (lr) used for calling functions. We "bl " to call a function, and "blr" to return back to the call site. The lr is only a single register, so if we call another function from inside this function (ie. nested calls), software must save away the lr on the software stack