On Wed, 27 Jul 2016 17:32:06 +1000 Balbir Singh <bsinghar...@gmail.com> wrote:
> From: Balbir Singh <bsinghar...@gmail.com> > > Currently the power management bits are broken w.r.t. relocation. > There are direct branches from system_reset_pSeries to > power7_wakeup_*. The correct way to do it is to do what > the slb miss handler does, which is jump to a small stub within > the first 64k of the relocated address and then jump to the > actual location. > > The code has been lightly tested (not the kvm bits), I would highly > appreciate a review of the code. I suspect there might be easy > to find bugs :) > > Cc: b...@kernel.crashing.org > Cc: m...@ellerman.id.au > Cc: pau...@samba.org > Cc: npig...@gmail.com > Cc: sva...@linux.vnet.ibm.com > > Signed-off-by: Balbir Singh <bsinghar...@gmail.com> > --- > arch/powerpc/kernel/exceptions-64s.S | 82 > ++++++++++++++++++++++-------------- 1 file changed, 51 > insertions(+), 31 deletions(-) > > diff --git a/arch/powerpc/kernel/exceptions-64s.S > b/arch/powerpc/kernel/exceptions-64s.S index 8bcc1b4..64f9650 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -118,39 +118,21 @@ BEGIN_FTR_SECTION > cmpwi cr4,r5,1 > mtspr SPRN_HSPRG0,r13 > > - lbz r0,PACA_THREAD_IDLE_STATE(r13) > - cmpwi cr2,r0,PNV_THREAD_NAP > - bgt cr2,8f /* Either > sleep or Winkle */ - > - /* Waking up from nap should not cause hypervisor state loss > */ > - bgt cr3,. > - > - /* Waking up from nap */ > - li r0,PNV_THREAD_RUNNING > - stb r0,PACA_THREAD_IDLE_STATE(r13) /* Clear > thread state */ - > -#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > - li r0,KVM_HWTHREAD_IN_KERNEL > - stb r0,HSTATE_HWTHREAD_STATE(r13) > - /* Order setting hwthread_state vs. testing hwthread_req */ > - sync > - lbz r0,HSTATE_HWTHREAD_REQ(r13) > - cmpwi r0,0 > - beq 1f > - b kvm_start_guest > -1: > +#ifndef CONFIG_RELOCATABLE > + b power7_wakeup_common > +#else > + /* > + * We can't just use a direct branch to power7_wakeup_common > + * because the distance from here to there depends on where > + * the kernel ends up being put. > + */ > + mfctr r11 > + ld r10, PACAKBASE(r13) > + LOAD_HANDLER(r10, power7_wakeup_common) > + mtctr r10 > + bctr > #endif So r10 and r11 are safe to use (as well as existing registers being used without saving) because we are returning via the nap functions that caller will expect to trash volatile registers, yes? In that case I can't see a problem with this. Thanks, Nick _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
