Messages in this thread | | | Date | Wed, 28 Jun 2017 14:36:46 +1000 | From | Nicholas Piggin <> | Subject | Re: [PATCH] powernv:idle: Clear r12 on wakeup from stop lite |
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On Wed, 28 Jun 2017 06:46:49 +0530 Akshay Adiga <akshay.adiga@linux.vnet.ibm.com> wrote:
> pnv_wakeup_noloss expects R12 to contain SRR1 value to determine if > the wakeup reason is an HMI in CHECK_HMI_INTERRUPT. > > When we wakeup with ESL=0, SRR1 will not contain the wakeup reason, so > there is no point setting R12 to SRR1. > > However, we don't set R12 at all and R12 contains garbage, and still > being used to check HMI assuming that it had SRR1. causing the > OPAL msglog to be filled with the following print: > HMI: Received HMI interrupt: HMER = 0x0040000000000000 > > This patch clears R12 after waking up from stop with ESL=EC=0, so that > we don't accidentally enter the HMI handler in pnv_wakeup_noloss if > the R12[42:45] corresponds to HMI as wakeup reason. > > Bug existed prior to "commit 9d29250136f6 ("powerpc/64s/idle: Avoid SRR > usage in idle sleep/wake paths") but was never hit in practice > > Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com> > Fixes: 9d29250136f6 ("powerpc/64s/idle: Avoid SRR usage in idle > sleep/wake paths")
Thanks guys, appreciate you finding and fixing my bug :)
I think this looks like the best fix. Really minor nitpick but you could adjust the line widths on the comment slightly (mpe might do that when merging).
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
> --- > arch/powerpc/kernel/idle_book3s.S | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S > index 1ea14b9..34794fd 100644 > --- a/arch/powerpc/kernel/idle_book3s.S > +++ b/arch/powerpc/kernel/idle_book3s.S > @@ -256,6 +256,21 @@ power_enter_stop: > bne .Lhandle_esl_ec_set > IDLE_STATE_ENTER_SEQ(PPC_STOP) > li r3,0 /* Since we didn't lose state, return 0 */ > + /* > + * pnv_wakeup_noloss expects R12 to contain SRR1 value > + * to determine if the wakeup reason is an HMI in > + * CHECK_HMI_INTERRUPT. > + * > + * However, when we wakeup with ESL=0, > + * SRR1 will not contain the wakeup reason, > + * so there is no point setting R12 to SRR1. > + * > + * Further, we clear R12 here, so that we > + * don't accidentally enter the HMI > + * in pnv_wakeup_noloss if the > + * R12[42:45] == WAKE_HMI. > + */ > + li r12, 0 > b pnv_wakeup_noloss > > .Lhandle_esl_ec_set:
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