From 4d0d7c02df680740da41f5f92a238c35796ca5be Mon Sep 17 00:00:00 2001 From: Akshay Adiga Date: Wed, 28 Jun 2017 06:46:49 +0530 Subject: powerpc/powernv/idle: Clear r12 on wakeup from stop lite 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 so r12 contains garbage (likely a kernel pointer), and is still used to check HMI assuming that it contained SRR1. This causes 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 value of r12[42:45] corresponds to HMI as wakeup reason. Prior to commit 9d29250136f6 ("powerpc/64s/idle: Avoid SRR usage in idle sleep/wake paths") this bug existed, in that we would incorrectly look at SRR1 to check for a HMI when SRR1 didn't contain a wakeup reason. However the SRR1 value would just happen to never have bits 42:45 set. Fixes: 9d29250136f6 ("powerpc/64s/idle: Avoid SRR usage in idle sleep/wake paths") Signed-off-by: Akshay Adiga Reviewed-by: Nicholas Piggin [mpe: Change log and comment massaging] Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/idle_book3s.S | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index f6518c768d2a..5adb390e773b 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -256,6 +256,19 @@ 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 the SRR1 value so + * it can 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 value of r12[42:45] == WAKE_HMI. + */ + li r12, 0 b pnv_wakeup_noloss .Lhandle_esl_ec_set: -- cgit v1.2.3-55-g7522