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powerpc/powernv: Fix bug due to labeling ambiguity in power_enter_stop 

Commit 09206b600c ("powernv: Pass PSSCR value and mask to
power9_idle_stop") added additional code in power_enter_stop() to
distinguish between stop requests whose PSSCR had ESL=EC=1 from those
which did not. When ESL=EC=1, we do a forward-jump to a location
labelled by "1", which had the code to handle the ESL=EC=1 case.

Unfortunately just a couple of instructions before this label, is the
macro IDLE_STATE_ENTER_SEQ() which also has a label "1" in its
expansion.

As a result, the current code can result in directly executing stop
instruction for deep stop requests with PSSCR ESL=EC=1, without saving
the hypervisor state.

Fix this BUG by labeling the location that handles ESL=EC=1 case with
a more descriptive label ".Lhandle_esl_ec_set" (local label suggestion
a la .Lxx from Anton Blanchard).

While at it, rename the label "2" labelling the location of the code
handling entry into deep stop states with ".Lhandle_deep_stop".

For a good measure, change the label in IDLE_STATE_ENTER_SEQ() macro
to an not-so commonly used value in order to avoid similar mishaps in
the future.

Fixes: 09206b600c ("powernv: Pass PSSCR value and mask to power9_idle_stop")
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Gautham R. Shenoy 2017-02-27 11:10:07 +05:30 committed by Michael Ellerman
parent 7a70d7288c
commit 424f8acd32
2 changed files with 8 additions and 6 deletions
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4
arch/powerpc/include/asm/cpuidle.h
View File

@ -70,8 +70,8 @@ static inline void report_invalid_psscr_val(u64 psscr_val, int err)
std r0,0(r1); \
ptesync; \
ld r0,0(r1); \
1: cmpd cr0,r0,r0; \
bne 1b; \
236: cmpd cr0,r0,r0; \
bne 236b; \
IDLE_INST; \
#define IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST) \

10
arch/powerpc/kernel/idle_book3s.S
View File

@ -276,19 +276,21 @@ power_enter_stop:
*/
andis. r4,r3,PSSCR_EC_ESL_MASK_SHIFTED
clrldi r3,r3,60 /* r3 = Bits[60:63] = Requested Level (RL) */
bne 1f
bne .Lhandle_esl_ec_set
IDLE_STATE_ENTER_SEQ(PPC_STOP)
li r3,0 /* Since we didn't lose state, return 0 */
b pnv_wakeup_noloss
.Lhandle_esl_ec_set:
/*
* Check if the requested state is a deep idle state.
*/
1: LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state)
LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state)
ld r4,ADDROFF(pnv_first_deep_stop_state)(r5)
cmpd r3,r4
bge 2f
bge .Lhandle_deep_stop
IDLE_STATE_ENTER_SEQ_NORET(PPC_STOP)
2:
.Lhandle_deep_stop:
/*
* Entering deep idle state.
* Clear thread bit in PACA_CORE_IDLE_STATE, save SPRs to