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

BugLink: http://bugs.launchpad.net/bugs/1666197
Commit 09206b600c76 ("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: 09206b600c76 ("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>
(cherry picked from commit 424f8acd328a111319ae30bf384e5dfb9bc8f8cb)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/arch/powerpc/include/asm/cpuidle.h b/arch/powerpc/include/asm/cpuidle.h
index fd321eb423cb44fef259cf47547a05ee1cc1f6a8..155731557c9bc08673881520c13d6db825fd91b0 100644 (file)
--- a/arch/powerpc/include/asm/cpuidle.h
+++ b/arch/powerpc/include/asm/cpuidle.h
@@ -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)                   \

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 4f6cf5596235e66f37199ec7742dcc6c9841d5ef..4724ccce7414da137f49cf3ceb9428198649e9e3 100644 (file)
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -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