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| author | Nicholas Piggin <npiggin@gmail.com> | 2017-04-19 23:05:45 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-23 20:31:39 +1000 |
| commit | 544686cae8e4f5bbcd153998dcaf4a3d5b94e6be (patch) | |
| tree | 51eaa1f72ea0c6967e930ffcd3fe1d2562940bbe /arch/powerpc/kernel/exceptions-64s.S | |
| parent | bf0153c143a694e7bb3b28d92eafd8b3ef6db870 (diff) | |
| download | linux-544686cae8e4f5bbcd153998dcaf4a3d5b94e6be.tar.gz linux-544686cae8e4f5bbcd153998dcaf4a3d5b94e6be.tar.bz2 linux-544686cae8e4f5bbcd153998dcaf4a3d5b94e6be.zip | |
powerpc/64s: Stop using bit in HSPRG0 to test winkle
The POWER8 idle code has a neat trick of programming the power on engine
to restore a low bit into HSPRG0, so idle wakeup code can test and see
if it has been programmed this way and therefore lost all state. Restore
time can be reduced if winkle has not been reached.
However this messes with our r13 PACA pointer, and requires HSPRG0 to be
written to. It also optimizes the slowest and most uncommon case at the
expense of another SPR write in the common nap state wakeup.
Remove this complexity and assume winkle sleeps always require a state
restore. This speedup could be made entirely contained within the winkle
idle code by counting per-core winkles and setting a thread bitmap when
all have gone to winkle.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 21 |
1 files changed, 3 insertions, 18 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 2f837a4a78a2..e390fcd04bcb 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -116,9 +116,7 @@ EXC_VIRT_NONE(0x4000, 0x100) EXC_REAL_BEGIN(system_reset, 0x100, 0x100) SET_SCRATCH0(r13) - GET_PACA(r13) - clrrdi r13,r13,1 /* Last bit of HSPRG0 is set if waking from winkle */ - EXCEPTION_PROLOG_PSERIES_PACA(PACA_EXGEN, system_reset_common, EXC_STD, + EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, EXC_STD, IDLETEST, 0x100) EXC_REAL_END(system_reset, 0x100, 0x100) @@ -148,14 +146,6 @@ EXC_REAL_BEGIN(machine_check, 0x200, 0x100) * vector */ SET_SCRATCH0(r13) /* save r13 */ - /* - * Running native on arch 2.06 or later, we may wakeup from winkle - * inside machine check. If yes, then last bit of HSPRG0 would be set - * to 1. Hence clear it unconditionally. - */ - GET_PACA(r13) - clrrdi r13,r13,1 - SET_PACA(r13) EXCEPTION_PROLOG_0(PACA_EXMC) BEGIN_FTR_SECTION b machine_check_powernv_early @@ -339,7 +329,7 @@ EXC_COMMON_BEGIN(machine_check_handle_early) * Go back to nap/sleep/winkle mode again if (b) is true. */ rlwinm. r11,r12,47-31,30,31 /* Was it in power saving mode? */ - beq 4f /* No, it wasn;t */ + beq 4f /* No, it wasn't */ /* Thread was in power saving mode. Go back to nap again. */ cmpwi r11,2 blt 3f @@ -369,13 +359,8 @@ EXC_COMMON_BEGIN(machine_check_handle_early) /* * Go back to winkle. Please note that this thread was woken up in * machine check from winkle and have not restored the per-subcore - * state. Hence before going back to winkle, set last bit of HSPRG0 - * to 1. This will make sure that if this thread gets woken up - * again at reset vector 0x100 then it will get chance to restore - * the subcore state. + * state. */ - ori r13,r13,1 - SET_PACA(r13) IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE) /* No return */ 4: |