]> git.karo-electronics.de Git - linux-beck.git/commitdiff
powernv/powerpc: Add winkle support for offline cpus
authorShreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Tue, 9 Dec 2014 18:56:53 +0000 (00:26 +0530)
committerMichael Ellerman <mpe@ellerman.id.au>
Sun, 14 Dec 2014 23:46:41 +0000 (10:46 +1100)
Winkle is a deep idle state supported in power8 chips. A core enters
winkle when all the threads of the core enter winkle. In this state
power supply to the entire chiplet i.e core, private L2 and private L3
is turned off. As a result it gives higher powersavings compared to
sleep.

But entering winkle results in a total hypervisor state loss. Hence the
hypervisor context has to be preserved before entering winkle and
restored upon wake up.

Power-on Reset Engine (PORE) is a dedicated engine which is responsible
for powering on the chiplet during wake up. It can be programmed to
restore the register contests of a few specific registers. This patch
uses PORE to restore register state wherever possible and uses stack to
save and restore rest of the necessary registers.

With hypervisor state restore things fall under three categories-
per-core state, per-subcore state and per-thread state. To manage this,
extend the infrastructure introduced for sleep. Mainly we add a paca
variable subcore_sibling_mask. Using this and the core_idle_state we can
distingush first thread in core and subcore.

Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
13 files changed:
arch/powerpc/include/asm/opal.h
arch/powerpc/include/asm/paca.h
arch/powerpc/include/asm/ppc-opcode.h
arch/powerpc/include/asm/processor.h
arch/powerpc/include/asm/reg.h
arch/powerpc/kernel/asm-offsets.c
arch/powerpc/kernel/exceptions-64s.S
arch/powerpc/kernel/idle_power7.S
arch/powerpc/platforms/powernv/opal-wrappers.S
arch/powerpc/platforms/powernv/setup.c
arch/powerpc/platforms/powernv/smp.c
arch/powerpc/platforms/powernv/subcore.c
arch/powerpc/platforms/powernv/subcore.h

index 3dea31c1080ce70ea1c08e84aa34f569c64df7f1..eb95b675109b64c47b58a29673c0fc5bc4cfaa46 100644 (file)
@@ -161,6 +161,7 @@ struct opal_sg_list {
 #define OPAL_PCI_EEH_FREEZE_SET                        97
 #define OPAL_HANDLE_HMI                                98
 #define OPAL_CONFIG_CPU_IDLE_STATE             99
+#define OPAL_SLW_SET_REG                       100
 #define OPAL_REGISTER_DUMP_REGION              101
 #define OPAL_UNREGISTER_DUMP_REGION            102
 #define OPAL_WRITE_TPO                         103
@@ -176,6 +177,7 @@ struct opal_sg_list {
  */
 #define OPAL_PM_NAP_ENABLED    0x00010000
 #define OPAL_PM_SLEEP_ENABLED  0x00020000
+#define OPAL_PM_WINKLE_ENABLED 0x00040000
 #define OPAL_PM_SLEEP_ENABLED_ER1      0x00080000
 
 #ifndef __ASSEMBLY__
@@ -913,6 +915,7 @@ int64_t opal_sensor_read(uint32_t sensor_hndl, int token, __be32 *sensor_data);
 int64_t opal_handle_hmi(void);
 int64_t opal_register_dump_region(uint32_t id, uint64_t start, uint64_t end);
 int64_t opal_unregister_dump_region(uint32_t id);
+int64_t opal_slw_set_reg(uint64_t cpu_pir, uint64_t sprn, uint64_t val);
 int64_t opal_pci_set_phb_cxl_mode(uint64_t phb_id, uint64_t mode, uint64_t pe_number);
 int64_t opal_ipmi_send(uint64_t interface, struct opal_ipmi_msg *msg,
                uint64_t msg_len);
index a0a16847bd40456aaaf5a6204f95b81a0a46401e..e5f22c6c4bf9dbbabec793b4293a92b854bafab0 100644 (file)
@@ -158,6 +158,8 @@ struct paca_struct {
        u8 thread_idle_state;           /* PNV_THREAD_RUNNING/NAP/SLEEP */
        /* Mask to indicate thread id in core */
        u8 thread_mask;
+       /* Mask to denote subcore sibling threads */
+       u8 subcore_sibling_mask;
 #endif
 
 #ifdef CONFIG_PPC_BOOK3S_64
index 6f8536208049f4c8f46708e45b4153927c36658a..5155be7c0d48d5196e5fbb35d4e9b6787a8b20cf 100644 (file)
 
 #define PPC_INST_NAP                   0x4c000364
 #define PPC_INST_SLEEP                 0x4c0003a4
+#define PPC_INST_WINKLE                        0x4c0003e4
 
 /* A2 specific instructions */
 #define PPC_INST_ERATWE                        0x7c0001a6
 
 #define PPC_NAP                        stringify_in_c(.long PPC_INST_NAP)
 #define PPC_SLEEP              stringify_in_c(.long PPC_INST_SLEEP)
+#define PPC_WINKLE             stringify_in_c(.long PPC_INST_WINKLE)
 
 /* BHRB instructions */
 #define PPC_CLRBHRB            stringify_in_c(.long PPC_INST_CLRBHRB)
index f5c45b37c0d4d45533b605fae6510341ac4b3144..bf117d8fb45fe773bb6154578961dd031c921f28 100644 (file)
@@ -453,6 +453,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 extern int powersave_nap;      /* set if nap mode can be used in idle loop */
 extern unsigned long power7_nap(int check_irq);
 extern unsigned long power7_sleep(void);
+extern unsigned long power7_winkle(void);
 extern void flush_instruction_cache(void);
 extern void hard_reset_now(void);
 extern void poweroff_now(void);
index a68ee15964b33b9ca3ba67c96e3c3d155b29554a..1c874fb533bbf22fe8ff019b328ae623214243bb 100644 (file)
 #define SPRN_DBAT7L    0x23F   /* Data BAT 7 Lower Register */
 #define SPRN_DBAT7U    0x23E   /* Data BAT 7 Upper Register */
 #define SPRN_PPR       0x380   /* SMT Thread status Register */
+#define SPRN_TSCR      0x399   /* Thread Switch Control Register */
 
 #define SPRN_DEC       0x016           /* Decrement Register */
 #define SPRN_DER       0x095           /* Debug Enable Regsiter */
 #define SPRN_BESCR     806     /* Branch event status and control register */
 #define   BESCR_GE     0x8000000000000000ULL /* Global Enable */
 #define SPRN_WORT      895     /* Workload optimization register - thread */
+#define SPRN_WORC      863     /* Workload optimization register - core */
 
 #define SPRN_PMC1      787
 #define SPRN_PMC2      788
index bbd27fe0c0399ed02dc4c0fbda521c4d38b4a9b3..f68de7a73faa70bf1b6cb197ea3e814d2de7b12a 100644 (file)
@@ -733,6 +733,8 @@ int main(void)
                        offsetof(struct paca_struct, thread_idle_state));
        DEFINE(PACA_THREAD_MASK,
                        offsetof(struct paca_struct, thread_mask));
+       DEFINE(PACA_SUBCORE_SIBLING_MASK,
+                       offsetof(struct paca_struct, subcore_sibling_mask));
 #endif
 
        return 0;
index 289fe718ecd4f9dd040aa3c875dd2976835fcfb2..c2df8150bd7a0425fc00ebcc78d784d6b280c146 100644 (file)
@@ -102,9 +102,7 @@ system_reset_pSeries:
 #ifdef CONFIG_PPC_P7_NAP
 BEGIN_FTR_SECTION
        /* Running native on arch 2.06 or later, check if we are
-        * waking up from nap. We only handle no state loss and
-        * supervisor state loss. We do -not- handle hypervisor
-        * state loss at this time.
+        * waking up from nap/sleep/winkle.
         */
        mfspr   r13,SPRN_SRR1
        rlwinm. r13,r13,47-31,30,31
@@ -112,7 +110,16 @@ BEGIN_FTR_SECTION
 
        cmpwi   cr3,r13,2
 
+       /*
+        * Check if last bit of HSPGR0 is set. This indicates whether we are
+        * waking up from winkle.
+        */
        GET_PACA(r13)
+       clrldi  r5,r13,63
+       clrrdi  r13,r13,1
+       cmpwi   cr4,r5,1
+       mtspr   SPRN_HSPRG0,r13
+
        lbz     r0,PACA_THREAD_IDLE_STATE(r13)
        cmpwi   cr2,r0,PNV_THREAD_NAP
        bgt     cr2,8f                          /* Either sleep or Winkle */
index 0f2c113c8ca5c8bc2fc4ae791198f158254976de..05adc8bbdef853b4c7adb27c5da88ceada1ea033 100644 (file)
 #include <asm/kvm_book3s_asm.h>
 #include <asm/opal.h>
 #include <asm/cpuidle.h>
+#include <asm/mmu-hash64.h>
 
 #undef DEBUG
 
+/*
+ * Use unused space in the interrupt stack to save and restore
+ * registers for winkle support.
+ */
+#define _SDR1  GPR3
+#define _RPR   GPR4
+#define _SPURR GPR5
+#define _PURR  GPR6
+#define _TSCR  GPR7
+#define _DSCR  GPR8
+#define _AMOR  GPR9
+#define _WORT  GPR10
+#define _WORC  GPR11
+
 /* Idle state entry routines */
 
 #define        IDLE_STATE_ENTER_SEQ(IDLE_INST)                         \
@@ -124,8 +139,8 @@ power7_enter_nap_mode:
        stb     r4,HSTATE_HWTHREAD_STATE(r13)
 #endif
        stb     r3,PACA_THREAD_IDLE_STATE(r13)
-       cmpwi   cr1,r3,PNV_THREAD_SLEEP
-       bge     cr1,2f
+       cmpwi   cr3,r3,PNV_THREAD_SLEEP
+       bge     cr3,2f
        IDLE_STATE_ENTER_SEQ(PPC_NAP)
        /* No return */
 2:
@@ -154,7 +169,8 @@ pnv_fastsleep_workaround_at_entry:
        bne-    lwarx_loop1
        isync
 
-common_enter: /* common code for all the threads entering sleep */
+common_enter: /* common code for all the threads entering sleep or winkle */
+       bgt     cr3,enter_winkle
        IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
 
 fastsleep_workaround_at_entry:
@@ -175,6 +191,30 @@ fastsleep_workaround_at_entry:
        stw     r0,0(r14)
        b       common_enter
 
+enter_winkle:
+       /*
+        * Note all register i.e per-core, per-subcore or per-thread is saved
+        * here since any thread in the core might wake up first
+        */
+       mfspr   r3,SPRN_SDR1
+       std     r3,_SDR1(r1)
+       mfspr   r3,SPRN_RPR
+       std     r3,_RPR(r1)
+       mfspr   r3,SPRN_SPURR
+       std     r3,_SPURR(r1)
+       mfspr   r3,SPRN_PURR
+       std     r3,_PURR(r1)
+       mfspr   r3,SPRN_TSCR
+       std     r3,_TSCR(r1)
+       mfspr   r3,SPRN_DSCR
+       std     r3,_DSCR(r1)
+       mfspr   r3,SPRN_AMOR
+       std     r3,_AMOR(r1)
+       mfspr   r3,SPRN_WORT
+       std     r3,_WORT(r1)
+       mfspr   r3,SPRN_WORC
+       std     r3,_WORC(r1)
+       IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
 
 _GLOBAL(power7_idle)
        /* Now check if user or arch enabled NAP mode */
@@ -197,6 +237,12 @@ _GLOBAL(power7_sleep)
        b       power7_powersave_common
        /* No return */
 
+_GLOBAL(power7_winkle)
+       li      r3,3
+       li      r4,1
+       b       power7_powersave_common
+       /* No return */
+
 #define CHECK_HMI_INTERRUPT                                            \
        mfspr   r0,SPRN_SRR1;                                           \
 BEGIN_FTR_SECTION_NESTED(66);                                          \
@@ -250,11 +296,23 @@ lwarx_loop2:
        bne     core_idle_lock_held
 
        cmpwi   cr2,r15,0
+       lbz     r4,PACA_SUBCORE_SIBLING_MASK(r13)
+       and     r4,r4,r15
+       cmpwi   cr1,r4,0        /* Check if first in subcore */
+
+       /*
+        * At this stage
+        * cr1 - 0b0100 if first thread to wakeup in subcore
+        * cr2 - 0b0100 if first thread to wakeup in core
+        * cr3-  0b0010 if waking up from sleep or winkle
+        * cr4 - 0b0100 if waking up from winkle
+        */
+
        or      r15,r15,r7              /* Set thread bit */
 
-       beq     cr2,first_thread
+       beq     cr1,first_thread_in_subcore
 
-       /* Not first thread in core to wake up */
+       /* Not first thread in subcore to wake up */
        stwcx.  r15,0,r14
        bne-    lwarx_loop2
        isync
@@ -269,13 +327,36 @@ core_idle_lock_loop:
        HMT_MEDIUM
        b       lwarx_loop2
 
-first_thread:
-       /* First thread in core to wakeup */
+first_thread_in_subcore:
+       /* First thread in subcore to wakeup */
        ori     r15,r15,PNV_CORE_IDLE_LOCK_BIT
        stwcx.  r15,0,r14
        bne-    lwarx_loop2
        isync
 
+       /*
+        * If waking up from sleep, subcore state is not lost. Hence
+        * skip subcore state restore
+        */
+       bne     cr4,subcore_state_restored
+
+       /* Restore per-subcore state */
+       ld      r4,_SDR1(r1)
+       mtspr   SPRN_SDR1,r4
+       ld      r4,_RPR(r1)
+       mtspr   SPRN_RPR,r4
+       ld      r4,_AMOR(r1)
+       mtspr   SPRN_AMOR,r4
+
+subcore_state_restored:
+       /*
+        * Check if the thread is also the first thread in the core. If not,
+        * skip to clear_lock.
+        */
+       bne     cr2,clear_lock
+
+first_thread_in_core:
+
        /*
         * First thread in the core waking up from fastsleep. It needs to
         * call the fastsleep workaround code if the platform requires it.
@@ -296,12 +377,62 @@ timebase_resync:
        bl      opal_call_realmode;
        /* TODO: Check r3 for failure */
 
+       /*
+        * If waking up from sleep, per core state is not lost, skip to
+        * clear_lock.
+        */
+       bne     cr4,clear_lock
+
+       /* Restore per core state */
+       ld      r4,_TSCR(r1)
+       mtspr   SPRN_TSCR,r4
+       ld      r4,_WORC(r1)
+       mtspr   SPRN_WORC,r4
+
 clear_lock:
        andi.   r15,r15,PNV_CORE_IDLE_THREAD_BITS
        lwsync
        stw     r15,0(r14)
 
 common_exit:
+       /*
+        * Common to all threads.
+        *
+        * If waking up from sleep, hypervisor state is not lost. Hence
+        * skip hypervisor state restore.
+        */
+       bne     cr4,hypervisor_state_restored
+
+       /* Waking up from winkle */
+
+       /* Restore per thread state */
+       bl      __restore_cpu_power8
+
+       /* Restore SLB  from PACA */
+       ld      r8,PACA_SLBSHADOWPTR(r13)
+
+       .rept   SLB_NUM_BOLTED
+       li      r3, SLBSHADOW_SAVEAREA
+       LDX_BE  r5, r8, r3
+       addi    r3, r3, 8
+       LDX_BE  r6, r8, r3
+       andis.  r7,r5,SLB_ESID_V@h
+       beq     1f
+       slbmte  r6,r5
+1:     addi    r8,r8,16
+       .endr
+
+       ld      r4,_SPURR(r1)
+       mtspr   SPRN_SPURR,r4
+       ld      r4,_PURR(r1)
+       mtspr   SPRN_PURR,r4
+       ld      r4,_DSCR(r1)
+       mtspr   SPRN_DSCR,r4
+       ld      r4,_WORT(r1)
+       mtspr   SPRN_WORT,r4
+
+hypervisor_state_restored:
+
        li      r5,PNV_THREAD_RUNNING
        stb     r5,PACA_THREAD_IDLE_STATE(r13)
 
index 78289ed7058c1889d6985e94a81e5dfefa480b1d..54eca8b3b288f8fcca45ef5f44c5211832b3416f 100644 (file)
@@ -284,6 +284,7 @@ OPAL_CALL(opal_sensor_read,                 OPAL_SENSOR_READ);
 OPAL_CALL(opal_get_param,                      OPAL_GET_PARAM);
 OPAL_CALL(opal_set_param,                      OPAL_SET_PARAM);
 OPAL_CALL(opal_handle_hmi,                     OPAL_HANDLE_HMI);
+OPAL_CALL(opal_slw_set_reg,                    OPAL_SLW_SET_REG);
 OPAL_CALL(opal_register_dump_region,           OPAL_REGISTER_DUMP_REGION);
 OPAL_CALL(opal_unregister_dump_region,         OPAL_UNREGISTER_DUMP_REGION);
 OPAL_CALL(opal_pci_set_phb_cxl_mode,           OPAL_PCI_SET_PHB_CXL_MODE);
index 2e9b53bb73e2a85d95e234742489c75faa6c6b35..b700a329c31d448444d0f48e0fdd0b9176f1a825 100644 (file)
@@ -41,6 +41,7 @@
 #include <asm/code-patching.h>
 
 #include "powernv.h"
+#include "subcore.h"
 
 static void __init pnv_setup_arch(void)
 {
@@ -293,6 +294,72 @@ static void __init pnv_setup_machdep_rtas(void)
 
 static u32 supported_cpuidle_states;
 
+int pnv_save_sprs_for_winkle(void)
+{
+       int cpu;
+       int rc;
+
+       /*
+        * hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric accross
+        * all cpus at boot. Get these reg values of current cpu and use the
+        * same accross all cpus.
+        */
+       uint64_t lpcr_val = mfspr(SPRN_LPCR);
+       uint64_t hid0_val = mfspr(SPRN_HID0);
+       uint64_t hid1_val = mfspr(SPRN_HID1);
+       uint64_t hid4_val = mfspr(SPRN_HID4);
+       uint64_t hid5_val = mfspr(SPRN_HID5);
+       uint64_t hmeer_val = mfspr(SPRN_HMEER);
+
+       for_each_possible_cpu(cpu) {
+               uint64_t pir = get_hard_smp_processor_id(cpu);
+               uint64_t hsprg0_val = (uint64_t)&paca[cpu];
+
+               /*
+                * HSPRG0 is used to store the cpu's pointer to paca. Hence last
+                * 3 bits are guaranteed to be 0. Program slw to restore HSPRG0
+                * with 63rd bit set, so that when a thread wakes up at 0x100 we
+                * can use this bit to distinguish between fastsleep and
+                * deep winkle.
+                */
+               hsprg0_val |= 1;
+
+               rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
+               if (rc != 0)
+                       return rc;
+
+               rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
+               if (rc != 0)
+                       return rc;
+
+               /* HIDs are per core registers */
+               if (cpu_thread_in_core(cpu) == 0) {
+
+                       rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
+                       if (rc != 0)
+                               return rc;
+
+                       rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
+                       if (rc != 0)
+                               return rc;
+
+                       rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
+                       if (rc != 0)
+                               return rc;
+
+                       rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
+                       if (rc != 0)
+                               return rc;
+
+                       rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
+                       if (rc != 0)
+                               return rc;
+               }
+       }
+
+       return 0;
+}
+
 static void pnv_alloc_idle_core_states(void)
 {
        int i, j;
@@ -325,6 +392,11 @@ static void pnv_alloc_idle_core_states(void)
                        paca[cpu].thread_mask = 1 << j;
                }
        }
+
+       update_subcore_sibling_mask();
+
+       if (supported_cpuidle_states & OPAL_PM_WINKLE_ENABLED)
+               pnv_save_sprs_for_winkle();
 }
 
 u32 pnv_get_supported_cpuidle_states(void)
index c0691d0fb38504841694d5ed23bf164f9a8c0987..6c551a28e89979df16c100a8f4bcc8f357fce2d5 100644 (file)
@@ -167,12 +167,17 @@ static void pnv_smp_cpu_kill_self(void)
         */
        mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
        while (!generic_check_cpu_restart(cpu)) {
+
                ppc64_runlatch_off();
-               if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
+
+               if (idle_states & OPAL_PM_WINKLE_ENABLED)
+                       srr1 = power7_winkle();
+               else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
                                (idle_states & OPAL_PM_SLEEP_ENABLED_ER1))
                        srr1 = power7_sleep();
                else
                        srr1 = power7_nap(1);
+
                ppc64_runlatch_on();
 
                /*
index c87f96b79d1a02ed5f5371a2d02fc509deb3f3a1..f60f80ada9039451466a6b90f77bf091ade405e0 100644 (file)
@@ -160,6 +160,18 @@ static void wait_for_sync_step(int step)
        mb();
 }
 
+static void update_hid_in_slw(u64 hid0)
+{
+       u64 idle_states = pnv_get_supported_cpuidle_states();
+
+       if (idle_states & OPAL_PM_WINKLE_ENABLED) {
+               /* OPAL call to patch slw with the new HID0 value */
+               u64 cpu_pir = hard_smp_processor_id();
+
+               opal_slw_set_reg(cpu_pir, SPRN_HID0, hid0);
+       }
+}
+
 static void unsplit_core(void)
 {
        u64 hid0, mask;
@@ -179,6 +191,7 @@ static void unsplit_core(void)
        hid0 = mfspr(SPRN_HID0);
        hid0 &= ~HID0_POWER8_DYNLPARDIS;
        mtspr(SPRN_HID0, hid0);
+       update_hid_in_slw(hid0);
 
        while (mfspr(SPRN_HID0) & mask)
                cpu_relax();
@@ -215,6 +228,7 @@ static void split_core(int new_mode)
        hid0  = mfspr(SPRN_HID0);
        hid0 |= HID0_POWER8_DYNLPARDIS | split_parms[i].value;
        mtspr(SPRN_HID0, hid0);
+       update_hid_in_slw(hid0);
 
        /* Wait for it to happen */
        while (!(mfspr(SPRN_HID0) & split_parms[i].mask))
@@ -251,6 +265,25 @@ bool cpu_core_split_required(void)
        return true;
 }
 
+void update_subcore_sibling_mask(void)
+{
+       int cpu;
+       /*
+        * sibling mask for the first cpu. Left shift this by required bits
+        * to get sibling mask for the rest of the cpus.
+        */
+       int sibling_mask_first_cpu =  (1 << threads_per_subcore) - 1;
+
+       for_each_possible_cpu(cpu) {
+               int tid = cpu_thread_in_core(cpu);
+               int offset = (tid / threads_per_subcore) * threads_per_subcore;
+               int mask = sibling_mask_first_cpu << offset;
+
+               paca[cpu].subcore_sibling_mask = mask;
+
+       }
+}
+
 static int cpu_update_split_mode(void *data)
 {
        int cpu, new_mode = *(int *)data;
@@ -284,6 +317,7 @@ static int cpu_update_split_mode(void *data)
                /* Make the new mode public */
                subcores_per_core = new_mode;
                threads_per_subcore = threads_per_core / subcores_per_core;
+               update_subcore_sibling_mask();
 
                /* Make sure the new mode is written before we exit */
                mb();
index 148abc91debfd84735ac6c8967315dded6f8e8a9..84e02ae52895078036ea656f608b2c719f7ad994 100644 (file)
 #define SYNC_STEP_FINISHED     3       /* Set by secondary when split/unsplit is done */
 
 #ifndef __ASSEMBLY__
+
+#ifdef CONFIG_SMP
 void split_core_secondary_loop(u8 *state);
-#endif
+extern void update_subcore_sibling_mask(void);
+#else
+static inline void update_subcore_sibling_mask(void) { };
+#endif /* CONFIG_SMP */
+
+#endif /* __ASSEMBLY__ */