[POWERPC] Remove barriers from the SLB shadow buffer update
After talking to an IBM POWER hypervisor (PHYP) design and development guy, there seems to be no need for memory barriers when updating the SLB shadow buffer provided we only update it from the current CPU, which we do. Also, these guys see no need in the future for these barriers. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
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@ -385,15 +385,15 @@ BEGIN_FTR_SECTION
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oris r0,r6,(SLB_ESID_V)@h
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oris r0,r6,(SLB_ESID_V)@h
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ori r0,r0,(SLB_NUM_BOLTED-1)@l
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ori r0,r0,(SLB_NUM_BOLTED-1)@l
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/* Update the last bolted SLB */
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/* Update the last bolted SLB. No write barriers are needed
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* here, provided we only update the current CPU's SLB shadow
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* buffer.
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*/
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ld r9,PACA_SLBSHADOWPTR(r13)
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ld r9,PACA_SLBSHADOWPTR(r13)
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li r12,0
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li r12,0
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std r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */
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std r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */
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eieio
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std r7,SLBSHADOW_STACKVSID(r9) /* Save VSID */
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std r7,SLBSHADOW_STACKVSID(r9) /* Save VSID */
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eieio
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std r0,SLBSHADOW_STACKESID(r9) /* Save ESID */
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std r0,SLBSHADOW_STACKESID(r9) /* Save ESID */
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eieio
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slbie r6
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slbie r6
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slbie r6 /* Workaround POWER5 < DD2.1 issue */
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slbie r6 /* Workaround POWER5 < DD2.1 issue */
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@ -59,14 +59,12 @@ static inline void slb_shadow_update(unsigned long ea,
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{
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{
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/*
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/*
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* Clear the ESID first so the entry is not valid while we are
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* Clear the ESID first so the entry is not valid while we are
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* updating it.
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* updating it. No write barriers are needed here, provided
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* we only update the current CPU's SLB shadow buffer.
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*/
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*/
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get_slb_shadow()->save_area[entry].esid = 0;
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get_slb_shadow()->save_area[entry].esid = 0;
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smp_wmb();
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get_slb_shadow()->save_area[entry].vsid = mk_vsid_data(ea, flags);
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get_slb_shadow()->save_area[entry].vsid = mk_vsid_data(ea, flags);
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smp_wmb();
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get_slb_shadow()->save_area[entry].esid = mk_esid_data(ea, entry);
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get_slb_shadow()->save_area[entry].esid = mk_esid_data(ea, entry);
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smp_wmb();
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}
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}
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static inline void slb_shadow_clear(unsigned long entry)
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static inline void slb_shadow_clear(unsigned long entry)
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