1 files changed, 71 insertions, 62 deletions

diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S
index c71c79262a48..301f2e9d262e 100644
--- a/arch/ia64/kernel/ivt.S
+++ b/arch/ia64/kernel/ivt.S
@@ -91,16 +91,17 @@ ENTRY(vhpt_miss)
          * (the "original") TLB miss, which may either be caused by an instruction
          * fetch or a data access (or non-access).
          *
-         * What we do here is normal TLB miss handing for the _original_ miss, followed
-         * by inserting the TLB entry for the virtual page table page that the VHPT
-         * walker was attempting to access.  The latter gets inserted as long
-         * as both L1 and L2 have valid mappings for the faulting address.
-         * The TLB entry for the original miss gets inserted only if
-         * the L3 entry indicates that the page is present.
+         * What we do here is normal TLB miss handing for the _original_ miss,
+         * followed by inserting the TLB entry for the virtual page table page
+         * that the VHPT walker was attempting to access.  The latter gets
+         * inserted as long as page table entry above pte level have valid
+         * mappings for the faulting address.  The TLB entry for the original
+         * miss gets inserted only if the pte entry indicates that the page is
+         * present.
          *
          * do_page_fault gets invoked in the following cases:
          *      - the faulting virtual address uses unimplemented address bits
-         *      - the faulting virtual address has no L1, L2, or L3 mapping
+         *      - the faulting virtual address has no valid page table mapping
          */
         mov r16=cr.ifa                          // get address that caused the TLB miss
 #ifdef CONFIG_HUGETLB_PAGE
@@ -126,7 +127,7 @@ ENTRY(vhpt_miss)
 #endif
         ;;
         cmp.eq p6,p7=5,r17                      // is IFA pointing into to region 5?
-        shr.u r18=r22,PGDIR_SHIFT               // get bits 33-63 of the faulting address
+        shr.u r18=r22,PGDIR_SHIFT               // get bottom portion of pgd index bit
         ;;
 (p7)    dep r17=r17,r19,(PAGE_SHIFT-3),3        // put region number bits in place
 
@@ -137,38 +138,38 @@ ENTRY(vhpt_miss)
 (p6)    shr.u r21=r21,PGDIR_SHIFT+PAGE_SHIFT
 (p7)    shr.u r21=r21,PGDIR_SHIFT+PAGE_SHIFT-3
         ;;
-(p6)    dep r17=r18,r19,3,(PAGE_SHIFT-3)        // r17=PTA + IFA(33,42)*8
-(p7)    dep r17=r18,r17,3,(PAGE_SHIFT-6)        // r17=PTA + (((IFA(61,63) << 7) | IFA(33,39))*8)
+(p6)    dep r17=r18,r19,3,(PAGE_SHIFT-3)        // r17=pgd_offset for region 5
+(p7)    dep r17=r18,r17,3,(PAGE_SHIFT-6)        // r17=pgd_offset for region[0-4]
         cmp.eq p7,p6=0,r21                      // unused address bits all zeroes?
 #ifdef CONFIG_PGTABLE_4
-        shr.u r28=r22,PUD_SHIFT                 // shift L2 index into position
+        shr.u r28=r22,PUD_SHIFT                 // shift pud index into position
 #else
-        shr.u r18=r22,PMD_SHIFT                 // shift L3 index into position
+        shr.u r18=r22,PMD_SHIFT                 // shift pmd index into position
 #endif
         ;;
-        ld8 r17=[r17]                           // fetch the L1 entry (may be 0)
+        ld8 r17=[r17]                           // get *pgd (may be 0)
         ;;
-(p7)    cmp.eq p6,p7=r17,r0                     // was L1 entry NULL?
+(p7)    cmp.eq p6,p7=r17,r0                     // was pgd_present(*pgd) == NULL?
 #ifdef CONFIG_PGTABLE_4
-        dep r28=r28,r17,3,(PAGE_SHIFT-3)        // compute address of L2 page table entry
+        dep r28=r28,r17,3,(PAGE_SHIFT-3)        // r28=pud_offset(pgd,addr)
         ;;
-        shr.u r18=r22,PMD_SHIFT                 // shift L3 index into position
-(p7)    ld8 r29=[r28]                           // fetch the L2 entry (may be 0)
+        shr.u r18=r22,PMD_SHIFT                 // shift pmd index into position
+(p7)    ld8 r29=[r28]                           // get *pud (may be 0)
         ;;
-(p7)    cmp.eq.or.andcm p6,p7=r29,r0            // was L2 entry NULL?
-        dep r17=r18,r29,3,(PAGE_SHIFT-3)        // compute address of L3 page table entry
+(p7)    cmp.eq.or.andcm p6,p7=r29,r0            // was pud_present(*pud) == NULL?
+        dep r17=r18,r29,3,(PAGE_SHIFT-3)        // r17=pmd_offset(pud,addr)
 #else
-        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // compute address of L3 page table entry
+        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // r17=pmd_offset(pgd,addr)
 #endif
         ;;
-(p7)    ld8 r20=[r17]                           // fetch the L3 entry (may be 0)
-        shr.u r19=r22,PAGE_SHIFT                // shift L4 index into position
+(p7)    ld8 r20=[r17]                           // get *pmd (may be 0)
+        shr.u r19=r22,PAGE_SHIFT                // shift pte index into position
         ;;
-(p7)    cmp.eq.or.andcm p6,p7=r20,r0            // was L3 entry NULL?
-        dep r21=r19,r20,3,(PAGE_SHIFT-3)        // compute address of L4 page table entry
+(p7)    cmp.eq.or.andcm p6,p7=r20,r0            // was pmd_present(*pmd) == NULL?
+        dep r21=r19,r20,3,(PAGE_SHIFT-3)        // r21=pte_offset(pmd,addr)
         ;;
-(p7)    ld8 r18=[r21]                           // read the L4 PTE
-        mov r19=cr.isr                          // cr.isr bit 0 tells us if this is an insn miss
+(p7)    ld8 r18=[r21]                           // read *pte
+        mov r19=cr.isr                          // cr.isr bit 32 tells us if this is an insn miss
         ;;
 (p7)    tbit.z p6,p7=r18,_PAGE_P_BIT            // page present bit cleared?
         mov r22=cr.iha                          // get the VHPT address that caused the TLB miss
@@ -202,25 +203,33 @@ ENTRY(vhpt_miss)
         dv_serialize_data
 
         /*
-         * Re-check L2 and L3 pagetable.  If they changed, we may have received a ptc.g
+         * Re-check pagetable entry.  If they changed, we may have received a ptc.g
          * between reading the pagetable and the "itc".  If so, flush the entry we
-         * inserted and retry.
+         * inserted and retry.  At this point, we have:
+         *
+         * r28 = equivalent of pud_offset(pgd, ifa)
+         * r17 = equivalent of pmd_offset(pud, ifa)
+         * r21 = equivalent of pte_offset(pmd, ifa)
+         *
+         * r29 = *pud
+         * r20 = *pmd
+         * r18 = *pte
          */
-        ld8 r25=[r21]                           // read L4 entry again
-        ld8 r26=[r17]                           // read L3 PTE again
+        ld8 r25=[r21]                           // read *pte again
+        ld8 r26=[r17]                           // read *pmd again
 #ifdef CONFIG_PGTABLE_4
-        ld8 r19=[r28]                           // read L2 entry again
+        ld8 r19=[r28]                           // read *pud again
 #endif
         cmp.ne p6,p7=r0,r0
         ;;
-        cmp.ne.or.andcm p6,p7=r26,r20           // did L3 entry change
+        cmp.ne.or.andcm p6,p7=r26,r20           // did *pmd change
 #ifdef CONFIG_PGTABLE_4
-        cmp.ne.or.andcm p6,p7=r19,r29           // did L4 PTE change
+        cmp.ne.or.andcm p6,p7=r19,r29           // did *pud change
 #endif
         mov r27=PAGE_SHIFT<<2
         ;;
 (p6)    ptc.l r22,r27                           // purge PTE page translation
-(p7)    cmp.ne.or.andcm p6,p7=r25,r18           // did L4 PTE change
+(p7)    cmp.ne.or.andcm p6,p7=r25,r18           // did *pte change
         ;;
 (p6)    ptc.l r16,r27                           // purge translation
 #endif
@@ -235,19 +244,19 @@ END(vhpt_miss)
 ENTRY(itlb_miss)
         DBG_FAULT(1)
         /*
-         * The ITLB handler accesses the L3 PTE via the virtually mapped linear
+         * The ITLB handler accesses the PTE via the virtually mapped linear
          * page table.  If a nested TLB miss occurs, we switch into physical
-         * mode, walk the page table, and then re-execute the L3 PTE read
-         * and go on normally after that.
+         * mode, walk the page table, and then re-execute the PTE read and
+         * go on normally after that.
          */
         mov r16=cr.ifa                          // get virtual address
         mov r29=b0                              // save b0
         mov r31=pr                              // save predicates
 .itlb_fault:
-        mov r17=cr.iha                          // get virtual address of L3 PTE
+        mov r17=cr.iha                          // get virtual address of PTE
         movl r30=1f                             // load nested fault continuation point
         ;;
-1:      ld8 r18=[r17]                           // read L3 PTE
+1:      ld8 r18=[r17]                           // read *pte
         ;;
         mov b0=r29
         tbit.z p6,p0=r18,_PAGE_P_BIT            // page present bit cleared?
@@ -262,7 +271,7 @@ ENTRY(itlb_miss)
          */
         dv_serialize_data
 
-        ld8 r19=[r17]                           // read L3 PTE again and see if same
+        ld8 r19=[r17]                           // read *pte again and see if same
         mov r20=PAGE_SHIFT<<2                   // setup page size for purge
         ;;
         cmp.ne p7,p0=r18,r19
@@ -279,19 +288,19 @@ END(itlb_miss)
 ENTRY(dtlb_miss)
         DBG_FAULT(2)
         /*
-         * The DTLB handler accesses the L3 PTE via the virtually mapped linear
+         * The DTLB handler accesses the PTE via the virtually mapped linear
          * page table.  If a nested TLB miss occurs, we switch into physical
-         * mode, walk the page table, and then re-execute the L3 PTE read
-         * and go on normally after that.
+         * mode, walk the page table, and then re-execute the PTE read and
+         * go on normally after that.
          */
         mov r16=cr.ifa                          // get virtual address
         mov r29=b0                              // save b0
         mov r31=pr                              // save predicates
 dtlb_fault:
-        mov r17=cr.iha                          // get virtual address of L3 PTE
+        mov r17=cr.iha                          // get virtual address of PTE
         movl r30=1f                             // load nested fault continuation point
         ;;
-1:      ld8 r18=[r17]                           // read L3 PTE
+1:      ld8 r18=[r17]                           // read *pte
         ;;
         mov b0=r29
         tbit.z p6,p0=r18,_PAGE_P_BIT            // page present bit cleared?
@@ -306,7 +315,7 @@ dtlb_fault:
          */
         dv_serialize_data
 
-        ld8 r19=[r17]                           // read L3 PTE again and see if same
+        ld8 r19=[r17]                           // read *pte again and see if same
         mov r20=PAGE_SHIFT<<2                   // setup page size for purge
         ;;
         cmp.ne p7,p0=r18,r19
@@ -420,7 +429,7 @@ ENTRY(nested_dtlb_miss)
          *              r30:    continuation address
          *              r31:    saved pr
          *
-         * Output:      r17:    physical address of L3 PTE of faulting address
+         * Output:      r17:    physical address of PTE of faulting address
          *              r29:    saved b0
          *              r30:    continuation address
          *              r31:    saved pr
@@ -450,33 +459,33 @@ ENTRY(nested_dtlb_miss)
 (p6)    shr.u r21=r21,PGDIR_SHIFT+PAGE_SHIFT
 (p7)    shr.u r21=r21,PGDIR_SHIFT+PAGE_SHIFT-3
         ;;
-(p6)    dep r17=r18,r19,3,(PAGE_SHIFT-3)        // r17=PTA + IFA(33,42)*8
-(p7)    dep r17=r18,r17,3,(PAGE_SHIFT-6)        // r17=PTA + (((IFA(61,63) << 7) | IFA(33,39))*8)
+(p6)    dep r17=r18,r19,3,(PAGE_SHIFT-3)        // r17=pgd_offset for region 5
+(p7)    dep r17=r18,r17,3,(PAGE_SHIFT-6)        // r17=pgd_offset for region[0-4]
         cmp.eq p7,p6=0,r21                      // unused address bits all zeroes?
 #ifdef CONFIG_PGTABLE_4
-        shr.u r18=r22,PUD_SHIFT                 // shift L2 index into position
+        shr.u r18=r22,PUD_SHIFT                 // shift pud index into position
 #else
-        shr.u r18=r22,PMD_SHIFT                 // shift L3 index into position
+        shr.u r18=r22,PMD_SHIFT                 // shift pmd index into position
 #endif
         ;;
-        ld8 r17=[r17]                           // fetch the L1 entry (may be 0)
+        ld8 r17=[r17]                           // get *pgd (may be 0)
         ;;
-(p7)    cmp.eq p6,p7=r17,r0                     // was L1 entry NULL?
-        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // compute address of L2 page table entry
+(p7)    cmp.eq p6,p7=r17,r0                     // was pgd_present(*pgd) == NULL?
+        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // r17=p[u|m]d_offset(pgd,addr)
         ;;
 #ifdef CONFIG_PGTABLE_4
-(p7)    ld8 r17=[r17]                           // fetch the L2 entry (may be 0)
-        shr.u r18=r22,PMD_SHIFT                 // shift L3 index into position
+(p7)    ld8 r17=[r17]                           // get *pud (may be 0)
+        shr.u r18=r22,PMD_SHIFT                 // shift pmd index into position
         ;;
-(p7)    cmp.eq.or.andcm p6,p7=r17,r0            // was L2 entry NULL?
-        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // compute address of L2 page table entry
+(p7)    cmp.eq.or.andcm p6,p7=r17,r0            // was pud_present(*pud) == NULL?
+        dep r17=r18,r17,3,(PAGE_SHIFT-3)        // r17=pmd_offset(pud,addr)
         ;;
 #endif
-(p7)    ld8 r17=[r17]                           // fetch the L3 entry (may be 0)
-        shr.u r19=r22,PAGE_SHIFT                // shift L4 index into position
+(p7)    ld8 r17=[r17]                           // get *pmd (may be 0)
+        shr.u r19=r22,PAGE_SHIFT                // shift pte index into position
         ;;
-(p7)    cmp.eq.or.andcm p6,p7=r17,r0            // was L3 entry NULL?
-        dep r17=r19,r17,3,(PAGE_SHIFT-3)        // compute address of L4 page table entry
+(p7)    cmp.eq.or.andcm p6,p7=r17,r0            // was pmd_present(*pmd) == NULL?
+        dep r17=r19,r17,3,(PAGE_SHIFT-3)        // r17=pte_offset(pmd,addr);
 (p6)    br.cond.spnt page_fault
         mov b0=r30
         br.sptk.many b0                         // return to continuation point