2 files changed, 90 insertions, 11 deletions

diff --git a/arch/ia64/kernel/mca_asm.S b/arch/ia64/kernel/mca_asm.S
index 499a065f4e60..db32fc1d3935 100644
--- a/arch/ia64/kernel/mca_asm.S
+++ b/arch/ia64/kernel/mca_asm.S
@@ -489,24 +489,27 @@ ia64_state_save:
         ;;
         st8 [temp1]=r17,16      // pal_min_state
         st8 [temp2]=r6,16       // prev_IA64_KR_CURRENT
+        mov r6=IA64_KR(CURRENT_STACK)
+        ;;
+        st8 [temp1]=r6,16       // prev_IA64_KR_CURRENT_STACK
+        st8 [temp2]=r0,16       // prev_task, starts off as NULL
         mov r6=cr.ifa
         ;;
-        st8 [temp1]=r0,16       // prev_task, starts off as NULL
-        st8 [temp2]=r12,16      // cr.isr
+        st8 [temp1]=r12,16      // cr.isr
+        st8 [temp2]=r6,16       // cr.ifa
         mov r12=cr.itir
         ;;
-        st8 [temp1]=r6,16       // cr.ifa
-        st8 [temp2]=r12,16      // cr.itir
+        st8 [temp1]=r12,16      // cr.itir
+        st8 [temp2]=r11,16      // cr.iipa
         mov r12=cr.iim
         ;;
-        st8 [temp1]=r11,16      // cr.iipa
-        st8 [temp2]=r12,16      // cr.iim
-        mov r6=cr.iha
+        st8 [temp1]=r12,16      // cr.iim
 (p1)    mov r12=IA64_MCA_COLD_BOOT
 (p2)    mov r12=IA64_INIT_WARM_BOOT
+        mov r6=cr.iha
         ;;
-        st8 [temp1]=r6,16       // cr.iha
-        st8 [temp2]=r12         // os_status, default is cold boot
+        st8 [temp2]=r6,16       // cr.iha
+        st8 [temp1]=r12         // os_status, default is cold boot
         mov r6=IA64_MCA_SAME_CONTEXT
         ;;
         st8 [temp1]=r6          // context, default is same context
@@ -823,9 +826,12 @@ ia64_state_restore:
         ld8 r12=[temp1],16      // sal_ra
         ld8 r9=[temp2],16       // sal_gp
         ;;
-        ld8 r22=[temp1],24      // pal_min_state, virtual.  skip prev_task
+        ld8 r22=[temp1],16      // pal_min_state, virtual
         ld8 r21=[temp2],16      // prev_IA64_KR_CURRENT
         ;;
+        ld8 r16=[temp1],16      // prev_IA64_KR_CURRENT_STACK
+        ld8 r20=[temp2],16      // prev_task
+        ;;
         ld8 temp3=[temp1],16    // cr.isr
         ld8 temp4=[temp2],16    // cr.ifa
         ;;
@@ -846,6 +852,45 @@ ia64_state_restore:
         ld8 r8=[temp1]          // os_status
         ld8 r10=[temp2]         // context
 
+        /* Wire IA64_TR_CURRENT_STACK to the stack that we are resuming to.  To
+         * avoid any dependencies on the algorithm in ia64_switch_to(), just
+         * purge any existing CURRENT_STACK mapping and insert the new one.
+         *
+         * r16 contains prev_IA64_KR_CURRENT_STACK, r21 contains
+         * prev_IA64_KR_CURRENT, these values may have been changed by the C
+         * code.  Do not use r8, r9, r10, r22, they contain values ready for
+         * the return to SAL.
+         */
+
+        mov r15=IA64_KR(CURRENT_STACK)          // physical granule mapped by IA64_TR_CURRENT_STACK
+        ;;
+        shl r15=r15,IA64_GRANULE_SHIFT
+        ;;
+        dep r15=-1,r15,61,3                     // virtual granule
+        mov r18=IA64_GRANULE_SHIFT<<2           // for cr.itir.ps
+        ;;
+        ptr.d r15,r18
+        ;;
+        srlz.d
+
+        extr.u r19=r21,61,3                     // r21 = prev_IA64_KR_CURRENT
+        shl r20=r16,IA64_GRANULE_SHIFT          // r16 = prev_IA64_KR_CURRENT_STACK
+        movl r21=PAGE_KERNEL                    // page properties
+        ;;
+        mov IA64_KR(CURRENT_STACK)=r16
+        cmp.ne p6,p0=RGN_KERNEL,r19             // new stack is in the kernel region?
+        or r21=r20,r21                          // construct PA | page properties
+(p6)    br.spnt 1f                              // the dreaded cpu 0 idle task in region 5:(
+        ;;
+        mov cr.itir=r18
+        mov cr.ifa=r21
+        mov r20=IA64_TR_CURRENT_STACK
+        ;;
+        itr.d dtr[r20]=r21
+        ;;
+        srlz.d
+1:
+
         br.sptk b0
 
 //EndStub//////////////////////////////////////////////////////////////////////
@@ -982,6 +1027,7 @@ ia64_set_kernel_registers:
         add temp4=temp4, temp1  // &struct ia64_sal_os_state.os_gp
         add r12=temp1, temp3    // kernel stack pointer on MCA/INIT stack
         add r13=temp1, r3       // set current to start of MCA/INIT stack
+        add r20=temp1, r3       // physical start of MCA/INIT stack
         ;;
         ld8 r1=[temp4]          // OS GP from SAL OS state
         ;;
@@ -991,7 +1037,35 @@ ia64_set_kernel_registers:
         ;;
         mov IA64_KR(CURRENT)=r13
 
-        // FIXME: do I need to wire IA64_KR_CURRENT_STACK and IA64_TR_CURRENT_STACK?
+        /* Wire IA64_TR_CURRENT_STACK to the MCA/INIT handler stack.  To avoid
+         * any dependencies on the algorithm in ia64_switch_to(), just purge
+         * any existing CURRENT_STACK mapping and insert the new one.
+         */
+
+        mov r16=IA64_KR(CURRENT_STACK)          // physical granule mapped by IA64_TR_CURRENT_STACK
+        ;;
+        shl r16=r16,IA64_GRANULE_SHIFT
+        ;;
+        dep r16=-1,r16,61,3                     // virtual granule
+        mov r18=IA64_GRANULE_SHIFT<<2           // for cr.itir.ps
+        ;;
+        ptr.d r16,r18
+        ;;
+        srlz.d
+
+        shr.u r16=r20,IA64_GRANULE_SHIFT        // r20 = physical start of MCA/INIT stack
+        movl r21=PAGE_KERNEL                    // page properties
+        ;;
+        mov IA64_KR(CURRENT_STACK)=r16
+        or r21=r20,r21                          // construct PA | page properties
+        ;;
+        mov cr.itir=r18
+        mov cr.ifa=r13
+        mov r20=IA64_TR_CURRENT_STACK
+        ;;
+        itr.d dtr[r20]=r21
+        ;;
+        srlz.d
 
         br.sptk b0
 
diff --git a/include/asm-ia64/mca.h b/include/asm-ia64/mca.h
index 97a28b8b2ddd..c7d9c9ed38ba 100644
--- a/include/asm-ia64/mca.h
+++ b/include/asm-ia64/mca.h
@@ -80,7 +80,12 @@ struct ia64_sal_os_state {
         u64                     sal_ra;                 /* Return address in SAL, physical */
         u64                     sal_gp;                 /* GP of the SAL - physical */
         pal_min_state_area_t    *pal_min_state;         /* from R17.  physical in asm, virtual in C */
+        /* Previous values of IA64_KR(CURRENT) and IA64_KR(CURRENT_STACK).
+         * Note: if the MCA/INIT recovery code wants to resume to a new context
+         * then it must change these values to reflect the new kernel stack.
+         */
         u64                     prev_IA64_KR_CURRENT;   /* previous value of IA64_KR(CURRENT) */
+        u64                     prev_IA64_KR_CURRENT_STACK;
         struct task_struct      *prev_task;             /* previous task, NULL if it is not useful */
         /* Some interrupt registers are not saved in minstate, pt_regs or
          * switch_stack.  Because MCA/INIT can occur when interrupts are