5 files changed, 279 insertions, 222 deletions

diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index d3f093820bc7..9353adc18956 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -470,18 +470,6 @@ ENTRY(load_switch_stack)
         br.cond.sptk.many b7
 END(load_switch_stack)
 
-GLOBAL_ENTRY(__ia64_syscall)
-        .regstk 6,0,0,0
-        mov r15=in5                             // put syscall number in place
-        break __BREAK_SYSCALL
-        movl r2=errno
-        cmp.eq p6,p7=-1,r10
-        ;;
-(p6)    st4 [r2]=r8
-(p6)    mov r8=-1
-        br.ret.sptk.many rp
-END(__ia64_syscall)
-
 GLOBAL_ENTRY(execve)
         mov r15=__NR_execve                     // put syscall number in place
         break __BREAK_SYSCALL
@@ -637,7 +625,7 @@ END(ia64_ret_from_syscall)
  *            r8-r11: restored (syscall return value(s))
  *               r12: restored (user-level stack pointer)
  *               r13: restored (user-level thread pointer)
- *               r14: cleared
+ *               r14: set to __kernel_syscall_via_epc
  *               r15: restored (syscall #)
  *           r16-r17: cleared
  *               r18: user-level b6
@@ -658,7 +646,7 @@ END(ia64_ret_from_syscall)
  *                pr: restored (user-level pr)
  *                b0: restored (user-level rp)
  *                b6: restored
- *                b7: cleared
+ *                b7: set to __kernel_syscall_via_epc
  *           ar.unat: restored (user-level ar.unat)
  *            ar.pfs: restored (user-level ar.pfs)
  *            ar.rsc: restored (user-level ar.rsc)
@@ -704,72 +692,79 @@ ENTRY(ia64_leave_syscall)
         ;;
 (p6)    ld4 r31=[r18]                           // load current_thread_info()->flags
         ld8 r19=[r2],PT(B6)-PT(LOADRS)          // load ar.rsc value for "loadrs"
-        mov b7=r0               // clear b7
+        nop.i 0
         ;;
-        ld8 r23=[r3],PT(R11)-PT(AR_BSPSTORE)    // load ar.bspstore (may be garbage)
+        mov r16=ar.bsp                          // M2  get existing backing store pointer
         ld8 r18=[r2],PT(R9)-PT(B6)              // load b6
 (p6)    and r15=TIF_WORK_MASK,r31               // any work other than TIF_SYSCALL_TRACE?
         ;;
-        mov r16=ar.bsp                          // M2  get existing backing store pointer
+        ld8 r23=[r3],PT(R11)-PT(AR_BSPSTORE)    // load ar.bspstore (may be garbage)
 (p6)    cmp4.ne.unc p6,p0=r15, r0               // any special work pending?
 (p6)    br.cond.spnt .work_pending_syscall
         ;;
         // start restoring the state saved on the kernel stack (struct pt_regs):
         ld8 r9=[r2],PT(CR_IPSR)-PT(R9)
         ld8 r11=[r3],PT(CR_IIP)-PT(R11)
-        mov f6=f0               // clear f6
+(pNonSys) break 0               //      bug check: we shouldn't be here if pNonSys is TRUE!
         ;;
         invala                  // M0|1 invalidate ALAT
-        rsm psr.i | psr.ic      // M2 initiate turning off of interrupt and interruption collection
-        mov f9=f0               // clear f9
+        rsm psr.i | psr.ic      // M2   turn off interrupts and interruption collection
+        cmp.eq p9,p0=r0,r0      // A    set p9 to indicate that we should restore cr.ifs
 
-        ld8 r29=[r2],16         // load cr.ipsr
-        ld8 r28=[r3],16                 // load cr.iip
-        mov f8=f0               // clear f8
+        ld8 r29=[r2],16         // M0|1 load cr.ipsr
+        ld8 r28=[r3],16         // M0|1 load cr.iip
+        mov r22=r0              // A    clear r22
         ;;
         ld8 r30=[r2],16         // M0|1 load cr.ifs
         ld8 r25=[r3],16         // M0|1 load ar.unat
-        cmp.eq p9,p0=r0,r0      // set p9 to indicate that we should restore cr.ifs
+(pUStk) add r14=IA64_TASK_THREAD_ON_USTACK_OFFSET,r13
         ;;
         ld8 r26=[r2],PT(B0)-PT(AR_PFS)  // M0|1 load ar.pfs
-(pKStk) mov r22=psr             // M2 read PSR now that interrupts are disabled
-        mov f10=f0              // clear f10
+(pKStk) mov r22=psr                     // M2   read PSR now that interrupts are disabled
+        nop 0
         ;;
-        ld8 r21=[r2],PT(AR_RNAT)-PT(B0) // load b0
-        ld8 r27=[r3],PT(PR)-PT(AR_RSC)  // load ar.rsc
-        mov f11=f0              // clear f11
+        ld8 r21=[r2],PT(AR_RNAT)-PT(B0) // M0|1 load b0
+        ld8 r27=[r3],PT(PR)-PT(AR_RSC)  // M0|1 load ar.rsc
+        mov f6=f0                       // F    clear f6
         ;;
-        ld8 r24=[r2],PT(AR_FPSR)-PT(AR_RNAT)    // load ar.rnat (may be garbage)
-        ld8 r31=[r3],PT(R1)-PT(PR)              // load predicates
-(pUStk) add r14=IA64_TASK_THREAD_ON_USTACK_OFFSET,r13
+        ld8 r24=[r2],PT(AR_FPSR)-PT(AR_RNAT)    // M0|1 load ar.rnat (may be garbage)
+        ld8 r31=[r3],PT(R1)-PT(PR)              // M0|1 load predicates
+        mov f7=f0                               // F    clear f7
         ;;
-        ld8 r20=[r2],PT(R12)-PT(AR_FPSR)        // load ar.fpsr
-        ld8.fill r1=[r3],16     // load r1
-(pUStk) mov r17=1
+        ld8 r20=[r2],PT(R12)-PT(AR_FPSR)        // M0|1 load ar.fpsr
+        ld8.fill r1=[r3],16                     // M0|1 load r1
+(pUStk) mov r17=1                               // A
         ;;
-        srlz.d                  // M0  ensure interruption collection is off
-        ld8.fill r13=[r3],16
-        mov f7=f0               // clear f7
+(pUStk) st1 [r14]=r17                           // M2|3
+        ld8.fill r13=[r3],16                    // M0|1
+        mov f8=f0                               // F    clear f8
         ;;
-        ld8.fill r12=[r2]       // restore r12 (sp)
-        mov.m ar.ssd=r0         // M2 clear ar.ssd
-        mov r22=r0              // clear r22
+        ld8.fill r12=[r2]                       // M0|1 restore r12 (sp)
+        ld8.fill r15=[r3]                       // M0|1 restore r15
+        mov b6=r18                              // I0   restore b6
 
-        ld8.fill r15=[r3]       // restore r15
-(pUStk) st1 [r14]=r17
-        addl r3=THIS_CPU(ia64_phys_stacked_size_p8),r0
+        addl r17=THIS_CPU(ia64_phys_stacked_size_p8),r0 // A
+        mov f9=f0                                       // F    clear f9
+(pKStk) br.cond.dpnt.many skip_rbs_switch               // B
+
+        srlz.d                          // M0   ensure interruption collection is off (for cover)
+        shr.u r18=r19,16                // I0|1 get byte size of existing "dirty" partition
+        cover                           // B    add current frame into dirty partition & set cr.ifs
         ;;
-(pUStk) ld4 r17=[r3]            // r17 = cpu_data->phys_stacked_size_p8
-        mov.m ar.csd=r0         // M2 clear ar.csd
-        mov b6=r18              // I0  restore b6
+(pUStk) ld4 r17=[r17]                   // M0|1 r17 = cpu_data->phys_stacked_size_p8
+        mov r19=ar.bsp                  // M2   get new backing store pointer
+        mov f10=f0                      // F    clear f10
+
+        nop.m 0
+        movl r14=__kernel_syscall_via_epc // X
         ;;
-        mov r14=r0              // clear r14
-        shr.u r18=r19,16        // I0|1 get byte size of existing "dirty" partition
-(pKStk) br.cond.dpnt.many skip_rbs_switch
+        mov.m ar.csd=r0                 // M2   clear ar.csd
+        mov.m ar.ccv=r0                 // M2   clear ar.ccv
+        mov b7=r14                      // I0   clear b7 (hint with __kernel_syscall_via_epc)
 
-        mov.m ar.ccv=r0         // clear ar.ccv
-(pNonSys) br.cond.dpnt.many dont_preserve_current_frame
-        br.cond.sptk.many rbs_switch
+        mov.m ar.ssd=r0                 // M2   clear ar.ssd
+        mov f11=f0                      // F    clear f11
+        br.cond.sptk.many rbs_switch    // B
 END(ia64_leave_syscall)
 
 #ifdef CONFIG_IA32_SUPPORT
@@ -885,7 +880,7 @@ GLOBAL_ENTRY(ia64_leave_kernel)
         ldf.fill f7=[r2],PT(F11)-PT(F7)
         ldf.fill f8=[r3],32
         ;;
-        srlz.i                  // ensure interruption collection is off
+        srlz.d  // ensure that inter. collection is off (VHPT is don't care, since text is pinned)
         mov ar.ccv=r15
         ;;
         ldf.fill f11=[r2]
@@ -945,11 +940,10 @@ GLOBAL_ENTRY(ia64_leave_kernel)
          * NOTE: alloc, loadrs, and cover can't be predicated.
          */
 (pNonSys) br.cond.dpnt dont_preserve_current_frame
-
-rbs_switch:
         cover                           // add current frame into dirty partition and set cr.ifs
         ;;
         mov r19=ar.bsp                  // get new backing store pointer
+rbs_switch:
         sub r16=r16,r18                 // krbs = old bsp - size of dirty partition
         cmp.ne p9,p0=r0,r0              // clear p9 to skip restore of cr.ifs
         ;;
@@ -1024,14 +1018,14 @@ rse_clear_invalid:
         mov loc5=0
         mov loc6=0
         mov loc7=0
-(pRecurse) br.call.sptk.few b0=rse_clear_invalid
+(pRecurse) br.call.dptk.few b0=rse_clear_invalid
         ;;
         mov loc8=0
         mov loc9=0
         cmp.ne pReturn,p0=r0,in1        // if recursion count != 0, we need to do a br.ret
         mov loc10=0
         mov loc11=0
-(pReturn) br.ret.sptk.many b0
+(pReturn) br.ret.dptk.many b0
 #endif /* !CONFIG_ITANIUM */
 #       undef pRecurse
 #       undef pReturn
diff --git a/arch/ia64/kernel/fsys.S b/arch/ia64/kernel/fsys.S
index 0d8650f7fce7..f566ff43a389 100644
--- a/arch/ia64/kernel/fsys.S
+++ b/arch/ia64/kernel/fsys.S
@@ -531,91 +531,114 @@ GLOBAL_ENTRY(fsys_bubble_down)
         .altrp b6
         .body
         /*
-         * We get here for syscalls that don't have a lightweight handler.  For those, we
-         * need to bubble down into the kernel and that requires setting up a minimal
-         * pt_regs structure, and initializing the CPU state more or less as if an
-         * interruption had occurred.  To make syscall-restarts work, we setup pt_regs
-         * such that cr_iip points to the second instruction in syscall_via_break.
-         * Decrementing the IP hence will restart the syscall via break and not
-         * decrementing IP will return us to the caller, as usual.  Note that we preserve
-         * the value of psr.pp rather than initializing it from dcr.pp.  This makes it
-         * possible to distinguish fsyscall execution from other privileged execution.
+         * We get here for syscalls that don't have a lightweight
+         * handler.  For those, we need to bubble down into the kernel
+         * and that requires setting up a minimal pt_regs structure,
+         * and initializing the CPU state more or less as if an
+         * interruption had occurred.  To make syscall-restarts work,
+         * we setup pt_regs such that cr_iip points to the second
+         * instruction in syscall_via_break.  Decrementing the IP
+         * hence will restart the syscall via break and not
+         * decrementing IP will return us to the caller, as usual.
+         * Note that we preserve the value of psr.pp rather than
+         * initializing it from dcr.pp.  This makes it possible to
+         * distinguish fsyscall execution from other privileged
+         * execution.
          *
          * On entry:
-         *      - normal fsyscall handler register usage, except that we also have:
+         *      - normal fsyscall handler register usage, except
+         *        that we also have:
          *      - r18: address of syscall entry point
          *      - r21: ar.fpsr
          *      - r26: ar.pfs
          *      - r27: ar.rsc
          *      - r29: psr
+         *
+         * We used to clear some PSR bits here but that requires slow
+         * serialization.  Fortuntely, that isn't really necessary.
+         * The rationale is as follows: we used to clear bits
+         * ~PSR_PRESERVED_BITS in PSR.L.  Since
+         * PSR_PRESERVED_BITS==PSR.{UP,MFL,MFH,PK,DT,PP,SP,RT,IC}, we
+         * ended up clearing PSR.{BE,AC,I,DFL,DFH,DI,DB,SI,TB}.
+         * However,
+         *
+         * PSR.BE : already is turned off in __kernel_syscall_via_epc()
+         * PSR.AC : don't care (kernel normally turns PSR.AC on)
+         * PSR.I  : already turned off by the time fsys_bubble_down gets
+         *          invoked
+         * PSR.DFL: always 0 (kernel never turns it on)
+         * PSR.DFH: don't care --- kernel never touches f32-f127 on its own
+         *          initiative
+         * PSR.DI : always 0 (kernel never turns it on)
+         * PSR.SI : always 0 (kernel never turns it on)
+         * PSR.DB : don't care --- kernel never enables kernel-level
+         *          breakpoints
+         * PSR.TB : must be 0 already; if it wasn't zero on entry to
+         *          __kernel_syscall_via_epc, the branch to fsys_bubble_down
+         *          will trigger a taken branch; the taken-trap-handler then
+         *          converts the syscall into a break-based system-call.
          */
-#       define PSR_PRESERVED_BITS       (IA64_PSR_UP | IA64_PSR_MFL | IA64_PSR_MFH | IA64_PSR_PK \
-                                         | IA64_PSR_DT | IA64_PSR_PP | IA64_PSR_SP | IA64_PSR_RT \
-                                         | IA64_PSR_IC)
         /*
-         * Reading psr.l gives us only bits 0-31, psr.it, and psr.mc.  The rest we have
-         * to synthesize.
+         * Reading psr.l gives us only bits 0-31, psr.it, and psr.mc.
+         * The rest we have to synthesize.
          */
-#       define PSR_ONE_BITS             ((3 << IA64_PSR_CPL0_BIT) | (0x1 << IA64_PSR_RI_BIT) \
+#       define PSR_ONE_BITS             ((3 << IA64_PSR_CPL0_BIT)       \
+                                         | (0x1 << IA64_PSR_RI_BIT)     \
                                          | IA64_PSR_BN | IA64_PSR_I)
 
-        invala
-        movl r8=PSR_ONE_BITS
+        invala                                  // M0|1
+        movl r14=ia64_ret_from_syscall          // X
 
-        mov r25=ar.unat                 // save ar.unat (5 cyc)
-        movl r9=PSR_PRESERVED_BITS
-
-        mov ar.rsc=0                    // set enforced lazy mode, pl 0, little-endian, loadrs=0
-        movl r28=__kernel_syscall_via_break
+        nop.m 0
+        movl r28=__kernel_syscall_via_break     // X    create cr.iip
         ;;
-        mov r23=ar.bspstore             // save ar.bspstore (12 cyc)
-        mov r31=pr                      // save pr (2 cyc)
-        mov r20=r1                      // save caller's gp in r20
+
+        mov r2=r16                              // A    get task addr to addl-addressable register
+        adds r16=IA64_TASK_THREAD_ON_USTACK_OFFSET,r16 // A
+        mov r31=pr                              // I0   save pr (2 cyc)
         ;;
-        mov r2=r16                      // copy current task addr to addl-addressable register
-        and r9=r9,r29
-        mov r19=b6                      // save b6 (2 cyc)
+        st1 [r16]=r0                            // M2|3 clear current->thread.on_ustack flag
+        addl r22=IA64_RBS_OFFSET,r2             // A    compute base of RBS
+        add r3=TI_FLAGS+IA64_TASK_SIZE,r2       // A
         ;;
-        mov psr.l=r9                    // slam the door (17 cyc to srlz.i)
-        or r29=r8,r29                   // construct cr.ipsr value to save
-        addl r22=IA64_RBS_OFFSET,r2     // compute base of RBS
+        ld4 r3=[r3]                             // M0|1 r3 = current_thread_info()->flags
+        lfetch.fault.excl.nt1 [r22]             // M0|1 prefetch register backing-store
+        nop.i 0
         ;;
-        // GAS reports a spurious RAW hazard on the read of ar.rnat because it thinks
-        // we may be reading ar.itc after writing to psr.l.  Avoid that message with
-        // this directive:
-        dv_serialize_data
-        mov.m r24=ar.rnat               // read ar.rnat (5 cyc lat)
-        lfetch.fault.excl.nt1 [r22]
-        adds r16=IA64_TASK_THREAD_ON_USTACK_OFFSET,r2
-
-        // ensure previous insn group is issued before we stall for srlz.i:
+        mov ar.rsc=0                            // M2   set enforced lazy mode, pl 0, LE, loadrs=0
+        nop.m 0
+        nop.i 0
         ;;
-        srlz.i                          // ensure new psr.l has been established
-        /////////////////////////////////////////////////////////////////////////////
-        ////////// from this point on, execution is not interruptible anymore
-        /////////////////////////////////////////////////////////////////////////////
-        addl r1=IA64_STK_OFFSET-IA64_PT_REGS_SIZE,r2    // compute base of memory stack
-        cmp.ne pKStk,pUStk=r0,r0        // set pKStk <- 0, pUStk <- 1
+        mov r23=ar.bspstore                     // M2 (12 cyc) save ar.bspstore
+        mov.m r24=ar.rnat                       // M2 (5 cyc) read ar.rnat (dual-issues!)
+        nop.i 0
         ;;
-        st1 [r16]=r0                    // clear current->thread.on_ustack flag
-        mov ar.bspstore=r22             // switch to kernel RBS
-        mov b6=r18                      // copy syscall entry-point to b6 (7 cyc)
-        add r3=TI_FLAGS+IA64_TASK_SIZE,r2
+        mov ar.bspstore=r22                     // M2 (6 cyc) switch to kernel RBS
+        movl r8=PSR_ONE_BITS                    // X
         ;;
-        ld4 r3=[r3]                             // r2 = current_thread_info()->flags
-        mov r18=ar.bsp                  // save (kernel) ar.bsp (12 cyc)
-        mov ar.rsc=0x3                  // set eager mode, pl 0, little-endian, loadrs=0
-        br.call.sptk.many b7=ia64_syscall_setup
+        mov r25=ar.unat                         // M2 (5 cyc) save ar.unat
+        mov r19=b6                              // I0   save b6 (2 cyc)
+        mov r20=r1                              // A    save caller's gp in r20
         ;;
-        ssm psr.i
-        movl r2=ia64_ret_from_syscall
+        or r29=r8,r29                           // A    construct cr.ipsr value to save
+        mov b6=r18                              // I0   copy syscall entry-point to b6 (7 cyc)
+        addl r1=IA64_STK_OFFSET-IA64_PT_REGS_SIZE,r2 // A compute base of memory stack
+
+        mov r18=ar.bsp                          // M2   save (kernel) ar.bsp (12 cyc)
+        cmp.ne pKStk,pUStk=r0,r0                // A    set pKStk <- 0, pUStk <- 1
+        br.call.sptk.many b7=ia64_syscall_setup // B
         ;;
-        mov rp=r2                               // set the real return addr
-        tbit.z p8,p0=r3,TIF_SYSCALL_TRACE
+        mov ar.rsc=0x3                          // M2   set eager mode, pl 0, LE, loadrs=0
+        mov rp=r14                              // I0   set the real return addr
+        and r3=_TIF_SYSCALL_TRACEAUDIT,r3       // A
         ;;
-(p10)   br.cond.spnt.many ia64_ret_from_syscall // p10==true means out registers are more than 8
-(p8)    br.call.sptk.many b6=b6         // ignore this return addr
-        br.cond.sptk ia64_trace_syscall
+        ssm psr.i                               // M2   we're on kernel stacks now, reenable irqs
+        cmp.eq p8,p0=r3,r0                      // A
+(p10)   br.cond.spnt.many ia64_ret_from_syscall // B    return if bad call-frame or r15 is a NaT
+
+        nop.m 0
+(p8)    br.call.sptk.many b6=b6                 // B    (ignore return address)
+        br.cond.spnt ia64_trace_syscall         // B
 END(fsys_bubble_down)
 
         .rodata
diff --git a/arch/ia64/kernel/gate.S b/arch/ia64/kernel/gate.S
index facf75acdc85..86948ce63e43 100644
--- a/arch/ia64/kernel/gate.S
+++ b/arch/ia64/kernel/gate.S
@@ -72,38 +72,40 @@ GLOBAL_ENTRY(__kernel_syscall_via_epc)
          * bundle get executed.  The remaining code must be safe even if
          * they do not get executed.
          */
-        adds r17=-1024,r15
-        mov r10=0                               // default to successful syscall execution
-        epc
+        adds r17=-1024,r15                      // A
+        mov r10=0                               // A    default to successful syscall execution
+        epc                                     // B    causes split-issue
 }
         ;;
-        rsm psr.be // note: on McKinley "rsm psr.be/srlz.d" is slightly faster than "rum psr.be"
-        LOAD_FSYSCALL_TABLE(r14)
-
-        mov r16=IA64_KR(CURRENT)                // 12 cycle read latency
-        tnat.nz p10,p9=r15
-        mov r19=NR_syscalls-1
+        rsm psr.be | psr.i                      // M2 (5 cyc to srlz.d)
+        LOAD_FSYSCALL_TABLE(r14)                // X
         ;;
-        shladd r18=r17,3,r14
-
-        srlz.d
-        cmp.ne p8,p0=r0,r0                      // p8 <- FALSE
-        /* Note: if r17 is a NaT, p6 will be set to zero.  */
-        cmp.geu p6,p7=r19,r17                   // (syscall > 0 && syscall < 1024+NR_syscalls)?
-        ;;
-(p6)    ld8 r18=[r18]
-        mov r21=ar.fpsr
-        add r14=-8,r14                          // r14 <- addr of fsys_bubble_down entry
-        ;;
-(p6)    mov b7=r18
-(p6)    tbit.z p8,p0=r18,0
-(p8)    br.dptk.many b7
-
-(p6)    rsm psr.i
-        mov r27=ar.rsc
-        mov r26=ar.pfs
+        mov r16=IA64_KR(CURRENT)                // M2 (12 cyc)
+        shladd r18=r17,3,r14                    // A
+        mov r19=NR_syscalls-1                   // A
+        ;;
+        lfetch [r18]                            // M0|1
+        mov r29=psr                             // M2 (12 cyc)
+        // If r17 is a NaT, p6 will be zero
+        cmp.geu p6,p7=r19,r17                   // A    (sysnr > 0 && sysnr < 1024+NR_syscalls)?
+        ;;
+        mov r21=ar.fpsr                         // M2 (12 cyc)
+        tnat.nz p10,p9=r15                      // I0
+        mov.i r26=ar.pfs                        // I0 (would stall anyhow due to srlz.d...)
+        ;;
+        srlz.d                                  // M0 (forces split-issue) ensure PSR.BE==0
+(p6)    ld8 r18=[r18]                           // M0|1
+        nop.i 0
+        ;;
+        nop.m 0
+(p6)    tbit.z.unc p8,p0=r18,0                  // I0 (dual-issues with "mov b7=r18"!)
+        nop.i 0
         ;;
-        mov r29=psr                             // read psr (12 cyc load latency)
+(p8)    ssm psr.i
+(p6)    mov b7=r18                              // I0
+(p8)    br.dptk.many b7                         // B
+
+        mov r27=ar.rsc                          // M2 (12 cyc)
 /*
  * brl.cond doesn't work as intended because the linker would convert this branch
  * into a branch to a PLT.  Perhaps there will be a way to avoid this with some
@@ -111,6 +113,8 @@ GLOBAL_ENTRY(__kernel_syscall_via_epc)
  * instead.
  */
 #ifdef CONFIG_ITANIUM
+(p6)    add r14=-8,r14                          // r14 <- addr of fsys_bubble_down entry
+        ;;
 (p6)    ld8 r14=[r14]                           // r14 <- fsys_bubble_down
         ;;
 (p6)    mov b7=r14
@@ -118,7 +122,7 @@ GLOBAL_ENTRY(__kernel_syscall_via_epc)
 #else
         BRL_COND_FSYS_BUBBLE_DOWN(p6)
 #endif
-
+        ssm psr.i
         mov r10=-1
 (p10)   mov r8=EINVAL
 (p9)    mov r8=ENOSYS
diff --git a/arch/ia64/kernel/ia64_ksyms.c b/arch/ia64/kernel/ia64_ksyms.c
index 7bbf019c9867..01572814abe4 100644
--- a/arch/ia64/kernel/ia64_ksyms.c
+++ b/arch/ia64/kernel/ia64_ksyms.c
@@ -58,9 +58,6 @@ EXPORT_SYMBOL(__strlen_user);
 EXPORT_SYMBOL(__strncpy_from_user);
 EXPORT_SYMBOL(__strnlen_user);
 
-#include <asm/unistd.h>
-EXPORT_SYMBOL(__ia64_syscall);
-
 /* from arch/ia64/lib */
 extern void __divsi3(void);
 extern void __udivsi3(void);
diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S
index d9c05d53435b..386087edabf2 100644
--- a/arch/ia64/kernel/ivt.S
+++ b/arch/ia64/kernel/ivt.S
@@ -1,7 +1,7 @@
 /*
  * arch/ia64/kernel/ivt.S
  *
- * Copyright (C) 1998-2001, 2003 Hewlett-Packard Co
+ * Copyright (C) 1998-2001, 2003, 2005 Hewlett-Packard Co
  *      Stephane Eranian <eranian@hpl.hp.com>
  *      David Mosberger <davidm@hpl.hp.com>
  * Copyright (C) 2000, 2002-2003 Intel Co
@@ -687,82 +687,118 @@ ENTRY(break_fault)
          * to prevent leaking bits from kernel to user level.
          */
         DBG_FAULT(11)
-        mov r16=IA64_KR(CURRENT)                // r16 = current task; 12 cycle read lat.
-        mov r17=cr.iim
-        mov r18=__IA64_BREAK_SYSCALL
-        mov r21=ar.fpsr
-        mov r29=cr.ipsr
-        mov r19=b6
-        mov r25=ar.unat
-        mov r27=ar.rsc
-        mov r26=ar.pfs
-        mov r28=cr.iip
-        mov r31=pr                              // prepare to save predicates
-        mov r20=r1
-        ;;
+        mov.m r16=IA64_KR(CURRENT)              // M2 r16 <- current task (12 cyc)
+        mov r29=cr.ipsr                         // M2 (12 cyc)
+        mov r31=pr                              // I0 (2 cyc)
+
+        mov r17=cr.iim                          // M2 (2 cyc)
+        mov.m r27=ar.rsc                        // M2 (12 cyc)
+        mov r18=__IA64_BREAK_SYSCALL            // A
+
+        mov.m ar.rsc=0                          // M2
+        mov.m r21=ar.fpsr                       // M2 (12 cyc)
+        mov r19=b6                              // I0 (2 cyc)
+        ;;
+        mov.m r23=ar.bspstore                   // M2 (12 cyc)
+        mov.m r24=ar.rnat                       // M2 (5 cyc)
+        mov.i r26=ar.pfs                        // I0 (2 cyc)
+
+        invala                                  // M0|1
+        nop.m 0                                 // M
+        mov r20=r1                              // A                    save r1
+
+        nop.m 0
+        movl r30=sys_call_table                 // X
+
+        mov r28=cr.iip                          // M2 (2 cyc)
+        cmp.eq p0,p7=r18,r17                    // I0 is this a system call?
+(p7)    br.cond.spnt non_syscall                // B  no ->
+        //
+        // From this point on, we are definitely on the syscall-path
+        // and we can use (non-banked) scratch registers.
+        //
+///////////////////////////////////////////////////////////////////////
+        mov r1=r16                              // A    move task-pointer to "addl"-addressable reg
+        mov r2=r16                              // A    setup r2 for ia64_syscall_setup
+        add r9=TI_FLAGS+IA64_TASK_SIZE,r16      // A    r9 = &current_thread_info()->flags
+
         adds r16=IA64_TASK_THREAD_ON_USTACK_OFFSET,r16
-        cmp.eq p0,p7=r18,r17                    // is this a system call? (p7 <- false, if so)
-(p7)    br.cond.spnt non_syscall
+        adds r15=-1024,r15                      // A    subtract 1024 from syscall number
+        mov r3=NR_syscalls - 1
         ;;
-        ld1 r17=[r16]                           // load current->thread.on_ustack flag
-        st1 [r16]=r0                            // clear current->thread.on_ustack flag
-        add r1=-IA64_TASK_THREAD_ON_USTACK_OFFSET,r16   // set r1 for MINSTATE_START_SAVE_MIN_VIRT
+        ld1.bias r17=[r16]                      // M0|1 r17 = current->thread.on_ustack flag
+        ld4 r9=[r9]                             // M0|1 r9 = current_thread_info()->flags
+        extr.u r8=r29,41,2                      // I0   extract ei field from cr.ipsr
+
+        shladd r30=r15,3,r30                    // A    r30 = sys_call_table + 8*(syscall-1024)
+        addl r22=IA64_RBS_OFFSET,r1             // A    compute base of RBS
+        cmp.leu p6,p7=r15,r3                    // A    syscall number in range?
         ;;
-        invala
 
-        /* adjust return address so we skip over the break instruction: */
+        lfetch.fault.excl.nt1 [r22]             // M0|1 prefetch RBS
+(p6)    ld8 r30=[r30]                           // M0|1 load address of syscall entry point
+        tnat.nz.or p7,p0=r15                    // I0   is syscall nr a NaT?
 
-        extr.u r8=r29,41,2                      // extract ei field from cr.ipsr
-        ;;
-        cmp.eq p6,p7=2,r8                       // isr.ei==2?
-        mov r2=r1                               // setup r2 for ia64_syscall_setup
-        ;;
-(p6)    mov r8=0                                // clear ei to 0
-(p6)    adds r28=16,r28                         // switch cr.iip to next bundle cr.ipsr.ei wrapped
-(p7)    adds r8=1,r8                            // increment ei to next slot
-        ;;
-        cmp.eq pKStk,pUStk=r0,r17               // are we in kernel mode already?
-        dep r29=r8,r29,41,2                     // insert new ei into cr.ipsr
+        mov.m ar.bspstore=r22                   // M2   switch to kernel RBS
+        cmp.eq p8,p9=2,r8                       // A    isr.ei==2?
         ;;
 
-        // switch from user to kernel RBS:
-        MINSTATE_START_SAVE_MIN_VIRT
-        br.call.sptk.many b7=ia64_syscall_setup
-        ;;
-        MINSTATE_END_SAVE_MIN_VIRT              // switch to bank 1
-        ssm psr.ic | PSR_DEFAULT_BITS
-        ;;
-        srlz.i                                  // guarantee that interruption collection is on
-        mov r3=NR_syscalls - 1
-        ;;
-(p15)   ssm psr.i                               // restore psr.i
-        // p10==true means out registers are more than 8 or r15's Nat is true
-(p10)   br.cond.spnt.many ia64_ret_from_syscall
-        ;;
-        movl r16=sys_call_table
+(p8)    mov r8=0                                // A    clear ei to 0
+(p7)    movl r30=sys_ni_syscall                 // X
 
-        adds r15=-1024,r15                      // r15 contains the syscall number---subtract 1024
-        movl r2=ia64_ret_from_syscall
-        ;;
-        shladd r20=r15,3,r16                    // r20 = sys_call_table + 8*(syscall-1024)
-        cmp.leu p6,p7=r15,r3                    // (syscall > 0 && syscall < 1024 + NR_syscalls) ?
-        mov rp=r2                               // set the real return addr
+(p8)    adds r28=16,r28                         // A    switch cr.iip to next bundle
+(p9)    adds r8=1,r8                            // A    increment ei to next slot
+        nop.i 0
         ;;
-(p6)    ld8 r20=[r20]                           // load address of syscall entry point
-(p7)    movl r20=sys_ni_syscall
 
-        add r2=TI_FLAGS+IA64_TASK_SIZE,r13
-        ;;
-        ld4 r2=[r2]                             // r2 = current_thread_info()->flags
-        ;;
-        and r2=_TIF_SYSCALL_TRACEAUDIT,r2       // mask trace or audit
+        mov.m r25=ar.unat                       // M2 (5 cyc)
+        dep r29=r8,r29,41,2                     // I0   insert new ei into cr.ipsr
+        adds r15=1024,r15                       // A    restore original syscall number
+        //
+        // If any of the above loads miss in L1D, we'll stall here until
+        // the data arrives.
+        //
+///////////////////////////////////////////////////////////////////////
+        st1 [r16]=r0                            // M2|3 clear current->thread.on_ustack flag
+        mov b6=r30                              // I0   setup syscall handler branch reg early
+        cmp.eq pKStk,pUStk=r0,r17               // A    were we on kernel stacks already?
+
+        and r9=_TIF_SYSCALL_TRACEAUDIT,r9       // A    mask trace or audit
+        mov r18=ar.bsp                          // M2 (12 cyc)
+(pKStk) br.cond.spnt .break_fixup               // B    we're already in kernel-mode -- fix up RBS
+        ;;
+.back_from_break_fixup:
+(pUStk) addl r1=IA64_STK_OFFSET-IA64_PT_REGS_SIZE,r1 // A    compute base of memory stack
+        cmp.eq p14,p0=r9,r0                     // A    are syscalls being traced/audited?
+        br.call.sptk.many b7=ia64_syscall_setup // B
+1:
+        mov ar.rsc=0x3                          // M2   set eager mode, pl 0, LE, loadrs=0
+        nop 0
+        bsw.1                                   // B (6 cyc) regs are saved, switch to bank 1
         ;;
-        cmp.eq p8,p0=r2,r0
-        mov b6=r20
+
+        ssm psr.ic | PSR_DEFAULT_BITS           // M2   now it's safe to re-enable intr.-collection
+        movl r3=ia64_ret_from_syscall           // X
         ;;
-(p8)    br.call.sptk.many b6=b6                 // ignore this return addr
-        br.cond.sptk ia64_trace_syscall
+
+        srlz.i                                  // M0   ensure interruption collection is on
+        mov rp=r3                               // I0   set the real return addr
+(p10)   br.cond.spnt.many ia64_ret_from_syscall // B    return if bad call-frame or r15 is a NaT
+
+(p15)   ssm psr.i                               // M2   restore psr.i
+(p14)   br.call.sptk.many b6=b6                 // B    invoke syscall-handker (ignore return addr)
+        br.cond.spnt.many ia64_trace_syscall    // B    do syscall-tracing thingamagic
         // NOT REACHED
+///////////////////////////////////////////////////////////////////////
+        // On entry, we optimistically assumed that we're coming from user-space.
+        // For the rare cases where a system-call is done from within the kernel,
+        // we fix things up at this point:
+.break_fixup:
+        add r1=-IA64_PT_REGS_SIZE,sp            // A    allocate space for pt_regs structure
+        mov ar.rnat=r24                         // M2   restore kernel's AR.RNAT
+        ;;
+        mov ar.bspstore=r23                     // M2   restore kernel's AR.BSPSTORE
+        br.cond.sptk .back_from_break_fixup
 END(break_fault)
 
         .org ia64_ivt+0x3000
@@ -837,8 +873,6 @@ END(interrupt)
          *      - r31: saved pr
          *      -  b0: original contents (to be saved)
          * On exit:
-         *      - executing on bank 1 registers
-         *      - psr.ic enabled, interrupts restored
          *      -  p10: TRUE if syscall is invoked with more than 8 out
          *              registers or r15's Nat is true
          *      -  r1: kernel's gp
@@ -846,8 +880,11 @@ END(interrupt)
          *      -  r8: -EINVAL if p10 is true
          *      - r12: points to kernel stack
          *      - r13: points to current task
+         *      - r14: preserved (same as on entry)
+         *      - p13: preserved
          *      - p15: TRUE if interrupts need to be re-enabled
          *      - ar.fpsr: set to kernel settings
+         *      -  b6: preserved (same as on entry)
          */
 GLOBAL_ENTRY(ia64_syscall_setup)
 #if PT(B6) != 0
@@ -915,10 +952,10 @@ GLOBAL_ENTRY(ia64_syscall_setup)
 (p13)   mov in5=-1
         ;;
         st8 [r16]=r21,PT(R8)-PT(AR_FPSR)        // save ar.fpsr
-        tnat.nz p14,p0=in6
+        tnat.nz p13,p0=in6
         cmp.lt p10,p9=r11,r8    // frame size can't be more than local+8
         ;;
-        stf8 [r16]=f1           // ensure pt_regs.r8 != 0 (see handle_syscall_error)
+        mov r8=1
 (p9)    tnat.nz p10,p0=r15
         adds r12=-16,r1         // switch to kernel memory stack (with 16 bytes of scratch)
 
@@ -929,9 +966,9 @@ GLOBAL_ENTRY(ia64_syscall_setup)
         mov r13=r2                              // establish `current'
         movl r1=__gp                            // establish kernel global pointer
         ;;
-(p14)   mov in6=-1
+        st8 [r16]=r8            // ensure pt_regs.r8 != 0 (see handle_syscall_error)
+(p13)   mov in6=-1
 (p8)    mov in7=-1
-        nop.i 0
 
         cmp.eq pSys,pNonSys=r0,r0               // set pSys=1, pNonSys=0
         movl r17=FPSR_DEFAULT
@@ -1002,6 +1039,8 @@ END(dispatch_illegal_op_fault)
         FAULT(17)
 
 ENTRY(non_syscall)
+        mov ar.rsc=r27                  // restore ar.rsc before SAVE_MIN_WITH_COVER
+        ;;
         SAVE_MIN_WITH_COVER
 
         // There is no particular reason for this code to be here, other than that