[POWERPC] Lazy interrupt disabling for 64-bit machines

This implements a lazy strategy for disabling interrupts.  This means
that local_irq_disable() et al. just clear the 'interrupts are
enabled' flag in the paca.  If an interrupt comes along, the interrupt
entry code notices that interrupts are supposed to be disabled, and
clears the EE bit in SRR1, clears the 'interrupts are hard-enabled'
flag in the paca, and returns.  This means that interrupts only
actually get disabled in the processor when an interrupt comes along.

When interrupts are enabled by local_irq_enable() et al., the code
sets the interrupts-enabled flag in the paca, and then checks whether
interrupts got hard-disabled.  If so, it also sets the EE bit in the
MSR to hard-enable the interrupts.

This has the potential to improve performance, and also makes it
easier to make a kernel that can boot on iSeries and on other 64-bit
machines, since this lazy-disable strategy is very similar to the
soft-disable strategy that iSeries already uses.

This version renames paca->proc_enabled to paca->soft_enabled, and
changes a couple of soft-disables in the kexec code to hard-disables,
which should fix the crash that Michael Ellerman saw.  This doesn't
yet use a reserved CR field for the soft_enabled and hard_enabled
flags.  This applies on top of Stephen Rothwell's patches to make it
possible to build a combined iSeries/other kernel.

Signed-off-by: Paul Mackerras <paulus@samba.org>

12 files changed, 160 insertions, 111 deletions

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index d06f378597bb..e96521530d21 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -118,7 +118,8 @@ int main(void)
         DEFINE(PACASTABRR, offsetof(struct paca_struct, stab_rr));
         DEFINE(PACAR1, offsetof(struct paca_struct, saved_r1));
         DEFINE(PACATOC, offsetof(struct paca_struct, kernel_toc));
-        DEFINE(PACAPROCENABLED, offsetof(struct paca_struct, proc_enabled));
+        DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
+        DEFINE(PACAHARDIRQEN, offsetof(struct paca_struct, hard_enabled));
         DEFINE(PACASLBCACHE, offsetof(struct paca_struct, slb_cache));
         DEFINE(PACASLBCACHEPTR, offsetof(struct paca_struct, slb_cache_ptr));
         DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
diff --git a/arch/powerpc/kernel/crash.c b/arch/powerpc/kernel/crash.c
index 1af41f7616dc..89b03c8da9d2 100644
--- a/arch/powerpc/kernel/crash.c
+++ b/arch/powerpc/kernel/crash.c
@@ -111,7 +111,7 @@ void crash_ipi_callback(struct pt_regs *regs)
         if (!cpu_online(cpu))
                 return;
 
-        local_irq_disable();
+        hard_irq_disable();
         if (!cpu_isset(cpu, cpus_in_crash))
                 crash_save_this_cpu(regs, cpu);
         cpu_set(cpu, cpus_in_crash);
@@ -289,7 +289,7 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
          * an SMP system.
          * The kernel is broken so disable interrupts.
          */
-        local_irq_disable();
+        hard_irq_disable();
 
         for_each_irq(irq) {
                 struct irq_desc *desc = irq_desc + irq;
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 748e74fcf541..efda48741b29 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -87,6 +87,10 @@ system_call_common:
         addi    r9,r1,STACK_FRAME_OVERHEAD
         ld      r11,exception_marker@toc(r2)
         std     r11,-16(r9)             /* "regshere" marker */
+        li      r10,1
+        stb     r10,PACASOFTIRQEN(r13)
+        stb     r10,PACAHARDIRQEN(r13)
+        std     r10,SOFTE(r1)
 #ifdef CONFIG_PPC_ISERIES
 BEGIN_FW_FTR_SECTION
         /* Hack for handling interrupts when soft-enabling on iSeries */
@@ -94,8 +98,6 @@ BEGIN_FW_FTR_SECTION
         andi.   r10,r12,MSR_PR          /* from kernel */
         crand   4*cr0+eq,4*cr1+eq,4*cr0+eq
         beq     hardware_interrupt_entry
-        lbz     r10,PACAPROCENABLED(r13)
-        std     r10,SOFTE(r1)
 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 #endif
         mfmsr   r11
@@ -460,9 +462,9 @@ _GLOBAL(ret_from_except_lite)
 #endif
 
 restore:
+        ld      r5,SOFTE(r1)
 #ifdef CONFIG_PPC_ISERIES
 BEGIN_FW_FTR_SECTION
-        ld      r5,SOFTE(r1)
         cmpdi   0,r5,0
         beq     4f
         /* Check for pending interrupts (iSeries) */
@@ -472,16 +474,16 @@ BEGIN_FW_FTR_SECTION
         beq+    4f                      /* skip do_IRQ if no interrupts */
 
         li      r3,0
-        stb     r3,PACAPROCENABLED(r13) /* ensure we are soft-disabled */
+        stb     r3,PACASOFTIRQEN(r13)   /* ensure we are soft-disabled */
         ori     r10,r10,MSR_EE
         mtmsrd  r10                     /* hard-enable again */
         addi    r3,r1,STACK_FRAME_OVERHEAD
         bl      .do_IRQ
         b       .ret_from_except_lite           /* loop back and handle more */
-
-4:      stb     r5,PACAPROCENABLED(r13)
+4:
 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 #endif
+        stb     r5,PACASOFTIRQEN(r13)
 
         ld      r3,_MSR(r1)
         andi.   r0,r3,MSR_RI
@@ -538,25 +540,15 @@ do_work:
         /* Check that preempt_count() == 0 and interrupts are enabled */
         lwz     r8,TI_PREEMPT(r9)
         cmpwi   cr1,r8,0
-#ifdef CONFIG_PPC_ISERIES
-BEGIN_FW_FTR_SECTION
         ld      r0,SOFTE(r1)
         cmpdi   r0,0
-END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
-#endif
-BEGIN_FW_FTR_SECTION
-        andi.   r0,r3,MSR_EE
-END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
         crandc  eq,cr1*4+eq,eq
         bne     restore
         /* here we are preempting the current task */
 1:
-#ifdef CONFIG_PPC_ISERIES
-BEGIN_FW_FTR_SECTION
         li      r0,1
-        stb     r0,PACAPROCENABLED(r13)
-END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
-#endif
+        stb     r0,PACASOFTIRQEN(r13)
+        stb     r0,PACAHARDIRQEN(r13)
         ori     r10,r10,MSR_EE
         mtmsrd  r10,1           /* reenable interrupts */
         bl      .preempt_schedule
@@ -639,8 +631,7 @@ _GLOBAL(enter_rtas)
         /* There is no way it is acceptable to get here with interrupts enabled,
          * check it with the asm equivalent of WARN_ON
          */
-        mfmsr   r6
-        andi.   r0,r6,MSR_EE
+        lbz     r0,PACASOFTIRQEN(r13)
 1:      tdnei   r0,0
 .section __bug_table,"a"
         .llong  1b,__LINE__ + 0x1000000, 1f, 2f
@@ -649,7 +640,13 @@ _GLOBAL(enter_rtas)
 1:      .asciz  __FILE__
 2:      .asciz "enter_rtas"
 .previous
-        
+
+        /* Hard-disable interrupts */
+        mfmsr   r6
+        rldicl  r7,r6,48,1
+        rotldi  r7,r7,16
+        mtmsrd  r7,1
+
         /* Unfortunately, the stack pointer and the MSR are also clobbered,
          * so they are saved in the PACA which allows us to restore
          * our original state after RTAS returns.
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 645c7f10fb28..c93d9f35a121 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -35,9 +35,7 @@
 #include <asm/thread_info.h>
 #include <asm/firmware.h>
 
-#ifdef CONFIG_PPC_ISERIES
 #define DO_SOFT_DISABLE
-#endif
 
 /*
  * We layout physical memory as follows:
@@ -308,7 +306,9 @@ exception_marker:
         std     r9,_LINK(r1);                                              \
         mfctr   r10;                    /* save CTR in stackframe       */ \
         std     r10,_CTR(r1);                                              \
+        lbz     r10,PACASOFTIRQEN(r13);                            \
         mfspr   r11,SPRN_XER;           /* save XER in stackframe       */ \
+        std     r10,SOFTE(r1);                                             \
         std     r11,_XER(r1);                                              \
         li      r9,(n)+1;                                                  \
         std     r9,_TRAP(r1);           /* set trap number              */ \
@@ -343,6 +343,34 @@ label##_pSeries:					\
         EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common)
 
 
+#define MASKABLE_EXCEPTION_PSERIES(n, label)                            \
+        . = n;                                                          \
+        .globl label##_pSeries;                                         \
+label##_pSeries:                                                        \
+        HMT_MEDIUM;                                                     \
+        mtspr   SPRN_SPRG1,r13;         /* save r13 */                  \
+        mfspr   r13,SPRN_SPRG3;         /* get paca address into r13 */ \
+        std     r9,PACA_EXGEN+EX_R9(r13);       /* save r9, r10 */      \
+        std     r10,PACA_EXGEN+EX_R10(r13);                             \
+        lbz     r10,PACASOFTIRQEN(r13);                                 \
+        mfcr    r9;                                                     \
+        cmpwi   r10,0;                                                  \
+        beq     masked_interrupt;                                       \
+        mfspr   r10,SPRN_SPRG1;                                         \
+        std     r10,PACA_EXGEN+EX_R13(r13);                             \
+        std     r11,PACA_EXGEN+EX_R11(r13);                             \
+        std     r12,PACA_EXGEN+EX_R12(r13);                             \
+        clrrdi  r12,r13,32;             /* get high part of &label */   \
+        mfmsr   r10;                                                    \
+        mfspr   r11,SPRN_SRR0;          /* save SRR0 */                 \
+        LOAD_HANDLER(r12,label##_common)                                \
+        ori     r10,r10,MSR_IR|MSR_DR|MSR_RI;                           \
+        mtspr   SPRN_SRR0,r12;                                          \
+        mfspr   r12,SPRN_SRR1;          /* and SRR1 */                  \
+        mtspr   SPRN_SRR1,r10;                                          \
+        rfid;                                                           \
+        b       .       /* prevent speculative execution */
+
 #define STD_EXCEPTION_ISERIES(n, label, area)           \
         .globl label##_iSeries;                         \
 label##_iSeries:                                        \
@@ -358,40 +386,32 @@ label##_iSeries:							\
         HMT_MEDIUM;                                                     \
         mtspr   SPRN_SPRG1,r13;         /* save r13 */                  \
         EXCEPTION_PROLOG_ISERIES_1(PACA_EXGEN);                         \
-        lbz     r10,PACAPROCENABLED(r13);                               \
+        lbz     r10,PACASOFTIRQEN(r13);                                 \
         cmpwi   0,r10,0;                                                \
         beq-    label##_iSeries_masked;                                 \
         EXCEPTION_PROLOG_ISERIES_2;                                     \
         b       label##_common;                                         \
 
-#ifdef DO_SOFT_DISABLE
+#ifdef CONFIG_PPC_ISERIES
 #define DISABLE_INTS                            \
-BEGIN_FW_FTR_SECTION;                           \
-        lbz     r10,PACAPROCENABLED(r13);       \
         li      r11,0;                          \
-        std     r10,SOFTE(r1);                  \
+        stb     r11,PACASOFTIRQEN(r13);         \
+BEGIN_FW_FTR_SECTION;                           \
+        stb     r11,PACAHARDIRQEN(r13);         \
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES);   \
+BEGIN_FW_FTR_SECTION;                           \
         mfmsr   r10;                            \
-        stb     r11,PACAPROCENABLED(r13);       \
         ori     r10,r10,MSR_EE;                 \
         mtmsrd  r10,1;                          \
 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 
-#define ENABLE_INTS                             \
-BEGIN_FW_FTR_SECTION;                           \
-        lbz     r10,PACAPROCENABLED(r13);       \
-        mfmsr   r11;                            \
-        std     r10,SOFTE(r1);                  \
-        ori     r11,r11,MSR_EE;                 \
-END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES);   \
-BEGIN_FW_FTR_SECTION;                           \
-        ld      r12,_MSR(r1);                   \
-        mfmsr   r11;                            \
-        rlwimi  r11,r12,0,MSR_EE;               \
-END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES);   \
-        mtmsrd  r11,1
+#else
+#define DISABLE_INTS                            \
+        li      r11,0;                          \
+        stb     r11,PACASOFTIRQEN(r13);         \
+        stb     r11,PACAHARDIRQEN(r13)
 
-#else   /* hard enable/disable interrupts */
-#define DISABLE_INTS
+#endif /* CONFIG_PPC_ISERIES */
 
 #define ENABLE_INTS                             \
         ld      r12,_MSR(r1);                   \
@@ -399,8 +419,6 @@ END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES);	\
         rlwimi  r11,r12,0,MSR_EE;               \
         mtmsrd  r11,1
 
-#endif
-
 #define STD_EXCEPTION_COMMON(trap, label, hdlr)         \
         .align  7;                                      \
         .globl label##_common;                          \
@@ -541,11 +559,11 @@ instruction_access_slb_pSeries:
         mfspr   r12,SPRN_SRR1           /* and SRR1 */
         b       .slb_miss_realmode      /* Rel. branch works in real mode */
 
-        STD_EXCEPTION_PSERIES(0x500, hardware_interrupt)
+        MASKABLE_EXCEPTION_PSERIES(0x500, hardware_interrupt)
         STD_EXCEPTION_PSERIES(0x600, alignment)
         STD_EXCEPTION_PSERIES(0x700, program_check)
         STD_EXCEPTION_PSERIES(0x800, fp_unavailable)
-        STD_EXCEPTION_PSERIES(0x900, decrementer)
+        MASKABLE_EXCEPTION_PSERIES(0x900, decrementer)
         STD_EXCEPTION_PSERIES(0xa00, trap_0a)
         STD_EXCEPTION_PSERIES(0xb00, trap_0b)
 
@@ -597,7 +615,24 @@ system_call_pSeries:
 /*** pSeries interrupt support ***/
 
         /* moved from 0xf00 */
-        STD_EXCEPTION_PSERIES(., performance_monitor)
+        MASKABLE_EXCEPTION_PSERIES(., performance_monitor)
+
+/*
+ * An interrupt came in while soft-disabled; clear EE in SRR1,
+ * clear paca->hard_enabled and return.
+ */
+masked_interrupt:
+        stb     r10,PACAHARDIRQEN(r13)
+        mtcrf   0x80,r9
+        ld      r9,PACA_EXGEN+EX_R9(r13)
+        mfspr   r10,SPRN_SRR1
+        rldicl  r10,r10,48,1            /* clear MSR_EE */
+        rotldi  r10,r10,16
+        mtspr   SPRN_SRR1,r10
+        ld      r10,PACA_EXGEN+EX_R10(r13)
+        mfspr   r13,SPRN_SPRG1
+        rfid
+        b       .
 
         .align  7
 _GLOBAL(do_stab_bolted_pSeries)
@@ -952,7 +987,8 @@ fast_exception_return:
         REST_8GPRS(2, r1)
 
         mfmsr   r10
-        clrrdi  r10,r10,2               /* clear RI (LE is 0 already) */
+        rldicl  r10,r10,48,1            /* clear EE */
+        rldicr  r10,r10,16,61           /* clear RI (LE is 0 already) */
         mtmsrd  r10,1
 
         mtspr   SPRN_SRR1,r12
@@ -1877,11 +1913,16 @@ _GLOBAL(__secondary_start)
         /* enable MMU and jump to start_secondary */
         LOAD_REG_ADDR(r3, .start_secondary_prolog)
         LOAD_REG_IMMEDIATE(r4, MSR_KERNEL)
-#ifdef DO_SOFT_DISABLE
+#ifdef CONFIG_PPC_ISERIES
 BEGIN_FW_FTR_SECTION
         ori     r4,r4,MSR_EE
 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 #endif
+BEGIN_FW_FTR_SECTION
+        stb     r7,PACASOFTIRQEN(r13)
+        stb     r7,PACAHARDIRQEN(r13)
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
+
         mtspr   SPRN_SRR0,r3
         mtspr   SPRN_SRR1,r4
         rfid
@@ -2019,15 +2060,18 @@ _STATIC(start_here_common)
 
         /* Load up the kernel context */
 5:
-#ifdef DO_SOFT_DISABLE
-BEGIN_FW_FTR_SECTION
         li      r5,0
-        stb     r5,PACAPROCENABLED(r13) /* Soft Disabled */
+        stb     r5,PACASOFTIRQEN(r13)   /* Soft Disabled */
+#ifdef CONFIG_PPC_ISERIES
+BEGIN_FW_FTR_SECTION
         mfmsr   r5
         ori     r5,r5,MSR_EE            /* Hard Enabled */
         mtmsrd  r5
 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 #endif
+BEGIN_FW_FTR_SECTION
+        stb     r5,PACAHARDIRQEN(r13)
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
 
         bl .start_kernel
 
diff --git a/arch/powerpc/kernel/idle_power4.S b/arch/powerpc/kernel/idle_power4.S
index 30de81da7b40..ba3195478600 100644
--- a/arch/powerpc/kernel/idle_power4.S
+++ b/arch/powerpc/kernel/idle_power4.S
@@ -30,6 +30,13 @@ END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP)
         beqlr
 
         /* Go to NAP now */
+        mfmsr   r7
+        rldicl  r0,r7,48,1
+        rotldi  r0,r0,16
+        mtmsrd  r0,1                    /* hard-disable interrupts */
+        li      r0,1
+        stb     r0,PACASOFTIRQEN(r13)   /* we'll hard-enable shortly */
+        stb     r0,PACAHARDIRQEN(r13)
 BEGIN_FTR_SECTION
         DSSALL
         sync
@@ -38,7 +45,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
         ld      r8,TI_LOCAL_FLAGS(r9)   /* set napping bit */
         ori     r8,r8,_TLF_NAPPING      /* so when we take an exception */
         std     r8,TI_LOCAL_FLAGS(r9)   /* it will return to our caller */
-        mfmsr   r7
         ori     r7,r7,MSR_EE
         oris    r7,r7,MSR_POW@h
 1:      sync
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 5e37bf14ef2d..67b21a008f6e 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -64,8 +64,9 @@
 #include <asm/ptrace.h>
 #include <asm/machdep.h>
 #include <asm/udbg.h>
-#ifdef CONFIG_PPC_ISERIES
+#ifdef CONFIG_PPC64
 #include <asm/paca.h>
+#include <asm/firmware.h>
 #endif
 
 int __irq_offset_value;
@@ -95,6 +96,27 @@ extern atomic_t ipi_sent;
 EXPORT_SYMBOL(irq_desc);
 
 int distribute_irqs = 1;
+
+void local_irq_restore(unsigned long en)
+{
+        get_paca()->soft_enabled = en;
+        if (!en)
+                return;
+
+        if (firmware_has_feature(FW_FEATURE_ISERIES)) {
+                if (get_paca()->lppaca_ptr->int_dword.any_int)
+                        iseries_handle_interrupts();
+                return;
+        }
+
+        if (get_paca()->hard_enabled)
+                return;
+        /* need to hard-enable interrupts here */
+        get_paca()->hard_enabled = en;
+        if ((int)mfspr(SPRN_DEC) < 0)
+                mtspr(SPRN_DEC, 1);
+        hard_irq_enable();
+}
 #endif /* CONFIG_PPC64 */
 
 int show_interrupts(struct seq_file *p, void *v)
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 807193a3c784..9179f0739ea2 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -49,6 +49,10 @@
 #include <asm/commproc.h>
 #endif
 
+#ifdef CONFIG_PPC64
+EXPORT_SYMBOL(local_irq_restore);
+#endif
+
 #ifdef CONFIG_PPC32
 extern void transfer_to_handler(void);
 extern void do_IRQ(struct pt_regs *regs);
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 4b2e32eab9dc..b1b0cda3f748 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -223,8 +223,8 @@ void early_setup_secondary(void)
 {
         struct paca_struct *lpaca = get_paca();
 
-        /* Mark enabled in PACA */
-        lpaca->proc_enabled = 0;
+        /* Mark interrupts enabled in PACA */
+        lpaca->soft_enabled = 0;
 
         /* Initialize hash table for that CPU */
         htab_initialize_secondary();
diff --git a/arch/powerpc/platforms/iseries/ksyms.c b/arch/powerpc/platforms/iseries/ksyms.c
index a2200842f4e5..2430848b98e7 100644
--- a/arch/powerpc/platforms/iseries/ksyms.c
+++ b/arch/powerpc/platforms/iseries/ksyms.c
@@ -19,9 +19,3 @@ EXPORT_SYMBOL(HvCall4);
 EXPORT_SYMBOL(HvCall5);
 EXPORT_SYMBOL(HvCall6);
 EXPORT_SYMBOL(HvCall7);
-
-#ifdef CONFIG_SMP
-EXPORT_SYMBOL(local_get_flags);
-EXPORT_SYMBOL(local_irq_disable);
-EXPORT_SYMBOL(local_irq_restore);
-#endif
diff --git a/arch/powerpc/platforms/iseries/misc.S b/arch/powerpc/platforms/iseries/misc.S
index 7641fc7e550a..2c6ff0fdac98 100644
--- a/arch/powerpc/platforms/iseries/misc.S
+++ b/arch/powerpc/platforms/iseries/misc.S
@@ -19,39 +19,8 @@
 
         .text
 
-/* unsigned long local_save_flags(void) */
-_GLOBAL(local_get_flags)
-        lbz     r3,PACAPROCENABLED(r13)
-        blr
-
-/* unsigned long local_irq_disable(void) */
-_GLOBAL(local_irq_disable)
-        lbz     r3,PACAPROCENABLED(r13)
-        li      r4,0
-        stb     r4,PACAPROCENABLED(r13)
-        blr                     /* Done */
-
-/* void local_irq_restore(unsigned long flags) */
-_GLOBAL(local_irq_restore)
-        lbz     r5,PACAPROCENABLED(r13)
-         /* Check if things are setup the way we want _already_. */
-        cmpw    0,r3,r5
-        beqlr
-        /* are we enabling interrupts? */
-        cmpdi   0,r3,0
-        stb     r3,PACAPROCENABLED(r13)
-        beqlr
-        /* Check pending interrupts */
-        /*   A decrementer, IPI or PMC interrupt may have occurred
-         *   while we were in the hypervisor (which enables) */
-        ld      r4,PACALPPACAPTR(r13)
-        ld      r4,LPPACAANYINT(r4)
-        cmpdi   r4,0
-        beqlr
-
-        /*
-         * Handle pending interrupts in interrupt context
-         */
+/* Handle pending interrupts in interrupt context */
+_GLOBAL(iseries_handle_interrupts)
         li      r0,0x5555
         sc
         blr
diff --git a/include/asm-powerpc/hw_irq.h b/include/asm-powerpc/hw_irq.h
index d40359204aba..c4a1ab608f6f 100644
--- a/include/asm-powerpc/hw_irq.h
+++ b/include/asm-powerpc/hw_irq.h
@@ -7,16 +7,30 @@
 #ifdef __KERNEL__
 
 #include <linux/errno.h>
+#include <linux/compiler.h>
 #include <asm/ptrace.h>
 #include <asm/processor.h>
 
 extern void timer_interrupt(struct pt_regs *);
 
-#ifdef CONFIG_PPC_ISERIES
+#ifdef CONFIG_PPC64
+#include <asm/paca.h>
+
+static inline unsigned long local_get_flags(void)
+{
+        return get_paca()->soft_enabled;
+}
+
+static inline unsigned long local_irq_disable(void)
+{
+        unsigned long flag = get_paca()->soft_enabled;
+        get_paca()->soft_enabled = 0;
+        barrier();
+        return flag;
+}
 
-extern unsigned long local_get_flags(void);
-extern unsigned long local_irq_disable(void);
 extern void local_irq_restore(unsigned long);
+extern void iseries_handle_interrupts(void);
 
 #define local_irq_enable()      local_irq_restore(1)
 #define local_save_flags(flags) ((flags) = local_get_flags())
@@ -24,17 +38,14 @@ extern void local_irq_restore(unsigned long);
 
 #define irqs_disabled()         (local_get_flags() == 0)
 
+#define hard_irq_enable()       __mtmsrd(mfmsr() | MSR_EE, 1)
+#define hard_irq_disable()      __mtmsrd(mfmsr() & ~MSR_EE, 1)
+
 #else
 
 #if defined(CONFIG_BOOKE)
 #define SET_MSR_EE(x)   mtmsr(x)
 #define local_irq_restore(flags)        __asm__ __volatile__("wrtee %0" : : "r" (flags) : "memory")
-#elif defined(__powerpc64__)
-#define SET_MSR_EE(x)   __mtmsrd(x, 1)
-#define local_irq_restore(flags) do { \
-        __asm__ __volatile__("": : :"memory"); \
-        __mtmsrd((flags), 1); \
-} while(0)
 #else
 #define SET_MSR_EE(x)   mtmsr(x)
 #define local_irq_restore(flags)        mtmsr(flags)
@@ -81,7 +92,7 @@ static inline void local_irq_save_ptr(unsigned long *flags)
 #define local_irq_save(flags)   local_irq_save_ptr(&flags)
 #define irqs_disabled()         ((mfmsr() & MSR_EE) == 0)
 
-#endif /* CONFIG_PPC_ISERIES */
+#endif /* CONFIG_PPC64 */
 
 #define mask_irq(irq)                                           \
         ({                                                      \
diff --git a/include/asm-powerpc/paca.h b/include/asm-powerpc/paca.h
index 0a4e5c93e8e6..0d3adc09c847 100644
--- a/include/asm-powerpc/paca.h
+++ b/include/asm-powerpc/paca.h
@@ -93,7 +93,8 @@ struct paca_struct {
         u64 stab_rr;                    /* stab/slb round-robin counter */
         u64 saved_r1;                   /* r1 save for RTAS calls */
         u64 saved_msr;                  /* MSR saved here by enter_rtas */
-        u8 proc_enabled;                /* irq soft-enable flag */
+        u8 soft_enabled;                /* irq soft-enable flag */
+        u8 hard_enabled;                /* set if irqs are enabled in MSR */
         u8 io_sync;                     /* writel() needs spin_unlock sync */
 
         /* Stuff for accurate time accounting */