Pull context-bitmap into release branch

4 files changed, 92 insertions, 76 deletions

diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 3af6de36a482..5add0bcf87a7 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -461,6 +461,7 @@ setup_arch (char **cmdline_p)
 #endif
 
         cpu_init();     /* initialize the bootstrap CPU */
+        mmu_context_init();     /* initialize context_id bitmap */
 
 #ifdef CONFIG_ACPI
         acpi_boot_init();
diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c
index c79a9b96d02b..41105d454423 100644
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -8,6 +8,8 @@
  *              Modified RID allocation for SMP
  *          Goutham Rao <goutham.rao@intel.com>
  *              IPI based ptc implementation and A-step IPI implementation.
+ * Rohit Seth <rohit.seth@intel.com>
+ * Ken Chen <kenneth.w.chen@intel.com>
  */
 #include <linux/config.h>
 #include <linux/module.h>
@@ -16,78 +18,75 @@
 #include <linux/sched.h>
 #include <linux/smp.h>
 #include <linux/mm.h>
+#include <linux/bootmem.h>
 
 #include <asm/delay.h>
 #include <asm/mmu_context.h>
 #include <asm/pgalloc.h>
 #include <asm/pal.h>
 #include <asm/tlbflush.h>
+#include <asm/dma.h>
 
 static struct {
         unsigned long mask;     /* mask of supported purge page-sizes */
-        unsigned long max_bits; /* log2() of largest supported purge page-size */
+        unsigned long max_bits; /* log2 of largest supported purge page-size */
 } purge;
 
 struct ia64_ctx ia64_ctx = {
         .lock =         SPIN_LOCK_UNLOCKED,
         .next =         1,
-        .limit =        (1 << 15) - 1,          /* start out with the safe (architected) limit */
         .max_ctx =      ~0U
 };
 
 DEFINE_PER_CPU(u8, ia64_need_tlb_flush);
 
 /*
+ * Initializes the ia64_ctx.bitmap array based on max_ctx+1.
+ * Called after cpu_init() has setup ia64_ctx.max_ctx based on
+ * maximum RID that is supported by boot CPU.
+ */
+void __init
+mmu_context_init (void)
+{
+        ia64_ctx.bitmap = alloc_bootmem((ia64_ctx.max_ctx+1)>>3);
+        ia64_ctx.flushmap = alloc_bootmem((ia64_ctx.max_ctx+1)>>3);
+}
+
+/*
  * Acquire the ia64_ctx.lock before calling this function!
  */
 void
 wrap_mmu_context (struct mm_struct *mm)
 {
-        unsigned long tsk_context, max_ctx = ia64_ctx.max_ctx;
-        struct task_struct *tsk;
-        int i;
+        int i, cpu;
+        unsigned long flush_bit;
 
-        if (ia64_ctx.next > max_ctx)
-                ia64_ctx.next = 300;    /* skip daemons */
-        ia64_ctx.limit = max_ctx + 1;
+        for (i=0; i <= ia64_ctx.max_ctx / BITS_PER_LONG; i++) {
+                flush_bit = xchg(&ia64_ctx.flushmap[i], 0);
+                ia64_ctx.bitmap[i] ^= flush_bit;
+        }
+ 
+        /* use offset at 300 to skip daemons */
+        ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
+                                ia64_ctx.max_ctx, 300);
+        ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
+                                ia64_ctx.max_ctx, ia64_ctx.next);
 
         /*
-         * Scan all the task's mm->context and set proper safe range
+         * can't call flush_tlb_all() here because of race condition
+         * with O(1) scheduler [EF]
          */
-
-        read_lock(&tasklist_lock);
-  repeat:
-        for_each_process(tsk) {
-                if (!tsk->mm)
-                        continue;
-                tsk_context = tsk->mm->context;
-                if (tsk_context == ia64_ctx.next) {
-                        if (++ia64_ctx.next >= ia64_ctx.limit) {
-                                /* empty range: reset the range limit and start over */
-                                if (ia64_ctx.next > max_ctx)
-                                        ia64_ctx.next = 300;
-                                ia64_ctx.limit = max_ctx + 1;
-                                goto repeat;
-                        }
-                }
-                if ((tsk_context > ia64_ctx.next) && (tsk_context < ia64_ctx.limit))
-                        ia64_ctx.limit = tsk_context;
-        }
-        read_unlock(&tasklist_lock);
-        /* can't call flush_tlb_all() here because of race condition with O(1) scheduler [EF] */
-        {
-                int cpu = get_cpu(); /* prevent preemption/migration */
-                for_each_online_cpu(i) {
-                        if (i != cpu)
-                                per_cpu(ia64_need_tlb_flush, i) = 1;
-                }
-                put_cpu();
-        }
+        cpu = get_cpu(); /* prevent preemption/migration */
+        for_each_online_cpu(i)
+                if (i != cpu)
+                        per_cpu(ia64_need_tlb_flush, i) = 1;
+        put_cpu();
         local_flush_tlb_all();
 }
 
 void
-ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start, unsigned long end, unsigned long nbits)
+ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
+                       unsigned long end, unsigned long nbits)
 {
         static DEFINE_SPINLOCK(ptcg_lock);
 
@@ -135,7 +134,8 @@ local_flush_tlb_all (void)
 }
 
 void
-flush_tlb_range (struct vm_area_struct *vma, unsigned long start, unsigned long end)
+flush_tlb_range (struct vm_area_struct *vma, unsigned long start,
+                 unsigned long end)
 {
         struct mm_struct *mm = vma->vm_mm;
         unsigned long size = end - start;
@@ -149,7 +149,8 @@ flush_tlb_range (struct vm_area_struct *vma, unsigned long start, unsigned long
 #endif
 
         nbits = ia64_fls(size + 0xfff);
-        while (unlikely (((1UL << nbits) & purge.mask) == 0) && (nbits < purge.max_bits))
+        while (unlikely (((1UL << nbits) & purge.mask) == 0) &&
+                        (nbits < purge.max_bits))
                 ++nbits;
         if (nbits > purge.max_bits)
                 nbits = purge.max_bits;
@@ -191,5 +192,5 @@ ia64_tlb_init (void)
         local_cpu_data->ptce_stride[0] = ptce_info.stride[0];
         local_cpu_data->ptce_stride[1] = ptce_info.stride[1];
 
-        local_flush_tlb_all();          /* nuke left overs from bootstrapping... */
+        local_flush_tlb_all();  /* nuke left overs from bootstrapping... */
 }
diff --git a/include/asm-ia64/mmu_context.h b/include/asm-ia64/mmu_context.h
index 8d6e72f7b08e..b5c65081a3aa 100644
--- a/include/asm-ia64/mmu_context.h
+++ b/include/asm-ia64/mmu_context.h
@@ -7,12 +7,13 @@
  */
 
 /*
- * Routines to manage the allocation of task context numbers.  Task context numbers are
- * used to reduce or eliminate the need to perform TLB flushes due to context switches.
- * Context numbers are implemented using ia-64 region ids.  Since the IA-64 TLB does not
- * consider the region number when performing a TLB lookup, we need to assign a unique
- * region id to each region in a process.  We use the least significant three bits in a
- * region id for this purpose.
+ * Routines to manage the allocation of task context numbers.  Task context
+ * numbers are used to reduce or eliminate the need to perform TLB flushes
+ * due to context switches.  Context numbers are implemented using ia-64
+ * region ids.  Since the IA-64 TLB does not consider the region number when
+ * performing a TLB lookup, we need to assign a unique region id to each
+ * region in a process.  We use the least significant three bits in aregion
+ * id for this purpose.
  */
 
 #define IA64_REGION_ID_KERNEL   0 /* the kernel's region id (tlb.c depends on this being 0) */
@@ -32,13 +33,17 @@
 struct ia64_ctx {
         spinlock_t lock;
         unsigned int next;      /* next context number to use */
-        unsigned int limit;     /* next >= limit => must call wrap_mmu_context() */
-        unsigned int max_ctx;   /* max. context value supported by all CPUs */
+        unsigned int limit;     /* available free range */
+        unsigned int max_ctx;   /* max. context value supported by all CPUs */
+                                /* call wrap_mmu_context when next >= max */
+        unsigned long *bitmap;  /* bitmap size is max_ctx+1 */
+        unsigned long *flushmap;/* pending rid to be flushed */
 };
 
 extern struct ia64_ctx ia64_ctx;
 DECLARE_PER_CPU(u8, ia64_need_tlb_flush);
 
+extern void mmu_context_init (void);
 extern void wrap_mmu_context (struct mm_struct *mm);
 
 static inline void
@@ -47,10 +52,10 @@ enter_lazy_tlb (struct mm_struct *mm, struct task_struct *tsk)
 }
 
 /*
- * When the context counter wraps around all TLBs need to be flushed because an old
- * context number might have been reused. This is signalled by the ia64_need_tlb_flush
- * per-CPU variable, which is checked in the routine below. Called by activate_mm().
- * <efocht@ess.nec.de>
+ * When the context counter wraps around all TLBs need to be flushed because
+ * an old context number might have been reused. This is signalled by the
+ * ia64_need_tlb_flush per-CPU variable, which is checked in the routine
+ * below. Called by activate_mm(). <efocht@ess.nec.de>
  */
 static inline void
 delayed_tlb_flush (void)
@@ -60,11 +65,9 @@ delayed_tlb_flush (void)
 
         if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
                 spin_lock_irqsave(&ia64_ctx.lock, flags);
-                {
-                        if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
-                                local_flush_tlb_all();
-                                __ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
-                        }
+                if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
+                        local_flush_tlb_all();
+                        __ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
                 }
                 spin_unlock_irqrestore(&ia64_ctx.lock, flags);
         }
@@ -76,20 +79,27 @@ get_mmu_context (struct mm_struct *mm)
         unsigned long flags;
         nv_mm_context_t context = mm->context;
 
-        if (unlikely(!context)) {
-                spin_lock_irqsave(&ia64_ctx.lock, flags);
-                {
-                        /* re-check, now that we've got the lock: */
-                        context = mm->context;
-                        if (context == 0) {
-                                cpus_clear(mm->cpu_vm_mask);
-                                if (ia64_ctx.next >= ia64_ctx.limit)
-                                        wrap_mmu_context(mm);
-                                mm->context = context = ia64_ctx.next++;
-                        }
+        if (likely(context))
+                goto out;
+
+        spin_lock_irqsave(&ia64_ctx.lock, flags);
+        /* re-check, now that we've got the lock: */
+        context = mm->context;
+        if (context == 0) {
+                cpus_clear(mm->cpu_vm_mask);
+                if (ia64_ctx.next >= ia64_ctx.limit) {
+                        ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
+                                        ia64_ctx.max_ctx, ia64_ctx.next);
+                        ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
+                                        ia64_ctx.max_ctx, ia64_ctx.next);
+                        if (ia64_ctx.next >= ia64_ctx.max_ctx)
+                                wrap_mmu_context(mm);
                 }
-                spin_unlock_irqrestore(&ia64_ctx.lock, flags);
+                mm->context = context = ia64_ctx.next++;
+                __set_bit(context, ia64_ctx.bitmap);
         }
+        spin_unlock_irqrestore(&ia64_ctx.lock, flags);
+out:
         /*
          * Ensure we're not starting to use "context" before any old
          * uses of it are gone from our TLB.
@@ -100,8 +110,8 @@ get_mmu_context (struct mm_struct *mm)
 }
 
 /*
- * Initialize context number to some sane value.  MM is guaranteed to be a brand-new
- * address-space, so no TLB flushing is needed, ever.
+ * Initialize context number to some sane value.  MM is guaranteed to be a
+ * brand-new address-space, so no TLB flushing is needed, ever.
  */
 static inline int
 init_new_context (struct task_struct *p, struct mm_struct *mm)
@@ -162,7 +172,10 @@ activate_context (struct mm_struct *mm)
                 if (!cpu_isset(smp_processor_id(), mm->cpu_vm_mask))
                         cpu_set(smp_processor_id(), mm->cpu_vm_mask);
                 reload_context(context);
-                /* in the unlikely event of a TLB-flush by another thread, redo the load: */
+                /*
+                 * in the unlikely event of a TLB-flush by another thread,
+                 * redo the load.
+                 */
         } while (unlikely(context != mm->context));
 }
 
@@ -175,8 +188,8 @@ static inline void
 activate_mm (struct mm_struct *prev, struct mm_struct *next)
 {
         /*
-         * We may get interrupts here, but that's OK because interrupt handlers cannot
-         * touch user-space.
+         * We may get interrupts here, but that's OK because interrupt
+         * handlers cannot touch user-space.
          */
         ia64_set_kr(IA64_KR_PT_BASE, __pa(next->pgd));
         activate_context(next);
diff --git a/include/asm-ia64/tlbflush.h b/include/asm-ia64/tlbflush.h
index b65c62702724..a35b323bae4c 100644
--- a/include/asm-ia64/tlbflush.h
+++ b/include/asm-ia64/tlbflush.h
@@ -51,6 +51,7 @@ flush_tlb_mm (struct mm_struct *mm)
         if (!mm)
                 return;
 
+        set_bit(mm->context, ia64_ctx.flushmap);
         mm->context = 0;
 
         if (atomic_read(&mm->mm_users) == 0)