1 files changed, 169 insertions, 0 deletions

diff --git a/include/asm-ppc64/mmu_context.h b/include/asm-ppc64/mmu_context.h
new file mode 100644
index 000000000000..c2e8e0466383
--- /dev/null
+++ b/include/asm-ppc64/mmu_context.h
@@ -0,0 +1,169 @@
+#ifndef __PPC64_MMU_CONTEXT_H
+#define __PPC64_MMU_CONTEXT_H
+
+#include <linux/config.h>
+#include <linux/kernel.h>       
+#include <linux/mm.h>   
+#include <asm/mmu.h>    
+#include <asm/cputable.h>
+
+/*
+ * Copyright (C) 2001 PPC 64 Team, IBM Corp
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ * Every architecture must define this function. It's the fastest
+ * way of searching a 140-bit bitmap where the first 100 bits are
+ * unlikely to be set. It's guaranteed that at least one of the 140
+ * bits is cleared.
+ */
+static inline int sched_find_first_bit(unsigned long *b)
+{
+        if (unlikely(b[0]))
+                return __ffs(b[0]);
+        if (unlikely(b[1]))
+                return __ffs(b[1]) + 64;
+        return __ffs(b[2]) + 128;
+}
+
+static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+#define NO_CONTEXT      0
+#define MAX_CONTEXT     (0x100000-1)
+
+extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
+extern void destroy_context(struct mm_struct *mm);
+
+extern void switch_stab(struct task_struct *tsk, struct mm_struct *mm);
+extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm);
+
+/*
+ * switch_mm is the entry point called from the architecture independent
+ * code in kernel/sched.c
+ */
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+                             struct task_struct *tsk)
+{
+        if (!cpu_isset(smp_processor_id(), next->cpu_vm_mask))
+                cpu_set(smp_processor_id(), next->cpu_vm_mask);
+
+        /* No need to flush userspace segments if the mm doesnt change */
+        if (prev == next)
+                return;
+
+#ifdef CONFIG_ALTIVEC
+        if (cpu_has_feature(CPU_FTR_ALTIVEC))
+                asm volatile ("dssall");
+#endif /* CONFIG_ALTIVEC */
+
+        if (cpu_has_feature(CPU_FTR_SLB))
+                switch_slb(tsk, next);
+        else
+                switch_stab(tsk, next);
+}
+
+#define deactivate_mm(tsk,mm)   do { } while (0)
+
+/*
+ * After we have set current->mm to a new value, this activates
+ * the context for the new mm so we see the new mappings.
+ */
+static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+        unsigned long flags;
+
+        local_irq_save(flags);
+        switch_mm(prev, next, current);
+        local_irq_restore(flags);
+}
+
+/* VSID allocation
+ * ===============
+ *
+ * We first generate a 36-bit "proto-VSID".  For kernel addresses this
+ * is equal to the ESID, for user addresses it is:
+ *      (context << 15) | (esid & 0x7fff)
+ *
+ * The two forms are distinguishable because the top bit is 0 for user
+ * addresses, whereas the top two bits are 1 for kernel addresses.
+ * Proto-VSIDs with the top two bits equal to 0b10 are reserved for
+ * now.
+ *
+ * The proto-VSIDs are then scrambled into real VSIDs with the
+ * multiplicative hash:
+ *
+ *      VSID = (proto-VSID * VSID_MULTIPLIER) % VSID_MODULUS
+ *      where   VSID_MULTIPLIER = 268435399 = 0xFFFFFC7
+ *              VSID_MODULUS = 2^36-1 = 0xFFFFFFFFF
+ *
+ * This scramble is only well defined for proto-VSIDs below
+ * 0xFFFFFFFFF, so both proto-VSID and actual VSID 0xFFFFFFFFF are
+ * reserved.  VSID_MULTIPLIER is prime, so in particular it is
+ * co-prime to VSID_MODULUS, making this a 1:1 scrambling function.
+ * Because the modulus is 2^n-1 we can compute it efficiently without
+ * a divide or extra multiply (see below).
+ *
+ * This scheme has several advantages over older methods:
+ *
+ *      - We have VSIDs allocated for every kernel address
+ * (i.e. everything above 0xC000000000000000), except the very top
+ * segment, which simplifies several things.
+ *
+ *      - We allow for 15 significant bits of ESID and 20 bits of
+ * context for user addresses.  i.e. 8T (43 bits) of address space for
+ * up to 1M contexts (although the page table structure and context
+ * allocation will need changes to take advantage of this).
+ *
+ *      - The scramble function gives robust scattering in the hash
+ * table (at least based on some initial results).  The previous
+ * method was more susceptible to pathological cases giving excessive
+ * hash collisions.
+ */
+
+/*
+ * WARNING - If you change these you must make sure the asm
+ * implementations in slb_allocate(), do_stab_bolted and mmu.h
+ * (ASM_VSID_SCRAMBLE macro) are changed accordingly.
+ *
+ * You'll also need to change the precomputed VSID values in head.S
+ * which are used by the iSeries firmware.
+ */
+
+static inline unsigned long vsid_scramble(unsigned long protovsid)
+{
+#if 0
+        /* The code below is equivalent to this function for arguments
+         * < 2^VSID_BITS, which is all this should ever be called
+         * with.  However gcc is not clever enough to compute the
+         * modulus (2^n-1) without a second multiply. */
+        return ((protovsid * VSID_MULTIPLIER) % VSID_MODULUS);
+#else /* 1 */
+        unsigned long x;
+
+        x = protovsid * VSID_MULTIPLIER;
+        x = (x >> VSID_BITS) + (x & VSID_MODULUS);
+        return (x + ((x+1) >> VSID_BITS)) & VSID_MODULUS;
+#endif /* 1 */
+}
+
+/* This is only valid for addresses >= KERNELBASE */
+static inline unsigned long get_kernel_vsid(unsigned long ea)
+{
+        return vsid_scramble(ea >> SID_SHIFT);
+}
+
+/* This is only valid for user addresses (which are below 2^41) */
+static inline unsigned long get_vsid(unsigned long context, unsigned long ea)
+{
+        return vsid_scramble((context << USER_ESID_BITS)
+                             | (ea >> SID_SHIFT));
+}
+
+#endif /* __PPC64_MMU_CONTEXT_H */