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htab.c

/*
 * iSeries hashtable management.
 *    Derived from pSeries_htab.c
 *
 * SMP scalability work:
 *    Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * 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.
 */
#include <asm/machdep.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/abs_addr.h>
#include <linux/spinlock.h>

#include "call_hpt.h"

static spinlock_t iSeries_hlocks[64] __cacheline_aligned_in_smp =
      { [0 ... 63] = SPIN_LOCK_UNLOCKED};

/*
 * Very primitive algorithm for picking up a lock
 */
static inline void iSeries_hlock(unsigned long slot)
{
      if (slot & 0x8)
            slot = ~slot;
      spin_lock(&iSeries_hlocks[(slot >> 4) & 0x3f]);
}

static inline void iSeries_hunlock(unsigned long slot)
{
      if (slot & 0x8)
            slot = ~slot;
      spin_unlock(&iSeries_hlocks[(slot >> 4) & 0x3f]);
}

static long iSeries_hpte_insert(unsigned long hpte_group, unsigned long va,
                   unsigned long pa, unsigned long rflags,
                   unsigned long vflags, int psize, int ssize)
{
      long slot;
      struct hash_pte lhpte;
      int secondary = 0;

      BUG_ON(psize != MMU_PAGE_4K);

      /*
       * The hypervisor tries both primary and secondary.
       * If we are being called to insert in the secondary,
       * it means we have already tried both primary and secondary,
       * so we return failure immediately.
       */
      if (vflags & HPTE_V_SECONDARY)
            return -1;

      iSeries_hlock(hpte_group);

      slot = HvCallHpt_findValid(&lhpte, va >> HW_PAGE_SHIFT);
      if (unlikely(lhpte.v & HPTE_V_VALID)) {
            if (vflags & HPTE_V_BOLTED) {
                  HvCallHpt_setSwBits(slot, 0x10, 0);
                  HvCallHpt_setPp(slot, PP_RWXX);
                  iSeries_hunlock(hpte_group);
                  if (slot < 0)
                        return 0x8 | (slot & 7);
                  else
                        return slot & 7;
            }
            BUG();
      }

      if (slot == -1)   { /* No available entry found in either group */
            iSeries_hunlock(hpte_group);
            return -1;
      }

      if (slot < 0) {         /* MSB set means secondary group */
            vflags |= HPTE_V_SECONDARY;
            secondary = 1;
            slot &= 0x7fffffffffffffff;
      }


      lhpte.v = hpte_encode_v(va, MMU_PAGE_4K, MMU_SEGSIZE_256M) |
            vflags | HPTE_V_VALID;
      lhpte.r = hpte_encode_r(phys_to_abs(pa), MMU_PAGE_4K) | rflags;

      /* Now fill in the actual HPTE */
      HvCallHpt_addValidate(slot, secondary, &lhpte);

      iSeries_hunlock(hpte_group);

      return (secondary << 3) | (slot & 7);
}

static unsigned long iSeries_hpte_getword0(unsigned long slot)
{
      struct hash_pte hpte;

      HvCallHpt_get(&hpte, slot);
      return hpte.v;
}

static long iSeries_hpte_remove(unsigned long hpte_group)
{
      unsigned long slot_offset;
      int i;
      unsigned long hpte_v;

      /* Pick a random slot to start at */
      slot_offset = mftb() & 0x7;

      iSeries_hlock(hpte_group);

      for (i = 0; i < HPTES_PER_GROUP; i++) {
            hpte_v = iSeries_hpte_getword0(hpte_group + slot_offset);

            if (! (hpte_v & HPTE_V_BOLTED)) {
                  HvCallHpt_invalidateSetSwBitsGet(hpte_group +
                                           slot_offset, 0, 0);
                  iSeries_hunlock(hpte_group);
                  return i;
            }

            slot_offset++;
            slot_offset &= 0x7;
      }

      iSeries_hunlock(hpte_group);

      return -1;
}

/*
 * The HyperVisor expects the "flags" argument in this form:
 *    bits  0..59 : reserved
 *    bit      60 : N
 *    bits 61..63 : PP2,PP1,PP0
 */
static long iSeries_hpte_updatepp(unsigned long slot, unsigned long newpp,
                  unsigned long va, int psize, int ssize, int local)
{
      struct hash_pte hpte;
      unsigned long want_v;

      iSeries_hlock(slot);

      HvCallHpt_get(&hpte, slot);
      want_v = hpte_encode_v(va, MMU_PAGE_4K, MMU_SEGSIZE_256M);

      if (HPTE_V_COMPARE(hpte.v, want_v) && (hpte.v & HPTE_V_VALID)) {
            /*
             * Hypervisor expects bits as NPPP, which is
             * different from how they are mapped in our PP.
             */
            HvCallHpt_setPp(slot, (newpp & 0x3) | ((newpp & 0x4) << 1));
            iSeries_hunlock(slot);
            return 0;
      }
      iSeries_hunlock(slot);

      return -1;
}

/*
 * Functions used to find the PTE for a particular virtual address.
 * Only used during boot when bolting pages.
 *
 * Input : vpn      : virtual page number
 * Output: PTE index within the page table of the entry
 *         -1 on failure
 */
static long iSeries_hpte_find(unsigned long vpn)
{
      struct hash_pte hpte;
      long slot;

      /*
       * The HvCallHpt_findValid interface is as follows:
       * 0xffffffffffffffff : No entry found.
       * 0x00000000xxxxxxxx : Entry found in primary group, slot x
       * 0x80000000xxxxxxxx : Entry found in secondary group, slot x
       */
      slot = HvCallHpt_findValid(&hpte, vpn);
      if (hpte.v & HPTE_V_VALID) {
            if (slot < 0) {
                  slot &= 0x7fffffffffffffff;
                  slot = -slot;
            }
      } else
            slot = -1;
      return slot;
}

/*
 * Update the page protection bits. Intended to be used to create
 * guard pages for kernel data structures on pages which are bolted
 * in the HPT. Assumes pages being operated on will not be stolen.
 * Does not work on large pages.
 *
 * No need to lock here because we should be the only user.
 */
static void iSeries_hpte_updateboltedpp(unsigned long newpp, unsigned long ea,
                              int psize, int ssize)
{
      unsigned long vsid,va,vpn;
      long slot;

      BUG_ON(psize != MMU_PAGE_4K);

      vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M);
      va = (vsid << 28) | (ea & 0x0fffffff);
      vpn = va >> HW_PAGE_SHIFT;
      slot = iSeries_hpte_find(vpn);
      if (slot == -1)
            panic("updateboltedpp: Could not find page to bolt\n");
      HvCallHpt_setPp(slot, newpp);
}

static void iSeries_hpte_invalidate(unsigned long slot, unsigned long va,
                            int psize, int ssize, int local)
{
      unsigned long hpte_v;
      unsigned long avpn = va >> 23;
      unsigned long flags;

      local_irq_save(flags);

      iSeries_hlock(slot);

      hpte_v = iSeries_hpte_getword0(slot);

      if ((HPTE_V_AVPN_VAL(hpte_v) == avpn) && (hpte_v & HPTE_V_VALID))
            HvCallHpt_invalidateSetSwBitsGet(slot, 0, 0);

      iSeries_hunlock(slot);

      local_irq_restore(flags);
}

void __init hpte_init_iSeries(void)
{
      ppc_md.hpte_invalidate  = iSeries_hpte_invalidate;
      ppc_md.hpte_updatepp    = iSeries_hpte_updatepp;
      ppc_md.hpte_updateboltedpp = iSeries_hpte_updateboltedpp;
      ppc_md.hpte_insert      = iSeries_hpte_insert;
      ppc_md.hpte_remove      = iSeries_hpte_remove;
}

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