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lscsa_alloc.c

/*
 * SPU local store allocation routines
 *
 * Copyright 2007 Benjamin Herrenschmidt, 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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>

#include <asm/spu.h>
#include <asm/spu_csa.h>
#include <asm/mmu.h>

#include "spufs.h"

static int spu_alloc_lscsa_std(struct spu_state *csa)
{
      struct spu_lscsa *lscsa;
      unsigned char *p;

      lscsa = vmalloc(sizeof(struct spu_lscsa));
      if (!lscsa)
            return -ENOMEM;
      memset(lscsa, 0, sizeof(struct spu_lscsa));
      csa->lscsa = lscsa;

      /* Set LS pages reserved to allow for user-space mapping. */
      for (p = lscsa->ls; p < lscsa->ls + LS_SIZE; p += PAGE_SIZE)
            SetPageReserved(vmalloc_to_page(p));

      return 0;
}

static void spu_free_lscsa_std(struct spu_state *csa)
{
      /* Clear reserved bit before vfree. */
      unsigned char *p;

      if (csa->lscsa == NULL)
            return;

      for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
            ClearPageReserved(vmalloc_to_page(p));

      vfree(csa->lscsa);
}

#ifdef CONFIG_SPU_FS_64K_LS

#define SPU_64K_PAGE_SHIFT    16
#define SPU_64K_PAGE_ORDER    (SPU_64K_PAGE_SHIFT - PAGE_SHIFT)
#define SPU_64K_PAGE_COUNT    (1ul << SPU_64K_PAGE_ORDER)

int spu_alloc_lscsa(struct spu_state *csa)
{
      struct page **pgarray;
      unsigned char     *p;
      int         i, j, n_4k;

      /* Check availability of 64K pages */
      if (!spu_64k_pages_available())
            goto fail;

      csa->use_big_pages = 1;

      pr_debug("spu_alloc_lscsa(csa=0x%p), trying to allocate 64K pages\n",
             csa);

      /* First try to allocate our 64K pages. We need 5 of them
       * with the current implementation. In the future, we should try
       * to separate the lscsa with the actual local store image, thus
       * allowing us to require only 4 64K pages per context
       */
      for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++) {
            /* XXX This is likely to fail, we should use a special pool
             *     similiar to what hugetlbfs does.
             */
            csa->lscsa_pages[i] = alloc_pages(GFP_KERNEL,
                                      SPU_64K_PAGE_ORDER);
            if (csa->lscsa_pages[i] == NULL)
                  goto fail;
      }

      pr_debug(" success ! creating vmap...\n");

      /* Now we need to create a vmalloc mapping of these for the kernel
       * and SPU context switch code to use. Currently, we stick to a
       * normal kernel vmalloc mapping, which in our case will be 4K
       */
      n_4k = SPU_64K_PAGE_COUNT * SPU_LSCSA_NUM_BIG_PAGES;
      pgarray = kmalloc(sizeof(struct page *) * n_4k, GFP_KERNEL);
      if (pgarray == NULL)
            goto fail;
      for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++)
            for (j = 0; j < SPU_64K_PAGE_COUNT; j++)
                  /* We assume all the struct page's are contiguous
                   * which should be hopefully the case for an order 4
                   * allocation..
                   */
                  pgarray[i * SPU_64K_PAGE_COUNT + j] =
                        csa->lscsa_pages[i] + j;
      csa->lscsa = vmap(pgarray, n_4k, VM_USERMAP, PAGE_KERNEL);
      kfree(pgarray);
      if (csa->lscsa == NULL)
            goto fail;

      memset(csa->lscsa, 0, sizeof(struct spu_lscsa));

      /* Set LS pages reserved to allow for user-space mapping.
       *
       * XXX isn't that a bit obsolete ? I think we should just
       * make sure the page count is high enough. Anyway, won't harm
       * for now
       */
      for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
            SetPageReserved(vmalloc_to_page(p));

      pr_debug(" all good !\n");

      return 0;
fail:
      pr_debug("spufs: failed to allocate lscsa 64K pages, falling back\n");
      spu_free_lscsa(csa);
      return spu_alloc_lscsa_std(csa);
}

void spu_free_lscsa(struct spu_state *csa)
{
      unsigned char *p;
      int i;

      if (!csa->use_big_pages) {
            spu_free_lscsa_std(csa);
            return;
      }
      csa->use_big_pages = 0;

      if (csa->lscsa == NULL)
            goto free_pages;

      for (p = csa->lscsa->ls; p < csa->lscsa->ls + LS_SIZE; p += PAGE_SIZE)
            ClearPageReserved(vmalloc_to_page(p));

      vunmap(csa->lscsa);
      csa->lscsa = NULL;

 free_pages:

      for (i = 0; i < SPU_LSCSA_NUM_BIG_PAGES; i++)
            if (csa->lscsa_pages[i])
                  __free_pages(csa->lscsa_pages[i], SPU_64K_PAGE_ORDER);
}

#else /* CONFIG_SPU_FS_64K_LS */

int spu_alloc_lscsa(struct spu_state *csa)
{
      return spu_alloc_lscsa_std(csa);
}

void spu_free_lscsa(struct spu_state *csa)
{
      spu_free_lscsa_std(csa);
}

#endif /* !defined(CONFIG_SPU_FS_64K_LS) */

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