FreeBSD/Linux Kernel Cross Reference
sys/mm/percpu-vm.c

     /*
      * mm/percpu-vm.c - vmalloc area based chunk allocation
      *
      * Copyright (C) 2010           SUSE Linux Products GmbH
      * Copyright (C) 2010           Tejun Heo <tj@kernel.org>
      *
      * This file is released under the GPLv2.
      *
      * Chunks are mapped into vmalloc areas and populated page by page.
     * This is the default chunk allocator.
     */
    
    static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
                                        unsigned int cpu, int page_idx)
    {
            /* must not be used on pre-mapped chunk */
            WARN_ON(chunk->immutable);
    
            return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
    }
    
    /**
     * pcpu_get_pages_and_bitmap - get temp pages array and bitmap
     * @chunk: chunk of interest
     * @bitmapp: output parameter for bitmap
     * @may_alloc: may allocate the array
     *
     * Returns pointer to array of pointers to struct page and bitmap,
     * both of which can be indexed with pcpu_page_idx().  The returned
     * array is cleared to zero and *@bitmapp is copied from
     * @chunk->populated.  Note that there is only one array and bitmap
     * and access exclusion is the caller's responsibility.
     *
     * CONTEXT:
     * pcpu_alloc_mutex and does GFP_KERNEL allocation if @may_alloc.
     * Otherwise, don't care.
     *
     * RETURNS:
     * Pointer to temp pages array on success, NULL on failure.
     */
    static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk,
                                                   unsigned long **bitmapp,
                                                   bool may_alloc)
    {
            static struct page **pages;
            static unsigned long *bitmap;
            size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
            size_t bitmap_size = BITS_TO_LONGS(pcpu_unit_pages) *
                                 sizeof(unsigned long);
    
            if (!pages || !bitmap) {
                    if (may_alloc && !pages)
                            pages = pcpu_mem_zalloc(pages_size);
                    if (may_alloc && !bitmap)
                            bitmap = pcpu_mem_zalloc(bitmap_size);
                    if (!pages || !bitmap)
                            return NULL;
            }
    
            bitmap_copy(bitmap, chunk->populated, pcpu_unit_pages);
    
            *bitmapp = bitmap;
            return pages;
    }
    
    /**
     * pcpu_free_pages - free pages which were allocated for @chunk
     * @chunk: chunk pages were allocated for
     * @pages: array of pages to be freed, indexed by pcpu_page_idx()
     * @populated: populated bitmap
     * @page_start: page index of the first page to be freed
     * @page_end: page index of the last page to be freed + 1
     *
     * Free pages [@page_start and @page_end) in @pages for all units.
     * The pages were allocated for @chunk.
     */
    static void pcpu_free_pages(struct pcpu_chunk *chunk,
                                struct page **pages, unsigned long *populated,
                                int page_start, int page_end)
    {
            unsigned int cpu;
            int i;
    
            for_each_possible_cpu(cpu) {
                    for (i = page_start; i < page_end; i++) {
                            struct page *page = pages[pcpu_page_idx(cpu, i)];
    
                            if (page)
                                    __free_page(page);
                    }
            }
    }
    
    /**
     * pcpu_alloc_pages - allocates pages for @chunk
     * @chunk: target chunk
     * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
     * @populated: populated bitmap
     * @page_start: page index of the first page to be allocated
    * @page_end: page index of the last page to be allocated + 1
    *
    * Allocate pages [@page_start,@page_end) into @pages for all units.
    * The allocation is for @chunk.  Percpu core doesn't care about the
    * content of @pages and will pass it verbatim to pcpu_map_pages().
    */
   static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
                               struct page **pages, unsigned long *populated,
                               int page_start, int page_end)
   {
           const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
           unsigned int cpu;
           int i;
   
           for_each_possible_cpu(cpu) {
                   for (i = page_start; i < page_end; i++) {
                           struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
   
                           *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
                           if (!*pagep) {
                                   pcpu_free_pages(chunk, pages, populated,
                                                   page_start, page_end);
                                   return -ENOMEM;
                           }
                   }
           }
           return 0;
   }
   
   /**
    * pcpu_pre_unmap_flush - flush cache prior to unmapping
    * @chunk: chunk the regions to be flushed belongs to
    * @page_start: page index of the first page to be flushed
    * @page_end: page index of the last page to be flushed + 1
    *
    * Pages in [@page_start,@page_end) of @chunk are about to be
    * unmapped.  Flush cache.  As each flushing trial can be very
    * expensive, issue flush on the whole region at once rather than
    * doing it for each cpu.  This could be an overkill but is more
    * scalable.
    */
   static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
                                    int page_start, int page_end)
   {
           flush_cache_vunmap(
                   pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
                   pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
   }
   
   static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
   {
           unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
   }
   
   /**
    * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
    * @chunk: chunk of interest
    * @pages: pages array which can be used to pass information to free
    * @populated: populated bitmap
    * @page_start: page index of the first page to unmap
    * @page_end: page index of the last page to unmap + 1
    *
    * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
    * Corresponding elements in @pages were cleared by the caller and can
    * be used to carry information to pcpu_free_pages() which will be
    * called after all unmaps are finished.  The caller should call
    * proper pre/post flush functions.
    */
   static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
                                struct page **pages, unsigned long *populated,
                                int page_start, int page_end)
   {
           unsigned int cpu;
           int i;
   
           for_each_possible_cpu(cpu) {
                   for (i = page_start; i < page_end; i++) {
                           struct page *page;
   
                           page = pcpu_chunk_page(chunk, cpu, i);
                           WARN_ON(!page);
                           pages[pcpu_page_idx(cpu, i)] = page;
                   }
                   __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
                                      page_end - page_start);
           }
   
           bitmap_clear(populated, page_start, page_end - page_start);
   }
   
   /**
    * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
    * @chunk: pcpu_chunk the regions to be flushed belong to
    * @page_start: page index of the first page to be flushed
    * @page_end: page index of the last page to be flushed + 1
    *
    * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
    * TLB for the regions.  This can be skipped if the area is to be
    * returned to vmalloc as vmalloc will handle TLB flushing lazily.
    *
    * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
    * for the whole region.
    */
   static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
                                         int page_start, int page_end)
   {
           flush_tlb_kernel_range(
                   pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
                   pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
   }
   
   static int __pcpu_map_pages(unsigned long addr, struct page **pages,
                               int nr_pages)
   {
           return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
                                           PAGE_KERNEL, pages);
   }
   
   /**
    * pcpu_map_pages - map pages into a pcpu_chunk
    * @chunk: chunk of interest
    * @pages: pages array containing pages to be mapped
    * @populated: populated bitmap
    * @page_start: page index of the first page to map
    * @page_end: page index of the last page to map + 1
    *
    * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
    * caller is responsible for calling pcpu_post_map_flush() after all
    * mappings are complete.
    *
    * This function is responsible for setting corresponding bits in
    * @chunk->populated bitmap and whatever is necessary for reverse
    * lookup (addr -> chunk).
    */
   static int pcpu_map_pages(struct pcpu_chunk *chunk,
                             struct page **pages, unsigned long *populated,
                             int page_start, int page_end)
   {
           unsigned int cpu, tcpu;
           int i, err;
   
           for_each_possible_cpu(cpu) {
                   err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
                                          &pages[pcpu_page_idx(cpu, page_start)],
                                          page_end - page_start);
                   if (err < 0)
                           goto err;
           }
   
           /* mapping successful, link chunk and mark populated */
           for (i = page_start; i < page_end; i++) {
                   for_each_possible_cpu(cpu)
                           pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
                                               chunk);
                   __set_bit(i, populated);
           }
   
           return 0;
   
   err:
           for_each_possible_cpu(tcpu) {
                   if (tcpu == cpu)
                           break;
                   __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
                                      page_end - page_start);
           }
           return err;
   }
   
   /**
    * pcpu_post_map_flush - flush cache after mapping
    * @chunk: pcpu_chunk the regions to be flushed belong to
    * @page_start: page index of the first page to be flushed
    * @page_end: page index of the last page to be flushed + 1
    *
    * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
    * cache.
    *
    * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
    * for the whole region.
    */
   static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
                                   int page_start, int page_end)
   {
           flush_cache_vmap(
                   pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
                   pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
   }
   
   /**
    * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
    * @chunk: chunk of interest
    * @off: offset to the area to populate
    * @size: size of the area to populate in bytes
    *
    * For each cpu, populate and map pages [@page_start,@page_end) into
    * @chunk.  The area is cleared on return.
    *
    * CONTEXT:
    * pcpu_alloc_mutex, does GFP_KERNEL allocation.
    */
   static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
   {
           int page_start = PFN_DOWN(off);
           int page_end = PFN_UP(off + size);
           int free_end = page_start, unmap_end = page_start;
           struct page **pages;
           unsigned long *populated;
           unsigned int cpu;
           int rs, re, rc;
   
           /* quick path, check whether all pages are already there */
           rs = page_start;
           pcpu_next_pop(chunk, &rs, &re, page_end);
           if (rs == page_start && re == page_end)
                   goto clear;
   
           /* need to allocate and map pages, this chunk can't be immutable */
           WARN_ON(chunk->immutable);
   
           pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);
           if (!pages)
                   return -ENOMEM;
   
           /* alloc and map */
           pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
                   rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);
                   if (rc)
                           goto err_free;
                   free_end = re;
           }
   
           pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
                   rc = pcpu_map_pages(chunk, pages, populated, rs, re);
                   if (rc)
                           goto err_unmap;
                   unmap_end = re;
           }
           pcpu_post_map_flush(chunk, page_start, page_end);
   
           /* commit new bitmap */
           bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
   clear:
           for_each_possible_cpu(cpu)
                   memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
           return 0;
   
   err_unmap:
           pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
           pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
                   pcpu_unmap_pages(chunk, pages, populated, rs, re);
           pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
   err_free:
           pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
                   pcpu_free_pages(chunk, pages, populated, rs, re);
           return rc;
   }
   
   /**
    * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
    * @chunk: chunk to depopulate
    * @off: offset to the area to depopulate
    * @size: size of the area to depopulate in bytes
    *
    * For each cpu, depopulate and unmap pages [@page_start,@page_end)
    * from @chunk.  If @flush is true, vcache is flushed before unmapping
    * and tlb after.
    *
    * CONTEXT:
    * pcpu_alloc_mutex.
    */
   static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
   {
           int page_start = PFN_DOWN(off);
           int page_end = PFN_UP(off + size);
           struct page **pages;
           unsigned long *populated;
           int rs, re;
   
           /* quick path, check whether it's empty already */
           rs = page_start;
           pcpu_next_unpop(chunk, &rs, &re, page_end);
           if (rs == page_start && re == page_end)
                   return;
   
           /* immutable chunks can't be depopulated */
           WARN_ON(chunk->immutable);
   
           /*
            * If control reaches here, there must have been at least one
            * successful population attempt so the temp pages array must
            * be available now.
            */
           pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);
           BUG_ON(!pages);
   
           /* unmap and free */
           pcpu_pre_unmap_flush(chunk, page_start, page_end);
   
           pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
                   pcpu_unmap_pages(chunk, pages, populated, rs, re);
   
           /* no need to flush tlb, vmalloc will handle it lazily */
   
           pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
                   pcpu_free_pages(chunk, pages, populated, rs, re);
   
           /* commit new bitmap */
           bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
   }
   
   static struct pcpu_chunk *pcpu_create_chunk(void)
   {
           struct pcpu_chunk *chunk;
           struct vm_struct **vms;
   
           chunk = pcpu_alloc_chunk();
           if (!chunk)
                   return NULL;
   
           vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
                                   pcpu_nr_groups, pcpu_atom_size);
           if (!vms) {
                   pcpu_free_chunk(chunk);
                   return NULL;
           }
   
           chunk->data = vms;
           chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
           return chunk;
   }
   
   static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
   {
           if (chunk && chunk->data)
                   pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
           pcpu_free_chunk(chunk);
   }
   
   static struct page *pcpu_addr_to_page(void *addr)
   {
           return vmalloc_to_page(addr);
   }
   
   static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
   {
           /* no extra restriction */
           return 0;
   }

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