powerpc: Rework dma-noncoherent to use generic vmalloc layer

This patch rewrites consistent dma allocations support to use vmalloc
layer to allocate virtual memory space from vmalloc pool and get rid
of CONFIG_CONSISTENT_{START,SIZE}.

This greatly simplifies the code by effectively removing a custom
allocator we had for virtual space.

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 57 insertions, 246 deletions

diff --git a/arch/powerpc/lib/dma-noncoherent.c b/arch/powerpc/lib/dma-noncoherent.c
index b7dc4c19f582..005a28d380af 100644
--- a/arch/powerpc/lib/dma-noncoherent.c
+++ b/arch/powerpc/lib/dma-noncoherent.c
@@ -29,121 +29,11 @@
 #include <linux/types.h>
 #include <linux/highmem.h>
 #include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
 
 #include <asm/tlbflush.h>
 
 /*
- * This address range defaults to a value that is safe for all
- * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
- * can be further configured for specific applications under
- * the "Advanced Setup" menu. -Matt
- */
-#define CONSISTENT_BASE (CONFIG_CONSISTENT_START)
-#define CONSISTENT_END  (CONFIG_CONSISTENT_START + CONFIG_CONSISTENT_SIZE)
-#define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
-
-/*
- * This is the page table (2MB) covering uncached, DMA consistent allocations
- */
-static pte_t *consistent_pte;
-static DEFINE_SPINLOCK(consistent_lock);
-
-/*
- * VM region handling support.
- *
- * This should become something generic, handling VM region allocations for
- * vmalloc and similar (ioremap, module space, etc).
- *
- * I envisage vmalloc()'s supporting vm_struct becoming:
- *
- *  struct vm_struct {
- *    struct vm_region  region;
- *    unsigned long     flags;
- *    struct page       **pages;
- *    unsigned int      nr_pages;
- *    unsigned long     phys_addr;
- *  };
- *
- * get_vm_area() would then call vm_region_alloc with an appropriate
- * struct vm_region head (eg):
- *
- *  struct vm_region vmalloc_head = {
- *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
- *      .vm_start       = VMALLOC_START,
- *      .vm_end         = VMALLOC_END,
- *  };
- *
- * However, vmalloc_head.vm_start is variable (typically, it is dependent on
- * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
- * would have to initialise this each time prior to calling vm_region_alloc().
- */
-struct ppc_vm_region {
-        struct list_head        vm_list;
-        unsigned long           vm_start;
-        unsigned long           vm_end;
-};
-
-static struct ppc_vm_region consistent_head = {
-        .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
-        .vm_start       = CONSISTENT_BASE,
-        .vm_end         = CONSISTENT_END,
-};
-
-static struct ppc_vm_region *
-ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
-{
-        unsigned long addr = head->vm_start, end = head->vm_end - size;
-        unsigned long flags;
-        struct ppc_vm_region *c, *new;
-
-        new = kmalloc(sizeof(struct ppc_vm_region), gfp);
-        if (!new)
-                goto out;
-
-        spin_lock_irqsave(&consistent_lock, flags);
-
-        list_for_each_entry(c, &head->vm_list, vm_list) {
-                if ((addr + size) < addr)
-                        goto nospc;
-                if ((addr + size) <= c->vm_start)
-                        goto found;
-                addr = c->vm_end;
-                if (addr > end)
-                        goto nospc;
-        }
-
- found:
-        /*
-         * Insert this entry _before_ the one we found.
-         */
-        list_add_tail(&new->vm_list, &c->vm_list);
-        new->vm_start = addr;
-        new->vm_end = addr + size;
-
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        return new;
-
- nospc:
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        kfree(new);
- out:
-        return NULL;
-}
-
-static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
-{
-        struct ppc_vm_region *c;
-
-        list_for_each_entry(c, &head->vm_list, vm_list) {
-                if (c->vm_start == addr)
-                        goto out;
-        }
-        c = NULL;
- out:
-        return c;
-}
-
-/*
  * Allocate DMA-coherent memory space and return both the kernel remapped
  * virtual and bus address for that space.
  */
@@ -151,21 +41,21 @@ void *
 __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
 {
         struct page *page;
-        struct ppc_vm_region *c;
         unsigned long order;
+        int i;
+        unsigned int nr_pages = PAGE_ALIGN(size)>>PAGE_SHIFT;
+        unsigned int array_size = nr_pages * sizeof(struct page *);
+        struct page **pages;
+        struct page *end;
         u64 mask = 0x00ffffff, limit; /* ISA default */
+        struct vm_struct *area;
 
-        if (!consistent_pte) {
-                printk(KERN_ERR "%s: not initialised\n", __func__);
-                dump_stack();
-                return NULL;
-        }
-
+        BUG_ON(!mem_init_done);
         size = PAGE_ALIGN(size);
         limit = (mask + 1) & ~mask;
-        if ((limit && size >= limit) || size >= (CONSISTENT_END - CONSISTENT_BASE)) {
-                printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
-                       size, mask);
+        if (limit && size >= limit) {
+                printk(KERN_WARNING "coherent allocation too big (requested "
+                                "%#x mask %#Lx)\n", size, mask);
                 return NULL;
         }
 
@@ -178,6 +68,8 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
         if (!page)
                 goto no_page;
 
+        end = page + (1 << order);
+
         /*
          * Invalidate any data that might be lurking in the
          * kernel direct-mapped region for device DMA.
@@ -188,48 +80,59 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
                 flush_dcache_range(kaddr, kaddr + size);
         }
 
+        split_page(page, order);
+
         /*
-         * Allocate a virtual address in the consistent mapping region.
+         * Set the "dma handle"
          */
-        c = ppc_vm_region_alloc(&consistent_head, size,
-                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
-        if (c) {
-                unsigned long vaddr = c->vm_start;
-                pte_t *pte = consistent_pte + CONSISTENT_OFFSET(vaddr);
-                struct page *end = page + (1 << order);
-
-                split_page(page, order);
-
-                /*
-                 * Set the "dma handle"
-                 */
-                *handle = page_to_phys(page);
+        *handle = page_to_phys(page);
+
+        area = get_vm_area_caller(size, VM_IOREMAP,
+                        __builtin_return_address(1));
+        if (!area)
+                goto out_free_pages;
+
+        if (array_size > PAGE_SIZE) {
+                pages = vmalloc(array_size);
+                area->flags |= VM_VPAGES;
+        } else {
+                pages = kmalloc(array_size, GFP_KERNEL);
+        }
+        if (!pages)
+                goto out_free_area;
 
-                do {
-                        BUG_ON(!pte_none(*pte));
+        area->pages = pages;
+        area->nr_pages = nr_pages;
 
-                        SetPageReserved(page);
-                        set_pte_at(&init_mm, vaddr,
-                                   pte, mk_pte(page, pgprot_noncached(PAGE_KERNEL)));
-                        page++;
-                        pte++;
-                        vaddr += PAGE_SIZE;
-                } while (size -= PAGE_SIZE);
+        for (i = 0; i < nr_pages; i++)
+                pages[i] = page + i;
 
-                /*
-                 * Free the otherwise unused pages.
-                 */
-                while (page < end) {
-                        __free_page(page);
-                        page++;
-                }
+        if (map_vm_area(area, pgprot_noncached(PAGE_KERNEL), &pages))
+                goto out_unmap;
 
-                return (void *)c->vm_start;
+        /*
+         * Free the otherwise unused pages.
+         */
+        page += nr_pages;
+        while (page < end) {
+                __free_page(page);
+                page++;
         }
 
+        return area->addr;
+out_unmap:
+        vunmap(area->addr);
+        if (array_size > PAGE_SIZE)
+                vfree(pages);
+        else
+                kfree(pages);
+        goto out_free_pages;
+out_free_area:
+        free_vm_area(area);
+out_free_pages:
         if (page)
                 __free_pages(page, order);
- no_page:
+no_page:
         return NULL;
 }
 EXPORT_SYMBOL(__dma_alloc_coherent);
@@ -239,104 +142,12 @@ EXPORT_SYMBOL(__dma_alloc_coherent);
  */
 void __dma_free_coherent(size_t size, void *vaddr)
 {
-        struct ppc_vm_region *c;
-        unsigned long flags, addr;
-        pte_t *ptep;
-
-        size = PAGE_ALIGN(size);
-
-        spin_lock_irqsave(&consistent_lock, flags);
-
-        c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
-        if (!c)
-                goto no_area;
-
-        if ((c->vm_end - c->vm_start) != size) {
-                printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
-                       __func__, c->vm_end - c->vm_start, size);
-                dump_stack();
-                size = c->vm_end - c->vm_start;
-        }
-
-        ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
-        addr = c->vm_start;
-        do {
-                pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
-                unsigned long pfn;
-
-                ptep++;
-                addr += PAGE_SIZE;
+        vfree(vaddr);
 
-                if (!pte_none(pte) && pte_present(pte)) {
-                        pfn = pte_pfn(pte);
-
-                        if (pfn_valid(pfn)) {
-                                struct page *page = pfn_to_page(pfn);
-                                ClearPageReserved(page);
-
-                                __free_page(page);
-                                continue;
-                        }
-                }
-
-                printk(KERN_CRIT "%s: bad page in kernel page table\n",
-                       __func__);
-        } while (size -= PAGE_SIZE);
-
-        flush_tlb_kernel_range(c->vm_start, c->vm_end);
-
-        list_del(&c->vm_list);
-
-        spin_unlock_irqrestore(&consistent_lock, flags);
-
-        kfree(c);
-        return;
-
- no_area:
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
-               __func__, vaddr);
-        dump_stack();
 }
 EXPORT_SYMBOL(__dma_free_coherent);
 
 /*
- * Initialise the consistent memory allocation.
- */
-static int __init dma_alloc_init(void)
-{
-        pgd_t *pgd;
-        pud_t *pud;
-        pmd_t *pmd;
-        pte_t *pte;
-        int ret = 0;
-
-        do {
-                pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
-                pud = pud_alloc(&init_mm, pgd, CONSISTENT_BASE);
-                pmd = pmd_alloc(&init_mm, pud, CONSISTENT_BASE);
-                if (!pmd) {
-                        printk(KERN_ERR "%s: no pmd tables\n", __func__);
-                        ret = -ENOMEM;
-                        break;
-                }
-
-                pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
-                if (!pte) {
-                        printk(KERN_ERR "%s: no pte tables\n", __func__);
-                        ret = -ENOMEM;
-                        break;
-                }
-
-                consistent_pte = pte;
-        } while (0);
-
-        return ret;
-}
-
-core_initcall(dma_alloc_init);
-
-/*
  * make an area consistent.
  */
 void __dma_sync(void *vaddr, size_t size, int direction)