Commit 84532a0f authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

Revert "powerpc: Rework dma-noncoherent to use generic vmalloc layer" 



This reverts commit 33f00dce.

    While it was a good idea to try to use the mm/vmalloc.c allocator instead
    of our own (in fact, ours is itself a dup on an old variant of the vmalloc
    one), unfortunately, the approach is terminally busted since
    dma_alloc_coherent() can be called at interrupt time or in atomic contexts
    and there's little chances we'll make the code in mm/vmalloc.c cope with\       that :-(

    Until we can get the generic code to forbid that idiocy and fix all
    drivers abusing it, we pretty much have no choice but revert to
    our custom virtual space allocator.

    There's also a problem with SMP safety since freeing such mapping
    would require an IPI which cannot be done at interrupt time.

    However, right now, I don't think we support any platform that is
    both SMP and has non-coherent DMA (don't laugh, I know such things
    do exist !) so we can sort that out later.

    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent cd86a536

arch/powerpc/Kconfig

+25 −0
Original line number Diff line number Diff line
@@ -868,6 +868,31 @@ config TASK_SIZE 
	default "0x80000000" if PPC_PREP || PPC_8xx

	default "0xc0000000"



config CONSISTENT_START_BOOL

	bool "Set custom consistent memory pool address"

	depends on ADVANCED_OPTIONS && NOT_COHERENT_CACHE

	help

	  This option allows you to set the base virtual address

	  of the consistent memory pool.  This pool of virtual

	  memory is used to make consistent memory allocations.



config CONSISTENT_START

	hex "Base virtual address of consistent memory pool" if CONSISTENT_START_BOOL

	default "0xfd000000" if (NOT_COHERENT_CACHE && 8xx)

	default "0xff100000" if NOT_COHERENT_CACHE



config CONSISTENT_SIZE_BOOL

	bool "Set custom consistent memory pool size"

	depends on ADVANCED_OPTIONS && NOT_COHERENT_CACHE

	help

	  This option allows you to set the size of the

	  consistent memory pool.  This pool of virtual memory

	  is used to make consistent memory allocations.



config CONSISTENT_SIZE

	hex "Size of consistent memory pool" if CONSISTENT_SIZE_BOOL

	default "0x00200000" if NOT_COHERENT_CACHE



config PIN_TLB

	bool "Pinned Kernel TLBs (860 ONLY)"

	depends on ADVANCED_OPTIONS && 8xx

arch/powerpc/lib/dma-noncoherent.c

+246 −57
Original line number Diff line number Diff line
@@ -29,10 +29,120 @@ 
#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.
@@ -41,21 +151,21 @@ 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;



	BUG_ON(!mem_init_done);

	if (!consistent_pte) {

		printk(KERN_ERR "%s: not initialised\n", __func__);

		dump_stack();

		return NULL;

	}



	size = PAGE_ALIGN(size);

	limit = (mask + 1) & ~mask;

	if (limit && size >= limit) {

		printk(KERN_WARNING "coherent allocation too big (requested "

				"%#x mask %#Lx)\n", size, mask);

	if ((limit && size >= limit) || size >= (CONSISTENT_END - CONSISTENT_BASE)) {

		printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",

		       size, mask);

		return NULL;

	}
@@ -68,8 +178,6 @@ __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.
@@ -80,6 +188,16 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp) 
		flush_dcache_range(kaddr, kaddr + size);

	}



	/*

	 * Allocate a virtual address in the consistent mapping region.

	 */

	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);



		/*
@@ -87,49 +205,28 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp) 
		 */

		*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;



	area->pages = pages;

	area->nr_pages = nr_pages;



	for (i = 0; i < nr_pages; i++)

		pages[i] = page + i;

		do {

			BUG_ON(!pte_none(*pte));



	if (map_vm_area(area, pgprot_noncached(PAGE_KERNEL), &pages))

		goto out_unmap;

			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);



		/*

		 * 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:

		return (void *)c->vm_start;

	}



	if (page)

		__free_pages(page, order);

 no_page:
@@ -142,11 +239,103 @@ EXPORT_SYMBOL(__dma_alloc_coherent); 
 */

void __dma_free_coherent(size_t size, void *vaddr)

{

	vfree(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;



		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.

 */

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