metag: Highmem support

/*

 * fixmap.h: compile-time virtual memory allocation

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 *

 * Copyright (C) 1998 Ingo Molnar

 *

 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999

 */

#ifndef _ASM_FIXMAP_H

#define _ASM_FIXMAP_H

#include <asm/pgtable.h>

#ifdef CONFIG_HIGHMEM

#include <linux/threads.h>

#include <asm/kmap_types.h>

#endif

/*

 * Here we define all the compile-time 'special' virtual

 * addresses. The point is to have a constant address at

 * compile time, but to set the physical address only

 * in the boot process. We allocate these special  addresses

 * from the end of the consistent memory region backwards.

 * Also this lets us do fail-safe vmalloc(), we

 * can guarantee that these special addresses and

 * vmalloc()-ed addresses never overlap.

 *

 * these 'compile-time allocated' memory buffers are

 * fixed-size 4k pages. (or larger if used with an increment

 * higher than 1) use fixmap_set(idx,phys) to associate

 * physical memory with fixmap indices.

 *

 * TLB entries of such buffers will not be flushed across

 * task switches.

 */

enum fixed_addresses {

#define FIX_N_COLOURS 8

#ifdef CONFIG_HIGHMEM

	/* reserved pte's for temporary kernel mappings */

	FIX_KMAP_BEGIN,

	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,

#endif

	__end_of_fixed_addresses

};

#define FIXADDR_TOP     (CONSISTENT_START - PAGE_SIZE)

#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)

#define FIXADDR_START	((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)

#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))

#define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)

extern void __this_fixmap_does_not_exist(void);

/*

 * 'index to address' translation. If anyone tries to use the idx

 * directly without tranlation, we catch the bug with a NULL-deference

 * kernel oops. Illegal ranges of incoming indices are caught too.

 */

static inline unsigned long fix_to_virt(const unsigned int idx)

{

	/*

	 * this branch gets completely eliminated after inlining,

	 * except when someone tries to use fixaddr indices in an

	 * illegal way. (such as mixing up address types or using

	 * out-of-range indices).

	 *

	 * If it doesn't get removed, the linker will complain

	 * loudly with a reasonably clear error message..

	 */

	if (idx >= __end_of_fixed_addresses)

		__this_fixmap_does_not_exist();

	return __fix_to_virt(idx);

}

static inline unsigned long virt_to_fix(const unsigned long vaddr)

{

	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);

	return __virt_to_fix(vaddr);

}

#define kmap_get_fixmap_pte(vaddr) \

	pte_offset_kernel( \

		pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \

		(vaddr) \

	)

/*

 * Called from pgtable_init()

 */

extern void fixrange_init(unsigned long start, unsigned long end,

	pgd_t *pgd_base);

#endif

#ifndef _ASM_HIGHMEM_H

#define _ASM_HIGHMEM_H

#include <asm/cacheflush.h>

#include <asm/kmap_types.h>

#include <asm/fixmap.h>

/*

 * Right now we initialize only a single pte table. It can be extended

 * easily, subsequent pte tables have to be allocated in one physical

 * chunk of RAM.

 */

/*

 * Ordering is (from lower to higher memory addresses):

 *

 * high_memory

 *			Persistent kmap area

 * PKMAP_BASE

 *			fixed_addresses

 * FIXADDR_START

 * FIXADDR_TOP

 *			Vmalloc area

 * VMALLOC_START

 * VMALLOC_END

 */

#define PKMAP_BASE		(FIXADDR_START - PMD_SIZE)

#define LAST_PKMAP		PTRS_PER_PTE

#define LAST_PKMAP_MASK		(LAST_PKMAP - 1)

#define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)

#define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))

#define kmap_prot		PAGE_KERNEL

static inline void flush_cache_kmaps(void)

{

	flush_cache_all();

}

/* declarations for highmem.c */

extern unsigned long highstart_pfn, highend_pfn;

extern pte_t *pkmap_page_table;

extern void *kmap_high(struct page *page);

extern void kunmap_high(struct page *page);

extern void kmap_init(void);

/*

 * The following functions are already defined by <linux/highmem.h>

 * when CONFIG_HIGHMEM is not set.

 */

#ifdef CONFIG_HIGHMEM

extern void *kmap(struct page *page);

extern void kunmap(struct page *page);

extern void *kmap_atomic(struct page *page);

extern void __kunmap_atomic(void *kvaddr);

extern void *kmap_atomic_pfn(unsigned long pfn);

extern struct page *kmap_atomic_to_page(void *ptr);

#endif

#endif

#include <linux/export.h>

#include <linux/highmem.h>

#include <linux/sched.h>

#include <linux/smp.h>

#include <linux/interrupt.h>

#include <asm/fixmap.h>

#include <asm/tlbflush.h>

static pte_t *kmap_pte;

unsigned long highstart_pfn, highend_pfn;

void *kmap(struct page *page)

{

	might_sleep();

	if (!PageHighMem(page))

		return page_address(page);

	return kmap_high(page);

}

EXPORT_SYMBOL(kmap);

void kunmap(struct page *page)

{

	BUG_ON(in_interrupt());

	if (!PageHighMem(page))

		return;

	kunmap_high(page);

}

EXPORT_SYMBOL(kunmap);

/*

 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because

 * no global lock is needed and because the kmap code must perform a global TLB

 * invalidation when the kmap pool wraps.

 *

 * However when holding an atomic kmap is is not legal to sleep, so atomic

 * kmaps are appropriate for short, tight code paths only.

 */

void *kmap_atomic(struct page *page)

{

	enum fixed_addresses idx;

	unsigned long vaddr;

	int type;

	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */

	pagefault_disable();

	if (!PageHighMem(page))

		return page_address(page);

	type = kmap_atomic_idx_push();

	idx = type + KM_TYPE_NR * smp_processor_id();

	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);

#ifdef CONFIG_DEBUG_HIGHMEM

	BUG_ON(!pte_none(*(kmap_pte - idx)));

#endif

	set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL));

	return (void *)vaddr;

}

EXPORT_SYMBOL(kmap_atomic);

void __kunmap_atomic(void *kvaddr)

{

	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;

	int idx, type;

	if (kvaddr >= (void *)FIXADDR_START) {

		type = kmap_atomic_idx();

		idx = type + KM_TYPE_NR * smp_processor_id();

		/*

		 * Force other mappings to Oops if they'll try to access this

		 * pte without first remap it.  Keeping stale mappings around

		 * is a bad idea also, in case the page changes cacheability

		 * attributes or becomes a protected page in a hypervisor.

		 */

		pte_clear(&init_mm, vaddr, kmap_pte-idx);

		flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);

		kmap_atomic_idx_pop();

	}

	pagefault_enable();

}

EXPORT_SYMBOL(__kunmap_atomic);

/*

 * This is the same as kmap_atomic() but can map memory that doesn't

 * have a struct page associated with it.

 */

void *kmap_atomic_pfn(unsigned long pfn)

{

	enum fixed_addresses idx;

	unsigned long vaddr;

	int type;

	pagefault_disable();

	type = kmap_atomic_idx_push();

	idx = type + KM_TYPE_NR * smp_processor_id();

	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);

#ifdef CONFIG_DEBUG_HIGHMEM

	BUG_ON(!pte_none(*(kmap_pte - idx)));

#endif

	set_pte(kmap_pte - idx, pfn_pte(pfn, PAGE_KERNEL));

	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);

	return (void *)vaddr;

}

struct page *kmap_atomic_to_page(void *ptr)

{

	unsigned long vaddr = (unsigned long)ptr;

	int idx;

	pte_t *pte;

	if (vaddr < FIXADDR_START)

		return virt_to_page(ptr);

	idx = virt_to_fix(vaddr);

	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);

	return pte_page(*pte);

}

void __init kmap_init(void)

{

	unsigned long kmap_vstart;

	/* cache the first kmap pte */

	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);

	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);

}