[linux.git] / mm / fremap.c

/*
 *   linux/mm/fremap.c
 * 
 * Explicit pagetable population and nonlinear (random) mappings support.
 *
 * started by Ingo Molnar, Copyright (C) 2002, 2003
 */

#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/file.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swapops.h>
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/syscalls.h>

#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

static inline void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
			unsigned long addr, pte_t *ptep)
{
	pte_t pte = *ptep;

	if (pte_none(pte))
		return;
	if (pte_present(pte)) {
		unsigned long pfn = pte_pfn(pte);

		flush_cache_page(vma, addr, pfn);
		pte = ptep_clear_flush(vma, addr, ptep);
		if (pfn_valid(pfn)) {
			struct page *page = pfn_to_page(pfn);
			if (!PageReserved(page)) {
				if (pte_dirty(pte))
					set_page_dirty(page);
				page_remove_rmap(page);
				page_cache_release(page);
				dec_mm_counter(mm, rss);
			}
		}
	} else {
		if (!pte_file(pte))
			free_swap_and_cache(pte_to_swp_entry(pte));
		pte_clear(mm, addr, ptep);
	}
}

/*
 * Install a file page to a given virtual memory address, release any
 * previously existing mapping.
 */
int install_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long addr, struct page *page, pgprot_t prot)
{
	struct inode *inode;
	pgoff_t size;
	int err = -ENOMEM;
	pte_t *pte;
	pmd_t *pmd;
	pud_t *pud;
	pgd_t *pgd;
	pte_t pte_val;

	pgd = pgd_offset(mm, addr);
	spin_lock(&mm->page_table_lock);
	
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		goto err_unlock;

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		goto err_unlock;

	pte = pte_alloc_map(mm, pmd, addr);
	if (!pte)
		goto err_unlock;

	/*
	 * This page may have been truncated. Tell the
	 * caller about it.
	 */
	err = -EINVAL;
	inode = vma->vm_file->f_mapping->host;
	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	if (!page->mapping || page->index >= size)
		goto err_unlock;

	zap_pte(mm, vma, addr, pte);

	inc_mm_counter(mm,rss);
	flush_icache_page(vma, page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));
	page_add_file_rmap(page);
	pte_val = *pte;
	pte_unmap(pte);
	update_mmu_cache(vma, addr, pte_val);

	err = 0;
err_unlock:
	spin_unlock(&mm->page_table_lock);
	return err;
}
EXPORT_SYMBOL(install_page);


/*
 * Install a file pte to a given virtual memory address, release any
 * previously existing mapping.
 */
int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long addr, unsigned long pgoff, pgprot_t prot)
{
	int err = -ENOMEM;
	pte_t *pte;
	pmd_t *pmd;
	pud_t *pud;
	pgd_t *pgd;
	pte_t pte_val;

	pgd = pgd_offset(mm, addr);
	spin_lock(&mm->page_table_lock);
	
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		goto err_unlock;

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		goto err_unlock;

	pte = pte_alloc_map(mm, pmd, addr);
	if (!pte)
		goto err_unlock;

	zap_pte(mm, vma, addr, pte);

	set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
	pte_val = *pte;
	pte_unmap(pte);
	update_mmu_cache(vma, addr, pte_val);
	spin_unlock(&mm->page_table_lock);
	return 0;

err_unlock:
	spin_unlock(&mm->page_table_lock);
	return err;
}


/***
 * sys_remap_file_pages - remap arbitrary pages of a shared backing store
 *                        file within an existing vma.
 * @start: start of the remapped virtual memory range
 * @size: size of the remapped virtual memory range
 * @prot: new protection bits of the range
 * @pgoff: to be mapped page of the backing store file
 * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
 *
 * this syscall works purely via pagetables, so it's the most efficient
 * way to map the same (large) file into a given virtual window. Unlike
 * mmap()/mremap() it does not create any new vmas. The new mappings are
 * also safe across swapout.
 *
 * NOTE: the 'prot' parameter right now is ignored, and the vma's default
 * protection is used. Arbitrary protections might be implemented in the
 * future.
 */
asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
	unsigned long __prot, unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct address_space *mapping;
	unsigned long end = start + size;
	struct vm_area_struct *vma;
	int err = -EINVAL;
	int has_write_lock = 0;

	if (__prot)
		return err;
	/*
	 * Sanitize the syscall parameters:
	 */
	start = start & PAGE_MASK;
	size = size & PAGE_MASK;

	/* Does the address range wrap, or is the span zero-sized? */
	if (start + size <= start)
		return err;

	/* Can we represent this offset inside this architecture's pte's? */
#if PTE_FILE_MAX_BITS < BITS_PER_LONG
	if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
		return err;
#endif

	/* We need down_write() to change vma->vm_flags. */
	down_read(&mm->mmap_sem);
 retry:
	vma = find_vma(mm, start);

	/*
	 * Make sure the vma is shared, that it supports prefaulting,
	 * and that the remapped range is valid and fully within
	 * the single existing vma.  vm_private_data is used as a
	 * swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED
	 * or VM_LOCKED, but VM_LOCKED could be revoked later on).
	 */
	if (vma && (vma->vm_flags & VM_SHARED) &&
		(!vma->vm_private_data ||
			(vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) &&
		vma->vm_ops && vma->vm_ops->populate &&
			end > start && start >= vma->vm_start &&
				end <= vma->vm_end) {

		/* Must set VM_NONLINEAR before any pages are populated. */
		if (pgoff != linear_page_index(vma, start) &&
		    !(vma->vm_flags & VM_NONLINEAR)) {
			if (!has_write_lock) {
				up_read(&mm->mmap_sem);
				down_write(&mm->mmap_sem);
				has_write_lock = 1;
				goto retry;
			}
			mapping = vma->vm_file->f_mapping;
			spin_lock(&mapping->i_mmap_lock);
			flush_dcache_mmap_lock(mapping);
			vma->vm_flags |= VM_NONLINEAR;
			vma_prio_tree_remove(vma, &mapping->i_mmap);
			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
			flush_dcache_mmap_unlock(mapping);
			spin_unlock(&mapping->i_mmap_lock);
		}

		err = vma->vm_ops->populate(vma, start, size,
					    vma->vm_page_prot,
					    pgoff, flags & MAP_NONBLOCK);

		/*
		 * We can't clear VM_NONLINEAR because we'd have to do
		 * it after ->populate completes, and that would prevent
		 * downgrading the lock.  (Locks can't be upgraded).
		 */
	}
	if (likely(!has_write_lock))
		up_read(&mm->mmap_sem);
	else
		up_write(&mm->mmap_sem);

	return err;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/mm/fremap.c
	3	*
	4	* Explicit pagetable population and nonlinear (random) mappings support.
	5	*
	6	* started by Ingo Molnar, Copyright (C) 2002, 2003
	7	*/
	8
	9	#include <linux/mm.h>
	10	#include <linux/swap.h>
	11	#include <linux/file.h>
	12	#include <linux/mman.h>
	13	#include <linux/pagemap.h>
	14	#include <linux/swapops.h>
	15	#include <linux/rmap.h>
	16	#include <linux/module.h>
	17	#include <linux/syscalls.h>
	18
	19	#include <asm/mmu_context.h>
	20	#include <asm/cacheflush.h>
	21	#include <asm/tlbflush.h>
	22
	23	static inline void zap_pte(struct mm_struct mm, struct vm_area_struct vma,
	24	unsigned long addr, pte_t *ptep)
	25	{
	26	pte_t pte = *ptep;
	27
	28	if (pte_none(pte))
	29	return;
	30	if (pte_present(pte)) {
	31	unsigned long pfn = pte_pfn(pte);
	32
	33	flush_cache_page(vma, addr, pfn);
	34	pte = ptep_clear_flush(vma, addr, ptep);
	35	if (pfn_valid(pfn)) {
	36	struct page *page = pfn_to_page(pfn);
	37	if (!PageReserved(page)) {
	38	if (pte_dirty(pte))
	39	set_page_dirty(page);
	40	page_remove_rmap(page);
	41	page_cache_release(page);
	42	dec_mm_counter(mm, rss);
	43	}
	44	}
	45	} else {
	46	if (!pte_file(pte))
	47	free_swap_and_cache(pte_to_swp_entry(pte));
	48	pte_clear(mm, addr, ptep);
	49	}
	50	}
	51
	52	/*
	53	* Install a file page to a given virtual memory address, release any
	54	* previously existing mapping.
	55	*/
	56	int install_page(struct mm_struct mm, struct vm_area_struct vma,
	57	unsigned long addr, struct page *page, pgprot_t prot)
	58	{
	59	struct inode *inode;
	60	pgoff_t size;
	61	int err = -ENOMEM;
	62	pte_t *pte;
	63	pmd_t *pmd;
	64	pud_t *pud;
65	pgd_t *pgd;
66	pte_t pte_val;
67
68	pgd = pgd_offset(mm, addr);
69	spin_lock(&mm->page_table_lock);
70
71	pud = pud_alloc(mm, pgd, addr);
72	if (!pud)
73	goto err_unlock;
74
75	pmd = pmd_alloc(mm, pud, addr);
76	if (!pmd)
77	goto err_unlock;
78
79	pte = pte_alloc_map(mm, pmd, addr);
80	if (!pte)
81	goto err_unlock;
82
83	/*
84	* This page may have been truncated. Tell the
85	* caller about it.
86	*/
87	err = -EINVAL;
88	inode = vma->vm_file->f_mapping->host;
89	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
90	if (!page->mapping \|\| page->index >= size)
91	goto err_unlock;
92
93	zap_pte(mm, vma, addr, pte);
94
95	inc_mm_counter(mm,rss);
96	flush_icache_page(vma, page);
97	set_pte_at(mm, addr, pte, mk_pte(page, prot));
98	page_add_file_rmap(page);
99	pte_val = *pte;
100	pte_unmap(pte);
101	update_mmu_cache(vma, addr, pte_val);
102
103	err = 0;
104	err_unlock:
105	spin_unlock(&mm->page_table_lock);
106	return err;
107	}
108	EXPORT_SYMBOL(install_page);
109
110
111	/*
112	* Install a file pte to a given virtual memory address, release any
113	* previously existing mapping.
114	*/
115	int install_file_pte(struct mm_struct mm, struct vm_area_struct vma,
116	unsigned long addr, unsigned long pgoff, pgprot_t prot)
117	{
118	int err = -ENOMEM;
119	pte_t *pte;
120	pmd_t *pmd;
121	pud_t *pud;
122	pgd_t *pgd;
123	pte_t pte_val;
124
125	pgd = pgd_offset(mm, addr);
126	spin_lock(&mm->page_table_lock);
127
128	pud = pud_alloc(mm, pgd, addr);
129	if (!pud)
130	goto err_unlock;
131
132	pmd = pmd_alloc(mm, pud, addr);
133	if (!pmd)
134	goto err_unlock;
135
136	pte = pte_alloc_map(mm, pmd, addr);
137	if (!pte)
138	goto err_unlock;
139
140	zap_pte(mm, vma, addr, pte);
141
142	set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
143	pte_val = *pte;
144	pte_unmap(pte);
145	update_mmu_cache(vma, addr, pte_val);
146	spin_unlock(&mm->page_table_lock);
147	return 0;
148
149	err_unlock:
150	spin_unlock(&mm->page_table_lock);
151	return err;
152	}
153
154
155	/***
156	* sys_remap_file_pages - remap arbitrary pages of a shared backing store
157	* file within an existing vma.
158	* @start: start of the remapped virtual memory range
159	* @size: size of the remapped virtual memory range
160	* @prot: new protection bits of the range
161	* @pgoff: to be mapped page of the backing store file
162	* @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
163	*
164	* this syscall works purely via pagetables, so it's the most efficient
165	* way to map the same (large) file into a given virtual window. Unlike
166	* mmap()/mremap() it does not create any new vmas. The new mappings are
167	* also safe across swapout.
168	*
169	* NOTE: the 'prot' parameter right now is ignored, and the vma's default
170	* protection is used. Arbitrary protections might be implemented in the
171	* future.
172	*/
173	asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
174	unsigned long __prot, unsigned long pgoff, unsigned long flags)
175	{
176	struct mm_struct *mm = current->mm;
177	struct address_space *mapping;
178	unsigned long end = start + size;
179	struct vm_area_struct *vma;
180	int err = -EINVAL;
181	int has_write_lock = 0;
182
183	if (__prot)
184	return err;
185	/*
186	* Sanitize the syscall parameters:
187	*/
188	start = start & PAGE_MASK;
189	size = size & PAGE_MASK;
190
191	/* Does the address range wrap, or is the span zero-sized? */
192	if (start + size <= start)
193	return err;
194
195	/* Can we represent this offset inside this architecture's pte's? */
196	#if PTE_FILE_MAX_BITS < BITS_PER_LONG
197	if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
198	return err;
199	#endif
200
201	/* We need down_write() to change vma->vm_flags. */
202	down_read(&mm->mmap_sem);
203	retry:
204	vma = find_vma(mm, start);
205
206	/*
207	* Make sure the vma is shared, that it supports prefaulting,
208	* and that the remapped range is valid and fully within
209	* the single existing vma. vm_private_data is used as a
210	* swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED
211	* or VM_LOCKED, but VM_LOCKED could be revoked later on).
212	*/
213	if (vma && (vma->vm_flags & VM_SHARED) &&
214	(!vma->vm_private_data \|\|
215	(vma->vm_flags & (VM_NONLINEAR\|VM_RESERVED))) &&
216	vma->vm_ops && vma->vm_ops->populate &&
217	end > start && start >= vma->vm_start &&
218	end <= vma->vm_end) {
219
220	/* Must set VM_NONLINEAR before any pages are populated. */
221	if (pgoff != linear_page_index(vma, start) &&
222	!(vma->vm_flags & VM_NONLINEAR)) {
223	if (!has_write_lock) {
224	up_read(&mm->mmap_sem);
225	down_write(&mm->mmap_sem);
226	has_write_lock = 1;
227	goto retry;
228	}
229	mapping = vma->vm_file->f_mapping;
230	spin_lock(&mapping->i_mmap_lock);
231	flush_dcache_mmap_lock(mapping);
232	vma->vm_flags \|= VM_NONLINEAR;
233	vma_prio_tree_remove(vma, &mapping->i_mmap);
234	vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
235	flush_dcache_mmap_unlock(mapping);
236	spin_unlock(&mapping->i_mmap_lock);
237	}
238
239	err = vma->vm_ops->populate(vma, start, size,
240	vma->vm_page_prot,
241	pgoff, flags & MAP_NONBLOCK);
242
243	/*
244	* We can't clear VM_NONLINEAR because we'd have to do
245	* it after ->populate completes, and that would prevent
246	* downgrading the lock. (Locks can't be upgraded).
247	*/
248	}
249	if (likely(!has_write_lock))
250	up_read(&mm->mmap_sem);
251	else
252	up_write(&mm->mmap_sem);
253
254	return err;
255	}
256