linux/mm/vmalloc.c
Pekka Enberg 80e93effce [PATCH] update kfree, vfree, and vunmap kerneldoc
This patch clarifies NULL handling of kfree() and vfree().  I addition,
wording of calling context restriction for vfree() and vunmap() are changed
from "may not" to "must not."

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 14:03:43 -07:00

594 lines
13 KiB
C

/*
* linux/mm/vmalloc.c
*
* Copyright (C) 1993 Linus Torvalds
* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
* SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
* Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
#include <asm/tlbflush.h>
DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;
static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
{
pte_t *pte;
pte = pte_offset_kernel(pmd, addr);
do {
pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
WARN_ON(!pte_none(ptent) && !pte_present(ptent));
} while (pte++, addr += PAGE_SIZE, addr != end);
}
static inline void vunmap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
vunmap_pte_range(pmd, addr, next);
} while (pmd++, addr = next, addr != end);
}
static inline void vunmap_pud_range(pgd_t *pgd, unsigned long addr,
unsigned long end)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
vunmap_pmd_range(pud, addr, next);
} while (pud++, addr = next, addr != end);
}
void unmap_vm_area(struct vm_struct *area)
{
pgd_t *pgd;
unsigned long next;
unsigned long addr = (unsigned long) area->addr;
unsigned long end = addr + area->size;
BUG_ON(addr >= end);
pgd = pgd_offset_k(addr);
flush_cache_vunmap(addr, end);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
vunmap_pud_range(pgd, addr, next);
} while (pgd++, addr = next, addr != end);
flush_tlb_kernel_range((unsigned long) area->addr, end);
}
static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pte_t *pte;
pte = pte_alloc_kernel(&init_mm, pmd, addr);
if (!pte)
return -ENOMEM;
do {
struct page *page = **pages;
WARN_ON(!pte_none(*pte));
if (!page)
return -ENOMEM;
set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
(*pages)++;
} while (pte++, addr += PAGE_SIZE, addr != end);
return 0;
}
static inline int vmap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_alloc(&init_mm, pud, addr);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);
if (vmap_pte_range(pmd, addr, next, prot, pages))
return -ENOMEM;
} while (pmd++, addr = next, addr != end);
return 0;
}
static inline int vmap_pud_range(pgd_t *pgd, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pud_t *pud;
unsigned long next;
pud = pud_alloc(&init_mm, pgd, addr);
if (!pud)
return -ENOMEM;
do {
next = pud_addr_end(addr, end);
if (vmap_pmd_range(pud, addr, next, prot, pages))
return -ENOMEM;
} while (pud++, addr = next, addr != end);
return 0;
}
int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
{
pgd_t *pgd;
unsigned long next;
unsigned long addr = (unsigned long) area->addr;
unsigned long end = addr + area->size - PAGE_SIZE;
int err;
BUG_ON(addr >= end);
pgd = pgd_offset_k(addr);
spin_lock(&init_mm.page_table_lock);
do {
next = pgd_addr_end(addr, end);
err = vmap_pud_range(pgd, addr, next, prot, pages);
if (err)
break;
} while (pgd++, addr = next, addr != end);
spin_unlock(&init_mm.page_table_lock);
flush_cache_vmap((unsigned long) area->addr, end);
return err;
}
struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end)
{
struct vm_struct **p, *tmp, *area;
unsigned long align = 1;
unsigned long addr;
if (flags & VM_IOREMAP) {
int bit = fls(size);
if (bit > IOREMAP_MAX_ORDER)
bit = IOREMAP_MAX_ORDER;
else if (bit < PAGE_SHIFT)
bit = PAGE_SHIFT;
align = 1ul << bit;
}
addr = ALIGN(start, align);
size = PAGE_ALIGN(size);
area = kmalloc(sizeof(*area), GFP_KERNEL);
if (unlikely(!area))
return NULL;
if (unlikely(!size)) {
kfree (area);
return NULL;
}
/*
* We always allocate a guard page.
*/
size += PAGE_SIZE;
write_lock(&vmlist_lock);
for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) {
if ((unsigned long)tmp->addr < addr) {
if((unsigned long)tmp->addr + tmp->size >= addr)
addr = ALIGN(tmp->size +
(unsigned long)tmp->addr, align);
continue;
}
if ((size + addr) < addr)
goto out;
if (size + addr <= (unsigned long)tmp->addr)
goto found;
addr = ALIGN(tmp->size + (unsigned long)tmp->addr, align);
if (addr > end - size)
goto out;
}
found:
area->next = *p;
*p = area;
area->flags = flags;
area->addr = (void *)addr;
area->size = size;
area->pages = NULL;
area->nr_pages = 0;
area->phys_addr = 0;
write_unlock(&vmlist_lock);
return area;
out:
write_unlock(&vmlist_lock);
kfree(area);
if (printk_ratelimit())
printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
return NULL;
}
/**
* get_vm_area - reserve a contingous kernel virtual area
*
* @size: size of the area
* @flags: %VM_IOREMAP for I/O mappings or VM_ALLOC
*
* Search an area of @size in the kernel virtual mapping area,
* and reserved it for out purposes. Returns the area descriptor
* on success or %NULL on failure.
*/
struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
{
return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
}
/* Caller must hold vmlist_lock */
struct vm_struct *__remove_vm_area(void *addr)
{
struct vm_struct **p, *tmp;
for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
if (tmp->addr == addr)
goto found;
}
return NULL;
found:
unmap_vm_area(tmp);
*p = tmp->next;
/*
* Remove the guard page.
*/
tmp->size -= PAGE_SIZE;
return tmp;
}
/**
* remove_vm_area - find and remove a contingous kernel virtual area
*
* @addr: base address
*
* Search for the kernel VM area starting at @addr, and remove it.
* This function returns the found VM area, but using it is NOT safe
* on SMP machines, except for its size or flags.
*/
struct vm_struct *remove_vm_area(void *addr)
{
struct vm_struct *v;
write_lock(&vmlist_lock);
v = __remove_vm_area(addr);
write_unlock(&vmlist_lock);
return v;
}
void __vunmap(void *addr, int deallocate_pages)
{
struct vm_struct *area;
if (!addr)
return;
if ((PAGE_SIZE-1) & (unsigned long)addr) {
printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
WARN_ON(1);
return;
}
area = remove_vm_area(addr);
if (unlikely(!area)) {
printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
addr);
WARN_ON(1);
return;
}
if (deallocate_pages) {
int i;
for (i = 0; i < area->nr_pages; i++) {
if (unlikely(!area->pages[i]))
BUG();
__free_page(area->pages[i]);
}
if (area->nr_pages > PAGE_SIZE/sizeof(struct page *))
vfree(area->pages);
else
kfree(area->pages);
}
kfree(area);
return;
}
/**
* vfree - release memory allocated by vmalloc()
*
* @addr: memory base address
*
* Free the virtually contiguous memory area starting at @addr, as
* obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
* NULL, no operation is performed.
*
* Must not be called in interrupt context.
*/
void vfree(void *addr)
{
BUG_ON(in_interrupt());
__vunmap(addr, 1);
}
EXPORT_SYMBOL(vfree);
/**
* vunmap - release virtual mapping obtained by vmap()
*
* @addr: memory base address
*
* Free the virtually contiguous memory area starting at @addr,
* which was created from the page array passed to vmap().
*
* Must not be called in interrupt context.
*/
void vunmap(void *addr)
{
BUG_ON(in_interrupt());
__vunmap(addr, 0);
}
EXPORT_SYMBOL(vunmap);
/**
* vmap - map an array of pages into virtually contiguous space
*
* @pages: array of page pointers
* @count: number of pages to map
* @flags: vm_area->flags
* @prot: page protection for the mapping
*
* Maps @count pages from @pages into contiguous kernel virtual
* space.
*/
void *vmap(struct page **pages, unsigned int count,
unsigned long flags, pgprot_t prot)
{
struct vm_struct *area;
if (count > num_physpages)
return NULL;
area = get_vm_area((count << PAGE_SHIFT), flags);
if (!area)
return NULL;
if (map_vm_area(area, prot, &pages)) {
vunmap(area->addr);
return NULL;
}
return area->addr;
}
EXPORT_SYMBOL(vmap);
void *__vmalloc_area(struct vm_struct *area, unsigned int __nocast gfp_mask, pgprot_t prot)
{
struct page **pages;
unsigned int nr_pages, array_size, i;
nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
array_size = (nr_pages * sizeof(struct page *));
area->nr_pages = nr_pages;
/* Please note that the recursion is strictly bounded. */
if (array_size > PAGE_SIZE)
pages = __vmalloc(array_size, gfp_mask, PAGE_KERNEL);
else
pages = kmalloc(array_size, (gfp_mask & ~__GFP_HIGHMEM));
area->pages = pages;
if (!area->pages) {
remove_vm_area(area->addr);
kfree(area);
return NULL;
}
memset(area->pages, 0, array_size);
for (i = 0; i < area->nr_pages; i++) {
area->pages[i] = alloc_page(gfp_mask);
if (unlikely(!area->pages[i])) {
/* Successfully allocated i pages, free them in __vunmap() */
area->nr_pages = i;
goto fail;
}
}
if (map_vm_area(area, prot, &pages))
goto fail;
return area->addr;
fail:
vfree(area->addr);
return NULL;
}
/**
* __vmalloc - allocate virtually contiguous memory
*
* @size: allocation size
* @gfp_mask: flags for the page level allocator
* @prot: protection mask for the allocated pages
*
* Allocate enough pages to cover @size from the page level
* allocator with @gfp_mask flags. Map them into contiguous
* kernel virtual space, using a pagetable protection of @prot.
*/
void *__vmalloc(unsigned long size, unsigned int __nocast gfp_mask, pgprot_t prot)
{
struct vm_struct *area;
size = PAGE_ALIGN(size);
if (!size || (size >> PAGE_SHIFT) > num_physpages)
return NULL;
area = get_vm_area(size, VM_ALLOC);
if (!area)
return NULL;
return __vmalloc_area(area, gfp_mask, prot);
}
EXPORT_SYMBOL(__vmalloc);
/**
* vmalloc - allocate virtually contiguous memory
*
* @size: allocation size
*
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
*
* For tight cotrol over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
}
EXPORT_SYMBOL(vmalloc);
#ifndef PAGE_KERNEL_EXEC
# define PAGE_KERNEL_EXEC PAGE_KERNEL
#endif
/**
* vmalloc_exec - allocate virtually contiguous, executable memory
*
* @size: allocation size
*
* Kernel-internal function to allocate enough pages to cover @size
* the page level allocator and map them into contiguous and
* executable kernel virtual space.
*
* For tight cotrol over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc_exec(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
}
/**
* vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
*
* @size: allocation size
*
* Allocate enough 32bit PA addressable pages to cover @size from the
* page level allocator and map them into contiguous kernel virtual space.
*/
void *vmalloc_32(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
}
EXPORT_SYMBOL(vmalloc_32);
long vread(char *buf, char *addr, unsigned long count)
{
struct vm_struct *tmp;
char *vaddr, *buf_start = buf;
unsigned long n;
/* Don't allow overflow */
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
read_lock(&vmlist_lock);
for (tmp = vmlist; tmp; tmp = tmp->next) {
vaddr = (char *) tmp->addr;
if (addr >= vaddr + tmp->size - PAGE_SIZE)
continue;
while (addr < vaddr) {
if (count == 0)
goto finished;
*buf = '\0';
buf++;
addr++;
count--;
}
n = vaddr + tmp->size - PAGE_SIZE - addr;
do {
if (count == 0)
goto finished;
*buf = *addr;
buf++;
addr++;
count--;
} while (--n > 0);
}
finished:
read_unlock(&vmlist_lock);
return buf - buf_start;
}
long vwrite(char *buf, char *addr, unsigned long count)
{
struct vm_struct *tmp;
char *vaddr, *buf_start = buf;
unsigned long n;
/* Don't allow overflow */
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
read_lock(&vmlist_lock);
for (tmp = vmlist; tmp; tmp = tmp->next) {
vaddr = (char *) tmp->addr;
if (addr >= vaddr + tmp->size - PAGE_SIZE)
continue;
while (addr < vaddr) {
if (count == 0)
goto finished;
buf++;
addr++;
count--;
}
n = vaddr + tmp->size - PAGE_SIZE - addr;
do {
if (count == 0)
goto finished;
*addr = *buf;
buf++;
addr++;
count--;
} while (--n > 0);
}
finished:
read_unlock(&vmlist_lock);
return buf - buf_start;
}