linux/mm/nommu.c
Linus Torvalds 5d22fc25d4 mm: remove more IS_ERR_VALUE abuses
The do_brk() and vm_brk() return value was "unsigned long" and returned
the starting address on success, and an error value on failure.  The
reasons are entirely historical, and go back to it basically behaving
like the mmap() interface does.

However, nobody actually wanted that interface, and it causes totally
pointless IS_ERR_VALUE() confusion.

What every single caller actually wants is just the simpler integer
return of zero for success and negative error number on failure.

So just convert to that much clearer and more common calling convention,
and get rid of all the IS_ERR_VALUE() uses wrt vm_brk().

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27 15:57:31 -07:00

1990 lines
48 KiB
C

/*
* linux/mm/nommu.c
*
* Replacement code for mm functions to support CPU's that don't
* have any form of memory management unit (thus no virtual memory).
*
* See Documentation/nommu-mmap.txt
*
* Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
* Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
* Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
* Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
* Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/vmacache.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/compiler.h>
#include <linux/mount.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/printk.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include "internal.h"
void *high_memory;
EXPORT_SYMBOL(high_memory);
struct page *mem_map;
unsigned long max_mapnr;
EXPORT_SYMBOL(max_mapnr);
unsigned long highest_memmap_pfn;
int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
int heap_stack_gap = 0;
atomic_long_t mmap_pages_allocated;
EXPORT_SYMBOL(mem_map);
/* list of mapped, potentially shareable regions */
static struct kmem_cache *vm_region_jar;
struct rb_root nommu_region_tree = RB_ROOT;
DECLARE_RWSEM(nommu_region_sem);
const struct vm_operations_struct generic_file_vm_ops = {
};
/*
* Return the total memory allocated for this pointer, not
* just what the caller asked for.
*
* Doesn't have to be accurate, i.e. may have races.
*/
unsigned int kobjsize(const void *objp)
{
struct page *page;
/*
* If the object we have should not have ksize performed on it,
* return size of 0
*/
if (!objp || !virt_addr_valid(objp))
return 0;
page = virt_to_head_page(objp);
/*
* If the allocator sets PageSlab, we know the pointer came from
* kmalloc().
*/
if (PageSlab(page))
return ksize(objp);
/*
* If it's not a compound page, see if we have a matching VMA
* region. This test is intentionally done in reverse order,
* so if there's no VMA, we still fall through and hand back
* PAGE_SIZE for 0-order pages.
*/
if (!PageCompound(page)) {
struct vm_area_struct *vma;
vma = find_vma(current->mm, (unsigned long)objp);
if (vma)
return vma->vm_end - vma->vm_start;
}
/*
* The ksize() function is only guaranteed to work for pointers
* returned by kmalloc(). So handle arbitrary pointers here.
*/
return PAGE_SIZE << compound_order(page);
}
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int foll_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking)
{
struct vm_area_struct *vma;
unsigned long vm_flags;
int i;
/* calculate required read or write permissions.
* If FOLL_FORCE is set, we only require the "MAY" flags.
*/
vm_flags = (foll_flags & FOLL_WRITE) ?
(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
vm_flags &= (foll_flags & FOLL_FORCE) ?
(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
for (i = 0; i < nr_pages; i++) {
vma = find_vma(mm, start);
if (!vma)
goto finish_or_fault;
/* protect what we can, including chardevs */
if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
!(vm_flags & vma->vm_flags))
goto finish_or_fault;
if (pages) {
pages[i] = virt_to_page(start);
if (pages[i])
get_page(pages[i]);
}
if (vmas)
vmas[i] = vma;
start = (start + PAGE_SIZE) & PAGE_MASK;
}
return i;
finish_or_fault:
return i ? : -EFAULT;
}
/*
* get a list of pages in an address range belonging to the specified process
* and indicate the VMA that covers each page
* - this is potentially dodgy as we may end incrementing the page count of a
* slab page or a secondary page from a compound page
* - don't permit access to VMAs that don't support it, such as I/O mappings
*/
long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
struct vm_area_struct **vmas)
{
int flags = 0;
if (write)
flags |= FOLL_WRITE;
if (force)
flags |= FOLL_FORCE;
return __get_user_pages(current, current->mm, start, nr_pages, flags,
pages, vmas, NULL);
}
EXPORT_SYMBOL(get_user_pages);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
int *locked)
{
return get_user_pages(start, nr_pages, write, force, pages, NULL);
}
EXPORT_SYMBOL(get_user_pages_locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags)
{
long ret;
down_read(&mm->mmap_sem);
ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
NULL, NULL);
up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(__get_user_pages_unlocked);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
{
return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
write, force, pages, 0);
}
EXPORT_SYMBOL(get_user_pages_unlocked);
/**
* follow_pfn - look up PFN at a user virtual address
* @vma: memory mapping
* @address: user virtual address
* @pfn: location to store found PFN
*
* Only IO mappings and raw PFN mappings are allowed.
*
* Returns zero and the pfn at @pfn on success, -ve otherwise.
*/
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
unsigned long *pfn)
{
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
return -EINVAL;
*pfn = address >> PAGE_SHIFT;
return 0;
}
EXPORT_SYMBOL(follow_pfn);
LIST_HEAD(vmap_area_list);
void vfree(const void *addr)
{
kfree(addr);
}
EXPORT_SYMBOL(vfree);
void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
{
/*
* You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
* returns only a logical address.
*/
return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
}
EXPORT_SYMBOL(__vmalloc);
void *vmalloc_user(unsigned long size)
{
void *ret;
ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
PAGE_KERNEL);
if (ret) {
struct vm_area_struct *vma;
down_write(&current->mm->mmap_sem);
vma = find_vma(current->mm, (unsigned long)ret);
if (vma)
vma->vm_flags |= VM_USERMAP;
up_write(&current->mm->mmap_sem);
}
return ret;
}
EXPORT_SYMBOL(vmalloc_user);
struct page *vmalloc_to_page(const void *addr)
{
return virt_to_page(addr);
}
EXPORT_SYMBOL(vmalloc_to_page);
unsigned long vmalloc_to_pfn(const void *addr)
{
return page_to_pfn(virt_to_page(addr));
}
EXPORT_SYMBOL(vmalloc_to_pfn);
long vread(char *buf, char *addr, unsigned long count)
{
/* Don't allow overflow */
if ((unsigned long) buf + count < count)
count = -(unsigned long) buf;
memcpy(buf, addr, count);
return count;
}
long vwrite(char *buf, char *addr, unsigned long count)
{
/* Don't allow overflow */
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
memcpy(addr, buf, count);
return count;
}
/*
* 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 control 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);
/*
* vzalloc - allocate virtually contiguous memory with zero fill
*
* @size: allocation size
*
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
* The memory allocated is set to zero.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vzalloc(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
PAGE_KERNEL);
}
EXPORT_SYMBOL(vzalloc);
/**
* vmalloc_node - allocate memory on a specific node
* @size: allocation size
* @node: numa node
*
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc_node(unsigned long size, int node)
{
return vmalloc(size);
}
EXPORT_SYMBOL(vmalloc_node);
/**
* vzalloc_node - allocate memory on a specific node with zero fill
* @size: allocation size
* @node: numa node
*
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
* The memory allocated is set to zero.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vzalloc_node(unsigned long size, int node)
{
return vzalloc(size);
}
EXPORT_SYMBOL(vzalloc_node);
#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 control 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);
/**
* vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
* @size: allocation size
*
* The resulting memory area is 32bit addressable and zeroed so it can be
* mapped to userspace without leaking data.
*
* VM_USERMAP is set on the corresponding VMA so that subsequent calls to
* remap_vmalloc_range() are permissible.
*/
void *vmalloc_32_user(unsigned long size)
{
/*
* We'll have to sort out the ZONE_DMA bits for 64-bit,
* but for now this can simply use vmalloc_user() directly.
*/
return vmalloc_user(size);
}
EXPORT_SYMBOL(vmalloc_32_user);
void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
{
BUG();
return NULL;
}
EXPORT_SYMBOL(vmap);
void vunmap(const void *addr)
{
BUG();
}
EXPORT_SYMBOL(vunmap);
void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
{
BUG();
return NULL;
}
EXPORT_SYMBOL(vm_map_ram);
void vm_unmap_ram(const void *mem, unsigned int count)
{
BUG();
}
EXPORT_SYMBOL(vm_unmap_ram);
void vm_unmap_aliases(void)
{
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);
/*
* Implement a stub for vmalloc_sync_all() if the architecture chose not to
* have one.
*/
void __weak vmalloc_sync_all(void)
{
}
/**
* alloc_vm_area - allocate a range of kernel address space
* @size: size of the area
*
* Returns: NULL on failure, vm_struct on success
*
* This function reserves a range of kernel address space, and
* allocates pagetables to map that range. No actual mappings
* are created. If the kernel address space is not shared
* between processes, it syncs the pagetable across all
* processes.
*/
struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
{
BUG();
return NULL;
}
EXPORT_SYMBOL_GPL(alloc_vm_area);
void free_vm_area(struct vm_struct *area)
{
BUG();
}
EXPORT_SYMBOL_GPL(free_vm_area);
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
struct page *page)
{
return -EINVAL;
}
EXPORT_SYMBOL(vm_insert_page);
/*
* sys_brk() for the most part doesn't need the global kernel
* lock, except when an application is doing something nasty
* like trying to un-brk an area that has already been mapped
* to a regular file. in this case, the unmapping will need
* to invoke file system routines that need the global lock.
*/
SYSCALL_DEFINE1(brk, unsigned long, brk)
{
struct mm_struct *mm = current->mm;
if (brk < mm->start_brk || brk > mm->context.end_brk)
return mm->brk;
if (mm->brk == brk)
return mm->brk;
/*
* Always allow shrinking brk
*/
if (brk <= mm->brk) {
mm->brk = brk;
return brk;
}
/*
* Ok, looks good - let it rip.
*/
flush_icache_range(mm->brk, brk);
return mm->brk = brk;
}
/*
* initialise the VMA and region record slabs
*/
void __init mmap_init(void)
{
int ret;
ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
VM_BUG_ON(ret);
vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
}
/*
* validate the region tree
* - the caller must hold the region lock
*/
#ifdef CONFIG_DEBUG_NOMMU_REGIONS
static noinline void validate_nommu_regions(void)
{
struct vm_region *region, *last;
struct rb_node *p, *lastp;
lastp = rb_first(&nommu_region_tree);
if (!lastp)
return;
last = rb_entry(lastp, struct vm_region, vm_rb);
BUG_ON(last->vm_end <= last->vm_start);
BUG_ON(last->vm_top < last->vm_end);
while ((p = rb_next(lastp))) {
region = rb_entry(p, struct vm_region, vm_rb);
last = rb_entry(lastp, struct vm_region, vm_rb);
BUG_ON(region->vm_end <= region->vm_start);
BUG_ON(region->vm_top < region->vm_end);
BUG_ON(region->vm_start < last->vm_top);
lastp = p;
}
}
#else
static void validate_nommu_regions(void)
{
}
#endif
/*
* add a region into the global tree
*/
static void add_nommu_region(struct vm_region *region)
{
struct vm_region *pregion;
struct rb_node **p, *parent;
validate_nommu_regions();
parent = NULL;
p = &nommu_region_tree.rb_node;
while (*p) {
parent = *p;
pregion = rb_entry(parent, struct vm_region, vm_rb);
if (region->vm_start < pregion->vm_start)
p = &(*p)->rb_left;
else if (region->vm_start > pregion->vm_start)
p = &(*p)->rb_right;
else if (pregion == region)
return;
else
BUG();
}
rb_link_node(&region->vm_rb, parent, p);
rb_insert_color(&region->vm_rb, &nommu_region_tree);
validate_nommu_regions();
}
/*
* delete a region from the global tree
*/
static void delete_nommu_region(struct vm_region *region)
{
BUG_ON(!nommu_region_tree.rb_node);
validate_nommu_regions();
rb_erase(&region->vm_rb, &nommu_region_tree);
validate_nommu_regions();
}
/*
* free a contiguous series of pages
*/
static void free_page_series(unsigned long from, unsigned long to)
{
for (; from < to; from += PAGE_SIZE) {
struct page *page = virt_to_page(from);
atomic_long_dec(&mmap_pages_allocated);
put_page(page);
}
}
/*
* release a reference to a region
* - the caller must hold the region semaphore for writing, which this releases
* - the region may not have been added to the tree yet, in which case vm_top
* will equal vm_start
*/
static void __put_nommu_region(struct vm_region *region)
__releases(nommu_region_sem)
{
BUG_ON(!nommu_region_tree.rb_node);
if (--region->vm_usage == 0) {
if (region->vm_top > region->vm_start)
delete_nommu_region(region);
up_write(&nommu_region_sem);
if (region->vm_file)
fput(region->vm_file);
/* IO memory and memory shared directly out of the pagecache
* from ramfs/tmpfs mustn't be released here */
if (region->vm_flags & VM_MAPPED_COPY)
free_page_series(region->vm_start, region->vm_top);
kmem_cache_free(vm_region_jar, region);
} else {
up_write(&nommu_region_sem);
}
}
/*
* release a reference to a region
*/
static void put_nommu_region(struct vm_region *region)
{
down_write(&nommu_region_sem);
__put_nommu_region(region);
}
/*
* update protection on a vma
*/
static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
{
#ifdef CONFIG_MPU
struct mm_struct *mm = vma->vm_mm;
long start = vma->vm_start & PAGE_MASK;
while (start < vma->vm_end) {
protect_page(mm, start, flags);
start += PAGE_SIZE;
}
update_protections(mm);
#endif
}
/*
* add a VMA into a process's mm_struct in the appropriate place in the list
* and tree and add to the address space's page tree also if not an anonymous
* page
* - should be called with mm->mmap_sem held writelocked
*/
static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
{
struct vm_area_struct *pvma, *prev;
struct address_space *mapping;
struct rb_node **p, *parent, *rb_prev;
BUG_ON(!vma->vm_region);
mm->map_count++;
vma->vm_mm = mm;
protect_vma(vma, vma->vm_flags);
/* add the VMA to the mapping */
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
i_mmap_lock_write(mapping);
flush_dcache_mmap_lock(mapping);
vma_interval_tree_insert(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
i_mmap_unlock_write(mapping);
}
/* add the VMA to the tree */
parent = rb_prev = NULL;
p = &mm->mm_rb.rb_node;
while (*p) {
parent = *p;
pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
/* sort by: start addr, end addr, VMA struct addr in that order
* (the latter is necessary as we may get identical VMAs) */
if (vma->vm_start < pvma->vm_start)
p = &(*p)->rb_left;
else if (vma->vm_start > pvma->vm_start) {
rb_prev = parent;
p = &(*p)->rb_right;
} else if (vma->vm_end < pvma->vm_end)
p = &(*p)->rb_left;
else if (vma->vm_end > pvma->vm_end) {
rb_prev = parent;
p = &(*p)->rb_right;
} else if (vma < pvma)
p = &(*p)->rb_left;
else if (vma > pvma) {
rb_prev = parent;
p = &(*p)->rb_right;
} else
BUG();
}
rb_link_node(&vma->vm_rb, parent, p);
rb_insert_color(&vma->vm_rb, &mm->mm_rb);
/* add VMA to the VMA list also */
prev = NULL;
if (rb_prev)
prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
__vma_link_list(mm, vma, prev, parent);
}
/*
* delete a VMA from its owning mm_struct and address space
*/
static void delete_vma_from_mm(struct vm_area_struct *vma)
{
int i;
struct address_space *mapping;
struct mm_struct *mm = vma->vm_mm;
struct task_struct *curr = current;
protect_vma(vma, 0);
mm->map_count--;
for (i = 0; i < VMACACHE_SIZE; i++) {
/* if the vma is cached, invalidate the entire cache */
if (curr->vmacache[i] == vma) {
vmacache_invalidate(mm);
break;
}
}
/* remove the VMA from the mapping */
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
i_mmap_lock_write(mapping);
flush_dcache_mmap_lock(mapping);
vma_interval_tree_remove(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
i_mmap_unlock_write(mapping);
}
/* remove from the MM's tree and list */
rb_erase(&vma->vm_rb, &mm->mm_rb);
if (vma->vm_prev)
vma->vm_prev->vm_next = vma->vm_next;
else
mm->mmap = vma->vm_next;
if (vma->vm_next)
vma->vm_next->vm_prev = vma->vm_prev;
}
/*
* destroy a VMA record
*/
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
{
if (vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
if (vma->vm_file)
fput(vma->vm_file);
put_nommu_region(vma->vm_region);
kmem_cache_free(vm_area_cachep, vma);
}
/*
* look up the first VMA in which addr resides, NULL if none
* - should be called with mm->mmap_sem at least held readlocked
*/
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma;
/* check the cache first */
vma = vmacache_find(mm, addr);
if (likely(vma))
return vma;
/* trawl the list (there may be multiple mappings in which addr
* resides) */
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end > addr) {
vmacache_update(addr, vma);
return vma;
}
}
return NULL;
}
EXPORT_SYMBOL(find_vma);
/*
* find a VMA
* - we don't extend stack VMAs under NOMMU conditions
*/
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
return find_vma(mm, addr);
}
/*
* expand a stack to a given address
* - not supported under NOMMU conditions
*/
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
return -ENOMEM;
}
/*
* look up the first VMA exactly that exactly matches addr
* - should be called with mm->mmap_sem at least held readlocked
*/
static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
unsigned long addr,
unsigned long len)
{
struct vm_area_struct *vma;
unsigned long end = addr + len;
/* check the cache first */
vma = vmacache_find_exact(mm, addr, end);
if (vma)
return vma;
/* trawl the list (there may be multiple mappings in which addr
* resides) */
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->vm_start < addr)
continue;
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end == end) {
vmacache_update(addr, vma);
return vma;
}
}
return NULL;
}
/*
* determine whether a mapping should be permitted and, if so, what sort of
* mapping we're capable of supporting
*/
static int validate_mmap_request(struct file *file,
unsigned long addr,
unsigned long len,
unsigned long prot,
unsigned long flags,
unsigned long pgoff,
unsigned long *_capabilities)
{
unsigned long capabilities, rlen;
int ret;
/* do the simple checks first */
if (flags & MAP_FIXED)
return -EINVAL;
if ((flags & MAP_TYPE) != MAP_PRIVATE &&
(flags & MAP_TYPE) != MAP_SHARED)
return -EINVAL;
if (!len)
return -EINVAL;
/* Careful about overflows.. */
rlen = PAGE_ALIGN(len);
if (!rlen || rlen > TASK_SIZE)
return -ENOMEM;
/* offset overflow? */
if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
return -EOVERFLOW;
if (file) {
/* files must support mmap */
if (!file->f_op->mmap)
return -ENODEV;
/* work out if what we've got could possibly be shared
* - we support chardevs that provide their own "memory"
* - we support files/blockdevs that are memory backed
*/
if (file->f_op->mmap_capabilities) {
capabilities = file->f_op->mmap_capabilities(file);
} else {
/* no explicit capabilities set, so assume some
* defaults */
switch (file_inode(file)->i_mode & S_IFMT) {
case S_IFREG:
case S_IFBLK:
capabilities = NOMMU_MAP_COPY;
break;
case S_IFCHR:
capabilities =
NOMMU_MAP_DIRECT |
NOMMU_MAP_READ |
NOMMU_MAP_WRITE;
break;
default:
return -EINVAL;
}
}
/* eliminate any capabilities that we can't support on this
* device */
if (!file->f_op->get_unmapped_area)
capabilities &= ~NOMMU_MAP_DIRECT;
if (!(file->f_mode & FMODE_CAN_READ))
capabilities &= ~NOMMU_MAP_COPY;
/* The file shall have been opened with read permission. */
if (!(file->f_mode & FMODE_READ))
return -EACCES;
if (flags & MAP_SHARED) {
/* do checks for writing, appending and locking */
if ((prot & PROT_WRITE) &&
!(file->f_mode & FMODE_WRITE))
return -EACCES;
if (IS_APPEND(file_inode(file)) &&
(file->f_mode & FMODE_WRITE))
return -EACCES;
if (locks_verify_locked(file))
return -EAGAIN;
if (!(capabilities & NOMMU_MAP_DIRECT))
return -ENODEV;
/* we mustn't privatise shared mappings */
capabilities &= ~NOMMU_MAP_COPY;
} else {
/* we're going to read the file into private memory we
* allocate */
if (!(capabilities & NOMMU_MAP_COPY))
return -ENODEV;
/* we don't permit a private writable mapping to be
* shared with the backing device */
if (prot & PROT_WRITE)
capabilities &= ~NOMMU_MAP_DIRECT;
}
if (capabilities & NOMMU_MAP_DIRECT) {
if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) ||
((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC))
) {
capabilities &= ~NOMMU_MAP_DIRECT;
if (flags & MAP_SHARED) {
pr_warn("MAP_SHARED not completely supported on !MMU\n");
return -EINVAL;
}
}
}
/* handle executable mappings and implied executable
* mappings */
if (path_noexec(&file->f_path)) {
if (prot & PROT_EXEC)
return -EPERM;
} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
/* handle implication of PROT_EXEC by PROT_READ */
if (current->personality & READ_IMPLIES_EXEC) {
if (capabilities & NOMMU_MAP_EXEC)
prot |= PROT_EXEC;
}
} else if ((prot & PROT_READ) &&
(prot & PROT_EXEC) &&
!(capabilities & NOMMU_MAP_EXEC)
) {
/* backing file is not executable, try to copy */
capabilities &= ~NOMMU_MAP_DIRECT;
}
} else {
/* anonymous mappings are always memory backed and can be
* privately mapped
*/
capabilities = NOMMU_MAP_COPY;
/* handle PROT_EXEC implication by PROT_READ */
if ((prot & PROT_READ) &&
(current->personality & READ_IMPLIES_EXEC))
prot |= PROT_EXEC;
}
/* allow the security API to have its say */
ret = security_mmap_addr(addr);
if (ret < 0)
return ret;
/* looks okay */
*_capabilities = capabilities;
return 0;
}
/*
* we've determined that we can make the mapping, now translate what we
* now know into VMA flags
*/
static unsigned long determine_vm_flags(struct file *file,
unsigned long prot,
unsigned long flags,
unsigned long capabilities)
{
unsigned long vm_flags;
vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
/* vm_flags |= mm->def_flags; */
if (!(capabilities & NOMMU_MAP_DIRECT)) {
/* attempt to share read-only copies of mapped file chunks */
vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (file && !(prot & PROT_WRITE))
vm_flags |= VM_MAYSHARE;
} else {
/* overlay a shareable mapping on the backing device or inode
* if possible - used for chardevs, ramfs/tmpfs/shmfs and
* romfs/cramfs */
vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
if (flags & MAP_SHARED)
vm_flags |= VM_SHARED;
}
/* refuse to let anyone share private mappings with this process if
* it's being traced - otherwise breakpoints set in it may interfere
* with another untraced process
*/
if ((flags & MAP_PRIVATE) && current->ptrace)
vm_flags &= ~VM_MAYSHARE;
return vm_flags;
}
/*
* set up a shared mapping on a file (the driver or filesystem provides and
* pins the storage)
*/
static int do_mmap_shared_file(struct vm_area_struct *vma)
{
int ret;
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
if (ret == 0) {
vma->vm_region->vm_top = vma->vm_region->vm_end;
return 0;
}
if (ret != -ENOSYS)
return ret;
/* getting -ENOSYS indicates that direct mmap isn't possible (as
* opposed to tried but failed) so we can only give a suitable error as
* it's not possible to make a private copy if MAP_SHARED was given */
return -ENODEV;
}
/*
* set up a private mapping or an anonymous shared mapping
*/
static int do_mmap_private(struct vm_area_struct *vma,
struct vm_region *region,
unsigned long len,
unsigned long capabilities)
{
unsigned long total, point;
void *base;
int ret, order;
/* invoke the file's mapping function so that it can keep track of
* shared mappings on devices or memory
* - VM_MAYSHARE will be set if it may attempt to share
*/
if (capabilities & NOMMU_MAP_DIRECT) {
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
if (ret == 0) {
/* shouldn't return success if we're not sharing */
BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
vma->vm_region->vm_top = vma->vm_region->vm_end;
return 0;
}
if (ret != -ENOSYS)
return ret;
/* getting an ENOSYS error indicates that direct mmap isn't
* possible (as opposed to tried but failed) so we'll try to
* make a private copy of the data and map that instead */
}
/* allocate some memory to hold the mapping
* - note that this may not return a page-aligned address if the object
* we're allocating is smaller than a page
*/
order = get_order(len);
total = 1 << order;
point = len >> PAGE_SHIFT;
/* we don't want to allocate a power-of-2 sized page set */
if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
total = point;
base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
if (!base)
goto enomem;
atomic_long_add(total, &mmap_pages_allocated);
region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
region->vm_start = (unsigned long) base;
region->vm_end = region->vm_start + len;
region->vm_top = region->vm_start + (total << PAGE_SHIFT);
vma->vm_start = region->vm_start;
vma->vm_end = region->vm_start + len;
if (vma->vm_file) {
/* read the contents of a file into the copy */
mm_segment_t old_fs;
loff_t fpos;
fpos = vma->vm_pgoff;
fpos <<= PAGE_SHIFT;
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = __vfs_read(vma->vm_file, base, len, &fpos);
set_fs(old_fs);
if (ret < 0)
goto error_free;
/* clear the last little bit */
if (ret < len)
memset(base + ret, 0, len - ret);
}
return 0;
error_free:
free_page_series(region->vm_start, region->vm_top);
region->vm_start = vma->vm_start = 0;
region->vm_end = vma->vm_end = 0;
region->vm_top = 0;
return ret;
enomem:
pr_err("Allocation of length %lu from process %d (%s) failed\n",
len, current->pid, current->comm);
show_free_areas(0);
return -ENOMEM;
}
/*
* handle mapping creation for uClinux
*/
unsigned long do_mmap(struct file *file,
unsigned long addr,
unsigned long len,
unsigned long prot,
unsigned long flags,
vm_flags_t vm_flags,
unsigned long pgoff,
unsigned long *populate)
{
struct vm_area_struct *vma;
struct vm_region *region;
struct rb_node *rb;
unsigned long capabilities, result;
int ret;
*populate = 0;
/* decide whether we should attempt the mapping, and if so what sort of
* mapping */
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
&capabilities);
if (ret < 0)
return ret;
/* we ignore the address hint */
addr = 0;
len = PAGE_ALIGN(len);
/* we've determined that we can make the mapping, now translate what we
* now know into VMA flags */
vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
/* we're going to need to record the mapping */
region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
if (!region)
goto error_getting_region;
vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
if (!vma)
goto error_getting_vma;
region->vm_usage = 1;
region->vm_flags = vm_flags;
region->vm_pgoff = pgoff;
INIT_LIST_HEAD(&vma->anon_vma_chain);
vma->vm_flags = vm_flags;
vma->vm_pgoff = pgoff;
if (file) {
region->vm_file = get_file(file);
vma->vm_file = get_file(file);
}
down_write(&nommu_region_sem);
/* if we want to share, we need to check for regions created by other
* mmap() calls that overlap with our proposed mapping
* - we can only share with a superset match on most regular files
* - shared mappings on character devices and memory backed files are
* permitted to overlap inexactly as far as we are concerned for in
* these cases, sharing is handled in the driver or filesystem rather
* than here
*/
if (vm_flags & VM_MAYSHARE) {
struct vm_region *pregion;
unsigned long pglen, rpglen, pgend, rpgend, start;
pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
pgend = pgoff + pglen;
for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
pregion = rb_entry(rb, struct vm_region, vm_rb);
if (!(pregion->vm_flags & VM_MAYSHARE))
continue;
/* search for overlapping mappings on the same file */
if (file_inode(pregion->vm_file) !=
file_inode(file))
continue;
if (pregion->vm_pgoff >= pgend)
continue;
rpglen = pregion->vm_end - pregion->vm_start;
rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
rpgend = pregion->vm_pgoff + rpglen;
if (pgoff >= rpgend)
continue;
/* handle inexactly overlapping matches between
* mappings */
if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
!(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
/* new mapping is not a subset of the region */
if (!(capabilities & NOMMU_MAP_DIRECT))
goto sharing_violation;
continue;
}
/* we've found a region we can share */
pregion->vm_usage++;
vma->vm_region = pregion;
start = pregion->vm_start;
start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
vma->vm_start = start;
vma->vm_end = start + len;
if (pregion->vm_flags & VM_MAPPED_COPY)
vma->vm_flags |= VM_MAPPED_COPY;
else {
ret = do_mmap_shared_file(vma);
if (ret < 0) {
vma->vm_region = NULL;
vma->vm_start = 0;
vma->vm_end = 0;
pregion->vm_usage--;
pregion = NULL;
goto error_just_free;
}
}
fput(region->vm_file);
kmem_cache_free(vm_region_jar, region);
region = pregion;
result = start;
goto share;
}
/* obtain the address at which to make a shared mapping
* - this is the hook for quasi-memory character devices to
* tell us the location of a shared mapping
*/
if (capabilities & NOMMU_MAP_DIRECT) {
addr = file->f_op->get_unmapped_area(file, addr, len,
pgoff, flags);
if (IS_ERR_VALUE(addr)) {
ret = addr;
if (ret != -ENOSYS)
goto error_just_free;
/* the driver refused to tell us where to site
* the mapping so we'll have to attempt to copy
* it */
ret = -ENODEV;
if (!(capabilities & NOMMU_MAP_COPY))
goto error_just_free;
capabilities &= ~NOMMU_MAP_DIRECT;
} else {
vma->vm_start = region->vm_start = addr;
vma->vm_end = region->vm_end = addr + len;
}
}
}
vma->vm_region = region;
/* set up the mapping
* - the region is filled in if NOMMU_MAP_DIRECT is still set
*/
if (file && vma->vm_flags & VM_SHARED)
ret = do_mmap_shared_file(vma);
else
ret = do_mmap_private(vma, region, len, capabilities);
if (ret < 0)
goto error_just_free;
add_nommu_region(region);
/* clear anonymous mappings that don't ask for uninitialized data */
if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
memset((void *)region->vm_start, 0,
region->vm_end - region->vm_start);
/* okay... we have a mapping; now we have to register it */
result = vma->vm_start;
current->mm->total_vm += len >> PAGE_SHIFT;
share:
add_vma_to_mm(current->mm, vma);
/* we flush the region from the icache only when the first executable
* mapping of it is made */
if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
flush_icache_range(region->vm_start, region->vm_end);
region->vm_icache_flushed = true;
}
up_write(&nommu_region_sem);
return result;
error_just_free:
up_write(&nommu_region_sem);
error:
if (region->vm_file)
fput(region->vm_file);
kmem_cache_free(vm_region_jar, region);
if (vma->vm_file)
fput(vma->vm_file);
kmem_cache_free(vm_area_cachep, vma);
return ret;
sharing_violation:
up_write(&nommu_region_sem);
pr_warn("Attempt to share mismatched mappings\n");
ret = -EINVAL;
goto error;
error_getting_vma:
kmem_cache_free(vm_region_jar, region);
pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
len, current->pid);
show_free_areas(0);
return -ENOMEM;
error_getting_region:
pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
len, current->pid);
show_free_areas(0);
return -ENOMEM;
}
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
unsigned long, prot, unsigned long, flags,
unsigned long, fd, unsigned long, pgoff)
{
struct file *file = NULL;
unsigned long retval = -EBADF;
audit_mmap_fd(fd, flags);
if (!(flags & MAP_ANONYMOUS)) {
file = fget(fd);
if (!file)
goto out;
}
flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
if (file)
fput(file);
out:
return retval;
}
#ifdef __ARCH_WANT_SYS_OLD_MMAP
struct mmap_arg_struct {
unsigned long addr;
unsigned long len;
unsigned long prot;
unsigned long flags;
unsigned long fd;
unsigned long offset;
};
SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
{
struct mmap_arg_struct a;
if (copy_from_user(&a, arg, sizeof(a)))
return -EFAULT;
if (offset_in_page(a.offset))
return -EINVAL;
return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
a.offset >> PAGE_SHIFT);
}
#endif /* __ARCH_WANT_SYS_OLD_MMAP */
/*
* split a vma into two pieces at address 'addr', a new vma is allocated either
* for the first part or the tail.
*/
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, int new_below)
{
struct vm_area_struct *new;
struct vm_region *region;
unsigned long npages;
/* we're only permitted to split anonymous regions (these should have
* only a single usage on the region) */
if (vma->vm_file)
return -ENOMEM;
if (mm->map_count >= sysctl_max_map_count)
return -ENOMEM;
region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
if (!region)
return -ENOMEM;
new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!new) {
kmem_cache_free(vm_region_jar, region);
return -ENOMEM;
}
/* most fields are the same, copy all, and then fixup */
*new = *vma;
*region = *vma->vm_region;
new->vm_region = region;
npages = (addr - vma->vm_start) >> PAGE_SHIFT;
if (new_below) {
region->vm_top = region->vm_end = new->vm_end = addr;
} else {
region->vm_start = new->vm_start = addr;
region->vm_pgoff = new->vm_pgoff += npages;
}
if (new->vm_ops && new->vm_ops->open)
new->vm_ops->open(new);
delete_vma_from_mm(vma);
down_write(&nommu_region_sem);
delete_nommu_region(vma->vm_region);
if (new_below) {
vma->vm_region->vm_start = vma->vm_start = addr;
vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
} else {
vma->vm_region->vm_end = vma->vm_end = addr;
vma->vm_region->vm_top = addr;
}
add_nommu_region(vma->vm_region);
add_nommu_region(new->vm_region);
up_write(&nommu_region_sem);
add_vma_to_mm(mm, vma);
add_vma_to_mm(mm, new);
return 0;
}
/*
* shrink a VMA by removing the specified chunk from either the beginning or
* the end
*/
static int shrink_vma(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long from, unsigned long to)
{
struct vm_region *region;
/* adjust the VMA's pointers, which may reposition it in the MM's tree
* and list */
delete_vma_from_mm(vma);
if (from > vma->vm_start)
vma->vm_end = from;
else
vma->vm_start = to;
add_vma_to_mm(mm, vma);
/* cut the backing region down to size */
region = vma->vm_region;
BUG_ON(region->vm_usage != 1);
down_write(&nommu_region_sem);
delete_nommu_region(region);
if (from > region->vm_start) {
to = region->vm_top;
region->vm_top = region->vm_end = from;
} else {
region->vm_start = to;
}
add_nommu_region(region);
up_write(&nommu_region_sem);
free_page_series(from, to);
return 0;
}
/*
* release a mapping
* - under NOMMU conditions the chunk to be unmapped must be backed by a single
* VMA, though it need not cover the whole VMA
*/
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
struct vm_area_struct *vma;
unsigned long end;
int ret;
len = PAGE_ALIGN(len);
if (len == 0)
return -EINVAL;
end = start + len;
/* find the first potentially overlapping VMA */
vma = find_vma(mm, start);
if (!vma) {
static int limit;
if (limit < 5) {
pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
current->pid, current->comm,
start, start + len - 1);
limit++;
}
return -EINVAL;
}
/* we're allowed to split an anonymous VMA but not a file-backed one */
if (vma->vm_file) {
do {
if (start > vma->vm_start)
return -EINVAL;
if (end == vma->vm_end)
goto erase_whole_vma;
vma = vma->vm_next;
} while (vma);
return -EINVAL;
} else {
/* the chunk must be a subset of the VMA found */
if (start == vma->vm_start && end == vma->vm_end)
goto erase_whole_vma;
if (start < vma->vm_start || end > vma->vm_end)
return -EINVAL;
if (offset_in_page(start))
return -EINVAL;
if (end != vma->vm_end && offset_in_page(end))
return -EINVAL;
if (start != vma->vm_start && end != vma->vm_end) {
ret = split_vma(mm, vma, start, 1);
if (ret < 0)
return ret;
}
return shrink_vma(mm, vma, start, end);
}
erase_whole_vma:
delete_vma_from_mm(vma);
delete_vma(mm, vma);
return 0;
}
EXPORT_SYMBOL(do_munmap);
int vm_munmap(unsigned long addr, size_t len)
{
struct mm_struct *mm = current->mm;
int ret;
down_write(&mm->mmap_sem);
ret = do_munmap(mm, addr, len);
up_write(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(vm_munmap);
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
return vm_munmap(addr, len);
}
/*
* release all the mappings made in a process's VM space
*/
void exit_mmap(struct mm_struct *mm)
{
struct vm_area_struct *vma;
if (!mm)
return;
mm->total_vm = 0;
while ((vma = mm->mmap)) {
mm->mmap = vma->vm_next;
delete_vma_from_mm(vma);
delete_vma(mm, vma);
cond_resched();
}
}
int vm_brk(unsigned long addr, unsigned long len)
{
return -ENOMEM;
}
/*
* expand (or shrink) an existing mapping, potentially moving it at the same
* time (controlled by the MREMAP_MAYMOVE flag and available VM space)
*
* under NOMMU conditions, we only permit changing a mapping's size, and only
* as long as it stays within the region allocated by do_mmap_private() and the
* block is not shareable
*
* MREMAP_FIXED is not supported under NOMMU conditions
*/
static unsigned long do_mremap(unsigned long addr,
unsigned long old_len, unsigned long new_len,
unsigned long flags, unsigned long new_addr)
{
struct vm_area_struct *vma;
/* insanity checks first */
old_len = PAGE_ALIGN(old_len);
new_len = PAGE_ALIGN(new_len);
if (old_len == 0 || new_len == 0)
return (unsigned long) -EINVAL;
if (offset_in_page(addr))
return -EINVAL;
if (flags & MREMAP_FIXED && new_addr != addr)
return (unsigned long) -EINVAL;
vma = find_vma_exact(current->mm, addr, old_len);
if (!vma)
return (unsigned long) -EINVAL;
if (vma->vm_end != vma->vm_start + old_len)
return (unsigned long) -EFAULT;
if (vma->vm_flags & VM_MAYSHARE)
return (unsigned long) -EPERM;
if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
return (unsigned long) -ENOMEM;
/* all checks complete - do it */
vma->vm_end = vma->vm_start + new_len;
return vma->vm_start;
}
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
unsigned long, new_len, unsigned long, flags,
unsigned long, new_addr)
{
unsigned long ret;
down_write(&current->mm->mmap_sem);
ret = do_mremap(addr, old_len, new_len, flags, new_addr);
up_write(&current->mm->mmap_sem);
return ret;
}
struct page *follow_page_mask(struct vm_area_struct *vma,
unsigned long address, unsigned int flags,
unsigned int *page_mask)
{
*page_mask = 0;
return NULL;
}
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t prot)
{
if (addr != (pfn << PAGE_SHIFT))
return -EINVAL;
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
return 0;
}
EXPORT_SYMBOL(remap_pfn_range);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
{
unsigned long pfn = start >> PAGE_SHIFT;
unsigned long vm_len = vma->vm_end - vma->vm_start;
pfn += vma->vm_pgoff;
return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_iomap_memory);
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff)
{
unsigned int size = vma->vm_end - vma->vm_start;
if (!(vma->vm_flags & VM_USERMAP))
return -EINVAL;
vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
vma->vm_end = vma->vm_start + size;
return 0;
}
EXPORT_SYMBOL(remap_vmalloc_range);
unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
return -ENOMEM;
}
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen,
int even_cows)
{
}
EXPORT_SYMBOL(unmap_mapping_range);
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
BUG();
return 0;
}
EXPORT_SYMBOL(filemap_fault);
void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
{
BUG();
}
EXPORT_SYMBOL(filemap_map_pages);
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
unsigned long addr, void *buf, int len, int write)
{
struct vm_area_struct *vma;
down_read(&mm->mmap_sem);
/* the access must start within one of the target process's mappings */
vma = find_vma(mm, addr);
if (vma) {
/* don't overrun this mapping */
if (addr + len >= vma->vm_end)
len = vma->vm_end - addr;
/* only read or write mappings where it is permitted */
if (write && vma->vm_flags & VM_MAYWRITE)
copy_to_user_page(vma, NULL, addr,
(void *) addr, buf, len);
else if (!write && vma->vm_flags & VM_MAYREAD)
copy_from_user_page(vma, NULL, addr,
buf, (void *) addr, len);
else
len = 0;
} else {
len = 0;
}
up_read(&mm->mmap_sem);
return len;
}
/**
* @access_remote_vm - access another process' address space
* @mm: the mm_struct of the target address space
* @addr: start address to access
* @buf: source or destination buffer
* @len: number of bytes to transfer
* @write: whether the access is a write
*
* The caller must hold a reference on @mm.
*/
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, int write)
{
return __access_remote_vm(NULL, mm, addr, buf, len, write);
}
/*
* Access another process' address space.
* - source/target buffer must be kernel space
*/
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
struct mm_struct *mm;
if (addr + len < addr)
return 0;
mm = get_task_mm(tsk);
if (!mm)
return 0;
len = __access_remote_vm(tsk, mm, addr, buf, len, write);
mmput(mm);
return len;
}
/**
* nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
* @inode: The inode to check
* @size: The current filesize of the inode
* @newsize: The proposed filesize of the inode
*
* Check the shared mappings on an inode on behalf of a shrinking truncate to
* make sure that that any outstanding VMAs aren't broken and then shrink the
* vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
* automatically grant mappings that are too large.
*/
int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
size_t newsize)
{
struct vm_area_struct *vma;
struct vm_region *region;
pgoff_t low, high;
size_t r_size, r_top;
low = newsize >> PAGE_SHIFT;
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
down_write(&nommu_region_sem);
i_mmap_lock_read(inode->i_mapping);
/* search for VMAs that fall within the dead zone */
vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
/* found one - only interested if it's shared out of the page
* cache */
if (vma->vm_flags & VM_SHARED) {
i_mmap_unlock_read(inode->i_mapping);
up_write(&nommu_region_sem);
return -ETXTBSY; /* not quite true, but near enough */
}
}
/* reduce any regions that overlap the dead zone - if in existence,
* these will be pointed to by VMAs that don't overlap the dead zone
*
* we don't check for any regions that start beyond the EOF as there
* shouldn't be any
*/
vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
if (!(vma->vm_flags & VM_SHARED))
continue;
region = vma->vm_region;
r_size = region->vm_top - region->vm_start;
r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
if (r_top > newsize) {
region->vm_top -= r_top - newsize;
if (region->vm_end > region->vm_top)
region->vm_end = region->vm_top;
}
}
i_mmap_unlock_read(inode->i_mapping);
up_write(&nommu_region_sem);
return 0;
}
/*
* Initialise sysctl_user_reserve_kbytes.
*
* This is intended to prevent a user from starting a single memory hogging
* process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
* mode.
*
* The default value is min(3% of free memory, 128MB)
* 128MB is enough to recover with sshd/login, bash, and top/kill.
*/
static int __meminit init_user_reserve(void)
{
unsigned long free_kbytes;
free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
return 0;
}
subsys_initcall(init_user_reserve);
/*
* Initialise sysctl_admin_reserve_kbytes.
*
* The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
* to log in and kill a memory hogging process.
*
* Systems with more than 256MB will reserve 8MB, enough to recover
* with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
* only reserve 3% of free pages by default.
*/
static int __meminit init_admin_reserve(void)
{
unsigned long free_kbytes;
free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
return 0;
}
subsys_initcall(init_admin_reserve);