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-rw-r--r--mm/nommu.c247
1 files changed, 193 insertions, 54 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index c576df71e3bb..564540662192 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -122,26 +122,50 @@ unsigned int kobjsize(const void *objp)
}
/*
- * The nommu dodgy version :-)
+ * 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
*/
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
{
+ struct vm_area_struct *vma;
+ unsigned long vm_flags;
int i;
- static struct vm_area_struct dummy_vma;
+
+ /* calculate required read or write permissions.
+ * - if 'force' is set, we only require the "MAY" flags.
+ */
+ vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+ vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
for (i = 0; i < len; 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])
page_cache_get(pages[i]);
}
if (vmas)
- vmas[i] = &dummy_vma;
+ vmas[i] = vma;
start += PAGE_SIZE;
}
- return(i);
+
+ return i;
+
+finish_or_fault:
+ return i ? : -EFAULT;
}
EXPORT_SYMBOL(get_user_pages);
@@ -286,6 +310,77 @@ static void show_process_blocks(void)
}
#endif /* DEBUG */
+/*
+ * add a VMA into a process's mm_struct in the appropriate place in the list
+ * - should be called with mm->mmap_sem held writelocked
+ */
+static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
+{
+ struct vm_list_struct **ppv;
+
+ for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
+ if ((*ppv)->vma->vm_start > vml->vma->vm_start)
+ break;
+
+ vml->next = *ppv;
+ *ppv = vml;
+}
+
+/*
+ * 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_list_struct *loop, *vml;
+
+ /* search the vm_start ordered list */
+ vml = NULL;
+ for (loop = mm->context.vmlist; loop; loop = loop->next) {
+ if (loop->vma->vm_start > addr)
+ break;
+ vml = loop;
+ }
+
+ if (vml && vml->vma->vm_end > addr)
+ return vml->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);
+}
+
+/*
+ * look up the first VMA exactly that exactly matches addr
+ * - should be called with mm->mmap_sem at least held readlocked
+ */
+static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
+ unsigned long addr)
+{
+ struct vm_list_struct *vml;
+
+ /* search the vm_start ordered list */
+ for (vml = mm->context.vmlist; vml; vml = vml->next) {
+ if (vml->vma->vm_start == addr)
+ return vml->vma;
+ if (vml->vma->vm_start > addr)
+ break;
+ }
+
+ return NULL;
+}
+
+/*
+ * find a VMA in the global tree
+ */
static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
{
struct vm_area_struct *vma;
@@ -305,6 +400,9 @@ static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
return NULL;
}
+/*
+ * add a VMA in the global tree
+ */
static void add_nommu_vma(struct vm_area_struct *vma)
{
struct vm_area_struct *pvma;
@@ -351,6 +449,9 @@ static void add_nommu_vma(struct vm_area_struct *vma)
rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
}
+/*
+ * delete a VMA from the global list
+ */
static void delete_nommu_vma(struct vm_area_struct *vma)
{
struct address_space *mapping;
@@ -828,8 +929,7 @@ unsigned long do_mmap_pgoff(struct file *file,
realalloc += kobjsize(vml);
askedalloc += sizeof(*vml);
- vml->next = current->mm->context.vmlist;
- current->mm->context.vmlist = vml;
+ add_vma_to_mm(current->mm, vml);
up_write(&nommu_vma_sem);
@@ -908,6 +1008,11 @@ static void put_vma(struct vm_area_struct *vma)
}
}
+/*
+ * release a mapping
+ * - under NOMMU conditions the parameters must match exactly to the mapping to
+ * be removed
+ */
int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
{
struct vm_list_struct *vml, **parent;
@@ -917,10 +1022,13 @@ int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
printk("do_munmap:\n");
#endif
- for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next)
+ for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
+ if ((*parent)->vma->vm_start > addr)
+ break;
if ((*parent)->vma->vm_start == addr &&
((len == 0) || ((*parent)->vma->vm_end == end)))
goto found;
+ }
printk("munmap of non-mmaped memory by process %d (%s): %p\n",
current->pid, current->comm, (void *) addr);
@@ -946,7 +1054,20 @@ int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
return 0;
}
-/* Release all mmaps. */
+asmlinkage long sys_munmap(unsigned long addr, size_t len)
+{
+ int ret;
+ struct mm_struct *mm = current->mm;
+
+ down_write(&mm->mmap_sem);
+ ret = do_munmap(mm, addr, len);
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+
+/*
+ * Release all mappings
+ */
void exit_mmap(struct mm_struct * mm)
{
struct vm_list_struct *tmp;
@@ -973,37 +1094,26 @@ void exit_mmap(struct mm_struct * mm)
}
}
-asmlinkage long sys_munmap(unsigned long addr, size_t len)
-{
- int ret;
- struct mm_struct *mm = current->mm;
-
- down_write(&mm->mmap_sem);
- ret = do_munmap(mm, addr, len);
- up_write(&mm->mmap_sem);
- return ret;
-}
-
unsigned long do_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)
+ * expand (or shrink) an existing mapping, potentially moving it at the same
+ * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
*
- * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
- * This option implies MREMAP_MAYMOVE.
+ * under NOMMU conditions, we only permit changing a mapping's size, and only
+ * as long as it stays within the hole allocated by the kmalloc() call in
+ * do_mmap_pgoff() and the block is not shareable
*
- * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the
- * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable
+ * MREMAP_FIXED is not supported under NOMMU conditions
*/
unsigned long do_mremap(unsigned long addr,
unsigned long old_len, unsigned long new_len,
unsigned long flags, unsigned long new_addr)
{
- struct vm_list_struct *vml = NULL;
+ struct vm_area_struct *vma;
/* insanity checks first */
if (new_len == 0)
@@ -1012,58 +1122,46 @@ unsigned long do_mremap(unsigned long addr,
if (flags & MREMAP_FIXED && new_addr != addr)
return (unsigned long) -EINVAL;
- for (vml = current->mm->context.vmlist; vml; vml = vml->next)
- if (vml->vma->vm_start == addr)
- goto found;
-
- return (unsigned long) -EINVAL;
+ vma = find_vma_exact(current->mm, addr);
+ if (!vma)
+ return (unsigned long) -EINVAL;
- found:
- if (vml->vma->vm_end != vml->vma->vm_start + old_len)
+ if (vma->vm_end != vma->vm_start + old_len)
return (unsigned long) -EFAULT;
- if (vml->vma->vm_flags & VM_MAYSHARE)
+ if (vma->vm_flags & VM_MAYSHARE)
return (unsigned long) -EPERM;
if (new_len > kobjsize((void *) addr))
return (unsigned long) -ENOMEM;
/* all checks complete - do it */
- vml->vma->vm_end = vml->vma->vm_start + new_len;
+ vma->vm_end = vma->vm_start + new_len;
askedalloc -= old_len;
askedalloc += new_len;
- return vml->vma->vm_start;
+ return vma->vm_start;
}
-/*
- * Look up the first VMA which satisfies addr < vm_end, NULL if none
- */
-struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+asmlinkage unsigned long sys_mremap(unsigned long addr,
+ unsigned long old_len, unsigned long new_len,
+ unsigned long flags, unsigned long new_addr)
{
- struct vm_list_struct *vml;
-
- for (vml = mm->context.vmlist; vml; vml = vml->next)
- if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end)
- return vml->vma;
+ unsigned long ret;
- return NULL;
+ 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;
}
-EXPORT_SYMBOL(find_vma);
-
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
unsigned int foll_flags)
{
return NULL;
}
-struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
-{
- return NULL;
-}
-
int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
unsigned long to, unsigned long size, pgprot_t prot)
{
@@ -1133,7 +1231,7 @@ int __vm_enough_memory(long pages, int cap_sys_admin)
* which are reclaimable, under pressure. The dentry
* cache and most inode caches should fall into this
*/
- free += atomic_read(&slab_reclaim_pages);
+ free += global_page_state(NR_SLAB_RECLAIMABLE);
/*
* Leave the last 3% for root
@@ -1206,3 +1304,44 @@ struct page *filemap_nopage(struct vm_area_struct *area,
BUG();
return NULL;
}
+
+/*
+ * 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 vm_area_struct *vma;
+ struct mm_struct *mm;
+
+ if (addr + len < addr)
+ return 0;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return 0;
+
+ 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)
+ len -= copy_to_user((void *) addr, buf, len);
+ else if (!write && vma->vm_flags & VM_MAYREAD)
+ len -= copy_from_user(buf, (void *) addr, len);
+ else
+ len = 0;
+ } else {
+ len = 0;
+ }
+
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ return len;
+}