1 files changed, 253 insertions, 0 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
new file mode 100644
index 000000000000..4ae3a46ff768
--- /dev/null
+++ b/mm/mlock.c
@@ -0,0 +1,253 @@
+/*
+ *      linux/mm/mlock.c
+ *
+ *  (C) Copyright 1995 Linus Torvalds
+ *  (C) Copyright 2002 Christoph Hellwig
+ */
+
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/mempolicy.h>
+#include <linux/syscalls.h>
+
+
+static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
+        unsigned long start, unsigned long end, unsigned int newflags)
+{
+        struct mm_struct * mm = vma->vm_mm;
+        pgoff_t pgoff;
+        int pages;
+        int ret = 0;
+
+        if (newflags == vma->vm_flags) {
+                *prev = vma;
+                goto out;
+        }
+
+        pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+        *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
+                          vma->vm_file, pgoff, vma_policy(vma));
+        if (*prev) {
+                vma = *prev;
+                goto success;
+        }
+
+        *prev = vma;
+
+        if (start != vma->vm_start) {
+                ret = split_vma(mm, vma, start, 1);
+                if (ret)
+                        goto out;
+        }
+
+        if (end != vma->vm_end) {
+                ret = split_vma(mm, vma, end, 0);
+                if (ret)
+                        goto out;
+        }
+
+success:
+        /*
+         * vm_flags is protected by the mmap_sem held in write mode.
+         * It's okay if try_to_unmap_one unmaps a page just after we
+         * set VM_LOCKED, make_pages_present below will bring it back.
+         */
+        vma->vm_flags = newflags;
+
+        /*
+         * Keep track of amount of locked VM.
+         */
+        pages = (end - start) >> PAGE_SHIFT;
+        if (newflags & VM_LOCKED) {
+                pages = -pages;
+                if (!(newflags & VM_IO))
+                        ret = make_pages_present(start, end);
+        }
+
+        vma->vm_mm->locked_vm -= pages;
+out:
+        if (ret == -ENOMEM)
+                ret = -EAGAIN;
+        return ret;
+}
+
+static int do_mlock(unsigned long start, size_t len, int on)
+{
+        unsigned long nstart, end, tmp;
+        struct vm_area_struct * vma, * prev;
+        int error;
+
+        len = PAGE_ALIGN(len);
+        end = start + len;
+        if (end < start)
+                return -EINVAL;
+        if (end == start)
+                return 0;
+        vma = find_vma_prev(current->mm, start, &prev);
+        if (!vma || vma->vm_start > start)
+                return -ENOMEM;
+
+        if (start > vma->vm_start)
+                prev = vma;
+
+        for (nstart = start ; ; ) {
+                unsigned int newflags;
+
+                /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
+
+                newflags = vma->vm_flags | VM_LOCKED;
+                if (!on)
+                        newflags &= ~VM_LOCKED;
+
+                tmp = vma->vm_end;
+                if (tmp > end)
+                        tmp = end;
+                error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
+                if (error)
+                        break;
+                nstart = tmp;
+                if (nstart < prev->vm_end)
+                        nstart = prev->vm_end;
+                if (nstart >= end)
+                        break;
+
+                vma = prev->vm_next;
+                if (!vma || vma->vm_start != nstart) {
+                        error = -ENOMEM;
+                        break;
+                }
+        }
+        return error;
+}
+
+asmlinkage long sys_mlock(unsigned long start, size_t len)
+{
+        unsigned long locked;
+        unsigned long lock_limit;
+        int error = -ENOMEM;
+
+        if (!can_do_mlock())
+                return -EPERM;
+
+        down_write(&current->mm->mmap_sem);
+        len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
+        start &= PAGE_MASK;
+
+        locked = len >> PAGE_SHIFT;
+        locked += current->mm->locked_vm;
+
+        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit >>= PAGE_SHIFT;
+
+        /* check against resource limits */
+        if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
+                error = do_mlock(start, len, 1);
+        up_write(&current->mm->mmap_sem);
+        return error;
+}
+
+asmlinkage long sys_munlock(unsigned long start, size_t len)
+{
+        int ret;
+
+        down_write(&current->mm->mmap_sem);
+        len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
+        start &= PAGE_MASK;
+        ret = do_mlock(start, len, 0);
+        up_write(&current->mm->mmap_sem);
+        return ret;
+}
+
+static int do_mlockall(int flags)
+{
+        struct vm_area_struct * vma, * prev = NULL;
+        unsigned int def_flags = 0;
+
+        if (flags & MCL_FUTURE)
+                def_flags = VM_LOCKED;
+        current->mm->def_flags = def_flags;
+        if (flags == MCL_FUTURE)
+                goto out;
+
+        for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
+                unsigned int newflags;
+
+                newflags = vma->vm_flags | VM_LOCKED;
+                if (!(flags & MCL_CURRENT))
+                        newflags &= ~VM_LOCKED;
+
+                /* Ignore errors */
+                mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
+        }
+out:
+        return 0;
+}
+
+asmlinkage long sys_mlockall(int flags)
+{
+        unsigned long lock_limit;
+        int ret = -EINVAL;
+
+        if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
+                goto out;
+
+        ret = -EPERM;
+        if (!can_do_mlock())
+                goto out;
+
+        down_write(&current->mm->mmap_sem);
+
+        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit >>= PAGE_SHIFT;
+
+        ret = -ENOMEM;
+        if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
+            capable(CAP_IPC_LOCK))
+                ret = do_mlockall(flags);
+        up_write(&current->mm->mmap_sem);
+out:
+        return ret;
+}
+
+asmlinkage long sys_munlockall(void)
+{
+        int ret;
+
+        down_write(&current->mm->mmap_sem);
+        ret = do_mlockall(0);
+        up_write(&current->mm->mmap_sem);
+        return ret;
+}
+
+/*
+ * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
+ * shm segments) get accounted against the user_struct instead.
+ */
+static DEFINE_SPINLOCK(shmlock_user_lock);
+
+int user_shm_lock(size_t size, struct user_struct *user)
+{
+        unsigned long lock_limit, locked;
+        int allowed = 0;
+
+        locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit >>= PAGE_SHIFT;
+        spin_lock(&shmlock_user_lock);
+        if (locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
+                goto out;
+        get_uid(user);
+        user->locked_shm += locked;
+        allowed = 1;
+out:
+        spin_unlock(&shmlock_user_lock);
+        return allowed;
+}
+
+void user_shm_unlock(size_t size, struct user_struct *user)
+{
+        spin_lock(&shmlock_user_lock);
+        user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        spin_unlock(&shmlock_user_lock);
+        free_uid(user);
+}