VM: add "vm_mmap()" helper function

This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.

This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c.  But that way we don't have
to export our internal do_mmap_pgoff() function.

Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead.  We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

15 files changed, 87 insertions, 97 deletions

diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c
index 9efbc1391b3c..89529c9f0605 100644
--- a/arch/tile/kernel/single_step.c
+++ b/arch/tile/kernel/single_step.c
@@ -346,12 +346,10 @@ void single_step_once(struct pt_regs *regs)
                 }
 
                 /* allocate a cache line of writable, executable memory */
-                down_write(&current->mm->mmap_sem);
-                buffer = (void __user *) do_mmap(NULL, 0, 64,
+                buffer = (void __user *) vm_mmap(NULL, 0, 64,
                                           PROT_EXEC | PROT_READ | PROT_WRITE,
                                           MAP_PRIVATE | MAP_ANONYMOUS,
                                           0);
-                up_write(&current->mm->mmap_sem);
 
                 if (IS_ERR((void __force *)buffer)) {
                         kfree(state);
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index b6817ee9033f..4824fb45560f 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -379,26 +379,22 @@ static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                         goto beyond_if;
                 }
 
-                down_write(&current->mm->mmap_sem);
-                error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
+                error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
                                 PROT_READ | PROT_EXEC,
                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
                                 MAP_EXECUTABLE | MAP_32BIT,
                                 fd_offset);
-                up_write(&current->mm->mmap_sem);
 
                 if (error != N_TXTADDR(ex)) {
                         send_sig(SIGKILL, current, 0);
                         return error;
                 }
 
-                down_write(&current->mm->mmap_sem);
-                error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
+                error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
                                 PROT_READ | PROT_WRITE | PROT_EXEC,
                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
                                 MAP_EXECUTABLE | MAP_32BIT,
                                 fd_offset + ex.a_text);
-                up_write(&current->mm->mmap_sem);
                 if (error != N_DATADDR(ex)) {
                         send_sig(SIGKILL, current, 0);
                         return error;
@@ -482,12 +478,10 @@ static int load_aout_library(struct file *file)
                 goto out;
         }
         /* Now use mmap to map the library into memory. */
-        down_write(&current->mm->mmap_sem);
-        error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
+        error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
                         PROT_READ | PROT_WRITE | PROT_EXEC,
                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT,
                         N_TXTOFF(ex));
-        up_write(&current->mm->mmap_sem);
         retval = error;
         if (error != start_addr)
                 goto out;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8beb9ce79364..1457be305fb1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6336,13 +6336,11 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
                 if (npages && !old.rmap) {
                         unsigned long userspace_addr;
 
-                        down_write(&current->mm->mmap_sem);
-                        userspace_addr = do_mmap(NULL, 0,
+                        userspace_addr = vm_mmap(NULL, 0,
                                                  npages * PAGE_SIZE,
                                                  PROT_READ | PROT_WRITE,
                                                  map_flags,
                                                  0);
-                        up_write(&current->mm->mmap_sem);
 
                         if (IS_ERR((void *)userspace_addr))
                                 return PTR_ERR((void *)userspace_addr);
diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index 30372f7b2d45..348b367debeb 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1510,8 +1510,8 @@ int drm_freebufs(struct drm_device *dev, void *data,
  * \param arg pointer to a drm_buf_map structure.
  * \return zero on success or a negative number on failure.
  *
- * Maps the AGP, SG or PCI buffer region with do_mmap(), and copies information
- * about each buffer into user space. For PCI buffers, it calls do_mmap() with
+ * Maps the AGP, SG or PCI buffer region with vm_mmap(), and copies information
+ * about each buffer into user space. For PCI buffers, it calls vm_mmap() with
  * offset equal to 0, which drm_mmap() interpretes as PCI buffers and calls
  * drm_mmap_dma().
  */
@@ -1553,18 +1553,14 @@ int drm_mapbufs(struct drm_device *dev, void *data,
                                 retcode = -EINVAL;
                                 goto done;
                         }
-                        down_write(&current->mm->mmap_sem);
-                        virtual = do_mmap(file_priv->filp, 0, map->size,
+                        virtual = vm_mmap(file_priv->filp, 0, map->size,
                                           PROT_READ | PROT_WRITE,
                                           MAP_SHARED,
                                           token);
-                        up_write(&current->mm->mmap_sem);
                 } else {
-                        down_write(&current->mm->mmap_sem);
-                        virtual = do_mmap(file_priv->filp, 0, dma->byte_count,
+                        virtual = vm_mmap(file_priv->filp, 0, dma->byte_count,
                                           PROT_READ | PROT_WRITE,
                                           MAP_SHARED, 0);
-                        up_write(&current->mm->mmap_sem);
                 }
                 if (virtual > -1024UL) {
                         /* Real error */
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 26d51979116b..392ce71ed6a1 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -581,10 +581,8 @@ int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data,
         obj->filp->f_op = &exynos_drm_gem_fops;
         obj->filp->private_data = obj;
 
-        down_write(&current->mm->mmap_sem);
-        addr = do_mmap(obj->filp, 0, args->size,
+        addr = vm_mmap(obj->filp, 0, args->size,
                         PROT_READ | PROT_WRITE, MAP_SHARED, 0);
-        up_write(&current->mm->mmap_sem);
 
         drm_gem_object_unreference_unlocked(obj);
 
diff --git a/drivers/gpu/drm/i810/i810_dma.c b/drivers/gpu/drm/i810/i810_dma.c
index b85337f06fbf..a4ba453b3d27 100644
--- a/drivers/gpu/drm/i810/i810_dma.c
+++ b/drivers/gpu/drm/i810/i810_dma.c
@@ -129,6 +129,7 @@ static int i810_map_buffer(struct drm_buf *buf, struct drm_file *file_priv)