VM: add "vm_mmap()" helper function
Linus Torvalds [Sat, 21 Apr 2012 00:13:58 +0000 (17:13 -0700)]
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:
arch/tile/kernel/single_step.c
arch/x86/ia32/ia32_aout.c
arch/x86/kvm/x86.c
drivers/gpu/drm/drm_bufs.c
drivers/gpu/drm/exynos/exynos_drm_gem.c
drivers/gpu/drm/i810/i810_dma.c
drivers/gpu/drm/i915/i915_gem.c
fs/binfmt_aout.c
fs/binfmt_elf.c
fs/binfmt_elf_fdpic.c
fs/binfmt_flat.c
fs/binfmt_som.c
include/linux/mm.h
mm/mmap.c
mm/nommu.c

index 9efbc13..89529c9 100644 (file)
@@ -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);
index b6817ee..4824fb4 100644 (file)
@@ -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;
index 8beb9ce..1457be3 100644 (file)
@@ -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);
index 30372f7..348b367 100644 (file)
@@ -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 */
index 26d5197..392ce71 100644 (file)
@@ -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);
 
index b85337f..a4ba453 100644 (file)
@@ -129,6 +129,7 @@ static int i810_map_buffer(struct drm_buf *buf, struct drm_file *file_priv)
        if (buf_priv->currently_mapped == I810_BUF_MAPPED)
                return -EINVAL;
 
+       /* This is all entirely broken */
        down_write(&current->mm->mmap_sem);
        old_fops = file_priv->filp->f_op;
        file_priv->filp->f_op = &i810_buffer_fops;
index 0e3c6ac..0d1e4b7 100644 (file)
@@ -1087,11 +1087,9 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
        if (obj == NULL)
                return -ENOENT;
 
-       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,
                       args->offset);
-       up_write(&current->mm->mmap_sem);
        drm_gem_object_unreference_unlocked(obj);
        if (IS_ERR((void *)addr))
                return addr;
index 8852749..d146e18 100644 (file)
@@ -319,24 +319,20 @@ 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,
                        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,
                                fd_offset + ex.a_text);
-               up_write(&current->mm->mmap_sem);
                if (error != N_DATADDR(ex)) {
                        send_sig(SIGKILL, current, 0);
                        return error;
@@ -417,12 +413,10 @@ 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,
                        N_TXTOFF(ex));
-       up_write(&current->mm->mmap_sem);
        retval = error;
        if (error != start_addr)
                goto out;
index 0708a0b..16f7354 100644 (file)
@@ -958,10 +958,8 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                   and some applications "depend" upon this behavior.
                   Since we do not have the power to recompile these, we
                   emulate the SVr4 behavior. Sigh. */
-               down_write(&current->mm->mmap_sem);
-               error = do_mmap(NULL, 0, PAGE_SIZE, PROT_READ | PROT_EXEC,
+               error = vm_mmap(NULL, 0, PAGE_SIZE, PROT_READ | PROT_EXEC,
                                MAP_FIXED | MAP_PRIVATE, 0);
-               up_write(&current->mm->mmap_sem);
        }
 
 #ifdef ELF_PLAT_INIT
@@ -1046,8 +1044,7 @@ static int load_elf_library(struct file *file)
                eppnt++;
 
        /* Now use mmap to map the library into memory. */
-       down_write(&current->mm->mmap_sem);
-       error = do_mmap(file,
+       error = vm_mmap(file,
                        ELF_PAGESTART(eppnt->p_vaddr),
                        (eppnt->p_filesz +
                         ELF_PAGEOFFSET(eppnt->p_vaddr)),
@@ -1055,7 +1052,6 @@ static int load_elf_library(struct file *file)
                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
                        (eppnt->p_offset -
                         ELF_PAGEOFFSET(eppnt->p_vaddr)));
-       up_write(&current->mm->mmap_sem);
        if (error != ELF_PAGESTART(eppnt->p_vaddr))
                goto out_free_ph;
 
index 9bd5612..d390a0f 100644 (file)
@@ -390,21 +390,17 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
            (executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
                stack_prot |= PROT_EXEC;
 
-       down_write(&current->mm->mmap_sem);
-       current->mm->start_brk = do_mmap(NULL, 0, stack_size, stack_prot,
+       current->mm->start_brk = vm_mmap(NULL, 0, stack_size, stack_prot,
                                         MAP_PRIVATE | MAP_ANONYMOUS |
                                         MAP_UNINITIALIZED | MAP_GROWSDOWN,
                                         0);
 
        if (IS_ERR_VALUE(current->mm->start_brk)) {
-               up_write(&current->mm->mmap_sem);
                retval = current->mm->start_brk;
                current->mm->start_brk = 0;
                goto error_kill;
        }
 
-       up_write(&current->mm->mmap_sem);
-
        current->mm->brk = current->mm->start_brk;
        current->mm->context.end_brk = current->mm->start_brk;
        current->mm->context.end_brk +=
@@ -955,10 +951,8 @@ static int elf_fdpic_map_file_constdisp_on_uclinux(
        if (params->flags & ELF_FDPIC_FLAG_EXECUTABLE)
                mflags |= MAP_EXECUTABLE;
 
-       down_write(&mm->mmap_sem);
-       maddr = do_mmap(NULL, load_addr, top - base,
+       maddr = vm_mmap(NULL, load_addr, top - base,
                        PROT_READ | PROT_WRITE | PROT_EXEC, mflags, 0);
-       up_write(&mm->mmap_sem);
        if (IS_ERR_VALUE(maddr))
                return (int) maddr;
 
@@ -1096,10 +1090,8 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 
                /* create the mapping */
                disp = phdr->p_vaddr & ~PAGE_MASK;
-               down_write(&mm->mmap_sem);
-               maddr = do_mmap(file, maddr, phdr->p_memsz + disp, prot, flags,
+               maddr = vm_mmap(file, maddr, phdr->p_memsz + disp, prot, flags,
                                phdr->p_offset - disp);
-               up_write(&mm->mmap_sem);
 
                kdebug("mmap[%d] <file> sz=%lx pr=%x fl=%x of=%lx --> %08lx",
                       loop, phdr->p_memsz + disp, prot, flags,
@@ -1143,10 +1135,8 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
                        unsigned long xmaddr;
 
                        flags |= MAP_FIXED | MAP_ANONYMOUS;
-                       down_write(&mm->mmap_sem);
-                       xmaddr = do_mmap(NULL, xaddr, excess - excess1,
+                       xmaddr = vm_mmap(NULL, xaddr, excess - excess1,
                                         prot, flags, 0);
-                       up_write(&mm->mmap_sem);
 
                        kdebug("mmap[%d] <anon>"
                               " ad=%lx sz=%lx pr=%x fl=%x of=0 --> %08lx",
index 024d20e..6b2daf9 100644 (file)
@@ -542,10 +542,8 @@ static int load_flat_file(struct linux_binprm * bprm,
                 */
                DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
 
-               down_write(&current->mm->mmap_sem);
-               textpos = do_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
+               textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
                                  MAP_PRIVATE|MAP_EXECUTABLE, 0);
-               up_write(&current->mm->mmap_sem);
                if (!textpos || IS_ERR_VALUE(textpos)) {
                        if (!textpos)
                                textpos = (unsigned long) -ENOMEM;
@@ -556,10 +554,8 @@ static int load_flat_file(struct linux_binprm * bprm,
 
                len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                len = PAGE_ALIGN(len);
-               down_write(&current->mm->mmap_sem);
-               realdatastart = do_mmap(0, 0, len,
+               realdatastart = vm_mmap(0, 0, len,
                        PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
-               up_write(&current->mm->mmap_sem);
 
                if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
                        if (!realdatastart)
@@ -603,10 +599,8 @@ static int load_flat_file(struct linux_binprm * bprm,
 
                len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                len = PAGE_ALIGN(len);
-               down_write(&current->mm->mmap_sem);
-               textpos = do_mmap(0, 0, len,
+               textpos = vm_mmap(0, 0, len,
                        PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
-               up_write(&current->mm->mmap_sem);
 
                if (!textpos || IS_ERR_VALUE(textpos)) {
                        if (!textpos)
index e4fc746..4517aaf 100644 (file)
@@ -147,10 +147,8 @@ static int map_som_binary(struct file *file,
        code_size = SOM_PAGEALIGN(hpuxhdr->exec_tsize);
        current->mm->start_code = code_start;
        current->mm->end_code = code_start + code_size;
-       down_write(&current->mm->mmap_sem);
-       retval = do_mmap(file, code_start, code_size, prot,
+       retval = vm_mmap(file, code_start, code_size, prot,
                        flags, SOM_PAGESTART(hpuxhdr->exec_tfile));
-       up_write(&current->mm->mmap_sem);
        if (retval < 0 && retval > -1024)
                goto out;
 
@@ -158,20 +156,16 @@ static int map_som_binary(struct file *file,
        data_size = SOM_PAGEALIGN(hpuxhdr->exec_dsize);
        current->mm->start_data = data_start;
        current->mm->end_data = bss_start = data_start + data_size;
-       down_write(&current->mm->mmap_sem);
-       retval = do_mmap(file, data_start, data_size,
+       retval = vm_mmap(file, data_start, data_size,
                        prot | PROT_WRITE, flags,
                        SOM_PAGESTART(hpuxhdr->exec_dfile));
-       up_write(&current->mm->mmap_sem);
        if (retval < 0 && retval > -1024)
                goto out;
 
        som_brk = bss_start + SOM_PAGEALIGN(hpuxhdr->exec_bsize);
        current->mm->start_brk = current->mm->brk = som_brk;
-       down_write(&current->mm->mmap_sem);
-       retval = do_mmap(NULL, bss_start, som_brk - bss_start,
+       retval = vm_mmap(NULL, bss_start, som_brk - bss_start,
                        prot | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, 0);
-       up_write(&current->mm->mmap_sem);
        if (retval > 0 || retval < -1024)
                retval = 0;
 out:
index cb61950..86a692c 100644 (file)
@@ -1393,31 +1393,20 @@ extern int install_special_mapping(struct mm_struct *mm,
 
 extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
 
-extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
-       unsigned long len, unsigned long prot,
-       unsigned long flag, unsigned long pgoff);
 extern unsigned long mmap_region(struct file *file, unsigned long addr,
        unsigned long len, unsigned long flags,
        vm_flags_t vm_flags, unsigned long pgoff);
-
-static inline unsigned long do_mmap(struct file *file, unsigned long addr,
-       unsigned long len, unsigned long prot,
-       unsigned long flag, unsigned long offset)
-{
-       unsigned long ret = -EINVAL;
-       if ((offset + PAGE_ALIGN(len)) < offset)
-               goto out;
-       if (!(offset & ~PAGE_MASK))
-               ret = do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
-out:
-       return ret;
-}
-
+extern unsigned long do_mmap(struct file *, unsigned long,
+        unsigned long, unsigned long,
+        unsigned long, unsigned long);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t);
 
 /* These take the mm semaphore themselves */
 extern unsigned long vm_brk(unsigned long, unsigned long);
 extern int vm_munmap(struct mm_struct *, unsigned long, size_t);
+extern unsigned long vm_mmap(struct file *, unsigned long,
+        unsigned long, unsigned long,
+        unsigned long, unsigned long);
 
 /* truncate.c */
 extern void truncate_inode_pages(struct address_space *, loff_t);
index 4af45f5..b38b47e 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -953,7 +953,7 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
  * The caller must hold down_write(&current->mm->mmap_sem).
  */
 
-unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
+static unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
                        unsigned long len, unsigned long prot,
                        unsigned long flags, unsigned long pgoff)
 {
@@ -1089,7 +1089,32 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 
        return mmap_region(file, addr, len, flags, vm_flags, pgoff);
 }
-EXPORT_SYMBOL(do_mmap_pgoff);
+
+unsigned long do_mmap(struct file *file, unsigned long addr,
+       unsigned long len, unsigned long prot,
+       unsigned long flag, unsigned long offset)
+{
+       if (unlikely(offset + PAGE_ALIGN(len) < offset))
+               return -EINVAL;
+       if (unlikely(offset & ~PAGE_MASK))
+               return -EINVAL;
+       return do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(do_mmap);
+
+unsigned long vm_mmap(struct file *file, unsigned long addr,
+       unsigned long len, unsigned long prot,
+       unsigned long flag, unsigned long offset)
+{
+       unsigned long ret;
+       struct mm_struct *mm = current->mm;
+
+       down_write(&mm->mmap_sem);
+       ret = do_mmap(file, addr, len, prot, flag, offset);
+       up_write(&mm->mmap_sem);
+       return ret;
+}
+EXPORT_SYMBOL(vm_mmap);
 
 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
                unsigned long, prot, unsigned long, flags,
index 11a69b2..dd00383 100644 (file)
@@ -1233,7 +1233,7 @@ enomem:
 /*
  * handle mapping creation for uClinux
  */
-unsigned long do_mmap_pgoff(struct file *file,
+static unsigned long do_mmap_pgoff(struct file *file,
                            unsigned long addr,
                            unsigned long len,
                            unsigned long prot,
@@ -1470,7 +1470,32 @@ error_getting_region:
        show_free_areas(0);
        return -ENOMEM;
 }
-EXPORT_SYMBOL(do_mmap_pgoff);
+
+unsigned long do_mmap(struct file *file, unsigned long addr,
+       unsigned long len, unsigned long prot,
+       unsigned long flag, unsigned long offset)
+{
+       if (unlikely(offset + PAGE_ALIGN(len) < offset))
+               return -EINVAL;
+       if (unlikely(offset & ~PAGE_MASK))
+               return -EINVAL;
+       return do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(do_mmap);
+
+unsigned long vm_mmap(struct file *file, unsigned long addr,
+       unsigned long len, unsigned long prot,
+       unsigned long flag, unsigned long offset)
+{
+       unsigned long ret;
+       struct mm_struct *mm = current->mm;
+
+       down_write(&mm->mmap_sem);
+       ret = do_mmap(file, addr, len, prot, flag, offset);
+       up_write(&mm->mmap_sem);
+       return ret;
+}
+EXPORT_SYMBOL(vm_mmap);
 
 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
                unsigned long, prot, unsigned long, flags,