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>

5 files changed, 15 insertions, 47 deletions

diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 88527492b917..d146e181d10d 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -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;
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 0708a0bf0ba9..16f735417072 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -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;
 
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9bd5612a8224..d390a0fffc65 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -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",
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 024d20ee3ca3..6b2daf99fab8 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -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)
diff --git a/fs/binfmt_som.c b/fs/binfmt_som.c
index e4fc746629a7..4517aaff61b4 100644
--- a/fs/binfmt_som.c
+++ b/fs/binfmt_som.c
@@ -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: