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List:       linux-kernel
Subject:    [PATCH] Uninline sys_mmap common code (reduce binary size)
From:       Michael Buesch <mbuesch () freenet ! de>
Date:       2006-02-24 15:07:38
Message-ID: 200602241607.38732.mbuesch () freenet ! de
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[Attachment #2 (multipart/mixed)]


This patch removes the inlinining of the new vs old mmap system
call common code.
This reduces the size of the resulting vmlinux for defconfig as follows:

mb@pc1:~/develop/git/linux-2.6$ size vmlinux.mmap*
   text    data     bss     dec     hex filename
3303749  521524  186564 4011837  3d373d vmlinux.mmapinline
3303557  521524  186564 4011645  3d367d vmlinux.mmapnoinline

The new sys_mmap2() has also one function call overhead removed, now.
(probably it was already optimized to a jmp before, but anyway...)


diff --git a/arch/i386/kernel/sys_i386.c b/arch/i386/kernel/sys_i386.c
index a4a6197..8fdb1fb 100644
--- a/arch/i386/kernel/sys_i386.c
+++ b/arch/i386/kernel/sys_i386.c
@@ -40,14 +40,13 @@ asmlinkage int sys_pipe(unsigned long __
 	return error;
 }
 
-/* common code for old and new mmaps */
-static inline long do_mmap2(
-	unsigned long addr, unsigned long len,
-	unsigned long prot, unsigned long flags,
-	unsigned long fd, unsigned long pgoff)
+asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
+			  unsigned long prot, unsigned long flags,
+			  unsigned long fd, unsigned long pgoff)
 {
 	int error = -EBADF;
-	struct file * file = NULL;
+	struct file *file = NULL;
+	struct mm_struct *mm = current->mm;
 
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 	if (!(flags & MAP_ANONYMOUS)) {
@@ -56,9 +55,9 @@ static inline long do_mmap2(
 			goto out;
 	}
 
-	down_write(&current->mm->mmap_sem);
+	down_write(&mm->mmap_sem);
 	error = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
-	up_write(&current->mm->mmap_sem);
+	up_write(&mm->mmap_sem);
 
 	if (file)
 		fput(file);
@@ -66,13 +65,6 @@ out:
 	return error;
 }
 
-asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
-	unsigned long prot, unsigned long flags,
-	unsigned long fd, unsigned long pgoff)
-{
-	return do_mmap2(addr, len, prot, flags, fd, pgoff);
-}
-
 /*
  * Perform the select(nd, in, out, ex, tv) and mmap() system
  * calls. Linux/i386 didn't use to be able to handle more than
@@ -101,7 +93,8 @@ asmlinkage int old_mmap(struct mmap_arg_
 	if (a.offset & ~PAGE_MASK)
 		goto out;
 
-	err = do_mmap2(a.addr, a.len, a.prot, a.flags, a.fd, a.offset >> PAGE_SHIFT);
+	err = sys_mmap2(a.addr, a.len, a.prot, a.flags,
+			a.fd, a.offset >> PAGE_SHIFT);
 out:
 	return err;
 }


-- 
Greetings Michael.

["uninline-mmap-common.patch" (text/x-diff)]

diff --git a/arch/i386/kernel/sys_i386.c b/arch/i386/kernel/sys_i386.c
index a4a6197..8fdb1fb 100644
--- a/arch/i386/kernel/sys_i386.c
+++ b/arch/i386/kernel/sys_i386.c
@@ -40,14 +40,13 @@ asmlinkage int sys_pipe(unsigned long __
 	return error;
 }
 
-/* common code for old and new mmaps */
-static inline long do_mmap2(
-	unsigned long addr, unsigned long len,
-	unsigned long prot, unsigned long flags,
-	unsigned long fd, unsigned long pgoff)
+asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
+			  unsigned long prot, unsigned long flags,
+			  unsigned long fd, unsigned long pgoff)
 {
 	int error = -EBADF;
-	struct file * file = NULL;
+	struct file *file = NULL;
+	struct mm_struct *mm = current->mm;
 
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 	if (!(flags & MAP_ANONYMOUS)) {
@@ -56,9 +55,9 @@ static inline long do_mmap2(
 			goto out;
 	}
 
-	down_write(&current->mm->mmap_sem);
+	down_write(&mm->mmap_sem);
 	error = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
-	up_write(&current->mm->mmap_sem);
+	up_write(&mm->mmap_sem);
 
 	if (file)
 		fput(file);
@@ -66,13 +65,6 @@ out:
 	return error;
 }
 
-asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
-	unsigned long prot, unsigned long flags,
-	unsigned long fd, unsigned long pgoff)
-{
-	return do_mmap2(addr, len, prot, flags, fd, pgoff);
-}
-
 /*
  * Perform the select(nd, in, out, ex, tv) and mmap() system
  * calls. Linux/i386 didn't use to be able to handle more than
@@ -101,7 +93,8 @@ asmlinkage int old_mmap(struct mmap_arg_
 	if (a.offset & ~PAGE_MASK)
 		goto out;
 
-	err = do_mmap2(a.addr, a.len, a.prot, a.flags, a.fd, a.offset >> PAGE_SHIFT);
+	err = sys_mmap2(a.addr, a.len, a.prot, a.flags,
+			a.fd, a.offset >> PAGE_SHIFT);
 out:
 	return err;
 }

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