linux-kernel - [PATCH v3 4/5] sysctl: delete mmap_rnd_bits_{min/max} and mmap_rnd_compat_bits

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Message-Id: <6456666b2d30e1d062101d9182738dbeb42f4c29.1726365007.git.wen.yang@linux.dev>
Date: Sun, 15 Sep 2024 10:08:30 +0800
From: Wen Yang <wen.yang@...ux.dev>
To: "Eric W . Biederman" <ebiederm@...ssion.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Kees Cook <keescook@...omium.org>,
	Joel Granados <j.granados@...sung.com>
Cc: Christian Brauner <brauner@...nel.org>,
	linux-kernel@...r.kernel.org,
	Wen Yang <wen.yang@...ux.dev>,
	Dave Young <dyoung@...hat.com>
Subject: [PATCH v3 4/5] sysctl: delete mmap_rnd_bits_{min/max} and mmap_rnd_compat_bits_{min/max} to save 16 bytes

By directly encoding CONFIG_ARCH_MMAP_RND_BITS_{MIN/MAX} and
CONFIG_ARCH_MMAP_RND_COMPAT_BITS_{MIN/MAX} into the ctl_table's min/max
field, unnecessary global variables can be removed, saving 16 bytes.

Signed-off-by: Wen Yang <wen.yang@...ux.dev>
Cc: Luis Chamberlain <mcgrof@...nel.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Joel Granados <j.granados@...sung.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Christian Brauner <brauner@...nel.org>
Cc: Dave Young <dyoung@...hat.com>
Cc: linux-kernel@...r.kernel.org
---
 include/linux/mm.h |  4 ----
 kernel/sysctl.c    | 12 ++++++------
 mm/mmap.c          |  4 ----
 3 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6549d0979b28..9d9c4a4f4708 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -87,13 +87,9 @@ extern int sysctl_legacy_va_layout;
 #endif
 
 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
-extern const int mmap_rnd_bits_min;
-extern int mmap_rnd_bits_max __ro_after_init;
 extern int mmap_rnd_bits __read_mostly;
 #endif
 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
-extern const int mmap_rnd_compat_bits_min;
-extern const int mmap_rnd_compat_bits_max;
 extern int mmap_rnd_compat_bits __read_mostly;
 #endif
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 86de15638e31..05197d46007d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2196,10 +2196,10 @@ static struct ctl_table vm_table[] = {
 		.procname	= "mmap_rnd_bits",
 		.data		= &mmap_rnd_bits,
 		.maxlen		= sizeof(mmap_rnd_bits),
-		.mode		= 0600,
+		.mode		= 0600 | SYSCTL_FLAG_MIN | SYSCTL_FLAG_MAX,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&mmap_rnd_bits_min,
-		.extra2		= (void *)&mmap_rnd_bits_max,
+		.min		= CONFIG_ARCH_MMAP_RND_BITS_MIN,
+		.max		= CONFIG_ARCH_MMAP_RND_BITS_MAX,
 	},
 #endif
 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
@@ -2207,10 +2207,10 @@ static struct ctl_table vm_table[] = {
 		.procname	= "mmap_rnd_compat_bits",
 		.data		= &mmap_rnd_compat_bits,
 		.maxlen		= sizeof(mmap_rnd_compat_bits),
-		.mode		= 0600,
+		.mode		= 0600 | SYSCTL_FLAG_MIN | SYSCTL_FLAG_MAX,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&mmap_rnd_compat_bits_min,
-		.extra2		= (void *)&mmap_rnd_compat_bits_max,
+		.min		= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN,
+		.max		= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX,
 	},
 #endif
 };
diff --git a/mm/mmap.c b/mm/mmap.c
index d0dfc85b209b..8ed6f0d31d95 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -63,13 +63,9 @@
 #endif
 
 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
-const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
-int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX;
 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
 #endif
 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
-const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
-const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
 #endif
 
-- 
2.25.1