kernel.h: removed REPEAT_BYTE from kernel.h

This patch creates wordpart.h and includes it in asm/word-at-a-time.h
for all architectures. WORD_AT_A_TIME_CONSTANTS depends on kernel.h
because of REPEAT_BYTE. Moving this to another header and including it
where necessary allows us to not include the bloated kernel.h. Making
this implicit dependency on REPEAT_BYTE explicit allows for later
improvements in the lib/string.c inclusion list.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Tanzir Hasan <tanzirh@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20231226-libstringheader-v6-1-80aa08c7652c@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>

12 files changed, 31 insertions, 17 deletions

diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h
index 352ab213520d..f9a3897b06e7 100644
--- a/arch/arm/include/asm/word-at-a-time.h
+++ b/arch/arm/include/asm/word-at-a-time.h
@@ -8,7 +8,8 @@
  * Little-endian word-at-a-time zero byte handling.
  * Heavily based on the x86 algorithm.
  */
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 
 struct word_at_a_time {
 	const unsigned long one_bits, high_bits;
diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h
index f3b151ed0d7a..14251abee23c 100644
--- a/arch/arm64/include/asm/word-at-a-time.h
+++ b/arch/arm64/include/asm/word-at-a-time.h
@@ -9,7 +9,8 @@
 
 #ifndef __AARCH64EB__
 
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 
 struct word_at_a_time {
 	const unsigned long one_bits, high_bits;
diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
index 30a12d208687..54653a863414 100644
--- a/arch/powerpc/include/asm/word-at-a-time.h
+++ b/arch/powerpc/include/asm/word-at-a-time.h
@@ -4,8 +4,8 @@
 /*
  * Word-at-a-time interfaces for PowerPC.
  */
-
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 #include <asm/asm-compat.h>
 #include <asm/extable.h>
 
diff --git a/arch/riscv/include/asm/word-at-a-time.h b/arch/riscv/include/asm/word-at-a-time.h
index f3f031e34191..3802cda71ab7 100644
--- a/arch/riscv/include/asm/word-at-a-time.h
+++ b/arch/riscv/include/asm/word-at-a-time.h
@@ -10,7 +10,8 @@
 
 
 #include <asm/asm-extable.h>
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 
 struct word_at_a_time {
 	const unsigned long one_bits, high_bits;
diff --git a/arch/s390/include/asm/word-at-a-time.h b/arch/s390/include/asm/word-at-a-time.h
index 2579f1694b82..203acd6e431b 100644
--- a/arch/s390/include/asm/word-at-a-time.h
+++ b/arch/s390/include/asm/word-at-a-time.h
@@ -2,7 +2,8 @@
 #ifndef _ASM_WORD_AT_A_TIME_H
 #define _ASM_WORD_AT_A_TIME_H
 
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 #include <asm/asm-extable.h>
 #include <asm/bitsperlong.h>
 
diff --git a/arch/sh/include/asm/word-at-a-time.h b/arch/sh/include/asm/word-at-a-time.h
index 4aa398455b94..95100ce128d6 100644
--- a/arch/sh/include/asm/word-at-a-time.h
+++ b/arch/sh/include/asm/word-at-a-time.h
@@ -5,6 +5,8 @@
 #ifdef CONFIG_CPU_BIG_ENDIAN
 # include <asm-generic/word-at-a-time.h>
 #else
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 /*
  * Little-endian version cribbed from x86.
  */
diff --git a/arch/x86/include/asm/word-at-a-time.h b/arch/x86/include/asm/word-at-a-time.h
index 46b4f1f7f354..e8d7d4941c4c 100644
--- a/arch/x86/include/asm/word-at-a-time.h
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -2,7 +2,8 @@
 #ifndef _ASM_WORD_AT_A_TIME_H
 #define _ASM_WORD_AT_A_TIME_H
 
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 
 /*
  * This is largely generic for little-endian machines, but the
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 2d6cdeab1f8a..6bb42b4fddb4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -47,6 +47,7 @@
 #include <linux/kern_levels.h>
 #include <linux/kstrtox.h>
 #include <linux/kthread.h>
+#include <linux/wordpart.h>
 
 #include <asm/page.h>
 #include <asm/memtype.h>
diff --git a/fs/namei.c b/fs/namei.c
index 4e0de939fea1..6a548c2c40b9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -17,8 +17,8 @@
 
 #include <linux/init.h>
 #include <linux/export.h>
-#include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/wordpart.h>
 #include <linux/fs.h>
 #include <linux/filelock.h>
 #include <linux/namei.h>
diff --git a/include/asm-generic/word-at-a-time.h b/include/asm-generic/word-at-a-time.h
index 95a1d214108a..ef3f841c6625 100644
--- a/include/asm-generic/word-at-a-time.h
+++ b/include/asm-generic/word-at-a-time.h
@@ -2,7 +2,8 @@
 #ifndef _ASM_WORD_AT_A_TIME_H
 #define _ASM_WORD_AT_A_TIME_H
 
-#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/wordpart.h>
 #include <asm/byteorder.h>
 
 #ifdef __BIG_ENDIAN
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d9ad21058eed..f4a1d582b79d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -39,14 +39,6 @@
 
 #define STACK_MAGIC	0xdeadbeef
 
-/**
- * REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value
- * @x: value to repeat
- *
- * NOTE: @x is not checked for > 0xff; larger values produce odd results.
- */
-#define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
-
 /* generic data direction definitions */
 #define READ			0
 #define WRITE			1
diff --git a/include/linux/wordpart.h b/include/linux/wordpart.h
new file mode 100644
index 000000000000..c9e6bd773ebd
--- /dev/null
+++ b/include/linux/wordpart.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_WORDPART_H
+#define _LINUX_WORDPART_H
+/**
+ * REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value
+ * @x: value to repeat
+ *
+ * NOTE: @x is not checked for > 0xff; larger values produce odd results.
+ */
+#define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
+
+#endif // _LINUX_WORDPART_H