linux-kernel - [PATCH v2 01/15] Add new macros for page-aligned data and bss sections.

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Date:	Tue, 28 Apr 2009 13:00:48 -0400
From:	Tim Abbott <tabbott@....EDU>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>,
	Anders Kaseorg <andersk@....edu>,
	Waseem Daher <wdaher@....edu>,
	Denys Vlasenko <vda.linux@...glemail.com>,
	Jeff Arnold <jbarnold@....edu>,
	Paul Mundt <lethal@...ux-sh.org>,
	David Howells <dhowells@...hat.com>,
	Tim Abbott <tabbott@....edu>, Sam Ravnborg <sam@...nborg.org>
Subject: [PATCH v2 01/15] Add new macros for page-aligned data and bss sections.

This patch is preparation for replacing most uses of
".bss.page_aligned" and ".data.page_aligned" in the kernel with
macros, so that the section name can later be changed without having
to touch a lot of the kernel.

The long-term goal here is to be able to change the kernel's magic
section names to those that are compatible with -ffunction-sections
-fdata-sections.  This requires renaming all magic sections with names
of the form ".data.foo".

Signed-off-by: Tim Abbott <tabbott@....edu>
Cc: Sam Ravnborg <sam@...nborg.org>
---
 include/asm-generic/vmlinux.lds.h |    8 ++++++++
 include/linux/linkage.h           |    9 +++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 89853bc..3d88c87 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -116,6 +116,14 @@
 	FTRACE_EVENTS()							\
 	TRACE_SYSCALLS()
 
+#define PAGE_ALIGNED_DATA						\
+	. = ALIGN(PAGE_SIZE);						\
+	*(.data.page_aligned)
+
+#define PAGE_ALIGNED_BSS						\
+	. = ALIGN(PAGE_SIZE);						\
+	*(.bss.page_aligned)
+
 #define RO_DATA(align)							\
 	. = ALIGN((align));						\
 	.rodata           : AT(ADDR(.rodata) - LOAD_OFFSET) {		\
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index fee9e59..af051fc 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -22,6 +22,15 @@
 #define __page_aligned_bss	__section(.bss.page_aligned) __aligned(PAGE_SIZE)
 
 /*
+ * For assembly routines.
+ *
+ * Note when using these that you must specify the appropriate
+ * alignment directives yourself
+ */
+#define __PAGE_ALIGNED_DATA	.section ".data.page_aligned", "aw", @progbits
+#define __PAGE_ALIGNED_BSS	.section ".bss.page_aligned", "aw", @nobits
+
+/*
  * This is used by architectures to keep arguments on the stack
  * untouched by the compiler by keeping them live until the end.
  * The argument stack may be owned by the assembly-language
-- 
1.6.2.1

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