build: add __page_aligned_data and __page_aligned_bss

Making a variable page-aligned by using
__attribute__((section(".data.page_aligned"))) is fragile because if
sizeof(variable) is not also a multiple of page size, it leaves
variables in the remainder of the section unaligned.

This patch introduces two new qualifiers, __page_aligned_data and
__page_aligned_bss to set the section *and* the alignment of
variables.  This makes page-aligned variables more robust because the
linker will make sure they're aligned properly.  Unfortunately it
requires *all* page-aligned data to use these macros...

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2008-05-28 15:02:14 +01:00 committed by Ingo Molnar
parent 1ecd27657b
commit a7bf0bd5e6
3 changed files with 6 additions and 3 deletions

View file

@ -1,6 +1,7 @@
#ifndef _LINUX_LINKAGE_H
#define _LINUX_LINKAGE_H
#include <linux/compiler.h>
#include <asm/linkage.h>
#ifdef __cplusplus
@ -17,6 +18,9 @@
# define asmregparm
#endif
#define __page_aligned_data __section(.data.page_aligned) __aligned(PAGE_SIZE)
#define __page_aligned_bss __section(.bss.page_aligned) __aligned(PAGE_SIZE)
/*
* This is used by architectures to keep arguments on the stack
* untouched by the compiler by keeping them live until the end.