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authorJeremy Fitzhardinge <jeremy@goop.org>2008-05-28 15:02:14 +0100
committerIngo Molnar <mingo@elte.hu>2008-07-08 12:48:13 +0200
commita7bf0bd5e6af7fe69342dabf2a3b721f0163469a (patch)
tree3f7e08f0df4c5eccf81732dcf95b8cc4efafa203
parent1ecd27657b735128a728ebf0c31fce5e1456718a (diff)
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>
-rw-r--r--arch/x86/kernel/setup64.c2
-rw-r--r--arch/x86/mm/ioremap.c3
-rw-r--r--include/linux/linkage.h4
3 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/setup64.c b/arch/x86/kernel/setup64.c
index 631ea6cc01d..fc1a56da824 100644
--- a/arch/x86/kernel/setup64.c
+++ b/arch/x86/kernel/setup64.c
@@ -40,7 +40,7 @@ EXPORT_SYMBOL(_cpu_pda);
struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };
-char boot_cpu_stack[IRQSTACKSIZE] __attribute__((section(".bss.page_aligned")));
+char boot_cpu_stack[IRQSTACKSIZE] __page_aligned_bss;
unsigned long __supported_pte_mask __read_mostly = ~0UL;
EXPORT_SYMBOL_GPL(__supported_pte_mask);
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 416ea415f5c..0561fde56a5 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -394,8 +394,7 @@ static int __init early_ioremap_debug_setup(char *str)
early_param("early_ioremap_debug", early_ioremap_debug_setup);
static __initdata int after_paging_init;
-static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)]
- __section(.bss.page_aligned);
+static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
{
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index 2119610b24f..9fd1f859021 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -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.