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Commit 67df197b authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Linus Torvalds
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[PATCH] x86/x86_64: mark rodata section read-only: x86-64 support 



x86-64 specific parts to make the .rodata section read only

Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c728252c

arch/x86_64/Kconfig.debug

+10 −0
Original line number Diff line number Diff line
@@ -9,6 +9,16 @@ config INIT_DEBUG 
	  Fill __init and __initdata at the end of boot. This helps debugging

	  illegal uses of __init and __initdata after initialization.



config DEBUG_RODATA

       bool "Write protect kernel read-only data structures"

       depends on DEBUG_KERNEL

       help

	 Mark the kernel read-only data as write-protected in the pagetables,

	 in order to catch accidental (and incorrect) writes to such const data.

	 This option may have a slight performance impact because a portion

	 of the kernel code won't be covered by a 2MB TLB anymore.

	 If in doubt, say "N".



config IOMMU_DEBUG

       depends on GART_IOMMU && DEBUG_KERNEL

       bool "Enable IOMMU debugging"

arch/x86_64/mm/init.c

+23 −0
Original line number Diff line number Diff line
@@ -498,6 +498,29 @@ void free_initmem(void) 
	printk ("Freeing unused kernel memory: %luk freed\n", (__init_end - __init_begin) >> 10);

}



#ifdef CONFIG_DEBUG_RODATA



extern char __start_rodata, __end_rodata;

void mark_rodata_ro(void)

{

	unsigned long addr = (unsigned long)&__start_rodata;



	for (; addr < (unsigned long)&__end_rodata; addr += PAGE_SIZE)

		change_page_attr_addr(addr, 1, PAGE_KERNEL_RO);



	printk ("Write protecting the kernel read-only data: %luk\n",

			(&__end_rodata - &__start_rodata) >> 10);



	/*

	 * change_page_attr_addr() requires a global_flush_tlb() call after it.

	 * We do this after the printk so that if something went wrong in the

	 * change, the printk gets out at least to give a better debug hint

	 * of who is the culprit.

	 */

	global_flush_tlb();

}

#endif



#ifdef CONFIG_BLK_DEV_INITRD

void free_initrd_mem(unsigned long start, unsigned long end)

{

include/asm-x86_64/cacheflush.h

+4 −0
Original line number Diff line number Diff line
@@ -27,4 +27,8 @@ void global_flush_tlb(void); 
int change_page_attr(struct page *page, int numpages, pgprot_t prot);

int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot);



#ifdef CONFIG_DEBUG_RODATA

void mark_rodata_ro(void);

#endif



#endif /* _X8664_CACHEFLUSH_H */