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Commit 5112be8e authored by Neeti Desai's avatar Neeti Desai
Browse files

arm64: Add support for FREE_PAGES_RDONLY 



Add config option to trigger page a fault if any
code attempts to write to a page on the buddy list

Change-Id: Ic5ab791c4117606519c7b9eb4c2876f246d23320
Signed-off-by: default avatarNeeti Desai <neetid@codeaurora.org>
parent b74ddb13

arch/arm64/Kconfig.debug

+13 −0
Original line number Diff line number Diff line
@@ -44,4 +44,17 @@ config FORCE_PAGES 


          If unsure say N.



config FREE_PAGES_RDONLY

        bool "Set pages as read only while on the buddy list"

        select FORCE_PAGES

        select PAGE_POISONING

        help

          Pages are always mapped in the kernel. This means that anyone

          can write to the page if they have the address. Enable this option

          to mark pages as read only to trigger a fault if any code attempts

          to write to a page on the buddy list. This may have a performance

          impact.



          If unsure, say N.



endmenu

arch/arm64/include/asm/cacheflush.h

+8 −0
Original line number Diff line number Diff line
@@ -169,4 +169,12 @@ int set_memory_ro(unsigned long addr, int numpages); 
int set_memory_rw(unsigned long addr, int numpages);

int set_memory_x(unsigned long addr, int numpages);

int set_memory_nx(unsigned long addr, int numpages);



#ifdef CONFIG_FREE_PAGES_RDONLY

#define mark_addr_rdonly(a)	set_memory_ro((unsigned long)a, 1);

#define mark_addr_rdwrite(a)	set_memory_rw((unsigned long)a, 1);

#else

#define mark_addr_rdonly(a)

#define mark_addr_rdwrite(a)

#endif

#endif

arch/arm64/mm/pageattr.c

+6 −4
Original line number Diff line number Diff line
@@ -66,11 +66,13 @@ static int change_memory_common(unsigned long addr, int numpages, 
	unsigned long end = start + size;

	int ret;



	if (!IS_ENABLED(CONFIG_FORCE_PAGES)) {

		if (start < MODULES_VADDR || start >= MODULES_END)

			return -EINVAL;



		if (end < MODULES_VADDR || end >= MODULES_END)

			return -EINVAL;

	}



	if (set)

		ret = apply_to_page_range(&init_mm, start, size,