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Commit 3eb4db73 authored by Linux Build Service Account's avatar Linux Build Service Account Committed by Gerrit - the friendly Code Review server
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Merge "mm: Mark free pages as read only"

parents d09bc854 a21cc736

arch/arm/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -85,6 +85,18 @@ 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.



# These options are only for real kernel hackers who want to get their hands dirty.

config DEBUG_LL

arch/arm/include/asm/cacheflush.h

+8 −0
Original line number Diff line number Diff line
@@ -462,4 +462,12 @@ 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

mm/debug-pagealloc.c

+10 −0
Original line number Diff line number Diff line
@@ -6,6 +6,14 @@ 
#include <linux/poison.h>

#include <linux/ratelimit.h>



#ifndef mark_addr_rdonly

#define mark_addr_rdonly(a)

#endif



#ifndef mark_addr_rdwrite

#define mark_addr_rdwrite(a)

#endif



static inline void set_page_poison(struct page *page)

{

	__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
@@ -27,6 +35,7 @@ static void poison_page(struct page *page) 


	set_page_poison(page);

	memset(addr, PAGE_POISON, PAGE_SIZE);

	mark_addr_rdonly(addr);

	kunmap_atomic(addr);

}
@@ -82,6 +91,7 @@ static void unpoison_page(struct page *page) 


	addr = kmap_atomic(page);

	check_poison_mem(addr, PAGE_SIZE);

	mark_addr_rdwrite(addr);

	clear_page_poison(page);

	kunmap_atomic(addr);

}