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Commit 6a11f75b authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

generic debug pagealloc 



CONFIG_DEBUG_PAGEALLOC is now supported by x86, powerpc, sparc64, and
s390.  This patch implements it for the rest of the architectures by
filling the pages with poison byte patterns after free_pages() and
verifying the poison patterns before alloc_pages().

This generic one cannot detect invalid page accesses immediately but
invalid read access may cause invalid dereference by poisoned memory and
invalid write access can be detected after a long delay.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 610a77e0

arch/avr32/mm/fault.c

+0 −18
Original line number Diff line number Diff line
@@ -250,21 +250,3 @@ asmlinkage void do_bus_error(unsigned long addr, int write_access, 
	dump_dtlb();

	die("Bus Error", regs, SIGKILL);

}
 


/*

 * This functionality is currently not possible to implement because

 * we're using segmentation to ensure a fixed mapping of the kernel

 * virtual address space.

 *

 * It would be possible to implement this, but it would require us to

 * disable segmentation at startup and load the kernel mappings into

 * the TLB like any other pages. There will be lots of trickery to

 * avoid recursive invocation of the TLB miss handler, though...

 */

#ifdef CONFIG_DEBUG_PAGEALLOC

void kernel_map_pages(struct page *page, int numpages, int enable)

{



}

EXPORT_SYMBOL(kernel_map_pages);

#endif

arch/powerpc/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -228,6 +228,9 @@ config PPC_OF_PLATFORM_PCI 
	depends on PPC64 # not supported on 32 bits yet

	default n



config ARCH_SUPPORTS_DEBUG_PAGEALLOC

	def_bool y



source "init/Kconfig"



source "kernel/Kconfig.freezer"

arch/powerpc/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ config DEBUG_STACK_USAGE 
config DEBUG_PAGEALLOC

        bool "Debug page memory allocations"

        depends on DEBUG_KERNEL && !HIBERNATION

	depends on ARCH_SUPPORTS_DEBUG_PAGEALLOC

        help

          Unmap pages from the kernel linear mapping after free_pages().

          This results in a large slowdown, but helps to find certain types

arch/s390/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -72,6 +72,9 @@ config PGSTE 
config VIRT_CPU_ACCOUNTING

	def_bool y



config ARCH_SUPPORTS_DEBUG_PAGEALLOC

	def_bool y



mainmenu "Linux Kernel Configuration"



config S390

arch/s390/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ source "lib/Kconfig.debug" 
config DEBUG_PAGEALLOC

	bool "Debug page memory allocations"

	depends on DEBUG_KERNEL

	depends on ARCH_SUPPORTS_DEBUG_PAGEALLOC

	help

	  Unmap pages from the kernel linear mapping after free_pages().

	  This results in a slowdown, but helps to find certain types of