Commit 5dff0381 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Martin Schwidefsky
Browse files

s390/kasan: add option for 4-level paging support 



By default 3-level paging is used when the kernel is compiled with
kasan support. Add 4-level paging option to support systems with more
then 3TB of physical memory and to cover 4-level paging specific code
with kasan as well.

Reviewed-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 135ff163

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ config ARCH_SUPPORTS_UPROBES 
config KASAN_SHADOW_OFFSET

	hex

	depends on KASAN

	default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING

	default 0x30000000000



config S390

arch/s390/include/asm/kasan.h

+5 −0
Original line number Diff line number Diff line
@@ -7,8 +7,13 @@ 
#ifdef CONFIG_KASAN



#define KASAN_SHADOW_SCALE_SHIFT 3

#ifdef CONFIG_KASAN_S390_4_LEVEL_PAGING

#define KASAN_SHADOW_SIZE						       \

	(_AC(1, UL) << (_REGION1_SHIFT - KASAN_SHADOW_SCALE_SHIFT))

#else

#define KASAN_SHADOW_SIZE						       \

	(_AC(1, UL) << (_REGION2_SHIFT - KASAN_SHADOW_SCALE_SHIFT))

#endif

#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)

#define KASAN_SHADOW_START	KASAN_SHADOW_OFFSET

#define KASAN_SHADOW_END	(KASAN_SHADOW_START + KASAN_SHADOW_SIZE)

arch/s390/kernel/setup.c

+3 −1
Original line number Diff line number Diff line
@@ -535,7 +535,9 @@ static void __init setup_memory_end(void) 
	/* Choose kernel address space layout: 3 or 4 levels. */

	vmalloc_size = VMALLOC_END ?: (128UL << 30) - MODULES_LEN;

	if (IS_ENABLED(CONFIG_KASAN)) {

		vmax = _REGION2_SIZE; /* 3-level kernel page table */

		vmax = IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)

			   ? _REGION1_SIZE

			   : _REGION2_SIZE;

	} else {

		tmp = (memory_end ?: max_physmem_end) / PAGE_SIZE;

		tmp = tmp * (sizeof(struct page) + PAGE_SIZE);

arch/s390/mm/kasan_init.c

+17 −6
Original line number Diff line number Diff line
@@ -252,12 +252,23 @@ void __init kasan_early_init(void) 
		pgt_prot &= ~_PAGE_NOEXEC;

	pte_z = __pte(__pa(kasan_zero_page) | pgt_prot);



	if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {

		/* 4 level paging */

		BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));

		BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));

		crst_table_init((unsigned long *)early_pg_dir,

				_REGION2_ENTRY_EMPTY);

		untracked_mem_end = vmax = _REGION1_SIZE;

		asce_type = _ASCE_TYPE_REGION2;

	} else {

		/* 3 level paging */

		BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));

		BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));

	crst_table_init((unsigned long *)early_pg_dir, _REGION3_ENTRY_EMPTY);

		crst_table_init((unsigned long *)early_pg_dir,

				_REGION3_ENTRY_EMPTY);

		untracked_mem_end = vmax = _REGION2_SIZE;

		asce_type = _ASCE_TYPE_REGION3;

	}



	/* init kasan zero shadow */

	crst_table_init((unsigned long *)kasan_zero_p4d, p4d_val(p4d_z));

lib/Kconfig.kasan

+9 −0
Original line number Diff line number Diff line
@@ -57,6 +57,15 @@ config KASAN_INLINE 


endchoice



config KASAN_S390_4_LEVEL_PAGING

	bool "KASan: use 4-level paging"

	depends on KASAN && S390

	help

	  Compiling the kernel with KASan disables automatic 3-level vs

	  4-level paging selection. 3-level paging is used by default (up

	  to 3TB of RAM with KASan enabled). This options allows to force

	  4-level paging instead.



config TEST_KASAN

	tristate "Module for testing kasan for bug detection"

	depends on m && KASAN

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