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

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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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Vasily Gorbik 2017-11-19 11:54:14 +01:00 committed by Martin Schwidefsky
parent 135ff16393
commit 5dff03813f
5 changed files with 35 additions and 7 deletions
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1
arch/s390/Kconfig
View File

@ -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

5
arch/s390/include/asm/kasan.h
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@ -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)

4
arch/s390/kernel/setup.c
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@ -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);

13
arch/s390/mm/kasan_init.c
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@ -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));

9
lib/Kconfig.kasan
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@ -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