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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 2458625..cc83135 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -59,6 +59,7 @@
config KASAN_SHADOW_OFFSET
hex
depends on KASAN
+ default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING
default 0x30000000000
config S390
diff --git a/arch/s390/include/asm/kasan.h b/arch/s390/include/asm/kasan.h
index 8b9ae18..70930fe 100644
--- a/arch/s390/include/asm/kasan.h
+++ b/arch/s390/include/asm/kasan.h
@@ -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)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index d754880..4b2039f 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -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);
diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c
index 40748af..5129847 100644
--- a/arch/s390/mm/kasan_init.c
+++ b/arch/s390/mm/kasan_init.c
@@ -252,12 +252,23 @@ void __init kasan_early_init(void)
pgt_prot &= ~_PAGE_NOEXEC;
pte_z = __pte(__pa(kasan_zero_page) | pgt_prot);
- /* 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);
- untracked_mem_end = vmax = _REGION2_SIZE;
- asce_type = _ASCE_TYPE_REGION3;
+ 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);
+ 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));
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index befb127..d0bad1b 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -57,6 +57,15 @@
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
